KR20230147268A - Dual Core-Shell Pt-Co Catalyst with Hydrogen Oxidation Selectivity and Preparation Method thereof - Google Patents
Dual Core-Shell Pt-Co Catalyst with Hydrogen Oxidation Selectivity and Preparation Method thereof Download PDFInfo
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- KR20230147268A KR20230147268A KR1020220046051A KR20220046051A KR20230147268A KR 20230147268 A KR20230147268 A KR 20230147268A KR 1020220046051 A KR1020220046051 A KR 1020220046051A KR 20220046051 A KR20220046051 A KR 20220046051A KR 20230147268 A KR20230147268 A KR 20230147268A
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- catalyst
- nanoparticles
- platinum
- carbon
- cobalt
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- 239000001257 hydrogen Substances 0.000 title abstract description 22
- 229910052739 hydrogen Inorganic materials 0.000 title abstract description 22
- 238000007254 oxidation reaction Methods 0.000 title abstract description 7
- 239000011258 core-shell material Substances 0.000 title description 3
- 230000003647 oxidation Effects 0.000 title description 3
- 239000003426 co-catalyst Substances 0.000 title description 2
- 125000004435 hydrogen atom Chemical class [H]* 0.000 title description 2
- 238000002360 preparation method Methods 0.000 title description 2
- 230000009977 dual effect Effects 0.000 title 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 124
- 239000003054 catalyst Substances 0.000 claims abstract description 64
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 56
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 52
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 43
- 239000002105 nanoparticle Substances 0.000 claims abstract description 31
- 229910017052 cobalt Inorganic materials 0.000 claims abstract description 14
- 239000010941 cobalt Substances 0.000 claims abstract description 14
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000004519 manufacturing process Methods 0.000 claims abstract description 12
- 238000010438 heat treatment Methods 0.000 claims description 13
- 239000002243 precursor Substances 0.000 claims description 11
- 239000013110 organic ligand Substances 0.000 claims description 7
- 239000000243 solution Substances 0.000 claims description 7
- 239000011259 mixed solution Substances 0.000 claims description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 18
- 239000000446 fuel Substances 0.000 abstract description 16
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 15
- 239000001301 oxygen Substances 0.000 abstract description 15
- 229910052760 oxygen Inorganic materials 0.000 abstract description 15
- 238000006722 reduction reaction Methods 0.000 abstract description 6
- 150000002431 hydrogen Chemical class 0.000 abstract description 4
- 239000011148 porous material Substances 0.000 abstract description 3
- 239000002245 particle Substances 0.000 description 22
- 229910052751 metal Inorganic materials 0.000 description 16
- 239000002184 metal Substances 0.000 description 16
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- 238000000034 method Methods 0.000 description 9
- 230000002441 reversible effect Effects 0.000 description 9
- 239000002082 metal nanoparticle Substances 0.000 description 8
- QWPPOHNGKGFGJK-UHFFFAOYSA-N hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 description 7
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- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 3
- 238000003917 TEM image Methods 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 239000006229 carbon black Substances 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 229910021389 graphene Inorganic materials 0.000 description 3
- 238000002173 high-resolution transmission electron microscopy Methods 0.000 description 3
- 239000002923 metal particle Substances 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- 229910052707 ruthenium Inorganic materials 0.000 description 3
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical group [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 3
- VEJOYRPGKZZTJW-FDGPNNRMSA-N (z)-4-hydroxypent-3-en-2-one;platinum Chemical compound [Pt].C\C(O)=C\C(C)=O.C\C(O)=C\C(C)=O VEJOYRPGKZZTJW-FDGPNNRMSA-N 0.000 description 2
- QGLWBTPVKHMVHM-KTKRTIGZSA-N (z)-octadec-9-en-1-amine Chemical compound CCCCCCCC\C=C/CCCCCCCCN QGLWBTPVKHMVHM-KTKRTIGZSA-N 0.000 description 2
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 2
- 229910000531 Co alloy Inorganic materials 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 229910001260 Pt alloy Inorganic materials 0.000 description 2
- CLBRCZAHAHECKY-UHFFFAOYSA-N [Co].[Pt] Chemical compound [Co].[Pt] CLBRCZAHAHECKY-UHFFFAOYSA-N 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- BKFAZDGHFACXKY-UHFFFAOYSA-N cobalt(II) bis(acetylacetonate) Chemical compound [Co+2].CC(=O)[CH-]C(C)=O.CC(=O)[CH-]C(C)=O BKFAZDGHFACXKY-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000000840 electrochemical analysis Methods 0.000 description 2
- 238000002848 electrochemical method Methods 0.000 description 2
- 231100001135 endothelial toxicity Toxicity 0.000 description 2
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- 239000000463 material Substances 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 239000002808 molecular sieve Substances 0.000 description 2
- CCCMONHAUSKTEQ-UHFFFAOYSA-N octadec-1-ene Chemical compound CCCCCCCCCCCCCCCCC=C CCCMONHAUSKTEQ-UHFFFAOYSA-N 0.000 description 2
- 239000005518 polymer electrolyte Substances 0.000 description 2
- 229920005597 polymer membrane Polymers 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- POILWHVDKZOXJZ-ARJAWSKDSA-M (z)-4-oxopent-2-en-2-olate Chemical compound C\C([O-])=C\C(C)=O POILWHVDKZOXJZ-ARJAWSKDSA-M 0.000 description 1
- KLFRPGNCEJNEKU-FDGPNNRMSA-L (z)-4-oxopent-2-en-2-olate;platinum(2+) Chemical compound [Pt+2].C\C([O-])=C\C(C)=O.C\C([O-])=C\C(C)=O KLFRPGNCEJNEKU-FDGPNNRMSA-L 0.000 description 1
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- 229920000557 Nafion® Polymers 0.000 description 1
- 229910002837 PtCo Inorganic materials 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- CUJRVFIICFDLGR-UHFFFAOYSA-N acetylacetonate Chemical compound CC(=O)[CH-]C(C)=O CUJRVFIICFDLGR-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910003481 amorphous carbon Inorganic materials 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- QZPSXPBJTPJTSZ-UHFFFAOYSA-N aqua regia Chemical compound Cl.O[N+]([O-])=O QZPSXPBJTPJTSZ-UHFFFAOYSA-N 0.000 description 1
- 239000011668 ascorbic acid Substances 0.000 description 1
- 235000010323 ascorbic acid Nutrition 0.000 description 1
- 229960005070 ascorbic acid Drugs 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- GQPLZGRPYWLBPW-UHFFFAOYSA-N calix[4]arene Chemical compound C1C(C=2)=CC=CC=2CC(C=2)=CC=CC=2CC(C=2)=CC=CC=2CC2=CC=CC1=C2 GQPLZGRPYWLBPW-UHFFFAOYSA-N 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 235000015165 citric acid Nutrition 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
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- 239000003792 electrolyte Substances 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
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- 235000019253 formic acid Nutrition 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 1
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000013507 mapping Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000036647 reaction Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000003252 repetitive effect Effects 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- 239000012279 sodium borohydride Substances 0.000 description 1
- 229910000033 sodium borohydride Inorganic materials 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- RWRDLPDLKQPQOW-UHFFFAOYSA-N tetrahydropyrrole Substances C1CCNC1 RWRDLPDLKQPQOW-UHFFFAOYSA-N 0.000 description 1
- 238000004758 underpotential deposition Methods 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/92—Metals of platinum group
- H01M4/921—Alloys or mixtures with metallic elements
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/002—Catalysts characterised by their physical properties
- B01J35/0073—Distribution of the active metal ingredient
- B01J35/0086—Distribution of the active metal ingredient egg-yolk like
-
- B01J35/398—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/082—Decomposition and pyrolysis
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/88—Processes of manufacture
- H01M4/8825—Methods for deposition of the catalytic active composition
- H01M4/8846—Impregnation
- H01M4/885—Impregnation followed by reduction of the catalyst salt precursor
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/92—Metals of platinum group
- H01M4/925—Metals of platinum group supported on carriers, e.g. powder carriers
- H01M4/926—Metals of platinum group supported on carriers, e.g. powder carriers on carbon or graphite
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M2008/1095—Fuel cells with polymeric electrolytes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Abstract
본 발명은 수소 가스에 대한 선택성을 갖는 공극이 형성된 탄소쉘에 둘러싸여 있어 연료전지의 음극에서의 산소환원반응을 방지함으로써 촉매의 성능과 내구성이 우수한 수소산화반응용 촉매 및 그 제조방법에 관한 것으로, 보다 상세하게는 백금과 코발트로 이루어진 나노입자;와 상기 나노입자 표면에 형성된 다공성 탄소쉘;로 이루어진 촉매에 관한 것이다.The present invention relates to a catalyst for hydrogen oxidation reaction with excellent catalyst performance and durability by preventing oxygen reduction reaction at the cathode of a fuel cell by preventing oxygen reduction reaction at the cathode of a fuel cell by being surrounded by a carbon shell formed with pores having selectivity for hydrogen gas, and to a method of manufacturing the same. In detail, it relates to a catalyst consisting of nanoparticles made of platinum and cobalt; and a porous carbon shell formed on the surface of the nanoparticles.
Description
본 발명은 수소 가스에 대한 선택성을 갖는 공극이 형성된 탄소쉘에 둘러싸여 있어 연료전지의 음극에서의 산소환원반응을 방지함으로써 촉매의 성능과 내구성이 우수한 수소산화반응용 촉매 및 그 제조방법에 관한 것이다. The present invention relates to a catalyst for hydrogen oxidation reaction that is surrounded by a carbon shell with pores having selectivity for hydrogen gas, thereby preventing oxygen reduction reaction at the cathode of a fuel cell, thereby providing excellent catalyst performance and durability, and a method for manufacturing the same.
연료전지는 연료의 화학에너지를 전기 화학적 반응에 의해 전기 및 열 에너지로 직접 변환시키는 장치로, 산화·환원반응을 이용한다는 점에 있어서는 보통의 화학전지와 동일하나, 반응물이 연속적으로 외부로부터 공급되고 반응 생성물은 연속적으로 계 외로 제거된다는 점에서 폐쇄계 내에서 전지 반응을 하는 화학전지와 구별된다. 수소에 의해 구동되는 연료전지는 화석 연료의 사용을 줄이고 지구 온난화의 영향을 약화시키기 위해 광범위하게 연구되고 있는 많은 재생에너지 기술 중 하나이다. 또한 다양한 유형의 연료전지 중에서도 고분자 전해질막 연료전지(PEMFC)는 높은 출력 밀도와 낮은 작동 온도로 인해 에너지 수요의 급속한 증가와 환경오염의 심화에 대한 가장 유망한 해결책으로 간주된다. A fuel cell is a device that directly converts the chemical energy of fuel into electrical and thermal energy through an electrochemical reaction. It is the same as an ordinary chemical cell in that it uses oxidation/reduction reactions, but the reactants are continuously supplied from the outside. It is distinguished from a chemical cell in which the cell reaction occurs within a closed system in that the reaction products are continuously removed out of the system. Fuel cells powered by hydrogen are one of many renewable energy technologies being extensively researched to reduce the use of fossil fuels and blunt the effects of global warming. Additionally, among various types of fuel cells, polymer electrolyte membrane fuel cells (PEMFC) are considered the most promising solution to the rapid increase in energy demand and worsening environmental pollution due to their high power density and low operating temperature.
수소자동차는 고분자 전해질막 연료전지의 대표적인 응용분야이다. 그러나 실제 차량 사용조건에서는 반복적인 정지/시동 작업으로 인한 문제가 발생한다. 즉, 발전 장치에 시동을 걸 때, 외부에서 유입되거나 또는 고분자 막을 통한 넘어 온 공기로 인해 시동 과정 중 순간적으로 수소는 음극의 일부분에만 존재하게 되고 이에 따라 수소가 공급되지 않는 부분, "수소 결핍 부분"이 존재하게 된다. 이에 따라 수소만 공급되어야 하는 음극에 공기(산소)가 존재하게 되며, 이는 바람직하지 않은 산소환원반응(ORR)을 유발하여 음극에서 정상 전위보다 더 높은 전위를 생성한다. 역전류 흐름으로 알려진 이러한 현상은 전극의 탄소지지체의 부식을 유발하고, 결과적으로 촉매의 성능저하와 내구성 저하를 촉진한다. Hydrogen vehicles are a representative application area for polymer electrolyte membrane fuel cells. However, under actual vehicle use conditions, problems arise due to repetitive stop/start operations. In other words, when starting a power generation device, hydrogen is present only in a portion of the cathode during the startup process due to air flowing in from the outside or passing through the polymer membrane, and as a result, the portion to which hydrogen is not supplied, the “hydrogen deficiency portion.” “It comes into existence. Accordingly, air (oxygen) is present in the cathode where only hydrogen should be supplied, which causes an undesirable oxygen reduction reaction (ORR) and generates a higher than normal potential at the cathode. This phenomenon, known as reverse current flow, causes corrosion of the carbon support of the electrode, which ultimately accelerates the performance and durability of the catalyst.
이에 따라 음극이 공기(산소)에 노출되었을 때 산소를 효과적으로 제거 또는 차단하여 수소 특이적인 반응이 가능한 촉매 개발의 필요성이 대두되어 왔다. Genorio 등(Nat. Mater. 9 (2010) 998-1003)은 산소 접촉을 차단하기 위하여 calix[4]arene과 같은 유기분자로 금속나노입자의 표면을 코팅한 촉매를 보고하였다. 그러나 장기간의 운전조건에서는 금속나노입자 표면에 화학적으로 코팅된 유기 분자가 쉽게 분리될 수 있기 때문에, 결과적으로 금속나노입자가 산소에 노출되어 역전류 흐름이 재발한다. 따라서 역전류 흐름은 PEMFC의 주요 과제로 남아 있으며, 이를 해결하기 위한 효과적인 연구 전략이 시급하다.Accordingly, there has been a need to develop a catalyst capable of hydrogen-specific reaction by effectively removing or blocking oxygen when the cathode is exposed to air (oxygen). Genorio et al. (Nat. Mater. 9 (2010) 998-1003) reported a catalyst in which the surface of metal nanoparticles was coated with organic molecules such as calix[4]arene to block oxygen contact. However, under long-term operating conditions, the organic molecules chemically coated on the surface of the metal nanoparticles can be easily separated, and as a result, the metal nanoparticles are exposed to oxygen and the reverse current flow recurs. Therefore, reverse current flow remains a major challenge in PEMFC, and effective research strategies to solve it are urgently needed.
최근에는 촉매 나노 입자를 그래핀 또는 탄소로 둘러싸는(캡슐화, encapsulation) 방법들이 보고되었다.Recently, methods of encapsulating catalyst nanoparticles with graphene or carbon have been reported.
등록특허 10-2172177은 역전류 현상의 원인이 되는 산소의 접근을 차단함으로써, 고분자막 연료전지의 내구성을 확보할 수 있도록 하는 백금코어의 표면에 다공성 탄소쉘 층이 형성된 연료전지용 촉매의 제조방법을 제시하고 있다. 이에 의해 수소산화반응에 대한 높은 선택성 및 내구성을 가지는 연료전지용 촉매가 제공되지만, 도면에서 볼 수 있듯이 백금 코어의 표면에서만 촉매작용이 있기 때문에 사용된 대부분의 백금이 비활성 상태 즉, 촉매로 활용되지 못하는 상태가 되어 낭비의 요소가 되고 있다.Registered patent 10-2172177 proposes a method of manufacturing a catalyst for fuel cells in which a porous carbon shell layer is formed on the surface of a platinum core, which ensures the durability of polymer membrane fuel cells by blocking access to oxygen, which causes reverse current phenomenon. I'm doing it. This provides a fuel cell catalyst with high selectivity and durability for the hydrogen oxidation reaction, but as can be seen in the figure, since catalysis occurs only on the surface of the platinum core, most of the platinum used is in an inactive state, that is, cannot be used as a catalyst. It has become an element of waste.
본 발명의 발명자에 의한 선행발명인 등록특허 10-2323270에는, 백금과 루테늄이 고르게 분포된 합금 나노입자가 수소에 대한 선택성을 갖는 다공성 탄소쉘로 둘러싸인 연료전지용 촉매의 제조방법이 개시되어 있다. 이 선행기술에 의하면 백금 사이에 존재하는 루테늄에 의해 CO 내피독성을 가짐과 동시에 표면의 탄소쉘에 의한 산소나 CO의 접근을 차단하는 분자체 기능에 의해 앞선 등록특허 10-2172177에서 제시된 방법에 의한 촉매에 비해 내구성과 전기화학적 특성이 우수한 연료전지용 촉매가 가능하게 된다. 그럼에도 불구하고 ⓐ 종래에 비해 백금의 활용도가 높긴 하지만 많은 비율의 백금이 촉매작용에 참여하지 못하고 여전히 합금 코어의 내부에 존재하면서 낭비되는 측면이 있으며, ⓑ 탄소쉘의 구조를 열처리 온도 및 수소분위기 열처리로 제어하던 등록특허 10-2172177과 등록특허 10-2323270의 선행발명에서 더 나아가 탄소쉘의 미세 구조를 완전히 제어하기 위한 핵심 매개변수를 설정할 필요성이 있다. Patent No. 10-2323270, a prior invention by the inventor of the present invention, discloses a method for manufacturing a catalyst for fuel cells in which alloy nanoparticles in which platinum and ruthenium are evenly distributed are surrounded by a porous carbon shell with selectivity for hydrogen. According to this prior art, it has CO endothelial toxicity due to ruthenium present between platinum, and at the same time, it has a molecular sieve function that blocks access to oxygen or CO by the carbon shell on the surface, using the method proposed in the previous registered patent 10-2172177. A fuel cell catalyst with superior durability and electrochemical properties compared to catalysts becomes possible. Nevertheless, although ⓐ the utilization of platinum is higher than before, a large proportion of platinum does not participate in the catalytic reaction and is still present inside the alloy core, which is wasted. ⓑ The structure of the carbon shell is heat treated at a heat treatment temperature and hydrogen atmosphere. There is a need to set key parameters to completely control the microstructure of the carbon shell, going further from the prior inventions of Registered Patent No. 10-2172177 and Patent No. 10-2323270, which were controlled by .
나아가 본 발명의 발명자들의 지속적인 연구 결과, 다음과 같은 두 가지 새로운 사실을 발견하게 되었다. Furthermore, as a result of continuous research by the inventors of the present invention, the following two new facts were discovered.
ⓐ 선행발명인 등록특허 10-2323270에서 백금과 루테늄이 고르게 분포되어 고용체(固溶體, solid solution) 형태의 나노입자가 되는 것과는 달리, 백금과 코발트 혼합 입자를 소정의 조건에서 열처리하면 백금과 코발트의 분포가 다른 금속 나노입자가 된다. ⓑ 각 금속의 탄소 용해도 차이를 활용하여 탄소 용해도가 상대적으로 큰 코발트를 백금에 합금시켜 보다 고밀도의 탄소쉘을 금속 입자 표면에 형성시켜 높은 수소산화반응 선택성을 보일 수 있다. ⓐ Unlike in the prior inventor's registered patent 10-2323270, where platinum and ruthenium are evenly distributed to form nanoparticles in the form of a solid solution, when platinum and cobalt mixed particles are heat treated under predetermined conditions, the platinum and cobalt are formed. It becomes metal nanoparticles with different distribution. ⓑ By utilizing the difference in carbon solubility of each metal, cobalt, which has relatively high carbon solubility, is alloyed with platinum to form a higher density carbon shell on the surface of the metal particle, showing high hydrogen oxidation reaction selectivity.
본 발명은 이러한 사실에 기초하여 창안된 것이다.The present invention was created based on these facts.
본 발명은 다음과 같은 특징을 가지는 백금합금 기반의 수소연료전지용 촉매를 제공하는 것을 목적으로 한다. The purpose of the present invention is to provide a catalyst for hydrogen fuel cells based on platinum alloy having the following characteristics.
- 사용된 백금의 대부분이 촉매작용에 참여함- Most of the platinum used participates in catalysis.
- 첨가되는 다른 금속에 의해 백금의 촉매작용이 방해받지 않음- The catalytic action of platinum is not hindered by other added metals.
- 첨가되는 다른 금속의 용출에 의한 성능 감소 없음- No reduction in performance due to elution of other added metals
- 강화된 고밀도 탄소쉘 층 확보- Secured reinforced high-density carbon shell layer
전술한 목적을 달성하기 위한 본 발명은 백금과 코발트로 이루어진 나노입자;와 상기 나노입자 표면에 형성된 다공성 탄소쉘;로 이루어진 촉매에 관한 것이다.The present invention to achieve the above-mentioned object relates to a catalyst consisting of nanoparticles made of platinum and cobalt; and a porous carbon shell formed on the surface of the nanoparticles.
본 발명에서 상기 나노입자는, 표면에 백금이, 내부에 코발트가 분포된 것일 수 있다. In the present invention, the nanoparticles may have platinum distributed on the surface and cobalt distributed inside.
본 발명에서 상기 나노입자의 백금과 코발트의 몰비는 1:1~1:3 인 것이 바람직한데, 이에 한정되는 것은 아니다. 금속의 몰비는 나노입자의 입자경, 나노입자의 표면의 백금 층(layer)의 두께, 백금과 코발트의 밀도(또는 단위 중량당 부피) 등을 고려하여 보다 정교하게 계산될 수 있을 것이다. In the present invention, the molar ratio of platinum and cobalt in the nanoparticles is preferably 1:1 to 1:3, but is not limited thereto. The molar ratio of metal can be calculated more precisely by considering the particle size of the nanoparticle, the thickness of the platinum layer on the surface of the nanoparticle, and the density (or volume per unit weight) of platinum and cobalt.
본 발명에서 상기 촉매의 EMSA(exposed metal surface area, 노출 금속 표면적) 값이 5~15 m2g-1일 수 있는데, 이에 제한되는 것은 아니다. In the present invention, the EMSA (exposed metal surface area) value of the catalyst may be 5 to 15 m 2 g -1 , but is not limited thereto.
전술한 목적을 달성하기 위한 또 다른 본 발명은 (A) 유기리간드를 포함하는 백금 전구체와 유기리간드를 포함하는 코발트 전구체 혼합 용액을 열분해하여 나노입자를 제조하는 단계; (B) 상기 단계에서 제조된 나노입자를 열처리하는 단계;를 포함하여 제조되는 것을 특징으로 하는 전술한 촉매의 제조방법에 관한 것이다. Another present invention for achieving the above-described object includes the steps of (A) producing nanoparticles by thermally decomposing a mixed solution of a platinum precursor containing an organic ligand and a cobalt precursor containing an organic ligand; (B) heat-treating the nanoparticles prepared in the above step;
본 발명에서 상기 '유기리간드'로는 아세틸아세토네이트(acac)와 같은 β-디케톤(β-diketone)이나 카르보닐(carbonyl) 또는 카르복실(carboxyl)을 예로 들 수 있으나, 이에 한정되는 것은 아니며 탄소원을 포함하고 열분해에 의해 금속으로 환원될 수 있는 것이라면 어느 것이라도 무방하다. In the present invention, the 'organic ligand' may include β-diketone such as acetylacetonate (acac), carbonyl, or carboxyl, but is not limited thereto and is not limited to carbon source. Any material that contains and can be reduced to metal by thermal decomposition may be used.
본 발명에서 상기 (A) 단계의 열분해는 유기리간드를 포함하는 금속 전구체를 금속의 합금 나노입자로 환원시킬 수 있는 조건이라면 어떠한 것이라도 무방하다. 즉, 단순 가열에 의한 열분해 반응에 의하거나, 열분해 반응 시 환원제를 추가로 투여하여 반응의 속도를 제어하는 것도 가능하다. 환원제로서는 포름산, 아스코르브산, 시트릭 산, 올레일아민, 포름알데히드, 소듐보로하이드라이드, 2-메틸-2-피롤리딘으로 이루어진 군으로부터 선택된 하나 또는 둘 이상의 혼합물을 사용하는 것이 가능하며, 이에 한정되지 않는다. In the present invention, the thermal decomposition in step (A) may be performed under any conditions as long as the metal precursor containing the organic ligand can be reduced to metal alloy nanoparticles. That is, it is possible to control the reaction rate through a thermal decomposition reaction by simple heating or by additionally administering a reducing agent during the thermal decomposition reaction. As a reducing agent, it is possible to use one or a mixture of two or more selected from the group consisting of formic acid, ascorbic acid, citric acid, oleylamine, formaldehyde, sodium borohydride, and 2-methyl-2-pyrrolidine. It is not limited to this.
본 발명에서 상기 (A) 단계가 열처리에 의해 이루어지는 경우에는 250~350℃에서 이루어질 수 있다. 그러나 이는 통상적인 열처리 온도로서 전구체로 사용하는 물질의 열분해가 가능한 온도에서 이루어져야 하는 것이 당연하고, 전구체의 종류에 따라 적절한 온도를 선택할 수 있으므로 상기 범위에 한정되는 것은 아니다. (A) 단계에서 금속 전구체는 환원되어 백금-코발트 나노입자로 환원된다. 이때 탄소는 금속에 대해 소정의 용해도를 갖기 때문에 백금-코발트 나노입자 내부에는 유기리간드 유래의 탄소가 존재한다. In the present invention, when step (A) is performed by heat treatment, it may be performed at 250 to 350°C. However, this is a normal heat treatment temperature, and it is natural that it must be carried out at a temperature at which thermal decomposition of the material used as a precursor is possible, and an appropriate temperature can be selected depending on the type of precursor, so it is not limited to the above range. In step (A), the metal precursor is reduced to platinum-cobalt nanoparticles. At this time, since carbon has a certain solubility in metals, carbon derived from organic ligands exists inside the platinum-cobalt nanoparticles.
본 발명에서 상기 (A) 단계는 용액 중 탄소지지체를 추가로 포함하여 진행될 수 있다. 이 경우 금속 나노입자는 탄소지지체에 담지된 상태로 형성된다. 탄소지지체로는 카본 블랙, 카본 나노튜브, 그래핀, 그래핀 옥사이드의 환원물, 무정형 카본 등을 사용할 수 있다. In the present invention, step (A) may be performed by additionally including a carbon support in the solution. In this case, the metal nanoparticles are formed while supported on a carbon support. Carbon black, carbon nanotubes, graphene, reduced products of graphene oxide, amorphous carbon, etc. can be used as the carbon support.
본 발명에서 상기 (B) 단계의 열처리에 의해 나노입자 내부에 존재하던 탄소가 분리되어 나노입자를 둘러싸는 탄소쉘로 재배열된다. 열처리에 의해 탄소쉘이 에칭되어 결정에 결함이 생기면서 EMSA이 형성되는데, 선행기술(등록특허 10-2323270)보다 훨씬 낮은 EMSA 예를 들면 5~15 m2g-1가 될 수 있도록 (B) 단계는 600~950℃, 바람직하게는 700~900℃, 더욱 바람직하게는 750~850℃의 Ar 분위기에서 진행될 수 있다. 그러나 온도나 불활성 기체의 종류와 농도와 같은 열처리 조건을 적절히 변화시켜 주면 나노입자를 둘러싸는 탄소쉘의 기공의 크기와 기공도를 다르게 제어할 수도 있을 것이다. In the present invention, through the heat treatment in step (B), the carbon present inside the nanoparticles is separated and rearranged into a carbon shell surrounding the nanoparticles. EMSA is formed as the carbon shell is etched by heat treatment, creating defects in the crystal. EMSA is much lower than the prior art (registration patent 10-2323270), for example, 5 to 15 m 2 g -1 (B) The step may be carried out in an Ar atmosphere at 600 to 950°C, preferably 700 to 900°C, more preferably 750 to 850°C. However, by appropriately changing heat treatment conditions such as temperature or the type and concentration of inert gas, the pore size and porosity of the carbon shell surrounding the nanoparticles can be controlled differently.
이상과 같이 본 발명에 의하면 첨가되는 Co가 금속코어의 내부 대부분의 공간을 차지하고 백금이 금속코어의 표면 쪽에 노출되어 있으므로 첨가 금속에 의한 방해 없이 대부분의 백금이 촉매로 작용할 수 있게 된다. 또한 같은 이유로 싸이클이 축적되더라도 Co가 용출되더라도 (용출되기 어렵지만) 촉매 성능에 악영향을 주지 않는다. As described above, according to the present invention, the added Co occupies most of the space inside the metal core and the platinum is exposed to the surface of the metal core, so most of the platinum can act as a catalyst without interference by the added metal. Also, for the same reason, even if Co is eluted even after cycles are accumulated, it does not adversely affect catalyst performance (although it is difficult to elude).
또한 본 발명에 의하면 탄소쉘이 산소와 CO의 내부침투를 방지할 수 있으면서 EMSA가 작아 밀도와 강도가 높기 때문에 내피독성과 내구성이 동반하여 우수한 촉매가 가능하게 된다.In addition, according to the present invention, the carbon shell can prevent internal penetration of oxygen and CO, and the EMSA is small, resulting in high density and strength, thereby enabling an excellent catalyst with endothelial toxicity and durability.
이러한 본 발명에 의한 촉매의 구조는 연료전지 촉매의 주요 과제인 Pt 사용량을 줄일 수 있어 수소전지의 경제성 향상에 기여하고, Pt 대부분이 촉매작용에 참여하므로 우수한 성능이 보장되며, 강고한 탄소쉘에 의해 PEMFC의 정지/시동 주기 동안 역전류 흐름을 방지하므로 내구성을 증대시킬 수 있게 한다. The structure of the catalyst according to the present invention contributes to improving the economic efficiency of hydrogen cells by reducing the amount of Pt used, which is a major problem in fuel cell catalysts. Excellent performance is guaranteed because most of the Pt participates in the catalysis reaction, and the strong carbon shell This prevents reverse current flow during the stop/start cycle of the PEMFC, thereby increasing durability.
도 1a~1c는 본 발명의 일실시예에 의해 제조된 촉매의 TEM 이미지(도 1a, 1b)와 이로부터 확인된 입자경 분포 그래프(도 1c).
도 2는 본 발명의 일실시예에 의해 제조된 촉매의 CV 커브와 CO 박리 커브.
도 3은 본 발명의 일실시예에 의해 제조된 촉매의 평균 입경과 EMSA.
도 4는 Pt1Co2@C/C의 표면 구조 분석 사진 및 도표.
도 5는 본 발명에 의한 촉매의 전기화학적 시험 데이터.FIGS. 1A to 1C are TEM images (FIGS. 1A, 1B) of the catalyst prepared according to an embodiment of the present invention and a particle diameter distribution graph (FIG. 1C) confirmed therefrom.
Figure 2 shows the CV curve and CO stripping curve of a catalyst prepared by an embodiment of the present invention.
Figure 3 shows the average particle diameter and EMSA of the catalyst prepared by one embodiment of the present invention.
Figure 4 is a photo and diagram of surface structure analysis of Pt 1 Co 2 @C/C.
Figure 5 shows electrochemical test data of the catalyst according to the present invention.
본 연구는 한국전력공사의 2021년 착수 사외공모 기초연구(개발연구)사업의 과제 연구비에 의해 지원되었다. (과제번호 : Ｒ21ＸＯ01-16)This study was supported by a project research grant from the Korea Electric Power Corporation's external public open basic research (development research) project launched in 2021. (Assignment number: R21XO01-16)
이하 첨부된 도면과 실시예를 들어 본 발명을 보다 상세히 설명한다. 그러나 이러한 도면과 실시예는 본 발명의 기술적 사상의 내용과 범위를 쉽게 설명하기 위한 예시일 뿐, 이에 의해 본 발명의 기술적 범위가 한정되거나 변경되는 것은 아니다. 이러한 예시에 기초하여 본 발명의 기술적 사상의 범위 안에서 다양한 변형과 변경이 가능함은 당업자에게는 당연할 것이다. Hereinafter, the present invention will be described in more detail with reference to the attached drawings and examples. However, these drawings and examples are merely examples for easily explaining the content and scope of the technical idea of the present invention, and the technical scope of the present invention is not limited or changed thereby. Based on these examples, it will be obvious to those skilled in the art that various modifications and changes are possible within the scope of the technical idea of the present invention.
본 발명은 PEMFC에서 역전류 흐름을 방지하기 위해 가스 선택성을 가진 탄소쉘 캡슐화 촉매 및 이의 제조방법에 관한 것이다. 촉매는 탄소원을 포함하는 금속 전구체를 열분해 및 열처리를 통해 금속 나노입자의 표면에 탄소쉘을 형성하여 합성하였으며, 촉매는 Pt 및 Co 합금 조성을 갖는다. Co에서 탄소의 높은 용해도는 탄소 껍질 두께와 구조를 제어할 수 있게 하여 기체 선택성을 개선하는 효과를 나타내었다. 또한 열처리 과정에서 Pt와 Co 사이의 분리 에너지 차이로 인해 Pt가 풍부한 표면이 형성되었다. 따라서 더 적은 Pt를 사용하여 동일한 촉매 활성을 얻을 수 있게 되었다. The present invention relates to a carbon shell encapsulated catalyst with gas selectivity to prevent reverse current flow in a PEMFC and a method for manufacturing the same. The catalyst was synthesized by forming a carbon shell on the surface of the metal nanoparticle through thermal decomposition and heat treatment of a metal precursor containing a carbon source, and the catalyst has a Pt and Co alloy composition. The high solubility of carbon in Co allowed control of the carbon shell thickness and structure, which had the effect of improving gas selectivity. Additionally, during the heat treatment process, a Pt-rich surface was formed due to the separation energy difference between Pt and Co. Therefore, the same catalytic activity could be obtained using less Pt.
[실시예][Example]
실시예 1 : 촉매의 제조 Example 1: Preparation of catalyst
제조예 : 이중 코어쉘 Pt-Co 촉매(PtManufacturing example: Double core-shell Pt-Co catalyst (Pt 1One CoCo 22 @C/C)의 제조@C/C) manufacturing
Carbon black(Vulcan XC72, Cabot) 0.1g과 올레일아민(Oleylamine, 70%, Sigma-Aldrich) 5ml를 1-옥타데켄(Octadecene, 90%, Alfa-Aesar) 120ml에 넣고 20분간 초음파로 잘 분산시켜 균일한 현탁액을 제조하였다. Pt(acac)2(Platinum acetylacetonate, 97%, Sigma-Aldrich) 0.0324g과 Co(acac)2(Cobalt acetylacetoante, 99%, Sigma-Aldrich) 0.0415g, 올레일아민 5ml 및 1-옥타데켄 40ml를 혼합한 후 투명한 용액이 될 때까지 30분간 초음파 처리하였다. 상기 두 용액을 혼합하고 5분간 초음파 처리한 후, Ar 대기, 120℃에서 1시간 동안 교반하여 용액 중 물을 제거하였다. 1시간 후, 300℃로 승온하여 2시간 유지하여 Pt 전구체와 Co 전구체를 열분해하였다. Add 0.1 g of Carbon black (Vulcan A homogeneous suspension was prepared. Mix 0.0324 g of Pt(acac) 2 (Platinum acetylacetonate, 97%, Sigma-Aldrich), 0.0415 g of Co(acac) 2 (Cobalt acetylacetoante, 99%, Sigma-Aldrich), 5 ml of oleylamine, and 40 ml of 1-octadecene. Afterwards, it was sonicated for 30 minutes until it became a clear solution. The two solutions were mixed and sonicated for 5 minutes, and then stirred for 1 hour at 120°C in Ar atmosphere to remove water from the solution. After 1 hour, the temperature was raised to 300°C and maintained for 2 hours to thermally decompose the Pt precursor and Co precursor.
반응이 종결되면 반응액을 80℃로 냉각한 후 여과하고 다량의 헥산(95%, Samchun Pure Chemical)과 에탄올(95%, Samchun Pure Chemical)로 순차적으로 세척하였다. 여과된 촉매를 60℃의 진공 오븐에서 건조하여 Pt1Co2@C/C ASP(as-prepared sample)를 얻었다.When the reaction was completed, the reaction solution was cooled to 80°C, filtered, and sequentially washed with a large amount of hexane (95%, Samchun Pure Chemical) and ethanol (95%, Samchun Pure Chemical). The filtered catalyst was dried in a vacuum oven at 60°C to obtain Pt 1 Co 2 @C/C ASP (as-prepared sample).
건조된 Pt1Co2@C/C ASP 촉매를 800℃ Ar 분위기에서 1시간 동안 열처리(annealing)하여 Pt1Co2@C/C 촉매를 제조하였다. 열처리 과정에서 탄소원은 금속 입자 격자 속으로 용해되고 분리 에너지의 차이로 인해 입자 표면에서 분리되어 탄소 코팅된 촉매가 형성된다.The dried Pt 1 Co 2 @C/C ASP catalyst was annealed at 800°C in an Ar atmosphere for 1 hour to prepare the Pt 1 Co 2 @C/C catalyst. During the heat treatment process, the carbon source is dissolved into the metal particle lattice and separated from the particle surface due to the difference in separation energy, forming a carbon-coated catalyst.
제조공정 중 Co(acac)2을 사용하지 않고 Pt(acac)2만 0.0509g 사용한 것을 제외하고는 1)과 동일한 방법으로 Pt 촉매를 제조하였다. 열처리 전의 시료는 Pt@C/C ASP로, 열처리 후의 시료는 Pt@C/C(비교예 1)로 명명하였다.A Pt catalyst was manufactured in the same manner as 1), except that only 0.0509 g of Pt(acac) 2 was used instead of Co(acac) 2 during the manufacturing process. The sample before heat treatment was named Pt@C/C ASP, and the sample after heat treatment was named Pt@C/C (Comparative Example 1).
백금 촉매가 카본 블랙 지지체에 담지된 상용의 Pt/C 촉매(Premetek)를 촉매 성능 평가를 위한 비교예 2로 사용하였다.A commercial Pt/C catalyst (Premetek) in which a platinum catalyst was supported on a carbon black support was used as Comparative Example 2 to evaluate catalyst performance.
실시예 2 : 촉매의 물리적/전기화학적 특성 평가Example 2: Evaluation of physical/electrochemical properties of catalyst
(1) 물리적 특성 평가 방법(1) Physical property evaluation method
TEM(Tecnai G2 F30 S-Twin, FEI)를 이용하여 실시예 1에서 제조된 촉매 입자의 크기 분포를 결정하였고, 고해상도 TEM(HR-TEM)(JEOL 2010 FasTEM microscope)으로 금속나노입자 위에 코팅된 카본쉘을 명확하게 확인하였다. TEM(HF5000, Hitachi)로 표면이 카본쉘로 둘러싸인 내부 나노입자에서 Pt가 풍부한 표면을 확인하였고, TEM(Titanubed G2 60-300, FEE)를 이용하여 EDS(energy dispersive spectroscopy)를 수행하였다. 제조된 촉매의 성능과 특성을 분석하기 위해 Si 4. Pt/C (Premetek)의 EDS spectrum을 대조구로 하였다. The size distribution of the catalyst particles prepared in Example 1 was determined using TEM (Tecnai G2 F30 S-Twin, FEI), and the carbon shell coated on the metal nanoparticles was determined using high-resolution TEM (HR-TEM) (JEOL 2010 FasTEM microscope). was clearly confirmed. The Pt-rich surface of the internal nanoparticle surrounded by a carbon shell was confirmed using TEM (HF5000, Hitachi), and energy dispersive spectroscopy (EDS) was performed using TEM (Titanubed G2 60-300, FEE). To analyze the performance and characteristics of the manufactured catalyst, the EDS spectrum of Si 4. Pt/C (Premetek) was used as a control.
시료를 왕수(aqua regia)로 전처리한 후 ICP-AES(OPTIMA 7300 DV, Perkin-Elmer)로 확인한 결과 Pt1Co2@C/C의 조성을 갖는 것을 확인하였다. After pre-treating the sample with aqua regia, it was confirmed to have the composition of Pt 1 Co 2 @C/C as a result of ICP-AES (OPTIMA 7300 DV, Perkin-Elmer).
(2) 전기화학적 특성 평가 방법(2) Electrochemical property evaluation method
모든 전기화학적 측정은 일반적인 전기화학적 방법(3극 셀)으로 측정하였다. 작업전극의 제조를 위하여 실시예 1에서 제조한 촉매 5mg을 Nafion ionomoer(5 wt%, Sigma-Aldrich) 68.7㎕ 및 2-프로판올(99.5 %, Sigma-Aldrich) 500㎕와 혼합하여 잉크 슬러리를 제조하였다. 슬러리 한 방울(5㎕)을 glassy carbon electrode(0.196 cm2, geometric surface area, Metrohm Autolab)에 적용시킨 다음 상온에서 건조시켰다. Glassy carbon의 총 금속 로딩은 44.85μg/cm2이었다. 백금선과 Ag/AgCl를 각각 상대전극과 기준전극으로 사용하였다. 모든 전위 값은 RHE(reversible hydrogen electrode, 가역수소전극)로 나타내었다. All electrochemical measurements were performed using a typical electrochemical method (3-pole cell). To prepare a working electrode, an ink slurry was prepared by mixing 5 mg of the catalyst prepared in Example 1 with 68.7 μl of Nafion ionomoer (5 wt%, Sigma-Aldrich) and 500 μl of 2-propanol (99.5 %, Sigma-Aldrich). . One drop (5㎕) of slurry was applied to a glassy carbon electrode (0.196 cm 2 , geometric surface area, Metrohm Autolab) and then dried at room temperature. The total metal loading of glassy carbon was 44.85 μg/cm 2 . Platinum wire and Ag/AgCl were used as the counter electrode and reference electrode, respectively. All potential values were expressed as RHE (reversible hydrogen electrode).
순환 전압전류도(CV; cyclic voltammograms)는 Ar로 포화된 0.1M HClO4, 20mVs-1에서 0.05-1.05V의 전위 범위에서 스캔되었다. Cyclic voltammograms (CV) were scanned in a potential range of 0.05-1.05 V at 20 mV s -1 in 0.1 M HClO 4 saturated with Ar.
ORR polarization curve는 O2로 포화된 0.1M HClO4에서 5mVs-1의 스캔 속도와, 0.05V와 1.05V 사이의 전위에서 1600rpm의 회전속도에서 측정되었고, HOR polarization curves는 H2로 포화된 0.1M HClO4에서 1mVs-1의 스캔 속도와, 0.05V와 0.1V 사이의 전위에서 1600rpm의 회전속도에서 측정되었다. The ORR polarization curves were measured at a scan rate of 5 mVs -1 in 0.1M HClO 4 saturated with O 2 and a rotation speed of 1600 rpm at potentials between 0.05V and 1.05V, and the HOR polarization curves were measured in 0.1M HClO 4 saturated with H 2 Measurements were made in HClO 4 at a scan rate of 1 mVs -1 and a rotation speed of 1600 rpm at potentials between 0.05 V and 0.1 V.
CO 박리(stripping) 시험으로 CO 산화 전류의 도입에 의한 촉매의 노출 금속 표면적(EMSA ; exposed metal surface area)을 정교하게 측정하였다.Through the CO stripping test, the exposed metal surface area (EMSA) of the catalyst was precisely measured by introducing a CO oxidation current.
작동전극(working electrode)에 0.05V를 가하면서 99.999% CO 가스를 0.1M HClO4에 15분 동안 버블링시켜 CO를 나노입자 표면 위에 흡착시켰다. 이어서 Ar 가스로 15분간 버블링하여 전해질 내의 잔류 CO 분자를 제거하였다. 20 mVs-1의 스캔 속도와 0.05와 1.05 VRHE의 포텐셜 범위에서 CO 박리가 수행되었다. While applying 0.05V to the working electrode, 99.999% CO gas was bubbled into 0.1M HClO 4 for 15 minutes to adsorb CO on the surface of the nanoparticles. Subsequently, residual CO molecules in the electrolyte were removed by bubbling with Ar gas for 15 minutes. CO stripping was performed at a scan rate of 20 mVs -1 and a potential range of 0.05 and 1.05 V RHE .
(3) 촉매의 물리적/전기화학적 특성(3) Physical/electrochemical properties of catalyst
도 1a~1c에 본 발명의 일실시예에 의해 제조된 촉매(Pt/C, Pt@C/C 및 Pt1Co2@C/C)의 다양한 해상도에서의 TEM 이미지(도 1a, 1b)와 이로부터 확인된 입자경 분포 그래프(도 1c), CV 커브(도 2의 (a)) 및 CO 박리 커브(도 2의 (b)), 및 평균 입경과 EMSA(도 3)를 도시하였다. 도 1a에서 내부에 있는 사진은 탄소쉘을 확인할 수 있는 각 나노입자의 고해상도 TEM 이미지이다. 도 4에 Pt1Co2@C/C의 표면 구조 분석을 도시하였다. 도 4에서 (a)의 빨간색 점은 Pt, (b)의 녹색 점은 Co, (c)의 빨간색 점과 녹색 점은 각각 Pt와 Co를 나타내는 EDS 매핑 이미지이다. 도 4에서 (d)는 라인 프로파일 및 삽입된 입자 이미지이다. 도 5에 본 발명에 의한 촉매의 전기화학적 시험 데이터를 도시하였다. 도 5에서 (a)는 Ar 포화 0.1M HClO4에서 HOR 분극 곡선, (b)는 Ar 포화 0.1M HClO4에서 ORR 분극 곡선의 변화, (c)는 HOR 선택성의 비교, (d)는 합금화 및 분자체 효과에 의해 향상된 기체 선택성을 나타내는 나노입자를 캡슐화하는 탄소쉘 층의 개략도이다.1A to 1C show TEM images (FIGS. 1A, 1B) at various resolutions of catalysts (Pt/C, Pt@C/C, and Pt 1 Co 2 @C/C) prepared by an embodiment of the present invention. The confirmed particle size distribution graph (FIG. 1c), CV curve (FIG. 2(a)), CO exfoliation curve (FIG. 2(b)), and average particle size and EMSA (FIG. 3) are shown. The photo inside in Figure 1a is a high-resolution TEM image of each nanoparticle where the carbon shell can be confirmed. Figure 4 shows the surface structure analysis of Pt 1 Co 2 @C/C. In Figure 4, the red dot in (a) is an EDS mapping image representing Pt, the green dot in (b) represents Co, and the red and green dots in (c) represent Pt and Co, respectively. In Figure 4 (d) is the line profile and inserted particle image. Figure 5 shows electrochemical test data of the catalyst according to the present invention. In Figure 5, (a) is the HOR polarization curve in Ar-saturated 0.1M HClO 4 , (b) is the change in ORR polarization curve in Ar-saturated 0.1M HClO 4 , (c) is a comparison of HOR selectivity, and (d) is alloying and Schematic diagram of the carbon shell layer encapsulating nanoparticles showing improved gas selectivity due to the molecular sieve effect.
도 1a~3에서 볼 수 있듯이, TEM으로 준비된 촉매의 표면에 탄소쉘의 존재를 확인할 수 있고 전기화학적 실험에 의해 촉매 표면의 구조를 알 수 있다. TEM 이미지와 입자경 분포를 보면 각 촉매(Pt/C, Pt@C/C 및 Pt1Co2@C/C) 입자는 잘 분산되어 있고 직경이 대략 2-3㎚였다. 도 1a (b), (c)의 내부사진에서 볼 수 있듯이, 탄소쉘이 입자 표면에 명확하게 존재하였다. CV 커브(도 2의 (a))를 보면 Pt@C/C와 Pt1Co2@C/C 각각의 수소 이온 흡착(Hupd : hydrogen underpotential deposition) 면적이 Pt/C보다 작은데 이는 전자의 입자 표면이 탄소쉘로 코팅되어 있기 때문이다. As can be seen in Figures 1a to 3, the presence of a carbon shell on the surface of the prepared catalyst can be confirmed by TEM, and the structure of the catalyst surface can be known by electrochemical experiments. Looking at the TEM image and particle size distribution, the particles of each catalyst (Pt/C, Pt@C/C, and Pt 1 Co 2 @C/C) were well dispersed and had a diameter of approximately 2-3 nm. As can be seen in the internal photographs of Figures 1a (b) and (c), the carbon shell was clearly present on the surface of the particle. Looking at the CV curve ((a) in Figure 2), the hydrogen ion adsorption (H upd : hydrogen underpotential deposition) area of Pt@C/C and Pt 1 Co 2 @C/C is smaller than that of Pt/C, which means that the electron particles This is because the surface is coated with a carbon shell.
입자 표면적은 도 2 (b)의 CO 박리 데이터에서 EMSA 값을 계산하여 분석되었으며, 이를 도 3의 입자 직경과 비교하였다. 도 1a의 TEM 데이터와 일치하여 세 시료 모두의 입자 크기는 비슷했지만 탄소쉘 코팅 촉매는 Pt/C보다 훨씬 낮은 EMSA 값을 가졌다.Particle surface area was analyzed by calculating EMSA values from the CO exfoliation data in Figure 2(b), and compared to the particle diameter in Figure 3. Consistent with the TEM data in Figure 1a, the particle sizes of all three samples were similar, but the carbon shell-coated catalyst had a much lower EMSA value than that of Pt/C.
흥미롭게도 Pt1Co2@C/C는 Pt@C/C보다 EMSA 값이 낮았다. 이는 Co의 합금 효과가 더 조밀한 탄소쉘의 형성으로 이어져 Pt@C/C에서보다 Pt1Co2@C/C에서 더 낮은 EMSA 값을 초래할 것으로 예측한 도 1a~3에서 제시된 구도와 일치하였다. Interestingly, Pt 1 Co 2 @C/C had a lower EMSA value than Pt@C/C. This was consistent with the plots presented in Figures 1a to 3, which predicted that the alloying effect of Co would lead to the formation of a denser carbon shell, resulting in lower EMSA values in Pt 1 Co 2 @C/C than in Pt@C/C. .
코어쉘 또는 백금이 풍부한 표면의 존재를 확인하기 위해 추가 EDS 분석을 수행하였다. 도 4의 (a)-(c)에 도시된 바와 같이, 많은 양의 Pt가 나노입자 표면에 분포되어 있다. 입자 분포를 명확하게 결정하기 위해 도 4의 (d)와 같이 촉매 나노 입자의 표면에서 EDS 라인 프로파일을 측정하였다. EDS 라인 프로파일은 입자 표면에 Pt가 풍부함을 확인시켜 주었다. 표면에서 Pt의 농축은 PtCo 합금 조성에 따른 어닐링 공정에서의 분리 에너지 차이의 결과이다. Pt와 Co는 처음에는 입자에 무작위로 분포되어 있다가 분리 에너지 차이로 인해 Pt 원자가 표면으로 이동하였다. 이렇게 입자 내부에 Co, 표면에 Pt가 분리농축되고 입자 위에 탄소쉘이 형성된 펼친 개념도가 도 5 (d)의 오른쪽 Pt1Co2@C/C로 표현되어 있다. Additional EDS analysis was performed to confirm the presence of a core-shell or platinum-rich surface. As shown in Figures 4 (a)-(c), a large amount of Pt is distributed on the surface of the nanoparticles. To clearly determine the particle distribution, the EDS line profile was measured on the surface of the catalyst nanoparticles as shown in Figure 4 (d). The EDS line profile confirmed the abundance of Pt on the particle surface. The enrichment of Pt at the surface is a result of differences in separation energy during the annealing process depending on the PtCo alloy composition. Pt and Co were initially randomly distributed in the particles, but due to the separation energy difference, Pt atoms moved to the surface. The unfolded conceptual diagram in which Co inside the particle and Pt on the surface are separated and concentrated and a carbon shell is formed on the particle is expressed as Pt 1 Co 2 @C/C on the right side of Figure 5 (d).
HOR 및 ORR 분극 곡선을 측정하여 가스 선택성과 역전류 흐름을 억제하는 능력을 분석하였다. 역전류 흐름을 억제하려면 수소는 촉매 표면과 접촉할 수 있어야 하지만 산소는 접촉하지 않아야 한다. 따라서 탄소쉘의 유무와 탄소쉘 구조의 차이에 따라 Pt/C, Pt@C/C 및 Pt1Co2@C/C의 기체 선택성 변화를 측정하여 해석하였다. 도 5 (a)에 도시된 바와 같이, Pt/C, Pt@C/C 및 Pt1Co2@C/C의 HOR 편광 곡선은 유사한 HOR 성능을 나타내었다. 대조적으로, 도 5 (b)의 ORR 편광 곡선은 Pt@C/C 및 Pt1Co2@C/C가 Pt/C보다 성능이 좋지 않음을 보여준다. Gas selectivity and the ability to suppress reverse current flow were analyzed by measuring HOR and ORR polarization curves. To suppress reverse current flow, hydrogen must be able to contact the catalyst surface, but oxygen must not. Therefore, changes in gas selectivity of Pt/C, Pt@C/C, and Pt 1 Co 2 @C/C were measured and analyzed depending on the presence or absence of a carbon shell and differences in carbon shell structure. As shown in Figure 5 (a), the HOR polarization curves of Pt/C, Pt@C/C, and Pt 1 Co 2 @C/C showed similar HOR performance. In contrast, the ORR polarization curve in Figure 5(b) shows that Pt@C/C and Pt 1 Co 2 @C/C perform worse than Pt/C.
이 현상은 도 5 (a) 및 (b)의 삽입 이미지로 설명할 수 있다. 선행 연구에 따르면 수소는 운동 직경이 비교적 작고 Pt@C/C 및 Pt1Co2@C/C의 입자 표면에 코팅된 탄소층을 쉽게 침투하여 내부 금속 입자와 반응할 수 있다. 따라서 탄소쉘 코팅된 촉매는 금속을 완전히 노출시킨 Pt/C와 유사한 HOR 성능을 나타냈다. 흥미롭게도 Pt1Co2@C/C 촉매는 Pt를 덜 함유했지만 HOR 성능은 순수한 Pt로 구성된 Pt/C 및 Pt@C/C 와 유사하였다. 이 현상은 도 4와 같이 Pt1Co2@C/C에서 Pt의 표면 농축에 기인한다.This phenomenon can be explained by the inserted images in Figures 5 (a) and (b). According to previous studies, hydrogen has a relatively small kinetic diameter and can easily penetrate the carbon layer coated on the particle surface of Pt@C/C and Pt 1 Co 2 @C/C and react with the internal metal particles. Therefore, the carbon shell-coated catalyst showed HOR performance similar to that of Pt/C with the metal fully exposed. Interestingly, although the Pt 1 Co 2 @C/C catalyst contained less Pt, the HOR performance was similar to that of Pt/C and Pt@C/C composed of pure Pt. This phenomenon is due to the surface enrichment of Pt in Pt 1 Co 2 @C/C, as shown in Figure 4.
HOR 및 ORR에 대한 도 4 (a) 및 (b)의 데이터는 아래 방정식에 따라 HOR 선택성 지수를 계산하는 데 사용되었다. 각 시료의 HOR 선택성은 도 5 (c)에 비교하여 나타내었다.The data in Figure 4(a) and (b) for HOR and ORR were used to calculate the HOR selectivity index according to the equation below. The HOR selectivity of each sample is compared in Figure 5 (c).
이 계산은 Pt1Co2@C/C가 Pt/C 및 Pt@C/C보다 각각 274.50% 및 130.51% 더 선택성이 있음을 나타낸니다. 이러한 가스 선택성의 차이는 도 5의 (d)에 표시된 분자체 효과에 기인한다. Pt/C의 표면은 완전히 노출된 금속 나노입자로 구성되어 있기 때문에 수소와 산소 모두 촉매 표면과 쉽게 접촉하여 반응하였다. 대조적으로, Pt@C/C 및 Pt1Co2@C/C를 둘러싸고 있는 탄소쉘은 운동역학 직경에 따라 수소를 투과하고 산소를 차단하여 기체 선택성을 유발할 수 있다. 나아가 Pt1Co2@C/C는 Co 합금으로부터 더 조밀한 탄소쉘을 형성하기 때문에 훨씬 더 높은 가스 선택성을 나타내었다. This calculation indicates that Pt 1 Co 2 @C/C is 274.50% and 130.51% more selective than Pt/C and Pt@C/C, respectively. This difference in gas selectivity is due to the molecular sieve effect shown in Figure 5(d). Because the surface of Pt/C is composed of completely exposed metal nanoparticles, both hydrogen and oxygen easily contacted and reacted with the catalyst surface. In contrast, the carbon shell surrounding Pt@C/C and Pt 1 Co 2 @C/C can permeate hydrogen and block oxygen depending on the kinetic diameter, resulting in gas selectivity. Furthermore, Pt 1 Co 2 @C/C showed much higher gas selectivity because it formed a denser carbon shell from the Co alloy.
Claims (8)
상기 나노입자 표면에 형성된 다공성 탄소쉘;로 이루어진 촉매.
Nanoparticles made of platinum and cobalt; and
A catalyst consisting of a porous carbon shell formed on the surface of the nanoparticles.
상기 나노입자는,
표면에 백금이, 내부에 코발트가 분포된 것을 특징으로 하는 촉매.
In claim 1,
The nanoparticles are,
A catalyst characterized by platinum distributed on the surface and cobalt distributed inside.
상기 나노입자의 백금과 코발트의 몰비는 1:1 ~ 1:3인 것을 특징으로 하는 촉매.
In claim 1,
A catalyst characterized in that the molar ratio of platinum and cobalt in the nanoparticles is 1:1 to 1:3.
EMSA 값이 5~15 m2g-1인 것을 특징으로 하는 촉매.
In claim 1,
A catalyst characterized in that the EMSA value is 5 to 15 m 2 g -1 .
(B) 상기 단계에서 제조된 나노입자를 열처리하는 단계;를
포함하여 제조되는 것을 특징으로 하는 청구항 1 내지 4 중 어느 한 항에 의한 촉매의 제조방법.
(A) preparing nanoparticles by thermally decomposing a mixed solution of a platinum precursor containing an organic ligand and a cobalt precursor containing an organic ligand;
(B) heat treating the nanoparticles prepared in the above step;
The method for producing the catalyst according to any one of claims 1 to 4, characterized in that it is produced by comprising:
상기 (A) 단계는 용액 중 탄소지지체를 추가로 포함하여 진행되는 것을 특징으로 하는 촉매의 제조방법.
In claim 5,
The method for producing a catalyst, characterized in that step (A) is carried out by additionally including a carbon support in the solution.
상기 (B) 단계는 Ar 분위기에서 진행되는 것을 특징으로 하는 촉매의 제조방법.
In claim 5,
The method for producing a catalyst, characterized in that step (B) is carried out in an Ar atmosphere.
상기 (B) 단계에서 열처리 온도는 600~950℃인 것을 특징으로 하는 촉매의 제조방법.In claim 5,
A method for producing a catalyst, characterized in that the heat treatment temperature in step (B) is 600 to 950 ° C.
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