A method for preparing a catalyst containing bimetallic oxides and transition metal sulfides and its application.

Abstract

The present application relates to the technical fields of energy materials and electrocatalysis, and particularly relates to a preparation method and application of a catalyst containing bimetallic oxide and transition metal sulfide, which comprises the following steps: firstly, mixing thiocarbamide, ammonium heptamolybdate and cobalt nitrate with ionized water in sequence, and preparing a uniform mixed solution by ultrasonic; then, putting the mixed solution and a current collector into a tetrafluoroethylene lining for hydrothermal reaction; after the reaction is completed and naturally cooled, washing, vacuum drying, and then the catalyst for alkaline electrolytic water oxygen evolution reaction containing bimetallic oxide and transition metal sulfide can be obtained. The catalyst prepared by the present application exhibits good stability and catalytic property in the alkaline electrolyte, and can obtain a higher current density at a lower overpotential. Meanwhile, the preparation method of the present application is simple in operation, short in time consumption, low in production cost, easy to realize large-scale production, and has excellent application prospect in the field of electrocatalysis.

Description

Technical Field

[0001] This invention relates to the fields of energy materials and electrocatalysis, and particularly to a method for preparing and applying a catalyst containing bimetallic oxides and transition metal sulfides. Background Technology

[0002] Hydrogen energy, as a clean and carbon-free secondary energy source and a high-quality energy carrier, will play a crucial role in the transformation of the energy structure. Currently, there are various methods for hydrogen production, including hydrogen production from fossil fuels (coal gasification, natural gas production, etc.), hydrogen production through water electrolysis, hydrogen production from industrial by-products, and novel hydrogen production methods (biomass, photocatalytic water splitting, thermochemical water cracking). Among these, water electrolysis is considered a highly efficient and promising hydrogen production technology due to its advantages of being environmentally friendly, flexible in production, and producing high-purity hydrogen. However, water electrolysis technology is not yet fully mature and has high costs, making large-scale production difficult. Therefore, the use of this method for hydrogen production is somewhat limited. As is well known, water electrolysis for hydrogen production involves the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). The HER refers to the process where protons or hydrated hydrogen ions gain electrons at the cathode of the electrolyzer, undergoing a reduction reaction to produce hydrogen gas. The OER refers to the process where hydroxide ions or water lose electrons at the anode of the electrolyzer, undergoing an oxidation reaction to produce oxygen gas. The hydrogen evolution reaction (OER) is simple and easy to carry out, while the oxygen evolution reaction (OER) is a four-electron reaction with a slower kinetic process and more complex steps. It is clear from this that the OER is a key factor limiting the efficiency of the entire water electrolysis device. Therefore, developing high-performance OER catalysts is particularly important for hydrogen production through water electrolysis.

[0003] Currently, catalysts commonly used in the oxygen evolution reaction (OER) of industrial hydrogen production can be classified into noble metal-based catalysts, transition metal-based catalysts, and non-noble metal-based catalysts. Among these, noble metal-based catalysts mainly utilize IrO2 and RuO2. While noble metal oxides (RuO2 and IrO2) exhibit good OER activity, their high price, scarce reserves, and poor stability in alkaline electrolytes limit their large-scale application. However, based on the d-electron theory of solid-state catalysis, the superior OER catalytic performance of noble metals is attributed to their high d-electron orbital proportions. First transition metal elements also possess a large number of d-orbital electrons, and compared to noble metal-based catalysts, transition metal catalysts are lower in cost and more readily available, effectively compensating for the shortcomings of noble metal-based catalysts. Furthermore, doping catalysts with heteroatoms can modify them, increasing the number of electrocatalytically active sites. Therefore, the development of transition metal-based and non-noble metal-based catalysts holds promise for replacing traditional noble metal-based catalysts. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for preparing a catalyst containing bimetallic oxides and transition metal sulfides, and its application. This catalyst utilizes a hydrothermal method to generate a large number of vacancies on nickel foam, facilitating the growth of CoMoO4 and CoS on the nickel foam. Using this method can improve the surface proton transport rate of the catalyst, accelerate oxygen evolution on the catalyst surface, and simultaneously construct a multidimensional catalyst with heterogeneous interfaces and localized oxygen vacancies, maintaining a high electrophilic state and thus improving OER catalytic performance.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

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

[0007] Step 1: Wash the current collector sequentially with ethanol, acetone, hydrochloric acid and deionized water using ultrasonication, dry it under vacuum and collect it for later use;

[0008] Step 2: Weigh a certain amount of thiourea, ammonium heptamolybdate and cobalt source and add them to deionized water in sequence, and prepare a homogeneous mixed solution by sonication;

[0009] Step 3: Place the prepared mixed solution and the pretreated current collector into the inner liner of the reactor for hydrothermal reaction. After the reaction is complete and the mixture cools naturally, remove the current collector, wash it with deionized water and then 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, or iron foam, and the size of the current collector is 3×3 to 10×10 cm. 2 .

[0011] Preferably, in step 1, the ultrasonic treatment is performed sequentially with ethanol for 10-40 minutes, acetone for 10-40 minutes, hydrochloric acid for 10-40 minutes, and deionized water for 10-40 minutes, and the temperature needs to be controlled at 10-20°C during the ultrasonic treatment.

[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 is 1-1.5g, the amount of ammonium heptamolybdate is 0.1-0.5g, and the amount of cobalt source is 0.5-0.030g.

[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 5–25 h, 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 obtained by the above preparation method in the oxygen evolution reaction in an alkaline electrolyte.

[0016] By employing the above technical solution: due to the modulation of reaction kinetics caused by vacancy introduction and heterojunction formation, in 1M KOH, at the same low overpotential (546mV), using Co... 10 MoO4@Co 10 The oxygen evolution reaction with S / NF as a catalyst exhibits a value of 1916 mA / cm². -2 The high current density of traditional noble metal-based catalysts for the oxygen evolution reaction (OER) is only 96.2 mA / cm². -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 electrolytic alkaline water catalyst containing bimetallic oxides and transition metal sulfides provided by this invention exhibits excellent catalytic effect, has 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. The water electrolysis catalyst containing bimetallic oxides and transition metal sulfides prepared in this invention exhibits excellent dispersibility, activity, and selectivity in alkaline electrolytes, and demonstrates excellent OER catalytic performance at a low overpotential (546mV@1916mAcm). -2 ), is the commercially available IrO2 (546mV@96.2mAcm). -2 The catalytic activity of oxygen evolution reaction in water electrolysis is more than 20 times that in the noble metal system. As can be seen from the above data, the catalytic activity of oxygen evolution reaction in water electrolysis under the three-electrode system is far higher than that under the noble metal system, indicating a very broad application prospect and excellent commercial value.

[0019] 2. This invention uses nickel foam as the substrate material and successfully supports an electrolytic alkaline water catalyst containing bimetallic oxides and transition metal sulfides on nickel foam via a hydrothermal synthesis method. The mild preparation conditions and short preparation time ensure the dispersion, activity, and selectivity of the produced catalyst. Attached Figure Description

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

[0021] Figure 2 Co prepared in Example 1 of this invention 10 MoO4@Co 10 SEM image of sample S and its corresponding EDS elemental distribution map;

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

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to 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 scope of protection of the present invention. The embodiments described in this invention are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] Example 1:

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

[0026] Step 1: Sonicate the nickel foam (3.0cm × 3.0cm, 0.5mm) sequentially with anhydrous ethanol for 30 min, acetone for 30 min, 3M HCl solution for 15 min, and deionized water for 30 min, maintaining the temperature between 10 and 20°C during sonication. Collect the foamed nickel after vacuum drying, maintaining the drying temperature between 40 and 60°C for later use.

[0027] Step 2: Weigh 1g of thiourea, 0.1g of ammonium heptamolybdate and 0.01g of cobalt nitrate, add them sequentially to deionized water, and sonicate to prepare a homogeneous mixed solution.

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

[0029] Example 2:

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

[0031] Step 1: Sonicate the nickel foam (3.0cm × 3.0cm, 0.5mm) sequentially with anhydrous ethanol for 30 min, acetone for 30 min, 3M HCl solution for 15 min, and deionized water for 30 min, maintaining the temperature between 10 and 20°C during sonication. Collect the foamed nickel after vacuum drying, maintaining the drying temperature between 40 and 60°C for later use.

[0032] Step 2: Weigh 1g of thiourea, 0.1g of ammonium heptamolybdate and 0.005g of cobalt nitrate, add them sequentially to deionized water, and sonicate to prepare a homogeneous mixed solution.

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

[0034] Example 3:

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

[0036] Step 1: Sonicate the nickel foam (3.0cm × 3.0cm, 0.5mm) sequentially with anhydrous ethanol for 30 min, acetone for 30 min, 3M HCl solution for 15 min, and deionized water for 30 min, maintaining the temperature between 10 and 20°C during sonication. Collect the foamed nickel after vacuum drying, maintaining the drying temperature between 40 and 60°C for later use.

[0037] Step 2: Weigh 1g of thiourea, 0.1g of ammonium heptamolybdate and 0.015g of cobalt nitrate, and add them sequentially to deionized water and sonicate to prepare a homogeneous mixed solution.

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

[0039] From the appendix Figure 1 The (020), (200), (220), and (-131) crystal planes of CoMoO4 and the (104) crystal plane of CoS can be observed, thus proving the successful preparation of CoMoO4 and CoS on nickel foam. (See attached image) Figure 2 Co prepared in Example 1 of this invention 10 MoO4@Co 10 SEM images of sample S and their corresponding EDS elemental distribution maps show that the relatively uniform distribution of elements in the EDS image indicates that CoMoO4 and CoS grow uniformly on the nickel foam surface; the SEM images reveal Co... 10 MoO4@Co 10 The microstructure of S is a spherical stack, which increases the surface area of ​​the catalyst and the number of electrochemical attachment sites, thereby improving the catalyst's performance. 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 acts as a catalyst (Mo4O) in the alkaline water electrolysis oxygen evolution reaction. 11 The preparation method of ( / NF) includes the following steps:

[0042] Step 1: Sonicate the nickel foam (3.0cm × 3.0cm, 0.5mm) sequentially with anhydrous ethanol for 30 min, acetone for 30 min, 3M HCl solution for 15 min, and deionized water for 30 min, maintaining the temperature between 10 and 20°C during sonication. Collect the foamed nickel after vacuum drying, maintaining the drying temperature between 40 and 60°C for later use.

[0043] Step 2: Weigh 1g of thiourea and 0.1g of ammonium heptamolybdate, add them sequentially to deionized water, and sonicate to prepare a homogeneous mixed solution.

[0044] Step 3: Transfer the prepared mixed solution and the pretreated current collector together into a polytetrafluoroethylene liner and react hydrothermally at 150°C for 10 hours. After the reaction is complete and the mixture cools naturally, remove the current collector, wash it with deionized water, and then vacuum dry it to obtain the product containing only Mo4O. 11 Catalyst.

[0045] Comparative Example 2:

[0046] Replacing Co in Example 1 with the commercially available catalyst IrO2 10 MoO4@Co 10 S / NF catalyst, preparation of IrO2@NF:

[0047] Step 1: Add 1.06 mg of IrO2 catalyst to a mixture of 252 μL isopropanol and 28 μL Nafion solution, sonicate for 1 h, and control the temperature at 10-20 °C during sonication to obtain a uniformly dispersed slurry.

[0048] Step 2: Sonicate the nickel foam (3.0cm×3.0cm, 0.5mm) sequentially with anhydrous ethanol for 30min, acetone for 30min, 3M HCl solution for 15min, and deionized water for 30min. Keep the temperature low during sonication. After vacuum drying, collect and set aside for later use. The drying temperature should be controlled between 40 and 60℃.

[0049] Step 3: Cut the nickel foam into pieces of 1.2cm × 0.2cm and 0.5mm. Then, under a heat lamp, evenly drip the slurry onto the cut nickel foam. After it dries, collect it for later use.

[0050] Comparative Example 3:

[0051] Preparation of blank nickel foam:

[0052] Step 1: Sonicate the nickel foam (3.0cm × 3.0cm, 0.5mm) sequentially with anhydrous ethanol for 30 min, acetone for 30 min, 3M HCl solution for 15 min, and deionized water for 30 min, maintaining the temperature between 10 and 20°C during sonication. Collect the foamed nickel after vacuum drying, maintaining the drying temperature between 40 and 60°C for later use.

[0053] Electrochemical testing:

[0054] Electrochemical performance was tested using an electrochemical workstation, specifically the Chenhua CHI630E model.

[0055] Using 1M KOH solution as the electrolyte and a three-electrode system, the Co prepared in Examples 1, 2, and 3 was tested. 10 MoO4@Co10S / NF、Co5MoO4@Co5S / NF、Co 15 MoO4@Co 15 S / NF, Mo4O prepared in Comparative Examples 1 and 2 11 Using NF / N and IrO2 / NF as working electrodes, and a mercury oxide electrode as a reference electrode, and a graphite electrode as a counter electrode, Co was measured. 10 MoO4@Co10 S / NF, Co5MoO4@Co5S / NF, Co 15 MoO4@Co 15 Linear sweep voltammetric curves of S / NF, MoS@NF, and IrO2@NF.

[0056] OER performance test:

[0057] Using linear sweep voltammetry to study Co5MoO4@Co5S / NF, Co 10 MoO4@Co10S / NF, Co 15 MoO4@Co 15 OER performance tests were performed on S / NF, MoS / NF, and IrO2 / NF, and the resulting OER polarization curves (LSV plots) are shown below. Figure 3 As shown. Co 10 MoO4@Co 10 S / NF at 100mAcm -2 At a current density of 354mV, it exhibits the smallest overpotential; and at 1916mAcm -2 At the current density, the overpotential is only 546mV.

[0058] In summary, the alkaline water electrolysis catalyst containing bimetallic oxides and transition metal sulfides prepared by this invention exhibits excellent catalytic performance, far exceeding that of noble metal catalysts (IrO2). The catalyst prepared by this invention, containing transition elements and bimetallic oxides and transition metal sulfides, can achieve high current densities even at relatively low overpotentials and demonstrates good stability at high current densities. The preparation method of this invention is simple, time-efficient, and low-cost, making it highly suitable for industrial production and use.

[0059] The descriptions and practices disclosed in this invention are readily apparent and understandable to those skilled in the art, and various modifications and refinements can be made without departing from the principles of this invention. Therefore, any modifications or improvements made without departing from the spirit of this invention should also be considered within the scope of protection of this invention.

Claims

1. A process for the preparation of a catalyst comprising a double metal oxide and a transition metal sulfide, characterized in that, Comprising the following steps: Step 1, the current collector is sequentially washed with ethanol, acetone, hydrochloric acid, deionized water, vacuum dried and collected for use; Step 2, a certain amount of thiourea, ammonium heptamolybdate and cobalt source are weighed and sequentially added into deionized water, and a uniform mixed solution is prepared by ultrasonic treatment; Step 3, the prepared mixed solution and the pretreated current collector are placed in the inner container of the reaction kettle for hydrothermal reaction, after the reaction is completed and natural cooling, the current collector is taken out, washed with deionized water and vacuum dried, to obtain a catalyst containing bimetallic oxide and transition metal sulfide; In step 2, the cobalt source is cobalt nitrate; the amount of thiourea is 1-1.5 g, the amount of ammonium heptamolybdate is 0.1-0.5 g, and the amount of cobalt source is 0.01 g, 0.005 g or 0.015 g.

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

3. The method for preparing a catalyst containing a bimetallic oxide and a transition metal sulfide according to claim 1, characterized in that, In step 1, the ethanol is ultrasonically treated for 10-40 min, the acetone is ultrasonically treated for 10-40 min, the hydrochloric acid is ultrasonically treated for 10-40 min, and the deionized water is ultrasonically treated for 10-40 min, and the temperature during ultrasonic treatment is controlled at 10-20℃.

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

5. The use of a catalyst containing bimetallic oxide and transition metal sulfide obtained by the preparation method of any one of claims 1-4 in the oxygen evolution reaction in alkaline electrolyte.

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