CN104923268A - Self-support transition metal selenide catalyst as well as preparation method and application thereof - Google Patents

Abstract

The invention provides a self-supporting transition metal selenide catalyst and a preparation method and application thereof, which belong to the field of water decomposition in an alkaline full electrolytic cell. It solves the technical problem that the catalytic activity of the existing catalyst is low or limited by the pH value. In the catalyst, selenium powder is dissolved in sodium borohydride aqueous solution, or a metal salt of a transition metal element is added to obtain a mixed solution; then a transition metal conductive substrate is added to the obtained mixed solution to react to obtain a self-supporting transition metal selenide catalyst ; or the metal salt of the transition metal element, selenium dioxide and lithium chloride are formulated into a transition metal selenide electrolyte; then the transition metal conductive substrate is used as a working electrode, and electrodeposition is carried out in the obtained transition metal selenide electrolyte , to obtain a self-supporting transition metal selenide catalyst. The preparation method of the invention is not affected by pH, and the prepared selenide catalyst is applied in a battery, and has excellent electrocatalytic hydrogen evolution and oxygen evolution performance.

Description

A kind of self-supporting transition metal selenide catalyst and its preparation method and application

technical field

The invention relates to the field of water decomposition in an alkaline full electrolytic cell, in particular to a self-supporting transition metal selenide catalyst and its preparation method and application.

Background technique

In the 21st century, energy crisis and environmental pollution have become two very serious problems facing the world. Therefore, in order to realize the sustainable development of human beings, it is extremely urgent to develop clean and renewable energy. Hydrogen is a high combustion value, high efficiency and clean energy. However, the current production of hydrogen energy is mainly obtained by reforming coal and natural gas, which will inevitably increase the consumption of non-renewable energy and bring about environmental pollution problems. Hydrogen production by electrolysis of water is an important means to achieve industrialization and low-cost production of hydrogen. The use of solar energy for photolysis of water or light-assisted electrolysis of water will be an ideal solution for a "sunshine economy". To realize electrolysis of water by electric energy or light-assisted electrolysis of water, it is very important to prepare high-performance catalysts with hydrogen evolution ability. However, due to the existence of hydrogen evolution overpotential (the main battery voltage of a commercial electrolyzer is 1.8-2.0 volts, which is higher than the theoretical minimum value of 1.23 volts), the cell pressure and energy consumption are high during the electrolysis process. Both cathodic hydrogen evolution and anodic oxygen evolution reactions require efficient electrocatalysts to overcome the high hydrolysis voltage and make the electrolysis process more efficient. Currently, compounds based on iridium and ruthenium exhibit the highest oxygen evolution activity, while platinum group metals are the most effective hydrogen evolution catalysts, but their rarity and high cost limit their wide application. It is of great significance to research and develop high-performance catalyst materials for hydrogen evolution and oxygen evolution that are abundant in the earth's crust. ; Angew.Chem.Int.Ed.2015,54,3897; J.Am.Chem.Soc.2014,136,16481), hydroxide (Angew.Chem.Int.Ed.2014,53,7584; J.Am.Chem.Soc.2014,136,16481); Am.Chem.Soc.2014,136,2843) etc.) and hydrogen evolution (chalcogenides (Angew.Chem.Int.Ed.2013,52,8546; Acc.Chem.Res.2014,47,2671), carbide (EnergyEnviron.Sci.2014,7,387), phosphides (J.Am.Chem.Soc.2014,136,7587; Angew.Chem.Int.Ed.2014,53,6710), etc.) have made great achievements in high-efficiency catalysts Progress.

Cui's research group first synthesized molybdenum selenide and tungsten selenide on carbon paper by selenization method and used them as cheap, efficient and stable hydrogen evolution catalysts (Nano Lett. 2013, 13, 3426). The research group once again proved that self-supporting cobalt selenide nanoparticles have good hydrogen evolution performance under acidic conditions (J.Am.Chem.Soc.2014, 136, 4897). So far, these catalysts are limited by cumbersome synthesis steps, deactivation or limited pH value. Water splitting requires minimal overpotential under strong acid or base (Energy Environ. Sci. 2012, 5, 7582), but still faces the challenge that acid-stable and efficient catalysts may be inactive or unstable under alkaline conditions. Therefore, the development and design of non-noble metal catalyst electrodes with high hydrogen and oxygen evolution in the same electrolyte has attracted much attention. recently reported the preparation of nickel-iron layered double hydroxides on commercial nickel grids and used them as bifunctional hydrogen and oxygen evolution catalysts for alkaline water electrolysis, with current densities up to 10 mA/m at 1.7 volts. ^cm2 , while the corresponding nickel hydroxide catalyst requires 1.82 volts to achieve the same current density (Science 2014, 345, 1593). However, its catalytic performance still needs to be further improved, and the development of high-performance hydrogen evolution and oxygen evolution catalysts is a huge challenge.

Contents of the invention

The invention provides a self-supporting transition metal selenide catalyst and its preparation method and application in order to solve the technical problem that the catalytic activity of the existing catalyst is low or limited by the pH value.

The invention provides a preparation method of a self-supporting transition metal selenide catalyst, the method comprising:

Step 1: dissolving selenium powder in aqueous solution of sodium borohydride, or adding metal salts of transition metal elements to obtain a mixed solution;

Step 2: adding the transition metal conductive substrate to the mixed solution obtained in Step 1 for reaction to obtain a self-supporting transition metal selenide catalyst.

Preferably, the metal salt of the transition metal element is nitrate, chloride, acetate, sulfuric acid, oxalic acid, citric acid, tartaric acid, carbonate of iron, cobalt, nickel, copper, molybdenum or tungsten one or more.

Preferably, the transition metal conductive substrate is nickel mesh, nickel foil, copper mesh, copper foil, stainless steel mesh, stainless steel foil, nickel-iron mesh, cobalt foil, titanium sheet, titanium mesh, molybdenum foil or tungsten foil.

Preferably, the reaction temperature in the second step is 100-250° C., and the reaction time is 0.5-48 hours.

The present invention also provides a preparation method of a self-supporting transition metal selenide catalyst, the method comprising:

Step 1: preparing a transition metal selenide electrolyte with metal salts of transition metal elements, selenium dioxide and lithium chloride;

Step 2: using the transition metal conductive substrate as a working electrode, performing electrodeposition in the transition metal selenide electrolyte obtained in step 1 to obtain a self-supporting transition metal selenide catalyst.

Preferably, the metal salt of the transition metal element is nitrate, chloride, acetate, sulfuric acid, oxalic acid, citric acid, tartaric acid, carbonate of iron, cobalt, nickel, copper, molybdenum or tungsten one or more.

Preferably, the transition metal conductive substrate is nickel mesh, nickel foil, copper mesh, copper foil, stainless steel mesh, stainless steel foil, nickel-iron mesh, cobalt foil, titanium sheet, titanium mesh, molybdenum foil or tungsten foil.

Preferably, the deposition time is 0.1-4 hours.

The present invention also provides the self-supporting transition metal selenide catalyst obtained by the above two preparation methods.

The present invention also provides the application of the self-supporting transition metal selenide catalyst in an electrolytic cell.

Beneficial effects of the present invention

The invention provides a self-supporting transition metal selenide catalyst and a preparation method thereof. The catalyst comprises dissolving selenium powder in an aqueous solution of sodium borohydride, or adding a metal salt of a transition metal element to obtain a mixed solution; Adding to the mixed solution obtained in step 1 for reaction to obtain a self-supporting transition metal selenide catalyst. Or the metal salt of the transition metal element, selenium dioxide and lithium chloride are formulated into a transition metal selenide electrolyte; deposition to obtain a self-supporting transition metal selenide catalyst. The above two preparation methods are simple, low in production cost, and not affected by pH. The prepared selenide catalyst is applied in batteries and has excellent electrocatalytic hydrogen evolution and oxygen evolution performance.

Description of drawings

Fig. 1 is the X-ray diffractogram of the nickel net that long has nickel selenide nanowire array that embodiment 1 obtains;

Fig. 2 is the scanning electron micrograph figure of the nickel net that the long nickel selenide nanowire array that Fig. 2 obtains;

Fig. 3 is the transmission electron microscope photograph figure of the nickel net that the long nickel selenide nanowire array that Fig. 3 obtains;

Fig. 4 is the polarization curve figure of the nickel mesh with the nickel selenide nanowire array obtained in embodiment 1 under alkaline conditions;

Fig. 5 is the scanning electron micrograph of the nickel-cobalt foil that grows nickel selenide nanowire array that embodiment 2 obtains;

Fig. 6 is the scanning electron micrograph figure of the self-supporting transition metal selenide catalyst that embodiment 6 prepares;

FIG. 7 is a polarization curve diagram of the self-supporting transition metal selenide catalyst prepared in Example 6. FIG.

Detailed ways

The invention provides a preparation method of a self-supporting transition metal selenide catalyst, the method comprising:

Step 1: dissolving selenium powder in aqueous solution of sodium borohydride, or adding metal salts of transition metal elements to obtain a mixed solution;

Step 2: adding the transition metal conductive substrate to the mixed solution obtained in Step 1 for reaction to obtain a self-supporting transition metal selenide catalyst.

According to the present invention, the selenium powder is first dissolved in the sodium borohydride aqueous solution to obtain the sodium selenium hydride solution, preferably added under the condition of magnetic stirring, and the mass ratio of the described selenium powder and sodium borohydride is preferably (0.01～0.1 ): (0.02～0.1); or adding a metal salt of a transition metal element to obtain a mixed solution; the molar ratio of the selenium powder to the metal salt of a transition metal element is preferably 1:0˜1:2. The metal salt of the transition metal element is preferably one of nitrate, chloride, acetate, sulfuric acid, oxalic acid, citric acid, tartaric acid, carbonate of iron, cobalt, nickel, copper, molybdenum or tungsten Various, more preferably zinc nitrate, cobalt nitrate, nickel nitrate, copper chloride, cobalt chloride, cobalt sulfate or nickel chloride.

According to the present invention, the transition metal conductive substrate is added to the above mixed solution for reaction, the transition metal conductive substrate is preferably washed with dilute hydrochloric acid, ethanol, and deionized water before adding, and the reaction temperature is preferably 100-250°C , the reaction time is preferably 0.5-48 hours, after the reaction is completed, the reaction product is washed and dried to obtain a self-supporting transition metal selenide catalyst. The transition metal conductive substrate is preferably nickel mesh, nickel foil, copper mesh, copper foil, stainless steel mesh, stainless steel foil, nickel-iron mesh, cobalt foil, titanium sheet, titanium mesh, molybdenum foil or tungsten foil.

The present invention also provides a preparation method of a self-supporting transition metal selenide catalyst, the method comprising:

Step 1: preparing a transition metal selenide electrolyte with metal salts of transition metal elements, selenium dioxide and lithium chloride;

Step 2: using the transition metal conductive substrate as a working electrode, performing electrodeposition in the transition metal selenide electrolyte obtained in step 1 to obtain a self-supporting transition metal selenide catalyst.

According to the present invention, the metal salt of the transition metal element, selenium dioxide and lithium chloride are formulated into a transition metal selenide electrolyte, and the mol ratio of the metal salt of the transition metal element and selenium dioxide is preferably (0.02～0.5 ): (0.04～1); the concentration of lithium chloride is preferably 0.05～0.5M. The metal salt of the transition metal element is preferably one of nitrate, chloride, acetate, sulfuric acid, oxalic acid, citric acid, tartaric acid, carbonate of iron, cobalt, nickel, copper, molybdenum or tungsten Various, more preferably zinc nitrate, cobalt nitrate, nickel nitrate, copper chloride, cobalt chloride, cobalt sulfate or nickel chloride.

According to the present invention, the transition metal selenide is electrodeposited using an electrochemical workstation (CHI660D) with the transition metal conductive substrate as the working electrode, the graphite sheet as the counter electrode, and saturated calomel as the reference electrode. The deposition time is preferably 0.1 to 4 hours. The deposited sample is preferably washed with distilled water and ethanol to obtain a self-supporting transition metal selenide catalyst. The transition metal conductive substrate is preferably nickel mesh, nickel foil, copper mesh, copper foil, stainless steel mesh, stainless steel foil, nickel-iron mesh, cobalt foil, titanium sheet, titanium mesh, molybdenum foil or tungsten foil.

The present invention also provides a self-supporting transition metal selenide catalyst prepared by any two methods above.

The present invention also provides the application of the above-mentioned self-supporting transition metal selenide catalyst in an electrolytic cell. The above-mentioned self-supporting transition metal selenide catalyst is used as a cathode, an anode or an anode-yang stage to assemble a full battery, and the electrode is tested by a CHI660D electrochemical workstation. Electrocatalytic hydrogen evolution and oxygen evolution performance in alkaline electrolyte.

Below in conjunction with embodiment the present invention is described in further detail.

Example 1

Weigh 0.059 grams of selenium powder and dissolve it in 1.5 milliliters of distilled water containing 0.065 grams of sodium borohydride with magnetic stirring to prepare a sodium selenium hydride solution, transfer the solution to a 50 milliliter reaction axe, and add 1 × 3 cm of washing Put the reaction ax into a 140°C oven to react for 12 hours, wash the product with distilled water and ethanol and put it in a 60°C oven to dry to obtain a nickel mesh with nickel selenide nanowire arrays.

Fig. 1 is the X-ray diffraction diagram of the nickel mesh with nickel selenide nanowire arrays obtained in Example 1, which shows that the final product is nickel selenide. Fig. 2 is the scanning electron micrograph of the nickel net that the long nickel selenide nanowire array that embodiment 1 obtains, wherein figure a is the scanning electron micrograph under the 50 μ m scale, and figure b is the scanning electron micrograph under the 500nm scale, and Fig. 2 shows The nickel mesh with nickel selenide nanowire arrays obtained in Example 1 has a diameter of 20-60 nanometers and a length of 2-5 microns. Fig. 3 is the transmission electron micrograph of the nickel mesh with the nickel selenide nanowire array obtained in Example 1, and Fig. 3 shows that the nickel mesh with the nickel selenide nanowire array has a smooth surface structure. Fig. 4 is the polarization curve figure that the long nickel selenide nanowire array that embodiment 1 makes is under alkaline conditions (1 mole of potassium hydroxide, pH=14); This figure illustrates that embodiment 1 obtains Compared with Pt/C and pure carbon cloth electrode, nickel selenide nanowire array catalyst has better hydrogen evolution performance. When j=10mA cm ^-2 , the potential of nickel selenide array electrode relative to standard hydrogen electrode is 1.63 volts.

Example 2

Weigh 0.059 grams of selenium powder and dissolve it in 1.5 milliliters of distilled water containing 0.065 grams of sodium borohydride with magnetic stirring to prepare a sodium selenium hydride solution, transfer the solution to a 50 milliliter reaction axe, and add 1 × 3 cm of washing Put the reaction ax into a 140°C oven to react for 12 hours, wash the product with distilled water and ethanol and put it into a 60°C oven to dry to obtain a nickel foil with nickel selenide nanowire arrays.

Fig. 5 is the scanning electron micrograph of the nickel foil that is long to have nickel selenide nanowire array that embodiment 2 obtains, and wherein figure a is the scanning electron micrograph under the 5 μ m scale, and figure b is the scanning electron micrograph under the 500nm scale, and Fig. 5 shows The nickel foil with nickel selenide nanowire arrays obtained in Example 2 has a diameter of 20-80 nanometers and a length of 1-6 microns. The nickel selenide nanowire array catalyst obtained in Example 2 was tested for hydrogen evolution performance. When j=10mA cm ⁻² , the potential of the nickel selenide array electrode relative to the standard hydrogen electrode was 1.65 volts.

Example 3

Weigh 0.059 grams of selenium powder and dissolve it in 1.5 milliliters of distilled water containing 0.065 grams of sodium borohydride with magnetic stirring to prepare a sodium selenium hydride solution, transfer the solution to a 50 milliliter reaction axe, and add 1 × 3 cm of washing The processed cobalt foil was placed in a 100°C oven for 48 hours to react, the product was washed with distilled water and ethanol, and then dried in a 60°C oven to obtain a cobalt foil with cobalt selenide nanowire arrays.

The cobalt foil catalyst with cobalt selenide nanowire array obtained in Example 3 was tested for hydrogen evolution performance. When j=10mA cm ⁻² , the potential of the cobalt selenide array electrode relative to the standard hydrogen electrode was 1.64 volts.

Example 4

Weigh 0.059 grams of selenium powder and dissolve it in 1.5 milliliters of distilled water containing 0.065 grams of sodium borohydride with magnetic stirring to prepare a sodium selenium hydride solution, transfer the solution to a 50 milliliter reaction axe, and add 1 × 3 cm of washing Put the reaction ax into a 140°C oven to react for 12 hours, wash the product with distilled water and ethanol and put it in a 60°C oven to dry to obtain a copper mesh with copper selenide nanowire arrays.

The copper mesh catalyst with copper selenide nanowire arrays obtained in Example 4 was tested for hydrogen evolution performance. When j=10mA cm ⁻² , the potential of the copper selenide array electrode relative to the standard hydrogen electrode was 1.67 volts.

Example 5

Weigh 0.059 grams of selenium powder and dissolve it in 1.5 milliliters of distilled water containing 0.065 grams of sodium borohydride with magnetic stirring to prepare a sodium selenium hydride solution, transfer the solution to a 50 milliliter reaction axe, and add 1 × 3 cm of washing The processed molybdenum foil was placed in an oven at 250°C for 0.5 hours, and the product was washed with distilled water and ethanol and dried in an oven at 60°C to obtain a molybdenum foil with molybdenum selenide nanowire arrays.

The molybdenum foil catalyst with the molybdenum selenide nanowire array obtained in Example 5 was tested for hydrogen evolution performance. When j=10mA cm ⁻² , the potential of the molybdenum selenide array electrode relative to the standard hydrogen electrode was 1.68 volts.

Example 6

Weigh 0.065 moles of nickel chloride, 0.035 moles of selenium dioxide and 0.2 moles of 0.05M lithium chloride to prepare an electrolyte, then use the titanium sheet as the working electrode, the graphite sheet as the counter electrode, and the saturated calomel as the reference electrode using an electrochemical workstation (CHI660D) The transition metal selenide was electrodeposited at a constant potential, and the deposition time was 2 hours. The deposited sample was washed with distilled water and ethanol to obtain a self-supporting transition metal selenide catalyst.

Fig. 6 is the scanning electron microscope picture of the self-supporting transition metal selenide catalyst that embodiment 6 prepares, and wherein figure a is the scanning electron microscope picture under the 2 μ m scale, and figure b is the scanning electron microscope picture under the 500nm scale, and this figure shows The titanium flakes are completely covered by nickel selenide nanoparticles. Fig. 7 is the (1 mole potassium hydroxide, pH=14) polarization curve figure of the self-supporting transition metal selenide catalyst that embodiment 6 prepares under alkaline conditions, and this figure illustrates the nickel selenide that embodiment 6 obtains Compared with Pt/C, nanoparticle catalyst has better hydrogen evolution performance. When j=10mA cm ^-2 , the potential of nickel selenide array electrode relative to standard hydrogen electrode is 1.61 volts.

Example 7

Take by weighing 0.02 mol of cobalt sulfate, 0.04 mol of selenium dioxide and 0.2 mol of 0.05M lithium chloride to prepare electrolyte, then use cobalt foil as working electrode, graphite sheet as counter electrode, and saturated calomel as reference electrode using electrochemical workstation ( CHI660D) Electrodeposit transition metal selenide under constant potential, and the deposition time is 4 hours. After the deposited sample is washed with distilled water and ethanol, a self-supporting transition metal selenide catalyst can be obtained.

The copper mesh catalyst with cobalt selenide nanoparticles obtained in Example 7 was tested for hydrogen evolution performance. When j=10mA cm ⁻² , the potential of the cobalt selenide nanoparticles relative to the standard hydrogen electrode was 1.64 volts.

Example 8

Take by weighing 0.5 mol of iron acetate, 1 mol of selenium dioxide and 0.2 mol of 0.5M lithium chloride to prepare an electrolyte, then use molybdenum foil as a working electrode, graphite sheet as a counter electrode, and saturated calomel as a reference electrode using an electrochemical workstation ( CHI660D) Electrodeposit transition metal selenide under constant potential, the deposition time is 0.5 hours, and the deposited sample can be obtained by washing with distilled water and ethanol to obtain a self-supporting transition metal selenide catalyst.

The copper mesh catalyst with iron selenide nanowire array obtained in Example 8 was tested for hydrogen evolution performance. When j=10mA cm ⁻² , the potential of the iron selenide array electrode relative to the standard hydrogen electrode was 1.65 volts.

Claims (9)

1. a preparation method of self-supporting transition metal selenide catalyst, is characterized in that, the method comprises: Step 1: dissolving selenium powder in aqueous solution of sodium borohydride, or adding metal salts of transition metal elements to obtain a mixed solution; Step 2: adding the transition metal conductive substrate to the mixed solution obtained in Step 1 for reaction to obtain a self-supporting transition metal selenide catalyst. 2. the preparation method of a kind of self-supporting transition metal selenide catalyst according to claim 1 is characterized in that, the metal salt of described transition metal element is the nitrate of iron, cobalt, nickel, copper, molybdenum or tungsten , chloride, acetate, sulfuric acid, oxalic acid, citric acid, tartaric acid, carbonate in one or more. 3. the preparation method of a kind of self-supporting transition metal selenide catalyst according to claim 1 is characterized in that, described transition metal conductive substrate is nickel mesh, nickel foil, copper mesh, copper foil, stainless steel mesh, stainless steel foil, nickel iron mesh, cobalt foil, titanium sheet, titanium mesh, molybdenum foil or tungsten foil. 4 . The preparation method of a self-supporting transition metal selenide catalyst according to claim 1 , characterized in that, the reaction temperature in the second step is 100-250° C., and the reaction time is 0.5-48 hours. 5. a preparation method of self-supporting transition metal selenide catalyst, it is characterized in that, the method comprises: Step 1: preparing a transition metal selenide electrolyte with metal salts of transition metal elements, selenium dioxide and lithium chloride; Step 2: using the transition metal conductive substrate as a working electrode, performing electrodeposition in the transition metal selenide electrolyte obtained in step 1 to obtain a self-supporting transition metal selenide catalyst. 6. the preparation method of a kind of self-supporting transition metal selenide catalyst according to claim 5 is characterized in that, described transition metal conductive substrate is nickel mesh, nickel foil, copper mesh, copper foil, stainless steel mesh, stainless steel foil, nickel iron mesh, cobalt foil, titanium sheet, titanium mesh, molybdenum foil or tungsten foil. 7. The preparation method of a self-supporting transition metal selenide catalyst according to claim 5, characterized in that, the deposition time is 0.1-4 hours. 8. The self-supporting transition metal selenide catalyst obtained by the preparation method described in claim 1 or 5. 9. the application of self-supporting transition metal selenide catalyst described in claim 8 aspect electrolytic cell.