An epitaxial heterojunction non-precious metal material and its preparation method and application

Abstract

The present invention relates to the field of catalyst preparation, and in particular to an epitaxial heterojunction non-precious metal material, a preparation method, and applications thereof. The material is a CoO / Mo2C bifunctional electrode material for hydrogen and oxygen evolution having a nanorod-like structure, formed by magnetron sputtering Mo2C onto a carbon cloth loaded with CoO using Mo2C as a target. The electrode material has high activity and a small overpotential in both the HER and OER reactions at the same current density. Compared with Co metal oxide water electrolysis catalytic materials, the electrolysis performance of the material is significantly improved, the material has long-term stability, and the cost is much lower than that of precious metal catalysts.

Description

Technical Field

[0001] The present invention relates to the field of catalyst preparation, in particular to an epitaxial heterojunction non-noble metal material and a preparation method and application thereof. Background Art

[0002] Hydrogen is one of the most ideal alternative energy carriers to traditional fossil fuels, with the following outstanding advantages: (1) its energy density (142 MJ / Kg) is much higher than that of gasoline (44 MJ / Kg); (2) its wide range of uses: it can not only be used as a fuel, but also as an important industrial raw material in many chemical processes, such as the Fischer-Tropsch reaction and ammonia synthesis reaction; (3) it can release energy through direct combustion or reaction in hydrogen fuel cells, with the only byproduct being water. Therefore, hydrogen is considered to be one of the most promising clean energy sources in the 21st century. However, to date, the main methods for industrial hydrogen production are still steam methane reforming and coal gasification. These processes produce low-purity hydrogen, consume a large amount of fossil fuels, and emit a large amount of pollutants and CO2. Therefore, there is an urgent need to seek clean and sustainable hydrogen production strategies.

[0003] Water electrolysis is an efficient and clean industrial hydrogen production technology that can produce high-purity hydrogen. Electrochemical water splitting consists of two half-reactions: the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. Although water electrolysis provides an efficient method for producing high-purity hydrogen, its practical application is limited by its strong uphill reaction and large overpotential. The use of OER and HER electrocatalysts is an effective way to reduce the overpotential of water splitting, thereby reducing energy consumption and increasing energy efficiency. Ideal HER and OER catalysts must meet two basic requirements: first, the electrocatalyst must be highly active, capable of generating higher current densities at smaller overpotentials; second, it must exhibit long-term stability. Currently, platinum group metals and oxides of Ir and Ru are benchmark electrocatalysts for HER and OER, respectively. However, the scarcity and high cost of these precious metals severely hinder their large-scale practical application.

[0004] Among the various catalysts currently used in water electrolysis, Co metal element is widely used. However, on this basis, how to improve the catalytic performance of Co metal oxide catalysts remains to be studied.

[0005] Currently, most methods for preparing heterojunctions are chemical synthesis methods, which are usually carried out in laboratory environments and are not conducive to large-scale industrial production. In addition, the thickness of the heterojunction film is difficult to control, and the distribution of the heterojunction is also uneven. These conditions limit the performance of the catalyst to a certain extent.

[0006] CN106605011B discloses a heterostructure for superactive hydrogen evolution electrocatalysis. The structure is formed by coating a first material (including metallic nickel) and a second material (including nickel oxide) on the surface of a porous substrate through annealing, and the second material is partially coated on the first material to form a heterojunction structure. This structure is used as an electrocatalytic material for a hydrogen evolution electrode. However, while its electrocatalytic performance is relatively excellent, its acid and alkali resistance is limited. Its structure is easily affected and destroyed in acids or alkalis, resulting in a rapid decline in its performance. Summary of the Invention

[0007] In response to the shortcomings of the above-mentioned existing technologies, an epitaxial heterojunction non-precious metal material and its preparation method and application are provided. The material has high activity and a small overpotential in both HER and OER reactions at the same current density. Compared with Co metal oxide water electrolysis catalytic materials, the performance of water electrolysis has been significantly improved, and it has long-term stability and the cost is much lower than that of precious metal catalysts.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is to use Mo2C as a target material for epitaxial heterojunction non-precious metal material, which is magnetron sputtered on a carbon cloth loaded with CoO to form a CoO / Mo2C dual-functional electrode material for hydrogen and oxygen evolution with a nanorod-like structure.

[0009] The above-mentioned epitaxial heterojunction non-noble metal material, the carbon cloth thickness is 0.1mm-0.2mm.

[0010] In the above-mentioned epitaxial heterojunction non-noble metal material, the diameter of the CoO / Mo2C nanorod structure is 200 nm.

[0011] The above-mentioned epitaxial heterojunction non-precious metal material can have a hydrogen production overpotential as low as 100mV and an oxygen production overpotential as low as 250mV.

[0012] The above-mentioned method for preparing the epitaxial heterojunction non-noble metal material comprises the following steps:

[0013] (1) Soak the carbon cloth (2*4cm) in 0.5-1mmolHNO3 for 12-24h, and wash it in deionized water until the pH is 7;

[0014] (2) Weigh 1-2g Co(NO)3·6H2O, 0.7-1.4g CO(NH2)2 and 0.2-0.4g NH4F in 100-200ml deionized water (DI) and stir for more than 0.5h until uniform;

[0015] (3) The prepared solution and the treated carbon cloth were placed in a polytetrafluoroethylene high-pressure reactor and placed in a homogeneous reactor for hydrothermal synthesis at a temperature of 120-150°C for 6 hours. After the reaction, the carbon cloth was washed with deionized water and vacuum dried at 60°C to obtain a pink or lavender CoO-loaded carbon cloth.

[0016] (4) Using Mo2C as the target, the above materials were subjected to magnetron sputtering in an Ar environment to prepare heterojunctions at a power of 30-40 W / cm -2 , Sputtering time: 1-2h, to obtain an orange precursor;

[0017] (5) Place the precursor in a tube furnace and heat it at a rate of 2-5°C / min under an Ar atmosphere with a gas flow rate of 20-60 mL / min. Keep it at 400-500°C for 2-3 h. After annealing, black CoO / Mo2C@CF is obtained.

[0018] An application of an epitaxial heterojunction non-precious metal material as an electrocatalyst for complete water splitting.

[0019] The present invention provides an epitaxial heterojunction non-precious metal material, its preparation method, and its application. The invention utilizes magnetron sputtering to prepare the heterostructure. Magnetron sputtering, a high-speed, low-temperature sputtering technology that developed rapidly in the 1970s, is a type of physical vapor deposition (PVD) characterized by fast film formation rates, low substrate temperatures, good film adhesion, and the ability to coat large areas. Therefore, coating with magnetron sputtering can result in a more uniform distribution of the heterojunction.

[0020] The deposition speed of heterojunction prepared by magnetron sputtering technology is fast, the substrate temperature rise is low, and the damage to the film layer is small. For most materials, sputtering can be achieved as long as the target material can be made, which is easy to industrialize.

[0021] It has high activity and a small overpotential in both HER and OER reactions at the same current density. Compared with Co metal oxide water electrolysis catalytic materials, the performance of water electrolysis has been significantly improved, and it has long-term stability and the cost is much lower than precious metal catalysts.

[0022] The catalyst of the present invention is a bifunctional CoO / Mo2C@CF electrode, which can effectively carry out complete water splitting, has a nanorod-like structure with rich active site surface, and has excellent electrocatalytic performance and long-term stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 :(a) Nanorod-like structure of CoO attached to carbon cloth;(b) Nanorod-like structure of CoO / Mo2C attached to carbon cloth;

[0024] Figure 2 : Hydrogen evolution performance comparison chart;

[0025] Figure 3 : Oxygen evolution performance comparison chart;

[0026] Figure 4 : Double water-lysis performance comparison chart. DETAILED DESCRIPTION

[0027] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] An epitaxial heterojunction non-precious metal material is a CoO / Mo2C dual-functional electrode material for hydrogen and oxygen evolution with a nanorod-like structure formed by magnetron sputtering on a carbon cloth loaded with CoO using Mo2C as a target.

[0030] The above-mentioned epitaxial heterojunction non-precious metal material, the carbon cloth thickness is 0.1mm-0.2mm, has high durability, and is very suitable for use in high acid, alkali, salt and atmospheric corrosion environments because it will not rust. Figure 2 、 3 Figures 4 and 5 show that compared to CoO, the composite material CoO / Mo2C has a lower overpotential at the same current density, indicating that hydrogen and oxygen evolution reactions and the overall hydrolysis process proceed more easily. Therefore, it can be concluded that CoO / Mo2C has excellent electrocatalytic performance. The overpotential for hydrogen evolution can be as low as 100mV, and the overpotential for oxygen evolution can be as low as 250mV.

[0031] In the above-mentioned epitaxial heterojunction non-noble metal material, the diameter of the CoO / Mo2C nanorod structure is 200 nm.

[0032] The above-mentioned method for preparing the epitaxial heterojunction non-noble metal material comprises the following steps:

[0033] (1) Soak the carbon cloth (2*4cm) in 0.5mmolHNO3 for 12h and wash it in deionized water until the pH is 7;

[0034] (2) Weigh 1g Co(NO)3·6H2O, 0.7g CO(NH2)2 and 0.2g NH4F in 100ml deionized water (DI) and stir for more than 0.5h until uniform;

[0035] (3) The prepared solution and the treated carbon cloth were placed in a polytetrafluoroethylene high-pressure reactor and placed in a homogeneous reactor for hydrothermal synthesis at a temperature of 120°C for 6 hours. After the reaction, the carbon cloth was washed with deionized water and vacuum dried at 60°C to obtain a pink or lavender CoO-loaded carbon cloth.

[0036] (4) Using Mo2C as the target, the above materials were subjected to magnetron sputtering in an Ar environment to prepare heterojunctions at a power of 30 W / cm -2 , sputtering time 1h, obtaining an orange precursor;

[0037] (5) The precursor was placed in a tube furnace, heated at a rate of 2°C / min under an Ar atmosphere with a gas flow rate of 20 mL / min, and kept at 400°C for 2 h. After annealing, black CoO / Mo2C@CF was obtained.

[0038] An application of an epitaxial heterojunction non-precious metal material as an electrocatalyst for complete water splitting. The catalyst is a bifunctional CoO / Mo2C@CF electrode, which effectively splits water. It features a nanorod-like structure with abundant active sites on the surface, exhibiting excellent electrocatalytic performance and long-term stability. It exhibits high activity and low overpotentials in both the HER and OER reactions at the same current density. Compared to Co-based metal oxide water electrolysis catalytic materials, it significantly improves water electrolysis performance and is much less expensive than precious metal catalysts.

[0039] Example 2

[0040] The same parts as those in Example 1 will not be described in detail. The difference between this embodiment and Example 1 is that the method for preparing the epitaxial heterojunction non-noble metal material comprises the following steps:

[0041] (1) Soak the carbon cloth (2*4cm) in 0.8mmolHNO3 for 18h and wash it in deionized water until the pH is 7;

[0042] (2) Weigh 1.5g Co(NO)3·6H2O, 1g CO(NH2)2 and 0.3g NH4F in 150ml deionized water (DI) and stir for more than 0.5h until homogeneous;

[0043] (3) The prepared solution and the treated carbon cloth were placed in a polytetrafluoroethylene high-pressure reactor and placed in a homogeneous reactor for hydrothermal synthesis at a temperature of 130°C for 6 hours. After the reaction, the mixture was washed with deionized water and vacuum dried at 60°C to obtain a pink or lavender CoO-loaded carbon cloth.

[0044] (4) Using Mo2C as the target, the above materials were subjected to magnetron sputtering in an Ar environment to prepare heterojunctions at a power of 35W / cm -2 , sputtering time 1.5h, obtaining an orange precursor;

[0045] (5) The precursor was placed in a tube furnace, heated at a rate of 3°C / min under an Ar atmosphere with a gas flow rate of 40 mL / min, and kept at 450°C for 2.5 h. After annealing, black CoO / Mo2C@CF was obtained.

[0046] Example 3

[0047] The same parts as those in Example 1 will not be described in detail. The difference between this embodiment and Example 1 is that the method for preparing the epitaxial heterojunction non-noble metal material comprises the following steps:

[0048] (1) Soak the carbon cloth (2*4cm) in 1mmolHNO3 for 24h and wash it in deionized water until the pH is 7;

[0049] (2) Weigh 2g Co(NO)3·6H2O, 1.4g CO(NH2)2 and 0.4g NH4F in 200ml deionized water (DI) and stir for more than 0.5h until uniform;

[0050] (3) The prepared solution and the treated carbon cloth were placed in a polytetrafluoroethylene high-pressure reactor and placed in a homogeneous reactor for hydrothermal synthesis at a temperature of 150°C for 6 hours. After the reaction, the mixture was washed with deionized water and vacuum dried at 60°C to obtain a pink or lavender CoO-loaded carbon cloth.

[0051] (4) Using Mo2C as the target, the above materials were subjected to magnetron sputtering in an Ar environment to prepare heterojunctions at a power of 40 W / cm -2 , sputtering time 1-2h, obtaining an orange precursor;

[0052] (5) The precursor was placed in a tube furnace, heated at a rate of 5 °C / min under an Ar atmosphere with a gas flow rate of 60 mL / min, and kept at 500 °C for 3 h. After annealing, black CoO / Mo2C@CF was obtained.

[0053] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. An epitaxial heterojunction non-precious metal material, characterized by: Mo2C is used as the target material and is magnetron sputtered onto a carbon cloth loaded with CoO to form a CoO / Mo2C dual-functional electrode material for hydrogen and oxygen evolution with a nanorod-like structure.

2. The epitaxial heterojunction non-noble metal material according to claim 1, characterized in that: The carbon cloth has a thickness of 0.1 mm to 0.2 mm.

3. The epitaxial heterojunction non-noble metal material according to claim 2, characterized in that: The diameter of the CoO / Mo2C nanorod structure is 200 nm.

4. The epitaxial heterojunction non-noble metal material according to claim 3, characterized in that: The overpotential for hydrogen production can be as low as 100mV, and the overpotential for oxygen production can be as low as 250mV.

5. A method for preparing an epitaxial heterojunction non-noble metal material according to any one of claims 1 to 4, characterized in that: The steps include: (1) Soak a 2*4cm carbon cloth in 0.5-1mmolHNO3 for 12-24h, and then wash it in deionized water until the pH is 7; (2) Weigh 1-2g Co(NO)3·6H2O, 0.7-1.4g CO(NH2)2 and 0.2-0.4g NH4F in 100-200ml deionized water (DI) and stir for more than 0.5h until uniform; (3) The prepared solution and the treated carbon cloth were placed in a polytetrafluoroethylene high-pressure reactor and placed in a homogeneous reactor for hydrothermal synthesis at a temperature of 120-150°C for 6 hours. After the reaction, the carbon cloth was washed with deionized water and vacuum dried at 60°C to obtain a pink or lavender CoO-loaded carbon cloth. (4) Using Mo2C as the target, magnetron sputtering was performed on CoO-loaded carbon cloth in an Ar environment to prepare heterojunctions. The power was 30-40W / cm -2 , Sputtering time: 1-2h, to obtain an orange precursor; (5) Place the precursor in a tube furnace and heat it at a rate of 2-5°C / min under an Ar environment with a gas flow rate of 20-60 mL / min. Keep it at 400-500°C for 2-3 h. After annealing, black CoO / Mo2C@CF is obtained.

6. A use of the epitaxial heterojunction non-precious metal material according to any one of claims 1 to 4, characterized in that: Used as an electrocatalyst for complete water splitting.

Images