WO2016017858A1 - Palladium nanodendrite-graphene nanohybrid based hydrogen sensor and method for manufacturing same - Google Patents

Palladium nanodendrite-graphene nanohybrid based hydrogen sensor and method for manufacturing same Download PDF

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WO2016017858A1
WO2016017858A1 PCT/KR2014/010104 KR2014010104W WO2016017858A1 WO 2016017858 A1 WO2016017858 A1 WO 2016017858A1 KR 2014010104 W KR2014010104 W KR 2014010104W WO 2016017858 A1 WO2016017858 A1 WO 2016017858A1
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palladium
graphene
nanodendrite
hydrogen
hydrogen sensor
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French (fr)
Korean (ko)
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정귀상
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울산대학교 산학협력단
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82B—NANOSTRUCTURES FORMED BY MANIPULATION OF INDIVIDUAL ATOMS, MOLECULES, OR LIMITED COLLECTIONS OF ATOMS OR MOLECULES AS DISCRETE UNITS; MANUFACTURE OR TREATMENT THEREOF
    • B82B3/00—Manufacture or treatment of nanostructures by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units

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  • the present invention relates to a palladium nanodendrite-graphene nanohybrid-based hydrogen sensor and a method for manufacturing the same, in detail, palladium used as a catalyst for the detection of hydrogen (H 2 ) synthesized by the reduction ratio of Pd precursor salt in CTAB environment (Pd) palladium nanodendrite-graphene nanohybrid-based hydrogen sensor by mixing nanodendrite and graphene oxide, making a hydrogen sensor with a hybrid formed of palladium (Pd) nanodendrite wrapped with graphene It relates to a manufacturing method.
  • Hydrogen (H 2 ) is a highly flammable gas and burns well at low concentrations of 4% in air.
  • combustible gases such as gasoline, propane, ethane, methane and propylene
  • hydrogen has a larger flammability range (4-75%).
  • hydrogen is the lightest component and the smallest molecule and therefore has the greatest tendency for leakage.
  • an improved hydrogen sensor is indispensable for many applications that require stability in some areas where there is a risk of hydrogen leakage and the presence of hydrogen even at traces of ppm.
  • Hydrogen sensors with high sensitivity, low detection limits (trace ppm), good selectivity, repeatability and stability at room temperature (RT) are generally preferred due to their simple and low cost in the sensor apparatus.
  • Palladium catalysts are not only very low cost but also have a high hydrogen absorption capacity compared to platinum catalysts. Therefore, palladium is the most popular for hydrogen detection materials, hydrogen storage, fuel cells and catalyst systems.
  • palladium catalysts are widely used to enhance hydrogen sensor properties.
  • silicon carbide is a porous matrix, aluminum oxide, etc., or a variety of palladium nanocrystals (cubes, cages, octahedrons, tetrahedrons, peppers to palladium nano-rods / -wires).
  • the palladium expands in volume by a small proportion and the palladium hybrid (PdH x ) during hydrogen absorption / desorption This can easily cause structural instability and hysteresis in the sensor.
  • the dense palladium nanoparticle catalyst has a lower surface area for hydrogen absorption / desorption due to its smaller surface active area and little internal space for volume expansion.
  • porous palladium nanoparticles can overcome this limitation, which can easily expand in volume during hydrogen absorption / desorption, and furthermore, in the palladium dendrite structure, these internal small holes allow deep hydrogen molecules to penetrate inside the palladium material. And increase the contact area between the palladium and hydrogen molecules, increasing the sensitivity of the hydrogen sensor.
  • the interesting palladium dendrite structures have many advantages such as hydrogen storage, fuel cell and catalyst due to their high area to volume ratio. Despite being studied in applications, the hydrogen sensing properties of palladium dendrites have been rarely reported before.
  • the present invention has been made to improve the above-mentioned problems, and the object of the present invention is to synthesize a new Pd nanodendrite-graphene hybrid for hydrogen (H 2 ) detection, Pd nanodendrite in a CTAB environment
  • the Pd nanodendrite is applied as a hydrogen (H 2 ) gas detection catalyst by synthesizing by the reduction ratio of the Pd precursor salt and wrapped with graphene to improve the sensitivity and selectivity, thereby increasing the hydrogen detection range even at low temperatures. It is to provide a dendrite-graphene nanohybrid-based hydrogen sensor and a method of manufacturing the same.
  • the palladium nanodendrite-graphene nanohybrid-based hydrogen sensor of the present invention uses graphene (Gr) to use palladium (Pd) nanodendrite as a catalyst for hydrogen (H 2 ) detection.
  • Gr graphene
  • the palladium (Pd) nanodendrite is a combination of spherical palladium nanoparticles having porous nano-pores, it is preferable that the colloidal nanodendrite of 60 ⁇ 70nm size.
  • the hydrogen (H 2 ) detection range of the hydrogen sensor is 1 ⁇ 1000ppm
  • the working temperature of the hydrogen sensor is preferably from room temperature (RT) to 50 °C.
  • cetyltrimethylammonium bromide is preferably injected into the mixture solution through a micropipette within several seconds.
  • the reducing agent is preferably 65% by weight of reducing agent hydrate (N 2 H 4 .H 2 O).
  • the ohmic (Ohmic) contact layer is a metal mask and the RF film deposition It is preferable to form by.
  • the hydrogen sensor based on palladium nanodendrite wrapped with graphene has a high reaction value of 25% and 1000 ppm hydrogen (H even at room temperature). 2 ) with very good repeatability.
  • the palladium nanodendrite-graphene nanohybrid-based hydrogen sensor of the present invention has the effect of having several times higher response value and faster reaction / recovery time than the conventional hydrogen sensor.
  • 2 is a TEM image of a palladium dendrite-graphene hybrid at various magnifications.
  • FIG. 5 shows UV-Vis spectra of palladium nanocrystals with different shapes of palladium dentite and palladium cubes.
  • FIG. 6 shows the reactivity of Pd nanodendrite-graphene hybrid with 1000 ppm H 2 at different temperatures (a) and repeatability at room temperature (b), 50 ° C. (c) and 100 ° C. (d).
  • FIG. 7 shows the reactivity (a) of the Pd nanodendrite-graphene hybrid with various hydrogen (H 2 ) concentrations, the detection limit of the sensor at 50 ° C. (b) and the selectivity of the hydrogen (H 2 ) sensor at room temperature (c).
  • FIG. 8 is a comparison of the hydrogen (H 2 ) sensing properties of graphene palladium dendrite-graphene with palladium NPs-graphene complex and palladium cube-graphene hybrid, where (a) is 1000 ppm at room temperature in one cycle, (b) is the effect of working temperature on the reactivity and reaction value (S) for various hydrogen (H 2 ) concentrations at room temperature (c)
  • the palladium nanodendrite-graphene nanohybrid-based hydrogen sensor and its manufacturing method according to the present invention will be described in detail as follows.
  • the resulting palladium dendrites were centrifuged at 10,000 rpm and re-diffused in deionized water (DI) five times to remove excess reactants from the solution. Finally, palladium nanodendrite was re-diffused in deionized water (DI) as a palladium suspension.
  • DI deionized water
  • Graphene oxide was prepared from the finest pure graphite powder (Merck, 99.99%, particle size 50 m or less) according to the Hummers method.
  • the palladium dendrite-graphene hybrid is similarly used in the previous invention with a palladium dendrite and graphene oxide (GO) suspension using a reducing agent hydrate (N 2 H 4 .H 2 O, Sigma-Aldrich, 65% by weight).
  • a reducing agent hydrate N 2 H 4 .H 2 O, Sigma-Aldrich, 65% by weight.
  • the resulting stable suspension of palladium nanodendrite-graphene hybrid is black and was used to make resistivity sensors.
  • the palladium nanodendrite-graphene hybrid was coated on a SiO 2 / Si substrate via airbrush injection (Hansa 381, N 2 as carrier gas) with 5 ml of a suspension of palladium nanodendrite-graphene hybrid. I was.
  • the hydrogen sensor manufacturing process is similar to our previous invention.
  • both pure Pd dendrites and Pd dendrite-graphene hybrids were used to make hydrogen sensors.
  • the basic steps are as follows: Pure Pd dendrites or Pd dendrites-graphene hybrids were coated on SiO 2 / Si substrates via air-brush injection (Hansa 381, N 2 as carrier gas) with a suspension of 5 ml or more.
  • the SiO 2 / Si matrix sensor chip was divided into several pieces with a fixed size of 0.5 ⁇ 1 cm 2.
  • the substrates Prior to spraying pure Pd dendrites or Pd dendrites-graphene hybrids onto SiO 2 / Si substrates, the substrates were washed in an ultrasonic bath of DI water and acetone.
  • the SiO 2 / Si matrix was heated to 200 ° C. on a hotplate while spraying.
  • Two ohmic contact layers were prepared for plating gold (Au) on the surface of Pd dendrites-Gr / SiO 2 / Si through a metal mask and RF sputtering (150 W, 7 mTorr working pressure); The diameter of the contact layer is 1 mm and the distance between the two contacts is 0.9 cm.
  • UV-Vis spectrometer HP 8453
  • the sensor was installed inside a chamber in an enclosed environment, and the Keithley probe station (SCS-4200) recorded the sensor's resistance value with a bias voltage fixed at 1V.
  • a computer-based mass flow controller (ATOVAC, GMC 1200) system was used to vary the concentration of hydrogen in synthetic air (Dukyang, Inc.) gas
  • the gas mixture was 50 standard cubic centimeters per minute (sccm) with distinct hydrogen concentrations.
  • the gas chamber was fed with synthetic air between each hydrogen pulse to allow the sensor's surface to return to atmospheric pressure. It became angry.
  • FIG. 1 shows the successful synthesis of palladium nanodendrite by easy and fast reduction ratio of metal precursor (PdCl 4 2- ) in CTAB environment.
  • Palladium nano dendrites are very constant with a size of 60-70 nm and are well distinguished as shown in Fig. 1 (a, b).
  • Palladium nanodendrite (such as porous palladium nanospheres) has many nano-pores as a result of a combination of tiny palladium nanoparticles in a spherical form.
  • TEM analysis was performed on the palladium dendrites-graphene hybrid.
  • 2 shows TEM images of palladium dendrites-graphene hybrids at various magnifications. These are many nano-pores that are alternately provided with palladium branches in palladium dendrites nanoparticles.
  • the TEM analysis results in the present invention are the same as those disclosed in the previous palladium dendrites structure.
  • HRTEM high resolution TEM
  • the intensity ratio between (111) and (200) diffraction (I (111) / I (200) ) is 1.16 and 0.33 for palladium dendrite-graphene and palladium cube-graphene hybrids, respectively.
  • This intensity ratio (I (111) / I (200) ) was smaller than that of 1.61 in the palladium NPs (former) -graphene composite, with the palladium dendrite plane consisting mainly of the (111) plane and the palladium NPs ( It still points to a lower crystallinity than that of the sphere) -graphene complex.
  • Low crystalline properties in palladium dendrites were confirmed by the poor intensity of the XRD peak, as shown in FIG. 4.
  • the degradation in the crystal quality of palladium dendrites compared to the palladium cubes can be observed in the UV-Vis spectrum as shown in FIG. 5.
  • the palladium nanocube particles had a Plasmon peak at 378 nm, widening from 378 nm to 426 nm and red-shifting in palladium dendrites.
  • the plasmon peak density of the UV-Vis spectrum of metal nanoparticles depends on the size and shape of the particles. Additionally, when the palladium shape changed from a low symmetrical cube to a high symmetrical sphere (palladium dendrite), the shoulder echo disappeared at 250 nm with weak reflection (weak dipole) and UV-Vis absorption spectrum at 229 nm. .
  • Figure 6 shows the effect of working temperature on the hydrogen sensing performance of the palladium dendrite-graphene hybrid.
  • hydrogen sensors exhibited increased resistance after exposure to hydrogen gas and reduced reaction values, reaction / recovery times with increasing operating temperature.
  • the sensor response S is defined as the following Equation 1 as a ratio of the resistance change of the resistivity sensor at a fixed bias voltage (1V) by exposure of hydrogen gas.
  • R a is the resistance of the sensor in the presence of synthetic air alone
  • R g is the resistance in the presence of hydrogen at a constant concentration.
  • the reaction values (S) of the hydrogen sensor with 1000 ppm hydrogen are 25.7%, 17.5% and 4.4% at room temperature, 50 ° C and 100 ° C, respectively.
  • palladium dendrites-graphene have two and three times higher sensitivity than previous studies on palladium NPs-graphene complexes and palladium cube-graphene hybrids, respectively.
  • FIG. 6 shows the response of a resistive hydrogen sensor based on a palladium dendrite-graphene hybrid to different operating temperatures in one test cycle with 1000 ppm hydrogen.
  • the dynamic absorption / desorption hydrogen gas molecules in palladium catalysts are similar to palladium NPs and palladium cubes, with high sensitivity at low temperatures (but slow reaction time of hydrogen molecules in palladium NPs, long diffusion lengths) and opposite at high temperatures.
  • B, c, d shows the repeatability of a hydrogen sensor based on palladium dendrite-graphene hybrids in three cycles with 1000 ppm hydrogen at various temperatures. As shown in Fig.
  • the hydrogen sensor had a good repeatability at room temperature and 50 ° C, and did not show good repeatability at 100 ° C as shown in Fig. 6 (d).
  • the sensing mechanism of palladium-graphene based hydrogen sensing has been described in the previous invention.
  • Palladium absorbs hydrogen molecules and transforms them into PdH x (which simultaneously expands the volume of palladium by a few percent), having a lower working function than pure palladium materials, and then a palladium dendrite-graphene hybrid Increasing the resistance at, encourages free electrons in palladium to move to graphene (a reduced number of holes in p-type graphene). Drift at the baseline of the sensor signal was observed during the hydrogen uptake / desorption process in the previous invention for the palladium NPs-graphene complex and palladium cube-graphene hybrid at room temperature.
  • FIG. 7A shows good linearity of the palladium dendrite-graphene sample following exposure to various hydrogen concentrations ranging from 1000 ppm to 1 ppm at a typical temperature of 50 ° C.
  • FIG. 7A shows good linearity of the palladium dendrite-graphene sample following exposure to various hydrogen concentrations ranging from 1000 ppm to 1 ppm at a typical temperature of 50 ° C.
  • FIG. 7A shows good linearity of the palladium dendrites-graphene hybrids have good linearity at working temperatures from room temperature to 100 ° C.
  • the limit of detection (LOD) of the hydrogen sensor is 1 ppm. Thanks to the good linearity, the low noise level and high sensitivity of graphene in the palladium dendrite-graphene hybrid ensures that the hydrogen sensor reliably responds even at low hydrogen concentrations (1-10 ppm), as shown in FIG. can do.
  • LOD limit of detection
  • Fig. 7 (b) shows the positive reaction with different hydrogen concentrations of 1.6 ppm and 10 ppm at a working temperature of 50 ° C. Palladium dendrite-graphene is compared with various oxidizing gases (NO 2 , O 2 ), reducing gas (CO x ) and hydrocarbon gas (C 2 H 2 ) at room temperature, as shown in Figure 7 (c). Shows good selectivity for hydrogen gas being produced.
  • NO 2 , O 2 oxidizing gases
  • CO x reducing gas
  • C 2 H 2 hydrocarbon gas
  • FIG. 8 shows a comparison of the hydrogen sensing properties of palladium dendrites-graphene hybrids with previous inventions for palladium NPs-graphene complexes and palladium cube-graphene hybrids.
  • the reaction value of the hydrogen sensor with 1000 ppm hydrogen at room temperature was 25.7% for the palladium dendrite-graphene hybrid, the palladium cube-graphene hybrid and the palladium NPs-graphene composite, respectively. 12.9% and 7%.
  • reaction / recovery times were 18/40 and 1.5 / 14 minutes for the palladium cube-graphene hybrid and palladium NPs-graphene, respectively.
  • hydrogen sensors based on palladium dendrite-graphene hybrids exhibited high sensitivity as well as fast reaction / recovery times at full range hydrogen concentrations of 1-1000 ppm, as shown in FIG.
  • the palladium dendrite-graphene sample shows lower stability at higher temperatures (100 ° C.) compared to the palladium cube-graphene hybrid and palladium NPs-graphene composite, as shown in FIG. 8 (c). gave.
  • the hydrogen sensor showed a rapid decrease in reaction with increasing temperature from room temperature to 100 ° C.
  • the palladium dendrite-graphene hybrid rapidly reduced its reaction value by increasing the working temperature from room temperature to 100 ° C. by 82% (to 1000 ppm).
  • Pd nano dendrites with a very uniform size of 60-70 nm were synthesized by an easy and fast reaction process of Pd precursor in CTAB environment and then used as a hydrogen (H 2 ) catalyst in hybrid formation with graphene.
  • the hydrogen (H 2 ) sensor based on the Pd dentite graphene hybrid has a high response of 25% and very good repeatability with 1000 ppm hydrogen (H 2 ) even at room temperature.
  • the sensor showed good linearity with a hydrogen (H 2 ) concentration range of 1 to 1000 ppm and a solid response at low concentrations of 1 to 10 ppm with a working temperature of 50 ° C.
  • Pd dendrites graphene hybrids have the weakness of degradation in large reactions at high temperatures (100 ° C.), It has several times higher response values as well as faster reaction / recovery times.
  • the high volume to area ratio and high porosity of the Pd dendrites have demonstrated better results for hydrogen (H 2 ) sensors based on Pd graphene composites / hybrids.
  • the present invention can be usefully used as a hydrogen sensor having a high reaction value of 25% and very good repeatability with 1000 ppm hydrogen (H 2 ) even at room temperature.

Abstract

The present invention relates to a palladium (Pd) nanodendrite-graphene nanohybrid based hydrogen sensor and a method for manufacturing the same. In the present invention, palladium (Pd) nanodendrites (porous Pd nanoshperes) were synthesized by an easy one-stage chemical pathway through a fast reaction process of a Pd precursor salt. Here, in the one-stage reaction, very uniform colloidal Pd dendrites with a size of 60-70 nm were simply reduced to graphene flakes by hydrazine (a reducing agent) in order to form a Pd dendrite graphene hybrid. A resistor type sensor used together with the Pd dendrite graphene had good linearity at room temperature and a detectable range of 1000 ppm to 1 ppm. Furthermore, the hydrogen (H2) sensor can show a distinctly different reaction even in the low hydrogen (H2) concentration range of 1 ppm to 10 ppm at a low work temperature of room temperature below 50°C. When compared with our previous invention with respect to the H2 detection on the basis of Pd graphene composite/hybrid, a novel Pd dendrite graphene hybrid has several advantages, such as a higher reaction value, favorable reproducibility, fast reaction/recovering time, and less hysteresis at a low work temperature, excluding a disadvantage, such as the deterioration in the reaction at a high temperature (100°C). From calculation results of hydrogen (H2) sensing, these advantages result from a high ratio of volume over area and a high porosity of the Pd dendrite nanostructure.

Description

팔라듐 나노덴드라이트-그래핀 나노하이브리드 기반 수소센서 및 그 제조방법Palladium nanodendrite-graphene nanohybrid-based hydrogen sensor and method of manufacturing the same
본 발명은 팔라듐 나노덴드라이트―그래핀 나노하이브리드 기반 수소센서 및 그 제조방법에 관한 것으로서, 상세히는 CTAB 환경에서 Pd 전구체 염의 환원비율에 의해 합성된 수소(H2) 탐지를 위한 촉매로 사용하는 팔라듐(Pd) 나노덴드라이트와 그래핀 산화물을 혼합하여, 그래핀으로 감싸여 지지된 팔라듐(Pd) 나노덴드라이트로 형성한 하이브리드로 수소센서를 만드는 팔라듐 나노덴드라이트―그래핀 나노하이브리드 기반 수소센서 및 그 제조방법에 관한 것이다.The present invention relates to a palladium nanodendrite-graphene nanohybrid-based hydrogen sensor and a method for manufacturing the same, in detail, palladium used as a catalyst for the detection of hydrogen (H 2 ) synthesized by the reduction ratio of Pd precursor salt in CTAB environment (Pd) palladium nanodendrite-graphene nanohybrid-based hydrogen sensor by mixing nanodendrite and graphene oxide, making a hydrogen sensor with a hybrid formed of palladium (Pd) nanodendrite wrapped with graphene It relates to a manufacturing method.
수소(H2)는 매우 가연성이 있는 가스이고 공기 중에서 4%의 낮은 농도에서도 잘 연소한다. 가솔린, 프로판, 에탄, 메탄 및 프로필렌과 같은 가연성의 가스 중에서 수소는 더 큰 가연 범위(4-75%)를 갖는다. 더욱이, 수소는 가장 가벼운 성분이고 가장 작은 분자이므로 누설에 가장 큰 경향을 갖는다. 따라서, 개선된 수소센서는 미량의 ppm에서조차 수소의 존재와 수소 누설의 위험이 있는 어떤 분야에서 안정성을 요구하기 위한 많은 응용을 위해서 불가결이다. 실온(RT)에서 높은 감도, 낮은 탐지 한계(미량의 ppm), 좋은 선택성, 반복성 및 안정성과 함께 수소센서는 센서 기구에서 간단하고 저비용에 기인하여 일반적으로 바람직하다. 나노입자, 나노-튜브/나노-와이어의 다양한 형태로 백금(Pt) 또는 팔라듐(Pd)을 포함하고 있는 귀금속 촉매와 다른 재료가 함께하는 복합체는 낮은 온도에서조차 수소 탐지에 대한 좋은 해결책으로 제시되었다. 팔라듐 촉매는 아주 저비용일 뿐만 아니라 백금 촉매와 비교하여 높은 수소 흡수 능력이 있다. 그러므로, 팔라듐은 수소 탐지 재료, 수소 저장, 연료전지 및 촉매 시스템에 대해서 가장 인기가 있다.Hydrogen (H 2 ) is a highly flammable gas and burns well at low concentrations of 4% in air. Among combustible gases such as gasoline, propane, ethane, methane and propylene, hydrogen has a larger flammability range (4-75%). Moreover, hydrogen is the lightest component and the smallest molecule and therefore has the greatest tendency for leakage. Thus, an improved hydrogen sensor is indispensable for many applications that require stability in some areas where there is a risk of hydrogen leakage and the presence of hydrogen even at traces of ppm. Hydrogen sensors with high sensitivity, low detection limits (trace ppm), good selectivity, repeatability and stability at room temperature (RT) are generally preferred due to their simple and low cost in the sensor apparatus. Complexes with precious metal catalysts containing platinum (Pt) or palladium (Pd) in various forms of nanoparticles, nano-tubes / nano-wires and other materials have been proposed as a good solution for hydrogen detection even at low temperatures. Palladium catalysts are not only very low cost but also have a high hydrogen absorption capacity compared to platinum catalysts. Therefore, palladium is the most popular for hydrogen detection materials, hydrogen storage, fuel cells and catalyst systems.
수소 센싱에 대한 우수한 촉매로써, 팔라듐 촉매는 수소 센서 성질을 강화하기 위해 폭 넓게 이용되고 있다. 팔라듐 촉매에 기반을 둔 수소 센싱을 개선하기 위해, 본 발명자는 실리콘 탄화물로서 다공성 기지, 산화알루미늄 등, 또는 다양한 팔라듐 나노결정(큐브, 케이지, 8면체, 사면체, 양추부터 팔라듐 나노-봉/-와이어/-튜브까지 변화된 팔라듐 촉매 구조를 이용하여 지지된 팔라듐 촉매 재료의 표면적을 강화하는 것에 초점을 두었다. 팔라듐은 미량의 비율에 의해 부피적으로 확장하고, 수소 흡수/탈착 동안에 팔라듐 하이브리드(PdHx)를 형성한다; 이것은 쉽게 센서에 구조적인 불안정성과 히스테리시스의 원인이 될 수 있다. 조밀한 팔라듐 나노입자 촉매는 보다 작은 표면 활동 면적과 부피 팽창에 대한 내부 공간이 조금도 없기 때문에 수소 흡수/탈착에 대해 낮은 내구성을 갖는다. 반대로, 많은 내부의 작은 구멍들과 함께 다공성 팔라듐 나노입자(팔라듐 덴드라이트)는 수소 흡수/탈착 동안에 쉽게 부피적으로 팽창시킬 수 있는 이러한 한계점을 극복할 수 있다. 더욱이, 팔라듐 덴드라이트 구조에서 이러한 내부의 작은 구멍들은 팔라듐 재료 내부에 깊게 수소 분자가 뚫고 들어가는 것을 허용하고 팔라듐과 수소 분자 사이에서 접촉 면적을 강화하는데, 이때 수소 센서에 감도를 점점 높게 한다. 관심을 끄는 팔라듐 덴드라이트 구조가 그들의 높은 면적 대비 부피 비율에 기인하여 수소 저장, 연료전지 및 촉매와 같은 많은 응용분야에서 연구되고 있음에도 불구하고, 팔라듐 덴드라이트의 수소 센싱 성질은 이전에 좀처럼 보고된 바가 없다.As an excellent catalyst for hydrogen sensing, palladium catalysts are widely used to enhance hydrogen sensor properties. In order to improve hydrogen sensing based on palladium catalysts, the present inventors have found that silicon carbide is a porous matrix, aluminum oxide, etc., or a variety of palladium nanocrystals (cubes, cages, octahedrons, tetrahedrons, peppers to palladium nano-rods / -wires). Focusing on enhancing the surface area of the supported palladium catalyst material using a palladium catalyst structure varied up to / -tube, the palladium expands in volume by a small proportion and the palladium hybrid (PdH x ) during hydrogen absorption / desorption This can easily cause structural instability and hysteresis in the sensor.The dense palladium nanoparticle catalyst has a lower surface area for hydrogen absorption / desorption due to its smaller surface active area and little internal space for volume expansion. Conversely, porous palladium nanoparticles (palladium) with many internal small holes Dendrite) can overcome this limitation, which can easily expand in volume during hydrogen absorption / desorption, and furthermore, in the palladium dendrite structure, these internal small holes allow deep hydrogen molecules to penetrate inside the palladium material. And increase the contact area between the palladium and hydrogen molecules, increasing the sensitivity of the hydrogen sensor.The interesting palladium dendrite structures have many advantages such as hydrogen storage, fuel cell and catalyst due to their high area to volume ratio. Despite being studied in applications, the hydrogen sensing properties of palladium dendrites have been rarely reported before.
지지된 팔라듐 재료의 관점에서, 탄소 기반 재료(탄소 나노튜브와 근래에 그래핀처럼)는 탁월한 기계적/전기적인 성질, 높은 장식적인 표면적 및 좋은 안정성의 면에서 가장 인기가 있다. 오늘날, 탄소 재료의 이차원적인 그래핀은 금속 촉매를 지지하기 위한 탁월한 성질을 보여주고 있다. 본 발명자의 이전 발명에서, 발명자는 팔라듐 나노입자-그패핀(Pd NPs-Gr) 복합체와 팔라듐 나노큐브-그래핀(Pd cube-Gr) 하이브리드를 준비하였고 그리고 나서 비저항 기반 수소 센서에 대한 센싱 재료로 응용하였다. 본 발명자의 이전 실험결과로부터, 이들 복합체/하이브리드는 낮은 탐지 한계 수준(미량의 ppm)과 함께 낮은 온도에서 수소 탐지의 개선을 보여준다. 그러나, 이것들은 매우 느린 반응시간과 히스테리시스 거동(센서 신호의 기본선에서 드리프트)의 단점이 남아있었다. 본 발명에서 우리는 수소 탐지를 위한 새로운 팔라듐 나노덴드라이트-그래핀(Pd dendrite-Gr) 하이브리드를 합성하였고 연구하였다. 게다가, 팔라듐 덴드라이트-그래핀 하이브리드의 수소 센싱 성질은 Pd NPs-Gr 복합체와 Pd 큐브-Gr 하이브리드에 대한 이전의 발명와 함께 평가되고 비교되었다.In terms of supported palladium materials, carbon-based materials (like carbon nanotubes and nowadays graphene) are most popular in terms of excellent mechanical / electrical properties, high decorative surface area and good stability. Today, two-dimensional graphene of carbon materials shows excellent properties for supporting metal catalysts. In the inventor's previous invention, the inventor prepared a palladium nanocube-graphene (Pd NPs-Gr) composite and a palladium nanocube-graphene (Pd cube-Gr) hybrid and then used it as a sensing material for the resistivity-based hydrogen sensor. Applied. From our previous experiments, these complexes / hybrids show an improvement in hydrogen detection at low temperatures with low detection limit levels (trace ppm). However, these remained the disadvantages of very slow response time and hysteresis behavior (drift in the baseline of the sensor signal). In the present invention, we have synthesized and studied a new palladium nanodendrite-graphene (Pd dendrite-Gr) hybrid for hydrogen detection. In addition, the hydrogen sensing properties of the palladium dendrite-graphene hybrid were evaluated and compared with previous inventions for the Pd NPs-Gr complex and the Pd cube-Gr hybrid.
본 발명은 상기한 바와 같은 제반 문제점을 개선하기 위해 안출된 것으로서, 그 목적은 수소(H2) 탐지를 위한 새로운 Pd 나노덴드라이트-그래핀 하이브리드를 합성한 것으로서, Pd 나노덴드라이트는 CTAB 환경에서 Pd 전구체 염의 환원비율에 의해 합성되고 그래핀으로 감싸여 지지하도록 함으로써, 상기 Pd 나노덴드라이트가 수소(H2) 가스 탐지 촉매로 적용되어 감도 및 선택성이 좋아져 낮은 온도에서도 수소 탐지 범위가 넓어진 팔라듐 나노덴드라이트―그래핀 나노하이브리드 기반 수소센서 및 그 제조방법을 제공함에 있다.The present invention has been made to improve the above-mentioned problems, and the object of the present invention is to synthesize a new Pd nanodendrite-graphene hybrid for hydrogen (H 2 ) detection, Pd nanodendrite in a CTAB environment The Pd nanodendrite is applied as a hydrogen (H 2 ) gas detection catalyst by synthesizing by the reduction ratio of the Pd precursor salt and wrapped with graphene to improve the sensitivity and selectivity, thereby increasing the hydrogen detection range even at low temperatures. It is to provide a dendrite-graphene nanohybrid-based hydrogen sensor and a method of manufacturing the same.
상기한 바와 같은 목적을 달성하기 위해 본 발명의 팔라듐 나노덴드라이트―그래핀 나노하이브리드 기반 수소센서는, 팔라듐(Pd) 나노덴드라이트를 수소(H2) 탐지를 위한 촉매로 사용하도록 그래핀(Gr)과 CTAB 환경에서 Pd 전구체 염의 환원비율에 의해 합성된 상기 팔라듐(Pd) 나노덴드라이트를 혼합하여 생성한 것으로, 그래핀(Gr) 플레이크에 부착된 개별적인 많은 팔라듐(Pd) 덴드라이트로 형성한 하이브리드로 만든 수소(H2)센서인 것을 특징으로 하고 있다.In order to achieve the above object, the palladium nanodendrite-graphene nanohybrid-based hydrogen sensor of the present invention uses graphene (Gr) to use palladium (Pd) nanodendrite as a catalyst for hydrogen (H 2 ) detection. ) Is a hybrid of palladium (Pd) dendrites formed by mixing the palladium (Pd) nano dendrites synthesized by the reduction ratio of Pd precursor salts in the CTAB environment and attached to graphene (Gr) flakes. It is characterized in that the hydrogen (H 2 ) sensor made of.
또 상기 팔라듐(Pd) 나노덴드라이트는 다공성 나노-세공을 갖는 구 형태의 팔라듐 나노입자의 조합체이며, 60∼70㎚ 크기의 콜로이드성의 나노덴드라이트인 것이 바람직하다.In addition, the palladium (Pd) nanodendrite is a combination of spherical palladium nanoparticles having porous nano-pores, it is preferable that the colloidal nanodendrite of 60 ~ 70nm size.
또 상기 수소센서의 수소(H2) 탐지 범위는 1∼1000ppm이며, 상기 수소센서의 작업 온도는 실온(RT)에서부터 50℃까지인 것이 바람직하다.In addition, the hydrogen (H 2 ) detection range of the hydrogen sensor is 1 ~ 1000ppm, the working temperature of the hydrogen sensor is preferably from room temperature (RT) to 50 ℃.
또 상기한 수소센서의 제조방법에 있어서, 일정 농도의 4염화칼륨팔라듐(K2PdCl4)과 아스코르브(ascorbic)산 용액을 이온제거수(DI)와 함께 첨가하여 교반하고, 시차를 두고 세틸트리메틸암모늄브롬화물(CTAB)에 첨가하여 교반함으로써 혼합물 용액을 준비하는 단계; 상기 단계에 의해 준비된 혼합물 용액을 원심분리하고 초과 반응물을 제거하기 위해 이온제거수(DI)에서 여러 번 확산한 후, 팔라듐 현탁액으로 이온제거수(DI)에서 재확산하여 팔라듐(Pd) 나노덴드라이트 용액을 합성하는 단계; 순수 그라파이트 분말로 준비되는 그래핀 산화물(GO) 수용액에 상기 팔라듐(Pd) 나노덴드라이트 용액을 첨가여 교반한 후, 환원제를 추가로 첨가하여 실온보다 더 높은 온도에서 교반하여, 팔라듐(Pd) 나노덴드라이트―그래핀 하이브리드의 혼합물을 형성하는 단계; 상기 환원제의 첨가에 의해 환원된 팔라듐(Pd) 나노덴드라이트―그래핀 하이브리드의 혼합물을 현탁액으로 하여 분사에 의해 SiO2/Si 기지에 피복시키는 단계; 및 상기 혼합물을 피복시키는 단계에 의해 형성된 Pd 덴드라이트-Gr/SiO2/Si 기지의 표면에 귀금속을 도금하여 오믹(Ohmic) 접촉층을 형성하는 단계;를 포함하여 수소센서를 제조하는 것을 특징으로 하고 있다.In the above-described method of manufacturing a hydrogen sensor, a constant concentration of potassium palladium tetrachloride (K 2 PdCl 4 ) and ascorbic acid solution is added together with deionized water (DI) and stirred, followed by cetyltrimethylammonium. Preparing a mixture solution by adding to a bromide (CTAB) and stirring; The mixture solution prepared by the above step was centrifuged and diffused several times in deionized water (DI) to remove excess reactant, followed by re-diffusion in deionized water (DI) with palladium suspension and palladium (Pd) nanodendrite Synthesizing a solution; The palladium (Pd) nanodendrite solution was added to the graphene oxide (GO) aqueous solution prepared as pure graphite powder, followed by stirring, followed by addition of a reducing agent, followed by stirring at a temperature higher than room temperature. Forming a mixture of dendrites-graphene hybrids; Coating the mixture of palladium (Pd) nanodendrite-graphene hybrids reduced by the addition of the reducing agent as a suspension to the SiO 2 / Si matrix by spraying; And forming an ohmic contact layer by plating a noble metal on the surface of the Pd dendrite-Gr / SiO 2 / Si matrix formed by coating the mixture. Doing.
또 상기 혼합물 용액을 준비하는 단계에서 세틸트리메틸암모늄브롬화물(CTAB)은 수초 내에 마이크로 피펫을 통하여 혼합물 용액에 주입하는 것이 바람직하다.In addition, in preparing the mixture solution, cetyltrimethylammonium bromide (CTAB) is preferably injected into the mixture solution through a micropipette within several seconds.
또 상기 환원제는 65중량%의 환원제 수화물(N2H4.H2O)인 것이 바람직하다.In addition, the reducing agent is preferably 65% by weight of reducing agent hydrate (N 2 H 4 .H 2 O).
또 상기 SiO2/Si 기지에 팔라듐(Pd) 나노덴드라이트―그래핀 복합체를 분사할 때 SiO2/Si 기지를 일정온도로 가열하며, 상기 오믹(Ohmic) 접촉층은 금속마스크와 RF 박막증착에 의해 형성하는 것이 바람직하다.Further palladium (Pd) nano dendrites on the SiO 2 / Si base-yes when ejecting pin composite and heating the SiO 2 / Si base at a constant temperature, the ohmic (Ohmic) contact layer is a metal mask and the RF film deposition It is preferable to form by.
본 발명의 팔라듐 나노덴드라이트―그래핀 나노하이브리드 기반 수소센서 및 그 제조방법에 의하면, 그래핀으로 감싼 팔라듐 나노덴드라이트에 기반을 둔 수소센서는 25%의 높은 반응값과 실온에서조차 1000ppm 수소(H2)와 함께 매우 좋은 반복성을 갖는 효과가 있다.According to the palladium nanodendrite-graphene nanohybrid-based hydrogen sensor of the present invention and a manufacturing method thereof, the hydrogen sensor based on palladium nanodendrite wrapped with graphene has a high reaction value of 25% and 1000 ppm hydrogen (H even at room temperature). 2 ) with very good repeatability.
또 1ppm에서 1000ppm까지의 수소 농도 범위로 좋은 선형성과 를 넓은 범위에서 탐지할 수 있고, 50℃의 작업온도로 1∼10ppm의 낮은 농도에서 확실한 반응을 보여주는 효과가 있다.In addition, it is possible to detect good linearity with a wide range of hydrogen concentrations from 1ppm to 1000ppm, and shows a positive response at a low concentration of 1-10ppm at a working temperature of 50 ° C.
본 발명의 팔라듐 나노덴드라이트―그래핀 나노하이브리드 기반 수소센서는 종래 수소센서보다 몇 배의 높은 반응값과 빠른 반응/회복시간을 갖는 효과가 있다.The palladium nanodendrite-graphene nanohybrid-based hydrogen sensor of the present invention has the effect of having several times higher response value and faster reaction / recovery time than the conventional hydrogen sensor.
도 1의 순수 팔라듐 덴드라이트와 팔라듐 덴드라이트-그래핀 하이브리드의 SEM 이미지로, (a)와 (c)는 저배율 이미지, (b)와 (d)는 고배율 이미지SEM image of the pure palladium dendrites and palladium dendrite-graphene hybrid of FIG. 1, wherein (a) and (c) are low magnification images, and (b) and (d) are high magnification images
도 2는 다양한 배율에서 팔라듐 덴드라이트-그래핀 하이브리드의 TEM 이미지2 is a TEM image of a palladium dendrite-graphene hybrid at various magnifications.
도 3은 팔라듐 덴드라이트-그래핀 하이브리드의 HRTEM 이미지3 is an HRTEM image of a palladium dendrite-graphene hybrid
도 4는 팔라듐 덴드라이트-그래핀과 팔라듐 큐브-그래핀 하이브리드의 XRD 패턴 비교4 is an XRD pattern comparison of palladium dendrites-graphene and palladium cube-graphene hybrids.
도 5는 팔라듐 덴트라이트와 팔라듐 큐브의 서로 다른 형상과 함께 팔라듐 나노결정의 UV-Vis 스펙트럼FIG. 5 shows UV-Vis spectra of palladium nanocrystals with different shapes of palladium dentite and palladium cubes.
도 6은 서로 다른 온도(a)에서 1000ppm H2와 함께 Pd 나노덴드라이트-그래핀 하이브리드의 반응성과 실온(b), 50℃(c) 및 100℃(d)에서의 반복성FIG. 6 shows the reactivity of Pd nanodendrite-graphene hybrid with 1000 ppm H 2 at different temperatures (a) and repeatability at room temperature (b), 50 ° C. (c) and 100 ° C. (d).
도 7은 다양한 수소(H2) 농도와 함께 Pd 나노덴드라이트-그래핀 하이브리드의 반응성(a)과 50℃에서 센서의 탐지 한계(b) 및 실온에서 수소(H2) 센서의 선택성(c)FIG. 7 shows the reactivity (a) of the Pd nanodendrite-graphene hybrid with various hydrogen (H 2 ) concentrations, the detection limit of the sensor at 50 ° C. (b) and the selectivity of the hydrogen (H 2 ) sensor at room temperature (c).
도 8은 팔라듐 NPs-그래핀 복합체 및 팔라듐 큐브-그래핀 하이브리드와 함께 그래핀팔라듐 덴드라이트-그래핀의 수소(H2) 센싱 성질의 비교로, (a)는 실온에서 1000ppm으로 하나의 사이클, (b)는 실온에서 다양한 수소(H2) 농도에 따른 반응성 및 반응값(S)에 대한 작업온도의 영향(c)FIG. 8 is a comparison of the hydrogen (H 2 ) sensing properties of graphene palladium dendrite-graphene with palladium NPs-graphene complex and palladium cube-graphene hybrid, where (a) is 1000 ppm at room temperature in one cycle, (b) is the effect of working temperature on the reactivity and reaction value (S) for various hydrogen (H 2 ) concentrations at room temperature (c)
이하, 본 발명에 따른 팔라듐 나노덴드라이트―그래핀 나노하이브리드 기반 수소센서 및 그 제조방법의 바람직한 실시예를 첨부한 도면을 참조로 하여 상세히 설명한다. 본 발명은 이하에서 개시되는 실시예에 한정되는 것이 아니라 서로 다른 다양한 형태로 구현될 수 있으며, 단지 본 실시예는 본 발명의 개시가 완전하도록 하며 통상의 지식을 가진 자에게 발명의 범주를 완전하게 알려주기 위하여 제공되는 것이다.Hereinafter, a preferred embodiment of the palladium nanodendrite-graphene nanohybrid-based hydrogen sensor and a method for manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, only this embodiment to make the disclosure of the present invention complete and to those skilled in the art to fully understand the scope of the invention It is provided to inform you.
본 발명에 따른 팔라듐 나노덴드라이트―그래핀 나노하이브리드 기반 수소센서 및 그 제조방법을 다음과 같이 구체적으로 설명하도록 한다.The palladium nanodendrite-graphene nanohybrid-based hydrogen sensor and its manufacturing method according to the present invention will be described in detail as follows.
먼저 본 발명에 따른 수소센서의 제조를 실험과정을 통해 설명하면 다음과 같다.First, the production of the hydrogen sensor according to the present invention will be described through an experimental procedure.
1.실험1. Experiment
1-1. 팔라듐 나노덴드라이트의 합성1-1. Synthesis of Palladium Nanodendrite
본 발명의 실험에서, 간단하게 5Mm의 4염화칼륨팔라듐(K2PdCl4:팔라듐 전구체 염, Sigma-Aldrich) 수용액 1㎖가 47㎖의 이온제거수(DI)에 교반과 함께 첨가되었다. 이때 새롭게 준비된 100Mm의 아스코르브 산(ascorbic acid) 수용액 1㎖는 강한 교반과 함께 혼합 용액에 첨가되었다. 30초 후, 30Mm의 세틸 트리메틸암모늄 브로마이드(CTAB, Sigma-Aldrich) 1㎖는 수초 내에 마이크로 피펫을 통하여 반응 혼합물에 주입되었고, 용액은 15분 동안 교반되었다. 결과적인 팔라듐 덴드라이트는 10,000rpm으로 원심분리 되었고 용액에서 초과 반응물을 제거하기 위해 다섯 번 이온제거수(DI)에서 재확산하였다. 마지막으로, 팔라듐 나노덴드라이트는 팔라듐 현탁액으로 이온제거수(DI)에서 재확산되었다.In the experiments of the present invention, simply 1 ml of 5 mM potassium palladium tetrachloride (K 2 PdCl 4 : palladium precursor salt, Sigma-Aldrich) aqueous solution was added to 47 ml of deionized water (DI) with stirring. At this time, 1 mL of a newly prepared 100 Mm ascorbic acid aqueous solution was added to the mixed solution with vigorous stirring. After 30 seconds, 1 ml of 30 Mm cetyl trimethylammonium bromide (CTAB, Sigma-Aldrich) was injected into the reaction mixture via a micropipette in a few seconds and the solution was stirred for 15 minutes. The resulting palladium dendrites were centrifuged at 10,000 rpm and re-diffused in deionized water (DI) five times to remove excess reactants from the solution. Finally, palladium nanodendrite was re-diffused in deionized water (DI) as a palladium suspension.
1.2 팔라듐 나노덴드라이트-그래핀 하이브리드의 합성1.2 Synthesis of Palladium Nanodendrite-Graphene Hybrid
그래핀 산화물(GO)은 허머스(Hummers) 방법에 따라 최고로 좋은 순수한 그라파이트 분말(Merck, 99.99%, 입자 사이즈 50 m 이하)로 준비되었다. 팔라듐 덴드라이트-그래핀 하이브리드는 이전의 발명에서와 같이 유사하게 환원제 수화물(N2H4.H2O, Sigma-Aldrich, 65중량%)을 이용하여 팔라듐 덴드라이트와 그래핀 산화물(GO) 현탁액으로부터 준비되었다. 팔라듐 나노덴드라이트-그래핀 하이브리드의 결과적인 안정적인 현탁액은 검은색이고, 비저항 센서를 제조하기 위해 사용되었다. 수소 센서 샘플 제조에서, 팔라듐 나노덴드라이트-그래핀 하이브리드는 팔라듐 나노덴드라이트-그래핀 하이브리드의 현탁액 5㎖로 에어 브러시 분사(Hansa 381, 운반가스로서 N2)를 통해 SiO2/Si 기지에 피복시켰다. 수소 센서 제조공정은 우리의 이전 발명과 유사하다.Graphene oxide (GO) was prepared from the finest pure graphite powder (Merck, 99.99%, particle size 50 m or less) according to the Hummers method. The palladium dendrite-graphene hybrid is similarly used in the previous invention with a palladium dendrite and graphene oxide (GO) suspension using a reducing agent hydrate (N 2 H 4 .H 2 O, Sigma-Aldrich, 65% by weight). Was prepared from. The resulting stable suspension of palladium nanodendrite-graphene hybrid is black and was used to make resistivity sensors. In the hydrogen sensor sample preparation, the palladium nanodendrite-graphene hybrid was coated on a SiO 2 / Si substrate via airbrush injection (Hansa 381, N 2 as carrier gas) with 5 ml of a suspension of palladium nanodendrite-graphene hybrid. I was. The hydrogen sensor manufacturing process is similar to our previous invention.
즉 수소(H2) 탐지의 비교를 위해, 순수 Pd 덴드라이트 용액과 Pd 덴드라이트-그래핀 하이브리드 양쪽은 수소센서를 만들기 위해 사용되었다. 기본적인 단계는 다음과 같다: 순수 Pd 덴드라이트 또는 Pd 덴드라이트-그래핀 하이브리드는 5㎖ 이상 현탁액으로 에어-브러시 분사(Hansa 381, 운반가스로써 N2)를 통하여 SiO2/Si 기지에 피복되었다. SiO2/Si 기지 센서 칩은 0.5×1㎠의 고정된 크기로 몇 가지 조각으로 분할되었다. SiO2/Si 기지 상에 순수 Pd 덴드라이트 또는 Pd 덴드라이트-그래핀 하이브리드를 분사하기 전에, 기지는 DI수와 아세톤의 초음파 배스에서 세척되었다. SiO2/Si 기지는 분사하는 동안 열판 상에서 200℃로 가열되었다. 2개의 오믹(Ohmic) 접촉층은 금속마스크와 RF 스퍼터링(150W, 7mTorr 작업압력)을 통하여 Pd 덴드라이트-Gr/SiO2/Si의 표면에 금(Au)을 도금하는 것에 제조되었다; 접촉층의 직경은 1mm이고, 2개의 접촉 사이의 거리는 0.9㎝이다.For comparison of hydrogen (H 2 ) detection, both pure Pd dendrites and Pd dendrite-graphene hybrids were used to make hydrogen sensors. The basic steps are as follows: Pure Pd dendrites or Pd dendrites-graphene hybrids were coated on SiO 2 / Si substrates via air-brush injection (Hansa 381, N 2 as carrier gas) with a suspension of 5 ml or more. The SiO 2 / Si matrix sensor chip was divided into several pieces with a fixed size of 0.5 × 1 cm 2. Prior to spraying pure Pd dendrites or Pd dendrites-graphene hybrids onto SiO 2 / Si substrates, the substrates were washed in an ultrasonic bath of DI water and acetone. The SiO 2 / Si matrix was heated to 200 ° C. on a hotplate while spraying. Two ohmic contact layers were prepared for plating gold (Au) on the surface of Pd dendrites-Gr / SiO 2 / Si through a metal mask and RF sputtering (150 W, 7 mTorr working pressure); The diameter of the contact layer is 1 mm and the distance between the two contacts is 0.9 cm.
팔라듐 나노덴드라이트-그래핀 하이브리드의 표면적은 JSM-6500F 전계방출 주사전자현미경(FE-SEM)을 이용하여 특징이 나타나게 되었다. 팔라듐 나노덴드라이트-그래핀 하이브리드의 투과전자현미경(TEM)과 고해상도 TEM (HRTEM) 이미지는 초고해상도 방사 전자현미경(JEOL JEM-2100F)을 이용하여 표시하였다. 팔라듐 나노덴드라이트-그래핀 하이브리드의 결정라인 특징은 CuK 1 방사선(1.5406Å으로 Rigaku 회절계를 이용하는 X-선 회절(XRD)을 이용하여 조사되었다. 팔라듐 나노결정의 흡수 스펙트럼은 λmax=664nm에서 UV-Vis 분광측정기(HP 8453) 에 의해 조사되었다. 센서는 둘러 싸여진 환경의 챔버 내부에 설치되었고, 1V로 고정된 바이어스 전압과 함께 Keithley 프로브 스테이션(SCS-4200)은 센서의 저항 값을 기록하였다. 컴퓨터를 이용한 질량 유량 제어기(ATOVAC, GMC 1200) 시스템은 합성 공기(덕양 주식회사) 가스에서 수소의 농도를 변화시키는 것에 사용되었다. 가스 혼합물은 별개의 수소 농도와 함께 분당 50 표준 큐빅 센치미터(sccm)의 일정한 흐름비율로 전달되었다. 가스 챔버는 센서의 표면을 대기압 조건으로 되돌려 허용하기 위해 각 수소 펄스 사이에서 합성 공기로 정화되었다.The surface area of the palladium nanodendrite-graphene hybrid was characterized using a JSM-6500F field emission scanning electron microscope (FE-SEM). Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) images of the palladium nanodendrite-graphene hybrid were displayed using an ultra-high resolution electron microscopy (JEOL JEM-2100F). Crystalline characterization of the palladium nanodendrite-graphene hybrid was investigated using X-ray diffraction (XRD) using a RiKaku diffractometer with CuK 1 radiation (1.5406 Hz.) The absorption spectrum of the palladium nanocrystals was measured at λ max = 664 nm. Irradiated by a UV-Vis spectrometer (HP 8453) The sensor was installed inside a chamber in an enclosed environment, and the Keithley probe station (SCS-4200) recorded the sensor's resistance value with a bias voltage fixed at 1V. A computer-based mass flow controller (ATOVAC, GMC 1200) system was used to vary the concentration of hydrogen in synthetic air (Dukyang, Inc.) gas The gas mixture was 50 standard cubic centimeters per minute (sccm) with distinct hydrogen concentrations. The gas chamber was fed with synthetic air between each hydrogen pulse to allow the sensor's surface to return to atmospheric pressure. It became angry.
2. 결과 및 토의2. Results and discussion
도 1은 CTAB 환경에서 금속 전구체(PdCl4 2-)의 손쉽고 빠른 환원비율에 의해 팔라듐 나노덴드라이트의 성공적인 합성을 보여준다. 팔라듐 나노덴드라이트는 60~70㎚의 크기로 매우 일정하고, 도 1(a, b)에서 보는 바와 같이 잘 구별된다. 팔라듐 나노덴드라이트(다공성 팔라듐 나노구와 같은)는 구와 같은 형태로 아주 작은 팔라듐 나노입자의 조합체의 결과로 많은 나노-세공을 갖고 있다. 안정제로서 CTAB의 존재에서 환원제와 같은 아스코르브 산과 함께 K2PdCl4의 팔라듐 전구체 염을 사용하였던 팔라듐 나노큐브의 합성에 대한 이전의 발명과 비교하여, 동일한 이들 화학 작용제는 다른 점에서는 이상적인 실험조건 하에서 환원제와 계면활성체의 주입 순서를 바로 변화하는 것에 의해 팔라듐 나노덴드라이트를 합성하는 것에 이용되었다. 팔라듐 나노큐브의 합성에서, CTAB는 아스코르브 산보다 먼저 주입되었고, 환원비율은 느렸고 팔라듐 큐브 모양의 형성을 초래하였다. 반대로, 본 발명에서 팔라듐 나노덴드라이트의 합성은, 아스코르브 산이 CTAB보다 먼저 주입되었는데 팔라듐의 전구체의 빠른 환원비율을 야기하였다. 팔라듐 이온의 빠른 환원비율 때문에, 반응의 초기 상태에서 더 작은 크기와 함께 많은 양의 시드가 될 것이고, 이어서 빠른 덴드라이트 입자의 성장을 초래하고 있다. 이 설명은 이전에 공개된 연구와 동일하다. 팔라듐 덴드라이트-그래핀 하이브리드의 합성에서, 그래핀 산화물(GO)의 환원제로서 히드라진(hydrazine)은 그래핀 산화물 면에 부착된 산소 기능적인 그룹을 제거할 것이고, 그들을 팔라듐 덴드라이트로 대체할 것이다. 그래핀 상에 장식된 결과적인 팔라듐 덴드라이트는 도 1(c, d)에서 보는 바와 같이, 그래핀 플레이크에 부착된 개별적인 많은 팔라듐 덴드라이트와 함께 하이브리드를 형성하였다.FIG. 1 shows the successful synthesis of palladium nanodendrite by easy and fast reduction ratio of metal precursor (PdCl 4 2- ) in CTAB environment. Palladium nano dendrites are very constant with a size of 60-70 nm and are well distinguished as shown in Fig. 1 (a, b). Palladium nanodendrite (such as porous palladium nanospheres) has many nano-pores as a result of a combination of tiny palladium nanoparticles in a spherical form. Compared to previous inventions for the synthesis of palladium nanocubes, which used a palladium precursor salt of K 2 PdCl 4 together with ascorbic acid as the reducing agent in the presence of CTAB as stabilizer, these same chemical agents differ in other respects under ideal experimental conditions. It was used to synthesize palladium nano dendrites by directly changing the order of implantation of and surfactants. In the synthesis of palladium nanocubes, CTAB was injected prior to ascorbic acid, the reduction rate was slow and resulted in the formation of palladium cube shapes. In contrast, the synthesis of palladium nanodendrite in the present invention resulted in a rapid reduction of the precursor of palladium when ascorbic acid was injected before CTAB. Due to the fast reduction rate of the palladium ions, there will be a large amount of seed with smaller size in the initial state of the reaction, which then leads to the rapid growth of dendrites. This description is identical to the previously published study. In the synthesis of palladium dendrite-graphene hybrids, hydrazine as a reducing agent of graphene oxide (GO) will remove oxygen functional groups attached to the graphene oxide side and replace them with palladium dendrites. The resulting palladium dendrites decorated on graphene formed a hybrid with many individual palladium dendrites attached to the graphene flakes, as shown in FIG. 1 (c, d).
팔라듐 덴드라이트의 나노-세공의 존재를 확인하기 위하여, TEM 분석이 팔라듐 덴드라이트-그래핀 하이브리드에 수행되었다. 도 2는 다양한 배율로 팔라듐 덴드라이트-그래핀 하이브리드의 TEM 이미지를 보여준다. 이것들은 팔라듐 덴드라이트 나노입자에서 교대로 팔라듐 가지가 제공된 많은 나노-세공이다. 본 발명에서 TEM 분석 결과는 이전의 팔라듐 덴드라이트 구조에서 공개한 것과 동일하다. 도 3에서 보는 바와 같이, 팔라듐 덴드라이트의 고해상도 TEM(HRTEM) 이미지는 주기가 없는 것과 함께 많은 가장자리 지대를 포함하였는데, 팔라듐 덴드라이트 나노입자의 결정라인 네트워크에서 다량이고 다평면을 가리킨다.To confirm the presence of nano-pores of palladium dendrites, TEM analysis was performed on the palladium dendrites-graphene hybrid. 2 shows TEM images of palladium dendrites-graphene hybrids at various magnifications. These are many nano-pores that are alternately provided with palladium branches in palladium dendrites nanoparticles. The TEM analysis results in the present invention are the same as those disclosed in the previous palladium dendrites structure. As seen in FIG. 3, high resolution TEM (HRTEM) images of palladium dendrites, including periods, included many edge zones, indicating a large and multiplanar plane in the crystalline network of palladium dendrites nanoparticles.
도 4는 팔라듐 덴드라이트-그래핀과 이전의 팔라듐 큐브-그래핀 하이브리드를 비교한 것을 보여준다. (200) 평면에 따라 선택적으로 성장을 하였던 팔라듐 나노큐브와 차이로, 팔라듐 덴드라이트는 팔라듐(111)의 바람직한 결정라인 평면을 가졌다. 도 4에서 XRD 패턴으로부터, 잘 알려진 피크는 회절 데이터에 대한 국제센터(JCPDS 01-087-0645)에 의해 표시되는 바와 같이, 팔라듐의 (111)과 (200) 면 반사에 대응되는 2θ=40.08°와 46.64°에서 각각 관찰되었다. (111)과 (200) 회절(I(111)/I(200)) 사이에 강도비율은 팔라듐 덴드라이트-그래핀과 팔라듐 큐브-그래핀 하이브리드에 대해 각각 1.16과 0.33이다. 이 강도비율(I(111)/I(200))은 팔라듐 NPs(구)-그래핀 복합체에서 1.61의 그것보다 더 작았는데, 팔라듐 덴드라이트의 면이 (111) 면으로 주로 구성되었고 팔라듐 NPs(구)-그래핀 복합체의 그것보다 여전히 더 낮은 결정화도를 가리키고 있다. 팔라듐 덴드라이트에서 낮은 결정라인 성질은 도 4에서 보는 바와 같이, XRD 피크의 빈약한 강도에 의해 확인하였다. 팔라듐 덴드라이트를 만들기 위한 빠른 환원 공정은 팔라듐 결정에서 "물리적인 결함"으로 알려진 바와 같이 많은 나노-세공을 만들었는데, 상기한 SEM과 TEM 분석 결과와 일치한다. 팔라듐 덴드라이트에서 빈약한 결정라인은 팔라듐 전구체에서 빠른 환원비율, 팔라듐 핵의 형성 및 신속하게 덴드라이트 입자의 성장을 위한 조합체에 대해서 설명하였다. 4 shows a comparison of palladium dendrites-graphene and previous palladium cube-graphene hybrids. In contrast to the palladium nanocube, which had selectively grown along the (200) plane, palladium dendrites had a preferred crystalline plane of palladium (111). From the XRD pattern in FIG. 4, the well-known peak is 2θ = 40.08 ° corresponding to the (111) and (200) plane reflections of palladium, as indicated by the International Center for Diffraction Data (JCPDS 01-087-0645). And at 46.64 °, respectively. The intensity ratio between (111) and (200) diffraction (I (111) / I (200) ) is 1.16 and 0.33 for palladium dendrite-graphene and palladium cube-graphene hybrids, respectively. This intensity ratio (I (111) / I (200) ) was smaller than that of 1.61 in the palladium NPs (former) -graphene composite, with the palladium dendrite plane consisting mainly of the (111) plane and the palladium NPs ( It still points to a lower crystallinity than that of the sphere) -graphene complex. Low crystalline properties in palladium dendrites were confirmed by the poor intensity of the XRD peak, as shown in FIG. 4. The rapid reduction process for making palladium dendrites produced many nano-pores, known as "physical defects" in palladium crystals, consistent with the SEM and TEM analysis results described above. Poor crystal lines in palladium dendrites have described combinations for fast reduction rates in palladium precursors, formation of palladium nuclei and rapid growth of dendrites.
팔라듐 큐브와 비교하는 팔라듐 덴드라이트의 결정 품질에서 저하는 도 5에서 보는 바와 같이 UV-Vis 스펙트럼에서 관찰될 수 있다. 팔라듐 나노큐브 입자는 378㎚에서 플라즈몬(Plasmon) 피크를 갖는데, 팔라듐 덴드라이트에서는 378㎚에서 426㎚까지 넓혀졌고 적색-이동이였다. 금속 나노입자의 UV-Vis 스펙트럼의 플라즈몬 피크 밀도는 입자의 크기와 모양에 의존한다. 부가적으로, 팔라듐 모양이 낮은 대칭의 큐브에서 높은 대칭의 구(팔라듐 덴드라이트)까지 변화하였을 때, 229㎚에서 약한 반향(약한 쌍극자)과 UV-Vis 흡수 스펙트럼으로 250㎚에서 숄더 반향이 사라졌다.The degradation in the crystal quality of palladium dendrites compared to the palladium cubes can be observed in the UV-Vis spectrum as shown in FIG. 5. The palladium nanocube particles had a Plasmon peak at 378 nm, widening from 378 nm to 426 nm and red-shifting in palladium dendrites. The plasmon peak density of the UV-Vis spectrum of metal nanoparticles depends on the size and shape of the particles. Additionally, when the palladium shape changed from a low symmetrical cube to a high symmetrical sphere (palladium dendrite), the shoulder echo disappeared at 250 nm with weak reflection (weak dipole) and UV-Vis absorption spectrum at 229 nm. .
도 6은 팔라듐 덴드라이트-그래핀 하이브리드의 수소 센싱 수행능력에 대한 작업온도의 효과를 보여준다. 일반적으로, 수소 센서는 수소 가스에 노출 후에 증가된 저항을 나타내었고 작업온도의 증가와 함께 반응 값, 반응/회복 시간을 감소시켰다. 센서 반응(S)은 수소 가스의 노출에 의해 고정된 바이어스 전압(1V)에서 비저항 센서의 저항변화의 비율로서 다음의 수학식 1과 같이 정의되었다.Figure 6 shows the effect of working temperature on the hydrogen sensing performance of the palladium dendrite-graphene hybrid. In general, hydrogen sensors exhibited increased resistance after exposure to hydrogen gas and reduced reaction values, reaction / recovery times with increasing operating temperature. The sensor response S is defined as the following Equation 1 as a ratio of the resistance change of the resistivity sensor at a fixed bias voltage (1V) by exposure of hydrogen gas.
수학식 1
Figure PCTKR2014010104-appb-M000001
 Equation 1
Figure PCTKR2014010104-appb-M000001
여기서 Ra는 합성 공기만의 존재에서 센서의 저항이고, Rg는 일정한 농도로 수소의 존재에서 저항이다. 1000ppm 수소와 함께 수소 센서의 반응 값(S)은 각각 실온, 50℃ 및 100℃에서 25.7%, 17.5% 및 4.4%이다. 실온에서 센서 반응과 비교하여, 팔라듐 덴드라이트-그래핀은 팔라듐 NPs-그래핀 복합체와 팔라듐 큐브-그래핀 하이브리드에 대한 이전의 연구보다 각각 2배와 3배의 더 높은 감도를 갖는다.Where R a is the resistance of the sensor in the presence of synthetic air alone, and R g is the resistance in the presence of hydrogen at a constant concentration. The reaction values (S) of the hydrogen sensor with 1000 ppm hydrogen are 25.7%, 17.5% and 4.4% at room temperature, 50 ° C and 100 ° C, respectively. Compared to sensor response at room temperature, palladium dendrites-graphene have two and three times higher sensitivity than previous studies on palladium NPs-graphene complexes and palladium cube-graphene hybrids, respectively.
도 6의 (a)는 1000ppm수소와 함께 하나의 시험 사이클에서 서로 다른 작업온도에 대한 팔라듐 덴드라이트-그래핀 하이브리드에 기반을 둔 비저항 수소 센서의 반응을 보여준다. 팔라듐 촉매에서 동적인 흡수/탈착 수소 가스 분자들은 팔라듐 NPs와 팔라듐 큐브와 유사하고, 낮은 온도에서 높은 감도(그러나 팔라듐 NPs에서 수소 분자의 느린 반응 시간, 확산 길이는 길다)이고 높은 온도에서는 반대이다. 도 6의 (b, c, d)는 다양한 온도에서 1000ppm 수소와 함께 3번의 사이클로 팔라듐 덴드라이트-그래핀 하이브리드에 기반을 둔 수소 센서의 반복성을 보여준다. 수소 센서는 도 6의 (b, c)에 도시한 바와 같이, 실온과 50℃에서 바람직한 반복성을 갖고 도 6의 (d)에 도시한 바와 같이, 100℃에서 좋은 반복성을 나타내지 않았다. 팔라듐-그래핀에 기반을 둔 수소 센싱의 센싱 메커니즘은 이전의 발명에서 설명되었다. 6 (a) shows the response of a resistive hydrogen sensor based on a palladium dendrite-graphene hybrid to different operating temperatures in one test cycle with 1000 ppm hydrogen. The dynamic absorption / desorption hydrogen gas molecules in palladium catalysts are similar to palladium NPs and palladium cubes, with high sensitivity at low temperatures (but slow reaction time of hydrogen molecules in palladium NPs, long diffusion lengths) and opposite at high temperatures. (B, c, d) of FIG. 6 shows the repeatability of a hydrogen sensor based on palladium dendrite-graphene hybrids in three cycles with 1000 ppm hydrogen at various temperatures. As shown in Fig. 6 (b, c), the hydrogen sensor had a good repeatability at room temperature and 50 ° C, and did not show good repeatability at 100 ° C as shown in Fig. 6 (d). The sensing mechanism of palladium-graphene based hydrogen sensing has been described in the previous invention.
팔라듐은 수소 분자를 흡수하고 그것들을 PdHx(몇 퍼센트에 의해 팔라듐의 부피를 동시에 확장하고 있는)로 변화시키는데, 순수한 팔라듐 재료보다 더 낮은 작업 기능을 가지고 있고, 그리고 나서 팔라듐 덴드라이트-그래핀 하이브리드에서 저항을 증가시키는 것으로 그래핀(p형 그래핀에서 홀의 감소된 숫자)으로 이동하기 위해 팔라듐에서 자유전자를 북돋운다. 센서 신호의 기본선에서 드리프트는 실온에서 팔라듐 NPs-그래핀 복합체와 팔라듐 큐브-그래핀 하이브리드에 대한 이전의 발명에서 수소 흡수/탈착 공정 동안에 관찰되었다. 팔라듐 NPs 및 팔라듐 큐브와 비교하여 팔라듐 덴드라이트에 기반을 둔 수소 센서에서 흥미로운 점은 기본선에서 어떤 드리프트가 특별히 실온에서조차 기록되지 않는다는 것이다. 이 흥미로운 관찰은 팔라듐 덴드라이트에서 높은 내구성을 가리키는데, 수소 흡수/탈착 동안에 팔라듐 가지 사이에서 부피 팽창을 위해 많은 내부 공간이 주어지는 팔라듐 나노입자에서 매우 다공성이었다. 100℃에서 사이클과 사이클 사이에서 센서의 반응에 저하는 도 6의 (d)에 기록되었다. 반응값(S)은 도 6의 (d)에서 세 번의 시험 사이클 후에 24%로 감소되었다. 반면에 팔라듐 큐브-그래핀 하이브리드에서 반응 값은 20%이었다. 100℃에서 저하 반응은 높은 온도에서 수소 센서 흡수/탈착 동안에 팔라듐 촉매 재료의 불안정성에 의해 설명될 수 있는데, 팔라듐 큐브-그래핀이 이용된 수소 센서는 높은 온도에서 팔라듐 덴드라이트-그래핀 하이브리드보다 더욱 안정적이라는 것이다.Palladium absorbs hydrogen molecules and transforms them into PdH x (which simultaneously expands the volume of palladium by a few percent), having a lower working function than pure palladium materials, and then a palladium dendrite-graphene hybrid Increasing the resistance at, encourages free electrons in palladium to move to graphene (a reduced number of holes in p-type graphene). Drift at the baseline of the sensor signal was observed during the hydrogen uptake / desorption process in the previous invention for the palladium NPs-graphene complex and palladium cube-graphene hybrid at room temperature. What is interesting about the palladium dendrite-based hydrogen sensor compared to palladium NPs and palladium cubes is that no drift in the baseline is recorded especially at room temperature. This interesting observation indicates high durability in palladium dendrites, which are very porous in palladium nanoparticles, where a lot of internal space is given for volume expansion between palladium branches during hydrogen absorption / desorption. The degradation in the response of the sensor between cycles at 100 ° C. was recorded in FIG. 6D. The response value S was reduced to 24% after three test cycles in FIG. 6 (d). In the palladium cube-graphene hybrid, the reaction value was 20%. The degradation reaction at 100 ° C. can be explained by the instability of the palladium catalyst material during hydrogen sensor adsorption / desorption at high temperatures, where hydrogen sensors with palladium cube-graphene are more than palladium dendrite-graphene hybrids at high temperatures. It is stable.
도 7의 (a)는 50℃의 전형적인 온도에서 1000ppm부터 1ppm에 이르는 다양한 수소 농도로 노출하는 것에 뒤따르는 팔라듐 덴드라이트-그래핀 샘플의 좋은 선형성을 보여준다. 50℃에서뿐만 아니라, 팔라듐 덴드라이트-그래핀 하이브리드에 기반을 둔 수소 센서는 실온부터 100℃까지 작업 온도에서 좋은 선형성을 갖는다. 수소 센서의 탐지의 한계(LOD)는 1ppm이다. 좋은 선형성 덕분에, 팔라듐 덴드라이트-그래핀 하이브리드에서 그래핀의 저소음 수준 성질과 높은 감도로 수소 센서는 도 7의 (b)에 도시한 바와 같이, 낮은 수소 농도(1~10ppm)에서조차 확실하게 반응할 수 있다. 하이브리드에서, 좋은 전도성과 함께 그래핀은 팔라듐 덴드라이트 사이에서 전도 경로를 연결하고 형성하는데 도움을 주는데, 수소 센서에서 높은 신호 대비 소음 수준과 비저항 변화에서조차 산출(저항)에서 확실한 변화는 1ppm에서 오직 1%로 이끌고 있다. 도 7(b)는 50℃의 작업온도에서 1.6ppm과 10ppm의 서로 다른 수소 농도와 함께 확실한 반응을 보여준다. 팔라듐 덴드라이트-그래핀은 도 7(c)에 도시한 바와 같이, 실온에서 다양한 산화력이 있는 가스(NO2, O2), 환원 가스(COx) 및 탄화수소 가스(C2H2)와 비교되는 수소 가스를 위한 좋은 선택성을 보여준다. 이들 시험된 가스의 모든 농도는 100% 농도의 질소 가스를 제외하고, 1000ppm이었다. 센서의 가스 선택성은 동일한 시험조건(Kgas/different gas)에서 비교하였을 때 목표 가스의 반응 값과 다른 가스에 대한 반응 값의 비율을 통하여 평가되었다. 실온에서, KH2/NO2, KH2/C2H2와 KH2/COx 비율은 각각 9.6, 21.7 및 37.8이었다. 이들 비율은 수소와 함께 혼합된 COx와 C2H2의 존재가 많은 응용에서 매우 인기가 있기 때문에 팔라듐 덴드라이트-그래핀 하이브리드가 수소에 대한 매우 좋은 선택성을 가지고 있고 매우 의미가 있다는 것을 확인하였다.FIG. 7A shows good linearity of the palladium dendrite-graphene sample following exposure to various hydrogen concentrations ranging from 1000 ppm to 1 ppm at a typical temperature of 50 ° C. FIG. As well as at 50 ° C, hydrogen sensors based on palladium dendrites-graphene hybrids have good linearity at working temperatures from room temperature to 100 ° C. The limit of detection (LOD) of the hydrogen sensor is 1 ppm. Thanks to the good linearity, the low noise level and high sensitivity of graphene in the palladium dendrite-graphene hybrid ensures that the hydrogen sensor reliably responds even at low hydrogen concentrations (1-10 ppm), as shown in FIG. can do. In hybrids, with good conductivity, graphene helps to connect and form conduction paths between palladium dendrites, even at high signal-to-noise levels and resistivity variations in hydrogen sensors, a clear change in output (resistance) is only 1 at 1 ppm. Led to%. Fig. 7 (b) shows the positive reaction with different hydrogen concentrations of 1.6 ppm and 10 ppm at a working temperature of 50 ° C. Palladium dendrite-graphene is compared with various oxidizing gases (NO 2 , O 2 ), reducing gas (CO x ) and hydrocarbon gas (C 2 H 2 ) at room temperature, as shown in Figure 7 (c). Shows good selectivity for hydrogen gas being produced. All concentrations of these tested gases were 1000 ppm except for 100% concentration of nitrogen gas. The gas selectivity of the sensor was evaluated by the ratio of the response of the target gas to that of the other gases when compared under the same test conditions (K gas / different gas ). At room temperature, the K H2 / NO2 , K H2 / C2H2 and K H2 / COx ratios were 9.6, 21.7 and 37.8, respectively. These ratios confirm that the palladium dendrite-graphene hybrid has very good selectivity for hydrogen and is very meaningful because the presence of CO x and C 2 H 2 mixed with hydrogen is very popular in many applications. .
도 8은 팔라듐 NPs-그래핀 복합체와 팔라듐 큐브-그래핀 하이브리드에 대한 이전의 발명과 함께 팔라듐 덴드라이트-그래핀 하이브리드의 수소 센싱 성질을 비교한 것을 보여준다. 도 8(a)에 도시한 바와 같이, 실온에서 1000ppm 수소와 함께 수소 센서의 반응 값은 팔라듐 덴드라이트-그래핀 하이브리드와 팔라듐 큐브-그래핀 하이브리드 및 팔라듐 NPs-그래핀 복합체에 대해서 각각 25.7%, 12.9% 및 7%이었다. 반면에, 반응/회복 시간은 팔라듐 큐브-그래핀 하이브리드와 팔라듐 NPs-그래핀에 대해서 각각 18/40과 1.5/14분이었다. 일반적으로, 팔라듐 덴드라이트-그래핀 하이브리드에 기반을 둔 수소 센서는 도 8(a)에 도시한 바와 같이, 1∼1000ppm의 전체 범위 수소 농도에서 빠른 반응/회복 시간뿐만 아니라 높은 감도를 보였다.FIG. 8 shows a comparison of the hydrogen sensing properties of palladium dendrites-graphene hybrids with previous inventions for palladium NPs-graphene complexes and palladium cube-graphene hybrids. As shown in FIG. 8 (a), the reaction value of the hydrogen sensor with 1000 ppm hydrogen at room temperature was 25.7% for the palladium dendrite-graphene hybrid, the palladium cube-graphene hybrid and the palladium NPs-graphene composite, respectively. 12.9% and 7%. In contrast, reaction / recovery times were 18/40 and 1.5 / 14 minutes for the palladium cube-graphene hybrid and palladium NPs-graphene, respectively. In general, hydrogen sensors based on palladium dendrite-graphene hybrids exhibited high sensitivity as well as fast reaction / recovery times at full range hydrogen concentrations of 1-1000 ppm, as shown in FIG.
팔라듐 덴드라이트에서 기공의 상태는 조밀한 팔라듐 큐브와 비교하여 팔라듐에서 수소 흡수/탈착을 가속화시킨다. 그러나, 팔라듐 덴드라이트-그래핀 샘플은 도 8의 (c)에 도시한 바와 같이, 팔라듐 큐브-그래핀 하이브리드와 팔라듐 NPs-그래핀 복합체와 비교하여 높은 온도(100℃)에서 더 낮은 안정성을 보여주었다. 수소 센서는 실온에서 100℃까지 증가하는 온도와 함께 반응에서 빠른 감소를 보여주었다. 팔라듐 덴드라이트-그래핀 하이브리드는 실온에서 100℃까지 작업온도를 82%(1000ppm으로) 증가하는 것에 의해 그것의 반응 값을 빠르게 감소시켰다. 반면에, 이들 감소된 반응 값은 팔라듐 큐브-그래핀 하이브리드와 팔라듐 NPs-그래핀 복합체에서 각각 불과 27%와 49%이었다. 팔라듐 덴드라이트-그래핀 하이브리드의 수소 센싱 성질과 이전 발명의 평가는 다음의 표 1에 요약되었다.The state of the pores in palladium dendrites accelerates hydrogen absorption / desorption at palladium compared to the dense palladium cubes. However, the palladium dendrite-graphene sample shows lower stability at higher temperatures (100 ° C.) compared to the palladium cube-graphene hybrid and palladium NPs-graphene composite, as shown in FIG. 8 (c). gave. The hydrogen sensor showed a rapid decrease in reaction with increasing temperature from room temperature to 100 ° C. The palladium dendrite-graphene hybrid rapidly reduced its reaction value by increasing the working temperature from room temperature to 100 ° C. by 82% (to 1000 ppm). On the other hand, these reduced response values were only 27% and 49% in the palladium cube-graphene hybrid and palladium NPs-graphene complex, respectively. The hydrogen sensing properties of the palladium dendrite-graphene hybrid and the evaluation of the previous invention are summarized in Table 1 below.
표 1 팔라듐 NPs-그래핀 복합체와 팔라듐 큐브-그래핀 하이브리드에 대한 이전 발명과 비교한 팔라듐 덴드라이트-그래핀 하이브리드의 수소(H2) 센싱 성질의 평가
센싱 재료 반응값 S(%) 반응시간(분) 회복시간(분) 100℃에서 반응값에 저하(%) 반복성/드리프트
팔라듐 NPs-그래핀 복합체 7% 1.5 14 49% Ok/Yes
팔라듐 큐브-그래핀 하이브리드 12.9% 18 40 27% Good/Little
팔라듐 덴드라이트 하이브리드 25.7% 6 8 82% Very Good/No
Table 1 Evaluation of the hydrogen (H <sub> 2 </ sub>) sensing properties of palladium dendrites-graphene hybrids compared to previous inventions for palladium NPs-graphene complexes and palladium cube-graphene hybrids
Sensing material Response value S (%) Response time (minutes) Recovery time (minutes) Reduction in reaction value at 100 ℃ (%) Repeatability / Drift
Palladium NPs-Graphene Complex 7% 1.5 14 49% Ok / Yes
Palladium Cube-Graphene Hybrid 12.9% 18 40 27% Good / Little
Palladium dendrite hybrid 25.7% 6 8 82% Very Good / No
3. 결론3. Conclusion
본 발명에서 60~70nm의 매우 균일한 크기로 Pd 나노 덴드라이트는 CTAB 환경에서 Pd 전구체의 손쉬운 빠른 반응공정에 의해 합성되었고 그리고 나서 그래핀과 함께 하이브리드 형성으로 수소(H2) 촉매로 사용되었다. Pd 덴트라이트 그래핀 하이브리드에 기초를 둔 수소(H2) 센서는 25%의 높은 반응값과 실온에서조차 1000ppm 수소(H2)와 함께 매우 좋은 반복성을 갖는다. 부가적으로, 센서는 1∼1000ppm의 수소(H2) 농도범위로 좋은 선형성과 50℃의 작업온도로 1∼10ppm의 낮은 농도에서 확실한 반응을 보여주었다. 그래핀 복합체/하이브리드에 기초를 둔 수소(H2) 탐지에 대한 본 발명자의 이전 발명과 대조하면, Pd 덴드라이트 그래핀 하이브리드는 높은 온도(100℃)에서 큰 반응에 저하의 약점을 제외하고, 몇 배의 더 높은 반응값 뿐만 아니라 빠른 반응/회복 시간을 갖는다. Pd 덴드라이트 구조의 높은 면적 대비 체적비율과 높은 다공성 상태는 Pd 그래핀 복합체/하이브리드에 기초를 둔 수소(H2) 센서에서 이들은 더 나은 결과를 설명하였다.In the present invention, Pd nano dendrites with a very uniform size of 60-70 nm were synthesized by an easy and fast reaction process of Pd precursor in CTAB environment and then used as a hydrogen (H 2 ) catalyst in hybrid formation with graphene. The hydrogen (H 2 ) sensor based on the Pd dentite graphene hybrid has a high response of 25% and very good repeatability with 1000 ppm hydrogen (H 2 ) even at room temperature. In addition, the sensor showed good linearity with a hydrogen (H 2 ) concentration range of 1 to 1000 ppm and a solid response at low concentrations of 1 to 10 ppm with a working temperature of 50 ° C. In contrast to the inventor's previous invention for hydrogen (H 2 ) based graphene complex / hybrid detection, Pd dendrites graphene hybrids have the weakness of degradation in large reactions at high temperatures (100 ° C.), It has several times higher response values as well as faster reaction / recovery times. The high volume to area ratio and high porosity of the Pd dendrites have demonstrated better results for hydrogen (H 2 ) sensors based on Pd graphene composites / hybrids.
이상과 같이 본 발명에 따른 팔라듐 나노덴드라이트―그래핀 나노복합체 기반 수소센서 및 그 제조방법에 대해서 예시한 도면을 참조로 하여 설명하였으나, 본 명세서에 개시된 실시예와 도면에 의해 본 발명이 한정되는 것은 아니며, 본 발명의 기술사상의 범위 내에서 당업자에 의해 다양한 변형이 이루어질 수 있음은 물론이다.As described above, the palladium nanodendrite-graphene nanocomposite-based hydrogen sensor and the manufacturing method thereof according to the present invention have been described with reference to the drawings, but the present invention is limited by the embodiments and drawings disclosed herein. Of course, various modifications can be made by those skilled in the art within the scope of the technical idea of the present invention.
본 발명은 25%의 높은 반응값과 실온에서조차 1000ppm 수소(H2)와 함께 매우 좋은 반복성을 갖는 수소센서로 유용하게 사용할 수 있다.The present invention can be usefully used as a hydrogen sensor having a high reaction value of 25% and very good repeatability with 1000 ppm hydrogen (H 2 ) even at room temperature.
또 1ppm에서 1000ppm까지의 수소 농도 범위로 좋은 선형성과 를 넓은 범위에서 탐지할 수 있고, 50℃의 작업온도로 1∼10ppm의 낮은 농도에서 확실한 반응을 보여주는 수소센서로 유용하게 사용할 수 있다..In addition, it can detect good linearity with a wide range of hydrogen concentrations from 1ppm to 1000ppm, and can be useful as a hydrogen sensor that shows a reliable reaction at a low concentration of 1-10ppm at a working temperature of 50 ° C.
또한 종래 수소센서보다 몇 배의 높은 반응값과 빠른 반응/회복시간을 갖는 수소센서로 유용하게 사용할 수 있다.In addition, it can be usefully used as a hydrogen sensor having several times higher response value and faster reaction / recovery time than the conventional hydrogen sensor.

Claims (10)

  1. 팔라듐(Pd) 나노덴드라이트를 수소(H2) 탐지를 위한 촉매로 사용하도록 그래핀(Gr)과 CTAB 환경에서 Pd 전구체 염의 환원비율에 의해 합성된 상기 팔라듐(Pd) 나노덴드라이트를 혼합하여 생성한 것으로, 그래핀(Gr) 플레이크에 부착된 개별적인 많은 팔라듐(Pd) 덴드라이트로 형성한 하이브리드로 만든 수소(H2)센서인 것을 특징으로 하는 팔라듐 나노덴드라이트―그래핀 나노복합체 기반 수소센서.Produced by mixing the palladium (Pd) nanodendrite synthesized by the reduction ratio of Pd precursor salt in graphene (Gr) and CTAB environment to use palladium (Pd) nanodendrite as a catalyst for hydrogen (H 2 ) detection In one embodiment, a palladium nanodendrite-graphene nanocomposite-based hydrogen sensor, characterized in that it is a hydrogen (H 2 ) sensor made of a hybrid formed of a large number of individual palladium (Pd) dendrites attached to graphene (Gr) flakes.
  2. 제1항에 있어서,The method of claim 1,
    상기 팔라듐(Pd) 나노덴드라이트는 다공성 나노-세공을 갖는 구 형태의 팔라듐 나노입자의 조합체인 것을 특징으로 하는 팔라듐 나노덴드라이트―그래핀 나노복합체 기반 수소센서.The palladium (Pd) nanodendrite is a palladium nanodendrite-graphene nanocomposite-based hydrogen sensor, characterized in that the combination of sphere-shaped palladium nanoparticles having porous nano-pores.
  3. 제1항에 있어서,The method of claim 1,
    상기 팔라듐(Pd) 나노덴드라이트는 60∼70㎚ 크기의 콜로이드성의 나노덴드라이트인 것을 특징으로 하는 팔라듐 나노덴드라이트―그래핀 나노복합체 기반 수소센서.The palladium (Pd) nano dendrites are colloidal nano dendrites having a size of 60 ~ 70 nm palladium nano dendrites-graphene nanocomposite-based hydrogen sensor.
  4. 제1항에 있어서,The method of claim 1,
    상기 수소센서의 수소(H2) 탐지 범위는 1∼1000ppm인 것을 특징으로 하는 팔라듐 나노덴드라이트―그래핀 나노복합체 기반 수소센서.Hydrogen (H 2 ) detection range of the hydrogen sensor is palladium nanodendrite-graphene nanocomposite-based hydrogen sensor, characterized in that 1 to 1000ppm.
  5. 제1항에 있어서,The method of claim 1,
    상기 수소센서의 작업 온도는 실온(RT)에서부터 50℃까지인 것을 특징으로 하는 팔라듐 나노덴드라이트―그래핀 나노복합체 기반 수소센서.The working temperature of the hydrogen sensor is a palladium nanodendrite-graphene nanocomposite-based hydrogen sensor, characterized in that from room temperature (RT) to 50 ℃.
  6. 제1항 내지 제5항 중 어느 한 항의 수소센서의 제조방법에 있어서,In the method of manufacturing a hydrogen sensor of any one of claims 1 to 5,
    일정 농도의 4염화칼륨팔라듐(K2PdCl4)과 아스코르브(ascorbic)산 용액을 이온제거수(DI)와 함께 첨가하여 교반하고, 시차를 두고 세틸트리메틸암모늄브롬화물(CTAB)에 첨가하여 교반함으로써 혼합물 용액을 준비하는 단계;A mixture of potassium palladium tetrachloride (K 2 PdCl 4 ) and ascorbic acid solution with deionized water (DI) was added and stirred, and the mixture was added to cetyltrimethylammonium bromide (CTAB) at a staggered time to stir. Preparing a solution;
    상기 단계에 의해 준비된 혼합물 용액을 원심분리하고 초과 반응물을 제거하기 위해 이온제거수(DI)에서 여러 번 확산한 후, 팔라듐 현탁액으로 이온제거수(DI)에서 재확산하여 팔라듐(Pd) 나노덴드라이트 용액을 합성하는 단계;The mixture solution prepared by the above step was centrifuged and diffused several times in deionized water (DI) to remove excess reactant, followed by re-diffusion in deionized water (DI) with palladium suspension and palladium (Pd) nanodendrite Synthesizing a solution;
    순수 그라파이트 분말로 준비되는 그래핀 산화물(GO) 수용액에 상기 팔라듐(Pd) 나노덴드라이트 용액을 첨가여 교반한 후, 환원제를 추가로 첨가하여 실온보다 더 높은 온도에서 교반하여, 팔라듐(Pd) 나노덴드라이트―그래핀 하이브리드의 혼합물을 형성하는 단계;The palladium (Pd) nanodendrite solution was added to the graphene oxide (GO) aqueous solution prepared as pure graphite powder, followed by stirring, followed by addition of a reducing agent, followed by stirring at a temperature higher than room temperature. Forming a mixture of dendrites-graphene hybrids;
    상기 환원제의 첨가에 의해 환원된 팔라듐(Pd) 나노덴드라이트―그래핀 하이브리드의 혼합물을 현탁액으로 하여 분사에 의해 SiO2/Si 기지에 피복시키는 단계; 및Coating the mixture of palladium (Pd) nanodendrite-graphene hybrids reduced by the addition of the reducing agent as a suspension to the SiO 2 / Si matrix by spraying; And
    상기 혼합물을 피복시키는 단계에 의해 형성된 Pd 덴드라이트-Gr/SiO2/Si 기지의 표면에 귀금속을 도금하여 오믹(Ohmic) 접촉층을 형성하는 단계;Plating an noble metal on the surface of the Pd dendrite-Gr / SiO 2 / Si matrix formed by coating the mixture to form an ohmic contact layer;
    를 포함하는 것을 특징으로 하는 팔라듐 나노덴드라이트―그래핀 나노복합체 기반 수소센서.Palladium nano dendrites-graphene nanocomposite-based hydrogen sensor comprising a.
  7. 제6항에 있어서,The method of claim 6,
    상기 혼합물 용액을 준비하는 단계에서 세틸트리메틸암모늄브롬화물(CTAB)은 수초 내에 마이크로 피펫을 통하여 혼합물 용액에 주입하는 것을 특징으로 하는 팔라듐 나노덴드라이트―그래핀 나노복합체 기반 수소센서.In preparing the mixture solution, cetyltrimethylammonium bromide (CTAB) is injected into the mixture solution through a micropipette within several seconds, characterized in that the palladium nanodendrite-graphene nanocomposite-based hydrogen sensor.
  8. 제6항에 있어서,The method of claim 6,
    상기 환원제는 65중량%의 환원제 수화물(N2H4.H2O)인 것을 특징으로 하는 팔라듐 나노덴드라이트―그래핀 나노복합체 기반 수소센서.The reducing agent is a palladium nanodendrite-graphene nanocomposite-based hydrogen sensor, characterized in that 65% by weight of reducing agent hydrate (N 2 H 4 .H 2 O).
  9. 제6항에 있어서,The method of claim 6,
    상기 SiO2/Si 기지에 팔라듐(Pd) 나노덴드라이트―그래핀 복합체를 분사할 때 SiO2/Si 기지를 일정온도로 가열하는 것을 특징으로 하는 팔라듐 나노덴드라이트―그래핀 나노복합체 기반 수소센서.Palladium nano dendrites which the SiO 2 / Si base when injecting the graphene composite is characterized in that the heating at a constant temperature-graphene nano-composite based on the hydrogen sensor of palladium (Pd) nano dendrites on the SiO 2 / Si base.
  10. 제6항에 있어서,The method of claim 6,
    상기 오믹(Ohmic) 접촉층은 금속마스크와 RF 박막증착에 의해 형성하는 것을 특징으로 하는 팔라듐 나노덴드라이트―그래핀 나노복합체 기반 수소센서.The ohmic contact layer is a palladium nanodendrite-graphene nanocomposite-based hydrogen sensor, characterized in that formed by a metal mask and RF thin film deposition.
PCT/KR2014/010104 2014-07-30 2014-10-27 Palladium nanodendrite-graphene nanohybrid based hydrogen sensor and method for manufacturing same WO2016017858A1 (en)

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