Preparation method and application of catalyst containing bimetallic oxide and transition metal sulfide

Abstract

The invention relates to the technical field of energy materials and electro-catalysis, in particular to a preparation method and application of a catalyst containing bimetallic oxide and transition metal sulfide.The preparation method comprises the steps that firstly, thiourea, ammonium heptamolybdate and cobalt nitrate are sequentially mixed with ionized water, and ultrasonic treatment is conducted to prepare a uniform mixed solution; and then putting the mixed solution and a current collector into a tetrafluoroethylene lining together for hydrothermal reaction, and after the reaction is completed and natural cooling is performed, washing and vacuum drying are performed to obtain the alkaline electrolytic water oxygen evolution reaction catalyst containing the bimetallic oxide and the transition metal sulfide. The catalyst prepared by the invention shows relatively good stability and catalytic property in alkaline electrolyte, and relatively high current density can be obtained under relatively low overpotential. Meanwhile, the preparation method is simple to operate, short in time consumption, low in production cost and easy to realize large-scale production, and has an excellent application prospect in the field of electro-catalysis.

Description

Technical Field

[0001] The present invention relates to the field of energy materials and electrocatalysis technology, and in particular to a preparation method and application of a catalyst containing bimetallic oxides and transition metal sulfides. Background Art

[0002] As a clean, carbon-free secondary energy source and high-quality energy carrier, hydrogen energy will play an important role in the transformation of energy structure. At present, there are many ways to produce hydrogen, including hydrogen production from fossil fuels (coal gasification, natural gas hydrogen production, etc.), water electrolysis, industrial by-product hydrogen production, and new hydrogen production methods (biomass, photolysis of water, thermochemical cracking of water hydrogen production). Among them, water electrolysis is considered to be an efficient and promising hydrogen production technology due to its advantages of green environmental protection, flexible production and high purity of hydrogen production. However, the development of water electrolysis hydrogen production technology is not very mature, and the cost is high, making it difficult to carry out large-scale production. Therefore, the use of this method to prepare hydrogen is subject to certain restrictions. As we all know, water electrolysis hydrogen production includes hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The hydrogen evolution reaction refers to the process in which protons or hydronium ions obtain electrons at the cathode of the electrolyzer, undergo a reduction reaction, and generate hydrogen precipitation; the oxygen evolution reaction refers to the process in which hydroxide ions or water lose electrons at the anode of the electrolyzer, undergo an oxidation reaction, and generate oxygen precipitation. The hydrogen evolution reaction is simple and easy to carry out, while the oxygen evolution reaction is a four-electron reaction with a relatively slow kinetic process and multiple and complex reaction steps. It is not difficult to see from the above that the oxygen evolution reaction is the key factor restricting the efficiency of the entire water electrolysis device. Therefore, the development of high-performance OER catalysts is particularly important for hydrogen production by electrolysis of water.

[0003] At present, the catalysts commonly used in the oxygen evolution reaction in industrial hydrogen production can be divided into precious metal-based catalysts, transition metal-based catalysts and non-precious metal-based catalysts. Among them, precious metal-based catalysts mainly use IrO2 and RuO2. Although precious metal oxides (RuO2 and IrO2) have good OER activity, they are expensive, scarce in reserves, and have poor stability in alkaline electrolytes, so they cannot be used on a large scale. However, through the d-electron theory of solid catalysis, it can be seen that the good OER catalytic performance of precious metals is due to the high proportion of d-electron orbital electrons, and the first transition metal elements also have a large number of d-orbital electrons. In addition, compared with precious metal-based catalysts, transition metal catalysts are low in cost and sufficient in source, which makes up for the shortcomings of precious metal-based catalysts very well. In addition, doping heteroatoms on the catalyst can modify the catalyst and increase the electrocatalytic active sites of the catalyst. Therefore, the development of transition metal-based catalysts and non-precious metal-based catalysts is expected to replace traditional precious metal-based catalysts. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art, and to propose a preparation method and application of a catalyst containing bimetallic oxides and transition metal sulfides, wherein the catalyst uses a hydrothermal method to generate a large number of vacancies on nickel foam, which is convenient for CoMoO4 and CoS to grow on nickel foam. This method can improve the surface proton transfer rate of the catalyst and accelerate the precipitation of oxygen on the catalyst surface. At the same time, this method can construct a multidimensional catalyst with a heterogeneous interface and localized oxygen vacancies, so that the catalyst maintains a high electrophilic state, thereby improving the OER catalytic performance.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a catalyst containing a bimetallic oxide and a transition metal sulfide comprises the following steps:

[0007] Step 1, ultrasonically wash the current collector with ethanol, acetone, hydrochloric acid, and deionized water in sequence, and collect and set aside after vacuum drying;

[0008] Step 2, weigh a certain amount of thiourea, ammonium heptamolybdate and a cobalt source and add them into deionized water in sequence, and prepare a uniform mixed solution by ultrasonication;

[0009] Step 3: Place the prepared mixed solution and the pretreated current collector in the inner tank of the reactor for hydrothermal reaction. After the reaction is complete and naturally cooled, take out the current collector, wash it with deionized water and vacuum dry it to obtain a catalyst containing bimetallic oxides and transition metal sulfides.

[0010] Preferably, in step 1, the current collector is any one of nickel foam, copper foam, and iron foam, and the size of the current collector is 3×3 to 10×10 cm 2 .

[0011] Preferably, in step 1, ethanol is ultrasonicated for 10 to 40 min, acetone is ultrasonicated for 10 to 40 min, hydrochloric acid is ultrasonicated for 10 to 40 min, and deionized water is ultrasonicated for 10 to 40 min in sequence, and the temperature needs to be controlled at 10 to 20° C. during the ultrasonication.

[0012] Preferably, in step 2, the cobalt source is any one of cobalt carbonate, cobalt oxalate and cobalt nitrate.

[0013] Preferably, in step 2, the amount of thiourea used is 1 to 1.5 g, the amount of ammonium heptamolybdate used is 0.1 to 0.5 g, and the amount of the cobalt source used is 0.5 to 0.030 g.

[0014] Preferably, in step 3, the inner liner of the reactor is made of tetrafluoroethylene, the hydrothermal reaction temperature is 140-220°C, the reaction time is 5-25h, and the vacuum drying temperature is 40-60°C.

[0015] The present invention also provides an application of a catalyst containing bimetallic oxides and transition metal sulfides of transition elements obtained by the above preparation method in an oxygen evolution reaction in an alkaline electrolyte.

[0016] By adopting the above technical scheme: due to the reaction kinetics modulation caused by the introduction of vacancies and the formation of heterojunctions, in 1M KOH, at the same lower overpotential (546mV), Co 10 MoO4@Co 10 The oxygen evolution reaction with S / NF as catalyst showed 1916 mA cm -2 The current density of the conventional noble metal-based catalyst for oxygen evolution reaction is only 96.2 mA cm -2 Low current density. Co10MoO4@Co 10 The OER catalytic performance of S / NF is 20 times that of commercial IrO2 / NF. From the above data, it can be seen that the electrolysis alkaline water catalyst containing bimetallic oxides and transition metal sulfides provided by the present invention has excellent catalytic effect, excellent application prospects and commercial value, and is widely applicable to large-scale production and use.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. A water electrolysis catalyst containing bimetallic oxides and transition metal sulfides prepared by the present invention exhibits excellent dispersibility, activity and selectivity in alkaline electrolyte, and has excellent OER catalytic performance at a low overpotential (546mV@1916mAcm -2 ), which is IrO2 (546mV@96.2mAcm) used in the market -2 ). From the above data, it can be seen that the catalytic activity of the oxygen evolution reaction of water electrolysis in the three-electrode system is much higher than that of the oxygen evolution reaction of water electrolysis in the precious metal system, and the application prospect is very broad and has excellent commercial value.

[0019] 2. The present invention uses nickel foam as a base material and successfully loads an electrolytic alkaline water catalyst containing bimetallic oxides and transition metal sulfides on the nickel foam by a hydrothermal synthesis method. The method has mild preparation conditions and low time consumption, so that the dispersion, activity and selectivity of the produced catalyst are guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Co prepared in Example 1, Example 2 and Example 3 of the present invention 10 MoO4@Co 10 S / NF, Co5MoO4@Co5S / NF, Co 15 MoO4@Co 15S / NF samples and Mo4O prepared in Comparative Examples 1 and 3 11 / NF, XRD pattern of NF sample;

[0021] Figure 2 Co prepared in Example 1 of the present invention 10 MoO4@Co 10 SEM image of S sample and its corresponding EDS element spectrum distribution diagram;

[0022] Figure 3 Co prepared in Example 1, Example 2, and Example 3 of the present invention 10 MoO4@Co 10 S / NF, Co5MoO4@Co5S / NF, Co 15 MoO4@Co 15 Comparison of the OER performance of the S / NF sample with MoS / NF and IrO2 / NF prepared in Comparative Examples 1 and 2. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the protection scope of the present invention. The embodiments described in the present invention are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0024] Embodiment 1:

[0025] A catalyst containing bimetallic oxide and transition metal sulfide (Co 10 MoO4@Co 10 The preparation method of S / NF) comprises the following steps:

[0026] Step 1: Nickel foam (3.0 cm×3.0 cm, 0.5 mm) was ultrasonicated with anhydrous ethanol for 30 min, acetone for 30 min, 3M HCl solution for 15 min, and deionized water for 30 min, and the temperature was controlled at 10-20° C. After vacuum drying, the foam was collected for later use, and the drying temperature was controlled at 40-60° C.

[0027] Step 2: Weigh 1 g of thiourea, 0.1 g of ammonium heptamolybdate and 0.01 g of cobalt nitrate, add them into deionized water in sequence, and prepare a uniform mixed solution by ultrasonication.

[0028] Step 3: Transfer the prepared mixed solution and the pretreated current collector to a polytetrafluoroethylene liner for hydrothermal reaction at 150°C for 10 hours. After the reaction is complete and the current collector is cooled naturally, take out the current collector, wash it with deionized water, and then vacuum dry it to obtain a catalyst containing bimetallic oxides and transition metal sulfides.

[0029] Embodiment 2:

[0030] A method for preparing a catalyst containing bimetallic oxides and transition metal sulfides (Co5MoO4@Co5S / NF) comprises the following steps:

[0031] Step 1: Nickel foam (3.0 cm×3.0 cm, 0.5 mm) was ultrasonicated with anhydrous ethanol for 30 min, acetone for 30 min, 3M HCl solution for 15 min, and deionized water for 30 min, and the temperature was controlled at 10-20° C. After vacuum drying, the foam was collected for later use, and the drying temperature was controlled at 40-60° C.

[0032] Step 2: Weigh 1 g of thiourea, 0.1 g of ammonium heptamolybdate and 0.005 g of cobalt nitrate, add them into deionized water in sequence, and prepare a uniform mixed solution by ultrasonication.

[0033] Step 3: Transfer the prepared mixed solution and the pretreated current collector to a polytetrafluoroethylene liner for hydrothermal reaction at 150°C for 10 hours. After the reaction is complete and the current collector is cooled naturally, take out the current collector, wash it with deionized water, and then vacuum dry it to obtain a catalyst containing bimetallic oxides and transition metal sulfides.

[0034] Embodiment 3:

[0035] A catalyst containing bimetallic oxide and transition metal sulfide (Co 15 MoO4@Co 15 The preparation method of S / NF) comprises the following steps:

[0036] Step 1: Nickel foam (3.0 cm×3.0 cm, 0.5 mm) was ultrasonicated with anhydrous ethanol for 30 min, acetone for 30 min, 3M HCl solution for 15 min, and deionized water for 30 min, and the temperature was controlled at 10-20° C. After vacuum drying, the foam was collected for later use, and the drying temperature was controlled at 40-60° C.

[0037] Step 2: Weigh 1 g of thiourea, 0.1 g of ammonium heptamolybdate and 0.015 g of cobalt nitrate, and add them into deionized water in sequence by ultrasonication to prepare a uniform mixed solution.

[0038] Step 3: Transfer the prepared solution and the pretreated current collector to a polytetrafluoroethylene liner for hydrothermal reaction at 150°C for 10 hours. After the reaction is complete and the current collector is cooled naturally, take it out, wash it with deionized water, and then vacuum dry it to obtain a catalyst containing bimetallic oxides and transition metal sulfides.

[0039] From the attached Figure 1 The (020), (200), (220), (-131) crystal planes of CoMoO4 and the (104) crystal plane of CoS can be observed, which proves that CoMoO4 and CoS are successfully prepared on nickel foam. Figure 2 Co prepared in Example 1 of the present invention 10 MoO4@Co 10 SEM image of the S sample and its corresponding EDS element spectrum distribution diagram. The relatively uniform distribution of elements in the EDS image indicates that CoMoO4 and CoS grow uniformly on the surface of nickel foam; the SEM image shows that Co 10 MoO4@Co 10 The microstructure of S is stacked together in a spherical shape, which increases the surface area of ​​the catalyst and the electrochemical attachment sites, thereby improving the performance of the catalyst. Figure 3 It can be seen that the performance of catalysts containing bimetallic oxides and transition metal sulfides is significantly improved compared to commercial IrO2.

[0040] Comparative Example 1

[0041] Molybdenum trioxide catalyst for oxygen evolution reaction in alkaline water electrolysis (Mo4O 11 / NF) preparation method, comprising the following steps:

[0042] Step 1: Nickel foam (3.0 cm×3.0 cm, 0.5 mm) was ultrasonicated with anhydrous ethanol for 30 min, acetone for 30 min, 3M HCl solution for 15 min, and deionized water for 30 min, and the temperature was controlled at 10-20° C. After vacuum drying, the foam was collected for later use, and the drying temperature was controlled at 40-60° C.

[0043] Step 2: Weigh 1 g of thiourea and 0.1 g of ammonium heptamolybdate, add them into deionized water in sequence, and prepare a uniform mixed solution by ultrasonication.

[0044] Step 3: Transfer the prepared mixed solution and the pretreated current collector to a polytetrafluoroethylene liner for hydrothermal reaction at 150°C for 10 hours. After the reaction is complete and the current collector is cooled naturally, take it out, wash it with deionized water, and then vacuum dry it to obtain a Mo4O 11 catalyst.

[0045] Comparative Example 2:

[0046] The commercial catalyst IrO2 was used to replace the Co in Example 1. 10 MoO4@Co 10 S / NF catalyst, preparation of IrO2@NF:

[0047] Step 1: Add 1.06 mg of IrO2 catalyst to a mixed solution of 252 μL of isopropanol and 28 μL of Nafion solution, and ultrasonicate for 1 h. During the ultrasonication, the temperature should be controlled at 10-20° C. to obtain a uniformly dispersed slurry.

[0048] Step 2: The nickel foam (3.0 cm×3.0 cm, 0.5 mm) was ultrasonicated with anhydrous ethanol for 30 min, acetone for 30 min, 3M HCl solution for 15 min, and deionized water for 30 min, and the temperature was kept low during the ultrasonication. The foam was collected and used after vacuum drying. The drying temperature was controlled at 40-60°C.

[0049] Step 3: Cut the nickel foam into 1.2cm×0.2cm, 0.5mm, and then evenly drip the slurry on the cut nickel foam under a baking lamp, and collect it after it dries for later use.

[0050] Comparative Example 3:

[0051] Preparation of blank nickel foam:

[0052] Step 1: Nickel foam (3.0 cm×3.0 cm, 0.5 mm) was ultrasonicated with anhydrous ethanol for 30 min, acetone for 30 min, 3M HCl solution for 15 min, and deionized water for 30 min, and the temperature was controlled at 10-20° C. After vacuum drying, the foam was collected for later use, and the drying temperature was controlled at 40-60° C.

[0053] Electrochemical testing:

[0054] The electrochemical performance was tested by an electrochemical workstation, and the electrochemical workstation used was Chenhua electrochemical workstation, model CHI630E.

[0055] 1M KOH solution was used as the electrolyte, and a three-electrode system was used to prepare the Co 10 MoO4@Co10S / NF, Co5MoO4@Co5S / NF, Co 15 MoO4@Co 15 S / NF, Mo4O prepared in Comparative Example 1 and Comparative Example 2 11 / NF, IrO2 / NF were used as working electrodes, mercury oxide electrode as reference electrode, and graphite electrode as counter electrode to measure Co 10 MoO4@Co10 S / NF, Co5MoO4@Co5S / NF, Co 15 MoO4@Co 15 Linear sweep voltammetry curves of S / NF, MoS@NF, and IrO2@NF.

[0056] OER performance test:

[0057] The linear sweep voltammetry was used to characterize the Co5MoO4@Co5S / NF, Co 10 MoO4@Co10S / NF、Co 15 MoO4@Co 15 S / NF, MoS / NF, IrO2 / NF were tested for OER performance, and the obtained OER polarization curves (LSV diagrams) are shown in Figure 3 As shown. 10 MoO4@Co 10 S / NF at 100mAcm -2 At a current density of 1.344 mA cm, it has a minimum overpotential of 354 mV; and at 1916 mA cm -2 At a current density of , the overpotential is only 546 mV.

[0058] In summary, the alkaline water electrolysis catalyst containing bimetallic oxides and transition metal sulfides prepared by the present invention has excellent catalytic performance, and the catalytic effect far exceeds that of the precious metal catalyst (IrO2). The catalyst containing bimetallic oxides and transition metal sulfides of transition elements prepared by the present invention can also achieve a large current density at a lower overpotential, and also shows good stability at a large current density. The preparation method of the present invention is simple, time-consuming, and has low production cost, and is very suitable for industrial production and use.

[0059] The description and practice disclosed in the present invention are easy to think and understand for ordinary technicians in the technical field, and several improvements and modifications can be made without departing from the principles of the present invention. Therefore, modifications or improvements made without departing from the spirit of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a catalyst containing a bimetallic oxide and a transition metal sulfide, characterized in that: The steps include: Step 1, ultrasonically wash the current collector with ethanol, acetone, hydrochloric acid, and deionized water in sequence, and collect and set aside after vacuum drying; Step 2, weigh a certain amount of thiourea, ammonium heptamolybdate and a cobalt source and add them into deionized water in sequence, and prepare a uniform mixed solution by ultrasonication; Step 3: Place the prepared mixed solution and the pretreated current collector in the inner tank of the reactor for hydrothermal reaction. After the reaction is complete and naturally cooled, take out the current collector, wash it with deionized water and vacuum dry it to obtain a catalyst containing bimetallic oxides and transition metal sulfides.

2. The method for preparing a catalyst containing bimetallic oxide and transition metal sulfide according to claim 1, characterized in that: In step 1, the current collector is any one of nickel foam, copper foam, and iron foam, and the size of the current collector is 3×3 to 10×10 cm 2 .

3. The method for preparing a catalyst containing bimetallic oxide and transition metal sulfide according to claim 1, characterized in that: In step 1, ethanol is ultrasonicated for 10 to 40 minutes, acetone is ultrasonicated for 10 to 40 minutes, hydrochloric acid is ultrasonicated for 10 to 40 minutes, and deionized water is ultrasonicated for 10 to 40 minutes in sequence, and the temperature needs to be controlled at 10 to 20° C. during the ultrasonication.

4. The method for preparing a catalyst containing bimetallic oxide and transition metal sulfide according to claim 1, characterized in that: In step 2, the cobalt source is any one of cobalt carbonate, cobalt oxalate and cobalt nitrate.

5. The method for preparing a catalyst containing bimetallic oxide and transition metal sulfide according to claim 1, characterized in that: In step 2, the amount of thiourea used is 1-1.5 g, the amount of ammonium heptamolybdate used is 0.1-0.5 g, and the amount of cobalt source used is 0.5-0.030 g.

6. The method for preparing a catalyst containing bimetallic oxide and transition metal sulfide according to claim 1, characterized in that: In step 3, the hydrothermal reaction temperature is 140-220°C, the reaction time is 5-25h, and the vacuum drying temperature is 40-60°C.

7. Use of a catalyst containing bimetallic oxide and transition metal sulfide obtained by the preparation method according to any one of claims 1 to 6 in oxygen evolution reaction in alkaline electrolyte.

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