CN114232020B - Water splitting catalyst and its prepn and application - Google Patents

Water splitting catalyst and its prepn and application Download PDF

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CN114232020B
CN114232020B CN202111507622.XA CN202111507622A CN114232020B CN 114232020 B CN114232020 B CN 114232020B CN 202111507622 A CN202111507622 A CN 202111507622A CN 114232020 B CN114232020 B CN 114232020B
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water splitting
cobalt
splitting catalyst
substrate
catalyst
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CN114232020A (en
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席聘贤
安丽
张楠
李庆宇
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Lanzhou University
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Lanzhou University
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
    • C25B11/057—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of a single element or compound
    • C25B11/065—Carbon
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
    • C25B11/075—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound
    • 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
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Abstract

The invention relates to a water splitting catalyst, a preparation method and a water splitting catalystApplication. The water splitting catalyst comprises a substrate and cobalt sulfide supported on the substrate, wherein the half-peak width of a peak of 2 theta in the range of 32-33 degrees in an X-ray diffraction pattern of the water splitting catalyst is H 1 The half-width of the peak of 2 theta in the range of 54.5 DEG to 55.5 DEG is H 2 Wherein, H is more than or equal to 1.1 2 /H 1 Less than or equal to 2.0. The water splitting catalyst provided by the invention has a unique nano-sheet array morphology assembled by nano-sheets and a characteristic structure with surface roughness increased along with the improvement of crystallinity. The low crystallinity and the relatively small roughness ensure the electron transmission and mass transfer diffusion, and the nano array assembled by the two-dimensional nano sheets provides rich reactive sites, so that the catalyst has excellent electrocatalytic water decomposition performance.

Description

Water splitting catalyst and its prepn and application
Technical Field
The invention belongs to the field of electrochemical catalysis, and particularly relates to a water splitting catalyst, a preparation method and application thereof.
Technical Field
In the past century, worldwide energy demands continue to grow due to the development of economic globalization and the ever-increasing population. From the relevant statistics recently released, 79.5% of the total energy consumed by humans in 2016 are dependent on traditional energy sources, such as: coal, oil, natural gas, however clean renewable energy sources like hydroelectric, wind, bioenergy and solar photovoltaics only provide 20.5% energy support. The current situation of high dependence on traditional fossil fuels inevitably accelerates the consumption degree of the traditional fossil fuels, and frequent natural disasters caused by the problems of environmental pollution, global warming and the like are warned, so that the development and utilization of clean sustainable energy are urgent. The hydrogen energy is clean and efficient, and the advantages of single combustion product, no pollution and the like make the hydrogen energy become one of the potential candidates of excellent energy carriers and future low-carbon energy systems. In a mass hydrogen production mode, electrocatalytic water splitting is widely studied as an efficient green and environment-friendly hydrogen production method.
The electrocatalytic water decomposition for preparing hydrogen is becoming one of the most promising hydrogen production modes for obtaining high-purity hydrogen by replacing the original industrial steam reforming technology due to the advantages of low price and easy availability of raw materials, convenient and quick operation and the like, and simultaneously provides possibility for the arrival of the hydrogen economy era. However, the complex four electron-proton coupled anodic Oxygen Evolution Reaction (OER) makes the driving voltage actually required for electrocatalytic water splitting often much higher than 1.23V of theory to overcome the electrical energy loss due to kinetic polarization overpotential. However, the commercial high-efficiency OER electrocatalyst is mainly Ir, ru noble metals and derivatives thereof, but the commercial high-efficiency OER electrocatalyst also has serious practical problems of rare earth crust reserves, complex preparation process, high application cost and the like, so that the energy requirements of the increasingly developed global villages are difficult to meet.
Therefore, we have urgent need to develop non-noble metal-based electrocatalyst materials with activity comparable to noble metals and high stability, so that they have high dual-function catalytic activities of HER and OER in the same electrolyte environment; and simultaneously has good conductivity and hydrophilicity so as to reduce the total overpotential of electrocatalytic water decomposition and thus reduce energy consumption.
Disclosure of Invention
In view of the problems and challenges in the art described above, the present invention provides a non-noble metal water splitting catalyst. The water splitting catalyst provided by the invention has a unique nano-sheet array morphology formed by assembling nano-sheets and a characteristic structure with increased surface roughness along with the improvement of crystallinity, the lower crystallinity and the relatively smaller roughness ensure electron transmission and mass transfer diffusion, and the nano-array formed by assembling the two-dimensional nano-sheets provides rich reactive sites, so that the catalyst provided by the invention has excellent electrocatalytic water splitting performance.
In a first aspect, the present invention provides a water splitting catalyst comprising a substrate and cobalt sulphide supported on the substrate, the water splitting catalyst having an X-ray diffraction pattern in which 2 theta is in the range of 32 deg. to 33 degThe half width of the internal peak is H 1 The half-width of the peak of 2 theta in the range of 54.5 DEG to 55.5 DEG is H 2 Wherein, H is more than or equal to 1.1 2 /H 1 Less than or equal to 2.0. According to some embodiments of the invention, H 2 /H 1 1.15, 1.25, 1.3, 1.35, 1.4, 1.45, 1.55, 1.6, 1.7, 1.8, 1.9 or any value therebetween. In some embodiments, 1.2.ltoreq.H 2 /H 1 Less than or equal to 1.5. In the present invention, the peak of 2 theta in the range of 32 deg. to 33 deg. in the X-ray diffraction pattern of the water splitting catalyst represents the characteristic peak of the cobalt sulfide (200) crystal face, and the peak of 2 theta in the range of 54.5 deg. to 55.5 deg. represents the characteristic peak of the cobalt sulfide (311) crystal face. The half-width ratio of the peaks of the two crystal faces is in the range, which shows that the water splitting catalyst has relatively low crystallinity, is favorable for the adsorption of water molecules and the transmission of electrons in the catalytic reaction process, optimizes the electronic structure of active sites, and can ensure the activity of the material and simultaneously ensure the material to have relatively excellent stability.
In some embodiments, 0.45 +.H 1 Less than or equal to 0.65, for example 0.46, 0.47, 0.48, 0.49, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.61, 0.63, 0.65 or any value therebetween. In some embodiments, 0.5 +.H 1 ≤0.6°。
In some embodiments, 0.7.ltoreq.H 2 Less than or equal to 0.9, e.g., 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.82, 0.85, 0.87, 0.89, or any value therebetween. In some embodiments, 0.7.ltoreq.H 2 ≤0.8°。
According to some embodiments of the invention, the intensity value of the peak of 2θ in the range of 32 ° to 33 ° in the X-ray diffraction pattern of the water splitting catalyst is I 1 Wherein, 100 is less than or equal to I 1 And +.300, such as 110, 130, 170, 180, 190, 200, 210, 230, 260, 270, 290 or any value therebetween. In some implementation ranges, 150.ltoreq.I 1 ≤250。
According to some embodiments of the invention, the water splitting catalyst comprises an X-ray diffractionThe intensity value of the peak of 2 theta in the range of 36-37 degrees in the map is I 2 Wherein, 50 is less than or equal to I 2 180, e.g., 60, 90, 110, 130, 140, 160, 170 or any value therebetween. In some embodiments, 100.ltoreq.I 2 And is less than or equal to 150. In the present invention, the peaks of 2 theta in the range of 36 DEG to 37 DEG in the X-ray diffraction pattern of the water splitting catalyst represent characteristic peaks of cobalt sulfide (210) crystal planes.
According to some embodiments of the invention, the intensity value of the peak of 2θ in the range of 54.5 ° to 55.5 ° in the X-ray diffraction pattern of the water splitting catalyst is I 3 Wherein, 50 is less than or equal to I 3 And 200, such as 70, 90, 110, 130, 140, 160, 180, 190 or any value therebetween. In some embodiments, 100.ltoreq.I 3 And is less than or equal to 150. In the invention, an X-ray diffraction pattern of the water splitting catalyst is obtained by testing an X-ray powder diffractometer (XRD, instrument model: miniFlex 600). Wherein the target material is Cu K alpha; the voltage and current are 40KV/15mA, the scanning angle range is 30-70 degrees, the testing step length is 0.02 degrees, and the scanning speed is 16 degrees/min.
According to some embodiments of the invention, the surface roughness of the water splitting catalyst is in the range of 0.5nm to 2.5nm, such as 0.7nm, 0.9nm, 1.1nm, 1.2nm, 1.4nm, 1.6nm, 1.8nm, 2.1m, 2.3nm or any value in between, as measured by atomic force microscopy. In some embodiments, the surface roughness of the water splitting catalyst is from 1.0nm to 2.0nm. In some embodiments, the surface roughness of the water splitting catalyst is from 1.2nm to 1.5nm.
In the present invention, the surface roughness of the water-splitting catalyst was tested by using a force microscope (MFP, instrument model: MFP-3D). And during the process, the height of the probe is adjusted, the surface morphology is characterized by using an air tapping mode, the scanning angle is 0, and the scanning speed is 256 lines/graph.
According to some embodiments of the invention, the cobalt sulfide comprises cos1.97. According to some embodiments of the invention, the water splitting catalyst has a nanoplatelet array morphology assembled from nanoplatelets.
According to some embodiments of the invention, the substrate is selected from one or more of carbon cloth and graphite sheet. In some embodiments, the substrate is carbon cloth, also known as carbon paper or carbon fiber cloth, which is a braid composed of carbon fibers interlaced.
According to some embodiments of the invention, the cobalt sulfide loading on the substrate is 0.5mg/cm 2 -3mg/cm 2 For example 0.7mg/cm 2 、0.9mg/cm 2 、1.0mg/cm 2 、1.2mg/cm 2 、1.4mg/cm 2 、1.6mg/cm 2 、1.8mg/cm 2 、2.2mg/cm 2 、2.5mg/cm 2 、2.7mg/cm 2 Or any value therebetween. In some embodiments, the cobalt sulfide loading on the substrate is 0.5mg/cm 2 -1.5mg/cm 2 。
The water splitting catalyst has unique nano sheet array morphology assembled by nano sheets and characteristic structure with surface roughness increased along with the improvement of crystallinity. The low crystallinity and the relatively small roughness ensure the electron transmission and mass transfer diffusion, and the nano array assembled by the two-dimensional nano sheets provides rich reactive sites, so that the catalyst has excellent electrocatalytic water decomposition performance.
In a second aspect, the present invention provides a process for preparing the water splitting catalyst of the first aspect, comprising
S1: providing a substrate loaded with basic cobalt carbonate;
s2: the substrate loaded with basic cobalt carbonate is sulfided at a temperature of 200 ℃ to 390 ℃ and in the presence of a sulfur source.
According to some embodiments of the invention, in S2, the temperature is 230 ℃, 270 ℃, 300 ℃, 330 ℃ or 370 ℃. In a gaming embodiment, the temperature is 250 ℃ to 350 ℃.
According to the invention, the crystallinity of cobalt sulfide in-situ growth process is regulated and controlled by temperature, so that cobalt sulfide nanosheet arrays with different crystallinity grown on a substrate are obtained.
According to some embodiments of the invention, the time of the vulcanization treatment in S2 is 0.5h-5h, e.g. 0.8h, 1.3h, 1.5h, 1.7h, 2.5h, 3h or 4h. In some embodiments, the time of the vulcanization treatment in S2 is 1h to 2h. In some embodiments, the sulfiding treatment is performed in an atmosphere of an inert carrier gas, preferably one of nitrogen or argon, more preferably argon; the carrier gas flow rate is preferably 50-200 standard milliliters per minute, more preferably 100 standard milliliters per minute.
According to some embodiments of the invention, the sulfur source has a mass of 0.1g to 1.0g. In some embodiments, the sulfur source has a mass of 0.3g to 0.7g. According to some embodiments of the invention, the sulfur source is selected from one or more of sublimated sulfur powder or thiourea.
According to some embodiments of the invention, in S1, the providing a substrate loaded with basic cobalt carbonate comprises:
s11: mixing a substrate with a solution containing a cobalt source and a mineralizer to obtain a first mixture;
s12: the first mixture is subjected to a hydrothermal reaction at a temperature of 100 ℃ to 150 ℃, preferably 110 ℃ to 130 ℃.
According to some embodiments of the invention, the molar ratio of the cobalt source to mineralizer is 0.5:1 to 1.5:1. In some embodiments, the molar ratio of cobalt source to mineralizer is from 0.8:1 to 1.0:1, e.g., 0.86:1.
In some embodiments, the solution containing a cobalt source and a mineralizer is an aqueous solution containing a cobalt source and a mineralizer, preferably the concentration of the cobalt source in the aqueous solution is from 6.5mmol/L to 7.5mmol/L, such as 6.9mmol/L, and/or the concentration of the mineralizer is from 7mmol/L to 9mmol/L, such as 7.99mmol/L.
According to some embodiments of the invention, the time of the hydrothermal reaction in S12 is 10h-30h, e.g. 12h, 14h, 16h, 18h, 22h, 25 or 27h. In some embodiments, the hydrothermal reaction in S12 is for a period of 15h to 20h.
According to some embodiments of the invention, the substrate surface may be washed with an acid solution, such as ultrasonic washing, followed by washing with an organic solvent and water and drying, prior to mixing the substrate with the solution containing the cobalt source and mineralizer. In some embodiments, the acid solution may be an organic acid solution or an inorganic acid solution, preferably at least one of formic acid, acetic acid, sulfuric acid, hydrochloric acid, and nitric acid. In some embodiments, the organic solvent may be an alcohol or ketone, such as methanol, ethanol, isopropanol, acetone, and the like, preferably ethanol or acetone.
According to some embodiments of the invention, the cobalt source is selected from one or more of soluble cobalt salts. In some embodiments, the cobalt source is selected from one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate. According to some embodiments of the invention, the mineralizer is selected from one or more of urea, ammonia, and sodium hydroxide.
According to some embodiments of the present invention, the method for preparing the water splitting catalyst specifically comprises the following steps:
step A, cutting carbon cloth, preferably cut carbon cloth (3×4cm 2 ) Ultrasonic cleaning is carried out on the surface attachments by using ultrapure water and ethanol. And then carrying out hydrophilic treatment on the carbon cloth after the decontamination treatment by using nitric acid and ethanol.
And B, immersing the carbon cloth subjected to hydrophilic treatment in aqueous solution of cobalt salt and mineralizer, packaging the carbon cloth in a high-pressure reaction kettle, heating the carbon cloth at 100-150 ℃ and preferably 120 ℃ for 10-30 hours and preferably 16 hours, naturally cooling the reaction kettle, taking out the carbon cloth, washing and drying.
And C, arranging the dried carbon obtained in the step B in a magnetic boat with a certain amount of sulfur source, loading the magnetic boat into a high-temperature tube furnace, heating the magnetic boat to 350-450 ℃ in an inert atmosphere, maintaining the temperature for 1-5 h, preferably 2h, and performing program cooling to obtain a final product.
The preparation method of the water splitting catalyst provided by the invention comprises the following steps: firstly, basic cobalt carbonate is grown on a substrate, and then chemical vapor deposition is adopted to realize vulcanization by taking the basic cobalt carbonate as a precursor. The unique nano-sheet array structure of the water splitting catalyst endows the water splitting catalyst with rich geometrical edge active sites, good hydrophilicity and mass transfer diffusion channels; the lower crystallinity is more beneficial to the adsorption of water molecules and the transmission of electrons in the catalytic reaction process, optimizes the electronic structure of an active site, ensures the activity of the material, ensures the material to have excellent stability, and shows the phenomenon of activity improvement in long-time stability. In addition, the water splitting catalyst is prepared by a hydrothermal method and a chemical vapor deposition method, and the synthesis process is simple and easy to amplify and has a higher application prospect.
In a third aspect, the present invention provides the use of a water splitting catalyst as described above for the preparation of hydrogen and/or oxygen by water splitting. According to some embodiments of the present invention, the present invention provides the use of the above-described water splitting catalyst in an air battery. In some embodiments, the air cell comprises at least one of an aluminum air cell and a zinc air cell.
In a fourth aspect, the present invention provides a water splitting process comprising subjecting water to electrolysis in the presence of a water splitting catalyst according to the present invention.
Drawings
Fig. 1 is an X-ray diffraction pattern (XRD) of the products prepared in example 1, comparative example 1 and comparative example 2.
Fig. 2 is a low-power and high-power Scanning Electron Microscope (SEM) photograph of the products prepared in example 1, comparative example 1 and comparative example 2. Wherein the upper, middle and lower are photographs of the prepared products of example 1, comparative example 1 and comparative example 2, respectively.
FIG. 3 is a Raman spectrum (Raman) of the products prepared in example 1, comparative example 1 and comparative example 2.
FIG. 4 is a graph showing the polarization curves and Tafel of the oxygen evolution reaction of the products prepared in example 1, comparative example 1 and comparative example 2 in 1mol/L KOH solution.
FIG. 5 is a chart showing the chronopotentiometric stability of the oxygen evolution reaction of the products prepared in example 1, comparative example 1 and comparative example 2 in 1mol/L KOH solution.
Detailed Description
The present invention will be further illustrated by the following specific examples, but the scope of the present invention is not limited thereto.
Deionized water used in the experiment process is ultrapure water with the conductivity of 18.25MΩ, and reagents used in the experiment are all analytically pure.
The main instruments and reagents used:
a Bio-Logic (SP-150) electrochemical workstation for cyclic voltammetry, linear sweep voltammetry, chronopotentiometric stability testing;
Milli-Q ultra-pure water System (Merck group, germany) was used to prepare ultra-pure water;
ME204/02 analytical balance (METTER-TOLEDO instruments Co., ltd.) was used to weigh the drug;
MiniFlex diffractometer (Japanese Physics, rigaku) for X-ray diffraction characterization;
apreo S field emission scanning electron microscope (FEI, siemens, USA) is used for the appearance characterization of the catalyst;
LabRAM HR Evolution raman spectroscopy (HORIBA Jobin Yvon s.a.s.) is used for structural spectroscopy characterization of catalysts;
DHG-9070A vacuum drying oven (Shanghai-constant scientific instruments Co., ltd.);
SB-5200D ultrasonic cleaner (Ningbo Xinzhi Biotech Co., ltd.);
PT-X platinum electrode clamp, platinum sheet electrode, hg/HgO reference electrode (Wuhan Gaoshirui technology Co., ltd.) for electrochemical test;
cobalt nitrate (beijing enoki technologies limited);
urea (colone chemicals limited, adult city);
sublimed sulfur (Chengdu Kelong chemical reagent plant);
potassium hydroxide (colone chemicals limited, adult city);
nitric acid (silver-improved chemical agent limited);
absolute ethanol (Li Anlong bohua pharmaceutical chemistry limited);
carbon cloth (Fuel Cell Store company).
The testing method comprises the following steps:
XRD test: testing by adopting an X-ray powder diffractometer (XRD, instrument model: miniFlex 600), wherein the target material is Cu K alpha; the voltage and current are 40KV/15mA, the scanning angle range is 30-70 degrees, the testing step length is 0.02 degrees, and the scanning speed is 16 degrees/min.
Surface roughness test: the test was performed using a magnetic microscope (MFP, instrument model: MFP-3D). During the process, the height of the probe is adjusted, the surface morphology is characterized by utilizing an air tapping mode, the scanning angle is 0, the scanning speed is 256 lines/graph, and the test voltage and the sensitivity can be changed in time according to the specific test condition.
Example 1Water splitting catalyst carbon cloth/cobalt sulfide (CFP-LC-CoS) 1.97 NS S ) Is prepared from
Step 1) cutting the cut carbon cloth (3X 4 cm) 2 ) Placing the carbon cloth into 50mL of ethanol, ultrasonically cleaning for 15min, taking out, alternately flushing with ultrapure water and ethanol for several times, spreading the flushed carbon cloth on the bottom of a beaker, dripping a little ethanol, and then adding concentrated nitric acid until the carbon cloth is not covered. After the reaction is finished, a large amount of ultrapure water is used for flushing for a plurality of times (all the operations are carried out in a fume hood), then ethanol and ultrapure water are respectively used for repeatedly and alternately carrying out ultrasonic treatment for 15min, and finally the treated carbon cloth is stored in the ultrapure water for standby.
Step 2) 2.008g of cobalt nitrate and 0.4800g of urea are completely dissolved in 80mL of ultrapure water in sequence, and are filled into a 100mL polytetrafluoroethylene high-pressure reaction kettle liner, and then a piece of carbon cloth (3X 4 cm) subjected to hydrophilic treatment in step 1) is vertically placed 2 ). The inner lining of the reaction kettle filled with the solution is filled into a stainless steel autoclave and then is transferred to an oven, and the temperature is raised to 120 ℃ and kept for 16 hours, and then the reaction kettle is naturally cooled to room temperature. The carbon cloth after the growth material is taken out is washed by a large amount of ultrapure water and dried at 50 ℃ overnight.
And 3) accurately weighing 0.5000g of sublimated sulfur powder in the magnetic boat A, and placing the sample dried in the step 2) in the magnetic boat B. Two magnetic boats were placed in the middle of the tube furnace in the order of A and B, and were maintained at a flow rate of 100 standard milliliters per minute of argon carrier gas, and were programmed to a temperature of 350℃for 2 hours at a temperature ramp rate of 10℃per minute. Cooling to 50 ℃ according to a cooling speed program of 100 ℃ per hour to obtain a final product CFP-LC-CoS 1.97 NS S Wherein LC-CoS 1.97 NS S The load amount on the carbon cloth is 0.921mg/cm 2 。
The final product CFP-LC-CoS obtained in this example 1.97 NS S XRD of (C) is shown in FIG. 1, wherein each characteristic peak has an intensity value,The half-width and roughness values of the final product are shown in Table 1, the low-power and high-power scanning electron micrographs are shown in FIG. 2, and the Raman spectrum is shown in FIG. 3.
The final product CFP-LC-CoS 1.97 NS S Cut into 0.5X2 cm 2 The electrode is clamped on a Pt electrode clamp and directly used as a working electrode, a platinum sheet electrode is used as a counter electrode, an Hg/HgO electrode is used as a reference electrode, and a three-electrode system is adopted to perform oxygen evolution reaction test and oxygen evolution reaction stability test in a 1mol/L KOH solution.
The oxygen evolution reaction test mode adopts cyclic voltammetry with a sweep rate of 5mV/s to obtain a corresponding polarization curve shown in FIG. 4, wherein 10mA/cm 2 The overpotential for the water splitting current density was only 278mV.
The stability test mode of the oxygen evolution reaction is a chronopotentiometry, and a curve shown in FIG. 5 is obtained. In the timing potential stability test, along with the test, in order to ensure that the same current is output, the catalytic potential of the catalyst is increased and then reduced in the whole test process, namely the tendency of secondary activation appears, and the catalyst is proved to have good water decomposition catalytic performance and excellent stability.
Comparative example 1Water splitting catalyst carbon cloth/cobalt sulfide (CFP-MC-CoS) 1.97 NS S ) Is prepared from
Step 1) cutting the cut carbon cloth (3X 4 cm) 2 ) Placing the carbon cloth into 50mL of ethanol, ultrasonically cleaning for 15min, taking out, alternately flushing with ultrapure water and ethanol for several times, spreading the flushed carbon cloth on the bottom of a beaker, dripping a little ethanol, and then adding concentrated nitric acid until the carbon cloth is not covered. After the reaction is finished, a large amount of ultrapure water is used for flushing for a plurality of times (all the operations are carried out in a fume hood), then ethanol and ultrapure water are respectively used for repeatedly and alternately carrying out ultrasonic treatment for 15min, and finally the treated carbon cloth is stored in the ultrapure water for standby.
Step 2) 2.008g of cobalt nitrate and 0.4800g of urea are completely dissolved in 80mL of ultrapure water in sequence, and are filled into a 100mL polytetrafluoroethylene high-pressure reaction kettle liner, and then a piece of carbon cloth (3X 4 cm) subjected to hydrophilic treatment in step 1) is vertically placed 2 ). Filling the inner lining of the reaction kettle filled with the solution into a stainless steel autoclave and transferringAnd (3) heating to 120 ℃ for 16 hours, and naturally cooling to room temperature. The carbon cloth after the growth material is taken out is washed by a large amount of ultrapure water and dried at 50 ℃ overnight.
And 3) accurately weighing 0.5000g of sublimated sulfur powder in the magnetic boat A, and placing the sample dried in the step 2) in the magnetic boat B. Two magnetic boats were placed in the middle of the tube furnace in the order of A and B, and were maintained at a flow rate of 100 standard milliliters per minute of argon carrier gas, and were programmed to a temperature of 400℃for 2 hours at a temperature ramp rate of 10℃per minute. Cooling to 50 ℃ according to a cooling speed program of 100 ℃ per hour to obtain a final product CFP-MC-CoS 1.97 NS S Wherein MC-CoS 1.97 NS S The loading capacity on the carbon cloth is 0.763mg/cm 2 。
The final product CFP-MC-CoS obtained in this comparative example 1.97 NS S The X-ray diffraction pattern of (2) is shown in FIG. 1, wherein the intensity values, half-peak widths, and roughness values of the final products of the characteristic peaks are shown in Table 1, the high-power and low-power electron micrographs are shown in FIG. 2, and the Raman spectrum is shown in FIG. 3.
The final product was used directly as a water-splitting electrode in a 1mol/L KOH solution by the same test method as in example 1, 10mA/cm as shown in FIG. 4 2 The overpotential of the water splitting current density is 322 mV; meanwhile, as shown in fig. 5, in the timing potential stability test, as the test proceeds, in order to ensure that the same magnitude of current is output, the catalytic potential of the catalyst is gradually increased in the whole test process, and the stability of the material is gradually deteriorated.
Comparative example 2Water splitting catalyst carbon cloth/cobalt sulfide (CFP-HC-CoS) 1.97 NS S ) Is prepared from
Step 1) cutting the cut carbon cloth (3X 4 cm) 2 ) Placing the carbon cloth into 50mL of ethanol, ultrasonically cleaning for 15min, taking out, alternately flushing with ultrapure water and ethanol for several times, spreading the flushed carbon cloth on the bottom of a beaker, dripping a little ethanol, and then adding concentrated nitric acid until the carbon cloth is not covered. Washing with a large amount of ultrapure water for several times after the reaction is completed (all in a fume hood), repeatedly and alternately ultrasonic with ethanol and ultrapure water for 15min, respectively, and storing the treated carbon clothThere is ultrapure water ready for use.
Step 2) 2.008g of cobalt nitrate and 0.4800g of urea are completely dissolved in 80mL of ultrapure water in sequence, and are filled into a 100mL polytetrafluoroethylene high-pressure reaction kettle liner, and then a piece of carbon cloth (3X 4 cm) subjected to hydrophilic treatment in step 1) is vertically placed 2 ). The inner lining of the reaction kettle filled with the solution is filled into a stainless steel autoclave and then is transferred to an oven, and the temperature is raised to 120 ℃ and kept for 16 hours, and then the reaction kettle is naturally cooled to room temperature. The carbon cloth after the growth material is taken out is washed by a large amount of ultrapure water and dried at 50 ℃ overnight.
And 3) accurately weighing 0.5000g of sublimated sulfur powder in the magnetic boat A, and placing the sample dried in the step 2) in the magnetic boat B. Two magnetic boats were placed in the middle of the tube furnace in the order of A and B, and were maintained at a flow rate of 100 standard milliliters per minute of argon carrier gas, and were programmed to a temperature of 450℃for 2 hours at a temperature ramp rate of 10℃per minute. Cooling to 50 ℃ according to a cooling speed program of 100 ℃ per hour to obtain a final product CFP-HC-CoS 1.97 NS S Wherein HC-CoS 1.97 NS S The loading amount on the carbon cloth is 0.963mg/cm 2 。
The final product CFP-HC-CoS obtained in this comparative example 1.97 NS S The X-ray diffraction pattern of (2) is shown in FIG. 1, wherein the intensity values, half-peak widths, and roughness values of the final products of the characteristic peaks are shown in Table 1, the high-power and low-power electron micrographs are shown in FIG. 2, and the Raman spectrum is shown in FIG. 3.
The final product was used directly as a water-splitting electrode in a 1mol/L KOH solution by the same test method as in example 1, as shown in FIG. 4, 10mA/cm 2 The overpotential for the water splitting current density is only 305mV; meanwhile, as shown in fig. 5, in the timing potential stability test, along with the test, in order to ensure that the same current is output, the catalytic potential of the catalyst is obviously increased in the whole test process, and the stability of the material is obviously deteriorated.
TABLE 1
Figure BDA0003404899160000101
It should be noted that the above-described embodiments are only for explaining the present invention and do not limit the present invention in any way. The invention has been described with reference to exemplary embodiments, but it is understood that the words which have been used are words of description and illustration, rather than words of limitation. Modifications may be made to the invention as defined in the appended claims, and the invention may be modified without departing from the scope and spirit of the invention. Although the invention is described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, as the invention extends to all other means and applications which perform the same function.

Claims (15)

1. A water splitting catalyst comprising a substrate and cobalt sulfide supported on the substrate, wherein the half-peak width of a peak of 2 theta in a range of 32 degrees to 33 degrees in an X-ray diffraction pattern of the water splitting catalyst is H1, and the half-peak width of a peak of 2 theta in a range of 54.5 degrees to 55.5 degrees is H2, wherein 1.2 is less than or equal to H2/H1 is less than or equal to 1.5;
the intensity value of a peak of 2 theta in the range of 32 DEG to 33 DEG is I1, the intensity value of a peak of 2 theta in the range of 36 DEG to 37 DEG is I2, and the intensity value of a peak of 2 theta in the range of 54.5 DEG to 55.5 DEG is I3, wherein 150.ltoreq.I1.ltoreq.250, 100.ltoreq.I2.ltoreq.150, 100.ltoreq.I3.ltoreq.150;
in atomic force microscope testing, the surface roughness of the water splitting catalyst is 1.0nm-2.0nm.
2. The water splitting catalyst of claim 1, wherein H1 is 0.45 ° -0.65 °; and/or H2 is more than or equal to 0.7 DEG and less than or equal to 0.9 deg.
3. The water splitting catalyst of claim 2, wherein H1 is 0.5 ° -0.6 °; and/or H2 is more than or equal to 0.7 DEG and less than or equal to 0.8 deg.
4. A water splitting catalyst as claimed in any of claims 1 to 3, characterized in that the surface roughness of the water splitting catalyst is 1.2nm to 1.5nm in atomic force microscopy.
5. A water splitting catalyst as claimed in any of claims 1 to 3, wherein the cobalt sulphide comprises cos1.97; and/or the water splitting catalyst has a nano-sheet array morphology assembled by nano-sheets; and/or the substrate is selected from one or more of carbon cloth and graphite sheet; and/or the cobalt sulphide loading on the substrate is 0.5mg/cm 2 -3mg/cm 2 。
6. The water splitting catalyst of claim 5, wherein the loading of cobalt sulfide on the substrate is 0.5mg/cm 2 -1.5mg/cm 2 。
7. The method for producing a water splitting catalyst according to any one of claims 1 to 6, comprising the steps of: s1: providing a substrate loaded with basic cobalt carbonate; s2: the substrate loaded with basic cobalt carbonate is sulfided at a temperature of 200 ℃ to 390 ℃ and in the presence of a sulfur source.
8. The preparation method according to claim 7, wherein in S2: the substrate loaded with basic cobalt carbonate is sulfided at a temperature of 250 ℃ to 350 ℃ and in the presence of a sulfur source.
9. The method of claim 7, wherein in S1, the providing a substrate loaded with basic cobalt carbonate comprises: s11: mixing a substrate with a solution containing a cobalt source and a mineralizer to obtain a first mixture; s12: the first mixture is subjected to a hydrothermal reaction at a temperature of 100 ℃ to 150 ℃.
10. The method according to claim 9, wherein in S12, the first mixture is subjected to a hydrothermal reaction at a temperature of 110 ℃ to 130 ℃.
11. The method of any one of claims 7 to 10, wherein the molar ratio of cobalt source to mineralizer is 0.5:1 to 1.5:1; and/or the sulfur source has a mass of 0.1g to 1.0g; and/or the vulcanizing treatment time in the step S2 is 0.5-5 h; and/or the hydrothermal reaction in S12 is performed for 10-30 hours.
12. The method of any one of claims 7 to 10, wherein the molar ratio of cobalt source to mineralizer is 0.8:1 to 1.0:1; and/or the sulfur source has a mass of 0.3g to 0.7g; and/or the time of vulcanization treatment in the step S2 is 1h-2h; and/or the hydrothermal reaction in S12 is carried out for 15-20 hours.
13. The method of any one of claims 7-10, wherein the cobalt source is selected from one or more of soluble cobalt salts; and/or the mineralizer is selected from one or more of urea, ammonia water and sodium hydroxide; and/or the sulfur source is selected from one or more of sublimed sulfur powder or thiourea.
14. The method of claim 13, wherein the cobalt source is selected from one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate.
15. Use of a water splitting catalyst according to any of claims 1-6 or a water splitting catalyst prepared according to the method of preparation of any of claims 7-14 for the preparation of hydrogen and/or oxygen by water splitting.
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