Nanotube-shaped hydrogen and oxygen evolution bifunctional catalyst as well as preparation method and application thereof

Abstract

The invention discloses a nanotube-shaped bifunctional catalyst for hydrogen evolution and oxygen evolution as well as a preparation method and application of the nanotube-shaped bifunctional catalyst. The catalyst is formed by co-loading active components, namely nanoparticles FeNiOx (OH) y and nanotube-shaped Cnts-Ni2O2 (OH), on reticular foamed nickel, wherein x is 0.5-2, and y is 1-3. Double active sites are provided for the catalyst through Ni2O2 (OH) and FeNiOx (OH) y, a special nanowire structure and a net-shaped substrate structure are maintained by adopting an electrodeposition method, electrolyte infiltration and gas evacuation are effectively promoted, transfer of electrons between the catalyst and a reaction system is accelerated, and the HER and OER performance of the catalyst is synchronously improved.

Description

Technical Field

[0001] The invention belongs to the technical field of water electrolysis and relates to a nano-tubular hydrogen and oxygen evolution dual-function catalyst and a preparation method and application thereof. Background Art

[0002] Energy and environment are the foundation of human survival and the driving force of sustainable social development. At present, the world's energy mainly comes from fossil energy such as coal, oil and natural gas. The process of its formation is very long. With the rapid increase of global population and economic development, the speed of human exploitation of fossil energy is much greater than its accumulation rate. At the same time, when fossil energy is burned, a large amount of pollutants such as carbon dioxide, nitrogen oxides and dust are emitted, which brings environmental problems such as haze, acid rain and greenhouse effect, which seriously threaten human health and survival. To a certain extent, human beings have further aggravated the world's energy crisis and environmental problems. However, in order to solve the current energy crisis and environmental problems and realize the sustainable development of human society and environment, in addition to raising environmental awareness and paying attention to ecological protection, it is more urgent to find new alternative energy and clean energy, especially renewable energy.

[0003] Today, renewable energy sources include solar energy, wind energy, hydropower, geothermal energy, tidal energy, etc. These energy sources all come from the sun and can be repeatedly generated and used. In addition, people have made great progress in the development and utilization of renewable resources. However, since these energy sources are affected by weather, geography and other factors in terms of energy conversion and storage, they can only be supplied intermittently in real life. Hydrogen energy, as a storable, efficient, clean and renewable new energy source, has become the clean energy with the greatest development potential in the 21st century. However, how to produce hydrogen sustainably is the first problem that humans need to solve in the future when they enter the hydrogen energy economy.

[0004] Using solar energy to electrolyze water to produce hydrogen is considered to be the most promising and sustainable way to produce hydrogen, but the relatively expensive cost of water electrolysis currently limits the development of electrolytic hydrogen production technology. The Gibbs free energy of water splitting is less than 0, and it cannot proceed spontaneously from a thermodynamic point of view, so efficient catalysts are required to increase the reaction rate and reduce energy consumption by reducing the activation energy. The overall reaction equation for water electrolysis contains two half-reaction equations: the cathode half-reaction and the anode half-reaction. Pt group metals and Ru and Ir-based compounds are considered to be the most advanced catalysts for HER and OER activity, respectively. IrO2 and Pt are used for HER and OER, and can reach 10mA·cm when an external voltage of 1.5V is applied. -2Current density (for integrated solar water splitting). However, since Pt, Ir, and Ru are all precious metals, their production costs are high, which is not conducive to large-scale use. There is an urgent need to find non-precious metals that are abundant on Earth and have high catalytic activity and good stability to replace these precious metals in catalyzing water electrolysis. At the same time, in order to carry out continuous water splitting reactions, the HER and OER catalysts must be placed in the same electrolyte. Considering that the general HER catalyst has a relatively low overpotential in acidic solutions, high catalytic activity, and good material stability, while the HER catalyst usually only has higher catalytic activity and material stability in alkaline solutions, therefore, from the perspective of simplifying the complexity of the water electrolysis system and reducing the system cost, the earth-abundant non-precious metal hydrogen and oxygen evolution bifunctional catalysts have become one of the current international research hotspots.

[0005] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0006] In order to solve the problems of low catalytic activity and inability to simultaneously possess HER and OER performances in existing non-precious metal catalysts used for water electrolysis, the first object of the present invention is to provide a nanotubular hydrogen and oxygen evolution bifunctional catalyst, which is a nanotubular hydrogen and oxygen evolution bifunctional catalyst. x (OH) y Providing dual active sites for the catalyst, combined with a special nanowire structure and mesh substrate structure, effectively promotes electrolyte infiltration and gas evacuation, accelerates the transfer of electrons between the catalyst and the reaction system, and simultaneously improves the HER and OER performance of the catalyst.

[0007] The second object of the present invention is to provide a method for preparing a nano-tubular bifunctional catalyst for hydrogen and oxygen evolution, wherein FeNiO is in situ loaded on a Cnts-Ni2O2(OH) / nickel foam composite material by an electrodeposition method. x (OH) y The active components not only maintain the nanotubular structure of Cnts-Ni2O2(OH), but also strengthen the binding force between the active components and the substrate.

[0008] The third object of the present invention is to provide an application of a nanotubular hydrogen and oxygen evolution bifunctional catalyst, which is used as an electrocatalyst for catalytic electrolysis of water to produce hydrogen, and has the advantages of relatively low overpotential, high catalytic activity, and low cost.

[0009] In order to achieve the above technical objectives, the present invention provides a nano-tubular hydrogen and oxygen evolution dual-function catalyst, which comprises active component nano-particles FeNiO x (OH)y The nanotube-shaped Cnts-Ni2O2(OH) active component is co-loaded on the reticulated nickel foam; wherein x is 0.5-2, and y is 1-3.

[0010] The key to the catalyst of the technical solution of the present invention having excellent OER and HER performance is the synergistic effect of the special morphology and active components. Specifically, Ni2O2(OH) has high capacitance and high oxygen evolution performance. The present invention introduces Ni2O2(OH) to attach to the surface of carbon nanotubes (Cnts) and uses the tubular structure of carbon nanotubes to promote electrolyte infiltration, gas evacuation and exert the activity of Ni2O2(OH), which is beneficial to improve the HER and OER performance of the composite material. And FeNiO x (OH) y The Fe and Ni atoms introduced in the reaction are both transition metals, and have similar electronic structures and small radius differences. The simultaneous introduction can promote the generation of OER active phases (such as NiOOH and FeOOH, and FeOOH and NiOOH can produce a synergistic effect, adjust the peripheral electronic arrangement, and reduce the energy barrier of OER) and reduce the activation energy of hydrogen evolution reaction. In addition, the nickel foam substrate used in the present invention has a reticular structure, which can not only provide physical support for the Cnts-Ni2O2(OH) active component, but also the nickel foam itself has good electronic conductivity. FeNiO x (OH) y It can grow and adhere on the surface and pores of nickel foam mesh. This loading method further strengthens the bonding between nickel mesh and Cnts-Ni2O2(OH) / FeNiO x (OH) y The close contact can serve as a channel for electron transmission, accelerating the transfer of electrons between the catalyst and the reaction system.

[0011] The difference in the values ​​of x and y in the present invention is mainly based on the different valence states of Ni and Fe.

[0012] As a preferred solution, the active component nanoparticles FeNiO x (OH) y The loading amount of FeNiO is 0.5-10wt%. x (OH) y The Fe and Ni atoms in the OER play a key role in promoting the generation of OER active phases and reducing the activation energy of hydrogen evolution reaction. When the loading is too low, the number of active sites participating in the reaction is reduced. When the loading is too high, agglomeration is likely to occur, and the ability of gas diffusion is hindered.

[0013] As a preferred solution, the loading amount of the nanotubular Cnts-Ni2O2(OH) active component is 10-30wt%. When the loading amount of the nanotubular Cnts-Ni2O2(OH) active component of the present invention is too low, the high capacitance and high oxygen evolution performance of Ni2O2(OH) itself cannot be fully utilized, and the tubular structure of the carbon nanotubes cannot be well used to promote electrolyte infiltration, gas evacuation, etc., while when the loading amount is too high, the active sites will be over-occupied, which is not conducive to the FeNiO x (OH) y Leverage synergy.

[0014] The present invention also provides a method for preparing a nano-tubular hydrogen and oxygen evolution dual-function catalyst, comprising the steps of dissolving and mixing a nickel salt and polyethylene glycol and then calcining the mixture to obtain a Ni2O2(OH) material; dispersing the Ni2O2(OH) material with Cnts in a solution and mixing the mixture to obtain a nano-tubular Cnts-Ni2O2(OH); dissolving the nano-tubular Cnts-Ni2O2(OH) and then dripping the mixture onto a foamed nickel substrate that has been pre-activated to obtain a Cnts-Ni2O2(OH) / foamed nickel composite material; using the Cnts-Ni2O2(OH) / foamed nickel composite material as a cathode and a platinum electrode as an anode, and electro-depositing nickel iron to obtain a Cnts-Ni2O2(OH) / FeNiO x (OH) y / Nickel foam composite material.

[0015] The preparation mechanism of the present invention is that during the calcination process, polyethylene glycol decomposes to provide oxygen and hydroxide and combines with the dispersed nickel ions to form Ni2O2(OH), and during the mixing process with Cnts, due to the functional groups on the surface of Cnts and physical adsorption, Ni2O2(OH) particles can be attached to the surface of Cnts. The tubular structure of Cnts provides a template effect for the growth and distribution of Ni2O2(OH), so that Ni2O2(OH) grows and assembles along the tube wall or the inner surface of the Cnts, thereby forming a nano-tubular Cnts-Ni2O2(OH) structure, and then obtaining a Cnts-Ni2O2(OH) / foam nickel composite material. This composite structure is conducive to the transmission of electrons and the diffusion of substances, and provides good electrical and mass transfer performance for subsequent hydrogen and oxygen evolution reactions. Finally, through the process of electrodeposition, the nickel ions and iron ions in the electrodeposition solution undergo a reduction reaction with part of the original Ni2O2(OH) on the cathode surface of the Cnts-Ni2O2(OH) / foam nickel composite material to form FeNiO x (OH) y It is in situ loaded on a nickel foam substrate while maintaining the tubular structure of the carbon nanotubes.

[0016] As a preferred solution, the activation pretreatment is to cut the nickel foam substrate and then sequentially perform acid washing, alcohol washing and water washing.

[0017] As a preferred solution, the nickel salt includes nickel nitrate.

[0018] As a preferred solution, the solid-liquid ratio of the nickel salt to the polyethylene glycol is 1 g / (6-12) mL. Further preferably, the number average molecular weight of PEG is 200.

[0019] As a preferred solution, the nickel salt and polyethylene glycol are dissolved and mixed for 1 to 2 hours, the calcination temperature is 500 to 700°C, and the calcination time is 1 to 2 hours. The calcination temperature selected in the present invention helps Ni2O2(OH) to form a stable crystal structure. Ni2O2(OH) corresponds to the orthorhombic system under certain conditions. If the calcination temperature is too low, the crystal structure may not develop completely, affecting the stability and activity of the catalyst; if the temperature is too high, it may cause the crystal structure to change or even be destroyed, which also reduces the catalytic performance. It is further preferred that the calcination temperature is 500 to 550°C.

[0020] As a preferred solution, the molar ratio of the Ni2O2(OH) material to Cnts is (7-9):1.

[0021] As a preferred solution, the process of dissolving the nanotubular Cnts-Ni2O2(OH) is as follows: dissolving the nanotubular Cnts-Ni2O2(OH) in water and controlling the concentration of the nanotubular Cnts-Ni2O2(OH) to be (1-2 mg) / 2 mL of CNTs and water; and the drop coating thickness is 100-200 μm. By controlling the drop coating thickness of the present invention, the loading amount of the nanotubular Cnts-Ni2O2(OH) on the nickel foam can be controlled within 10-30 wt%.

[0022] As a preferred solution, the electroplating of nickel iron uses an electroplating solution including nickel sulfate and iron sulfate, wherein the total concentration of nickel sulfate and iron sulfate is 2-10 mmol / L.

[0023] As a preferred solution, the molar ratio of nickel sulfate to iron sulfate is (5-1):(1-5) of nickel to iron. During the electrodeposition process, metal ions can undergo reduction deposition reaction on the electrode surface to form FeNiOx(OH)y with a specific structure and composition. 3+ and Ni 2+FeNiOx(OH)y catalysts with different Ni / Fe atomic ratios can be prepared by adjusting the molar concentration ratio, which shows that the ratio of metal ions has an important influence on the composition of the product. When the molar ratio of nickel to iron is too high, it means that the iron content is relatively low. In the OER process, iron is the main active site. When the iron content is insufficient, the number of active sites decreases and the catalytic reaction rate decreases. From the perspective of electronic structure, excessive nickel content will change the overall electron cloud distribution of the catalyst and affect the active site to the reaction intermediates. Further preferably, the molar ratio of nickel sulfate to iron sulfate is (4-2):(2-4) according to the molar ratio of nickel to iron, and further preferably (4-3):(2-3).

[0024] As a preferred solution, the electrodeposition of nickel iron adopts constant voltage deposition, the voltage range is -1 to -2V, and the deposition time is 15 to 60min. The reaction rate of the electrode surface deposited by the constant voltage in the present invention is relatively stable, which helps to deposit more uniformly. The active component FeNiO can be controlled within the deposition time selected by the present invention. x (OH) y The loading amount and the shorter deposition time cannot make NiFe fully react and deposit.

[0025] Finally, the present invention also provides an application of a nanotubular hydrogen and oxygen evolution bifunctional catalyst, which is used as an electrocatalyst for catalytic electrolysis of water to produce hydrogen, and has the advantages of relatively low overpotential, high catalytic activity, and low cost.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The preparation method of the hydrogen evolution catalyst of the present invention is not only easy to control the preparation conditions, but also the electrodeposited Cnts make the catalyst have a unique nanowire structure, and the introduction of Ni2O2(OH) attached to the surface of carbon nanotubes (Cnts) can promote electrolyte infiltration, gas evacuation and exert the activity of Ni2O2(OH) through the tubular structure, which is beneficial to improve the HER and OER performance of the composite material. x (OH) y The Fe and Ni atoms introduced in the reaction are both transition metals with similar electronic structures and small radius differences. Their simultaneous introduction can promote the formation of OER active phases (such as NiOOH) and reduce the activation energy of the hydrogen evolution reaction.

[0028] (2) The nickel foam substrate used in the present invention has a mesh structure, which can not only provide physical support for the Cnts-Ni2O2(OH) active component, but also the nickel foam itself has good electronic conductivity. x (OH) yIt can grow and adhere on the surface and pores of nickel foam mesh. This loading method further strengthens the bonding between nickel mesh and Cnts-Ni2O2(OH) / FeNiO x (OH) y The close contact between the nickel foam and the catalyst can serve as a channel for electron transmission, accelerating the transfer of electrons between the catalyst and the reaction system. The rigid and mesh-like structure of nickel foam increases the surface area of ​​the composite electrode, which is beneficial to mass transfer and improves the electrochemical activity of the electrode.

[0029] (3) The present invention in situ grows FeNiO by electrodeposition x (OH) y It can be more firmly combined with the base material, thus improving the stability of the catalyst.

[0030] (4) The present invention introduces Ni2O2(OH) with high capacitance and high oxygen evolution performance, which plays a great role in improving the catalytic performance of the hydrogen evolution catalyst and reducing the oxygen evolution overpotential.

[0031] (5) Cnts, FeNiO x (OH) y Composite catalyst for hydrogen and oxygen evolution Cnts-Ni2O2(OH) / FeNiO x (OH) y / Nickel foam can be used as the anode and cathode of the water electrolysis device, providing a premise for the continuous water splitting reaction with great practical application significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the XRD diagram of Cnts-Ni2O2(OH) / FeNiO2(OH)-1 / CF synthesized in Example 3 of the present invention.

[0033] Figure 2 Cnts-Ni2O2(OH) / FeNiO synthesized in Example 10 of the present invention 1.9 (OH) 1.2 -SEM image of 1 / CF.

[0034] Figure 3 1 is an LSV diagram of the oxygen evolution reaction of the composite materials of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 of the present invention.

[0035] Figure 4 1 is the LSV diagram of the hydrogen evolution reaction of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0036] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0037] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0038] Example 1

[0039] Preparation process of Cnts-Ni2O2(OH) / FeNiO(OH)3-5 / nickel foam electrode material:

[0040] (1) First, the nickel foam substrate material was cut into 3 cm × 5 cm sizes, and the cut nickel foam substrate was placed in 2 mol / L HCl for 15 min to remove the surface oxide layer; then, the acid-treated nickel foam substrate was ultrasonicated in ethanol and deionized water for 15 min to remove organic impurities on the surface, thereby obtaining the activated pretreated nickel foam.

[0041] (2) 6.87mmol Ni(NO3)2·6H2O and 12mL polyethylene glycol (PEG200) were co-heated and dissolved in a crucible, and the mixed solution was subjected to ultrasonic treatment for two hours. After that, the mixed solution was calcined at 500℃ for 0.5 hours to obtain nanotubular Ni2O2(OH) material. Then the prepared nanotubular Ni2O2(OH) material and CNT suspension (concentration of 1mg / 1mL, solvent is water) were co-dissolved in a molar ratio of 7:1, placed in an ultrasonicator for 120min of ultrasonic treatment, and then the obtained mixture was dried at 80℃, and then the dried material was dissolved in water and drop-coated on the activated pretreated nickel foam (1cm×1cm) to obtain Cnts-Ni2O2(OH) / nickel foam composite material (drop coating thickness of 100μm).

[0042] (3) Prepare 100 mL of 6 mM electrodeposition solution in which Ni:Fe=5:1, ferric sulfate as the source of iron, nickel sulfate as the source of nickel, and water as the solvent. Then use a platinum electrode as the anode and a Cnts-Ni2O2(OH) / nickel foam electrode as the cathode. Keep the distance between the cathode and the anode at 4 cm. At room temperature, apply a constant voltage of -1 V and electrodeposit for 30 min to obtain a Cnts-Ni2O2(OH) / FeNiO(OH)3-5 / nickel foam composite material, in which the loading amount of the active component FeNiO(OH)3 is 7.9 wt%, and the loading amount of the nanotubular Cnts-Ni2O2(OH) active component is 18.9 wt%.

[0043] Example 2

[0044] The difference between this embodiment and embodiment 1 is that the Ni:Fe ratio in the electrodeposition solution is changed to 4:2, and the other steps and conditions are the same, and Cnts-Ni2O2(OH) / FeNiO is obtained. 1.5 (OH)2-2 / nickel foam electrode material, hydrogen evolution reaction overpotential is 236mV, oxygen evolution reaction overpotential is 189mV, and the active component FeNiO 1.5 The loading amount of (OH)2 is 9.1wt%, and the loading amount of the nanotubular Cnts-Ni2O2(OH) active component is 17.5wt%.

[0045] Example 3

[0046] The only difference between this embodiment and embodiment 1 is that the Ni:Fe in the electrodeposition solution is changed to 3:3, and the other steps and conditions are the same, and a Cnts-Ni2O2(OH) / FeNiO2(OH)-1 / foam nickel electrode material is obtained, with a hydrogen evolution reaction overpotential of 212 mV and an oxygen evolution reaction overpotential of 171 mV, wherein the loading amount of the active component FeNiO2(OH) is 8.2 wt%, and the loading amount of the nanotubular Cnts-Ni2O2(OH) active component is 18.8 wt%.

[0047] Example 4

[0048] The difference between this embodiment and embodiment 1 is that the Ni:Fe ratio in the electrodeposition solution is changed to 2:4, and the other steps and conditions are the same, and Cnts-Ni2O2(OH) / FeNiO is obtained. 1.25 (OH) 2.5 -0.5 / Foam nickel electrode material, the overpotential of hydrogen evolution reaction is 237mV, the overpotential of oxygen evolution reaction is 190mV, and the active component FeNiO 1.25 (OH) 2.5 The loading amount of the nanotubular Cnts-Ni2O2(OH) active component is 7.9wt%, and the loading amount of the nanotubular Cnts-Ni2O2(OH) active component is 17.9wt%.

[0049] Example 5

[0050] The difference between this embodiment and embodiment 1 is that the Ni:Fe ratio in the electrodeposition solution is changed to 1:5, and the other steps and conditions are the same, and Cnts-Ni2O2(OH) / FeNiO is obtained. 1.4 (OH) 2.2 -0.2 / Foam nickel electrode material, the overpotential of hydrogen evolution reaction is 238mV, and the overpotential of oxygen evolution reaction is 193mV, in which the active component FeNiO 1.4 (OH) 2.2The loading amount of the nanotubular Cnts-Ni2O2(OH) active component is 8.1wt%, and the loading amount of the nanotubular Cnts-Ni2O2(OH) active component is 19.1wt%.

[0051] Example 6

[0052] The only difference between this embodiment and embodiment 3 is that the molar ratio of the nanotubular Ni2O2(OH) material and the CNT suspension is changed to 9:1, and the other steps and conditions are the same, and the Cnts-Ni2O2(OH) / FeNiO2(OH)-9 / nickel foam electrode material is obtained, and the overpotential of the hydrogen evolution reaction is 225mV, and the overpotential of the oxygen evolution reaction is 189mV.

[0053] Example 7

[0054] The only difference between this embodiment and embodiment 3 is that the molar ratio of the nanotubular Ni2O2(OH) material and the CNT suspension is changed to 8:1, and the other steps and conditions are the same, and the Cnts-Ni2O2(OH) / FeNiO2(OH)-8 / foam nickel electrode material is obtained, and the overpotential of the hydrogen evolution reaction is 221mV, and the overpotential of the oxygen evolution reaction is 180mV.

[0055] Example 8

[0056] The only difference between this embodiment and embodiment 3 is that the calcination temperature is increased to 550°C, and the other steps and conditions are the same to obtain Cnts-Ni2O2(OH) / FeNiO 1.85 (OH) 1.3 / Foam nickel electrode material, the overpotential of hydrogen evolution reaction is 223mV, and the overpotential of oxygen evolution reaction is 191mV.

[0057] Example 9

[0058] The only difference between this embodiment and embodiment 3 is that the calcination temperature is increased to 650°C, and the other steps and conditions are the same to obtain Cnts-Ni2O2(OH) / FeNiO 1.75 (OH) 1.5 / Foam nickel electrode material, the overpotential of hydrogen evolution reaction is 235mV, and the overpotential of oxygen evolution reaction is 202mV.

[0059] Example 10

[0060] Cnts-Ni2O2(OH) / FeNiO 1.9 (OH) 1.2 -1 / Preparation process of nickel foam electrode material:

[0061] (1) Substrate pretreatment is the same as in Example 1;

[0062] (2) 6.87mmol Ni(NO3)2·6H2O and 18mL polyethylene glycol (PEG200) were co-heated and dissolved in a crucible, and the mixed solution was subjected to ultrasonic treatment for two hours. After that, the mixed solution was calcined at 600℃ for 1.5 hours to obtain nanotubular Ni2O2(OH) material. Then the prepared nanotubular Ni2O2(OH) material and CNT suspension (concentration of 1mg / 1mL, solvent is water) were co-dissolved in a molar ratio of 8:1, placed in an ultrasonicator for 120min of ultrasonic treatment, and then the obtained mixture was dried at 80℃, and then the dried material was dissolved in water and drop-coated on the activated pretreated nickel foam (1cm×1cm) to obtain Cnts-Ni2O2(OH) / nickel foam composite material (drop coating thickness of 100μm).

[0063] (3) Prepare 100 mL of 6 mM electrodeposition solution in which Ni:Fe=3:3, ferric sulfate as the source of iron, nickel sulfate as the source of nickel, and water as the solvent. Then use a platinum electrode as the anode and a Cnts-Ni2O2(OH) / nickel foam electrode as the cathode. Keep the distance between the cathode and the anode at 4 cm. At room temperature, apply a constant voltage of -1.4 V and electrodeposit for 30 min to obtain Cnts-Ni2O2(OH) / FeNiO 1.9 (OH) 1.2 -1 / Foam nickel composite material. The active component FeNiO 1.9 (OH) 1.2 The loading amount of the nanotube-shaped Cnts-Ni2O2(OH) active component is 9.1wt%, and the loading amount of the nanotube-shaped Cnts-Ni2O2(OH) active component is 20.1wt%.

[0064] Comparative Example 1

[0065] The only difference between this comparative example and Example 5 is that Ni and Fe are not electrodeposited, and the remaining steps and conditions are the same to obtain a Cnts-Ni2O2(OH) / foam nickel composite material.

[0066] Comparative Example 2

[0067] The difference between this comparative example and Example 5 is that step 2) is not performed, and Ni and Fe are directly electrodeposited after substrate pretreatment, and the remaining steps and conditions are the same to obtain FeNiO 1.4 (OH) 2.2 -0.2 / Foam nickel composite material.

[0068] In order to avoid the influence of the XRD diffraction peak of the nickel foam substrate, the nickel foam substrate in Example 3 was replaced with an equal amount of carbon cloth to obtain a Cnts-Ni2O2(OH) / FeNiO2(OH)-1 / CF composite material, and XRD characterization was performed on it. The results are shown in Figure 1 As shown, the characteristic peak appearing at 26° is consistent with the XRD result of carbon cloth, indicating that the crystallinity of the catalyst is poor, which is closely related to improving the electrocatalytic performance of the material. In addition, the peak of Ni2O2(OH) can be clearly seen in the figure, indicating that Ni2O2(OH) was successfully loaded.

[0069] At the same time, the nickel foam substrate of Example 10 was replaced with an equal amount of carbon cloth to obtain Cnts-Ni2O2(OH) / FeNiO 1.9 (OH) 1.2 -1 / CF composites were characterized by SEM. Figure 2 As shown, Figure 2 It shows that the composite material prepared by the present invention has an obvious nanowire structure. This microstructure makes the composite material of the present invention conducive to promoting electrolyte infiltration and gas evacuation when used as an electrocatalyst, thereby significantly improving HER and OER performance.

[0070] Test examples: Cnts-Ni2O2(OH) / FeNiO(OH)3-5 / Foam nickel, Cnts-Ni2O2(OH) / FeNiO 1.5 Electrocatalytic performance of (OH)2-2 / nickel foam and Cnts-Ni2O2(OH) / FeNiO2(OH)-1 / nickel foam

[0071] In multiple experiments, Example 3 performed best. The polarization curve test was carried out using a three-electrode system in a 1.0 mol / L KOH solution, with an Ag / AgCl (internal filling solution: saturated KCl) electrode as the reference electrode, a Pt / C electrode as the counter electrode, and catalysts (Cnts-Ni2O2(OH) / FeNiO(OH)3-5, Cnts-Ni2O2(OH) / FeNiO 1.5 (OH)2-2, Cnts-Ni2O2(OH) / FeNiO2(OH)-1, FeNiO 1.4 (OH) 2.2 -0.2 and Cnts-Ni2O2(OH), with NF as the carrier) as the working electrode. The HER and OER catalytic activities of five samples of three groups of examples and two groups of comparative examples were tested in 1.0 mol / L KOH (pH = 13.6) solution. Figure 3 and Figure 4 shown.

[0072] Polarization curve of oxygen evolution reaction at 10 mA cm -2The overpotential of Cnts-Ni2O2(OH) / FeNiO2(OH)-1 / NF is the lowest at 171mV (Cnts-Ni2O2(OH) / FeNiO(OH)3-5 / nickel foam electrode material, the overpotential of oxygen evolution reaction is 191mV, Cnts-Ni2O2(OH) / FeNiO 1.5 (OH)2-2 / nickel foam electrode material, oxygen evolution reaction overpotential is 189mV, Cnts-Ni2O2(OH) / nickel foam electrode material, oxygen evolution reaction overpotential is 221mV, FeNiO 1.4 (OH) 2.2 -0.2 / nickel foam electrode material, oxygen evolution reaction overpotential is 241mV). The oxidation peak in the voltage range of 1.45 to 1.55V can be attributed to Ni 2+ To You 3+ The oxidation of NiOOH indicates the formation of NiOOH on the catalyst surface, which is the active phase in the OER process.

[0073] like Figure 4 The polarization curve of the hydrogen evolution reaction is shown at -10 mA cm -2 The lowest overpotential of Cnts-Ni2O2(OH) / FeNiO2(OH)-1 / NF is 212mV (Cnts-Ni2O2(OH) / FeNiO(OH)3-5 / nickel foam electrode material, the overpotential of hydrogen evolution reaction is 219mV, Cnts-Ni2O2(OH) / FeNiO 1.5 (OH)2-2 / nickel foam electrode material, hydrogen evolution reaction overpotential is 236mV, Cnts-Ni2O2(OH) / nickel foam electrode material, hydrogen evolution reaction overpotential is 245mV, FeNiO 1.4 (OH) 2.2 -0.2 / foam nickel electrode material, the overpotential of hydrogen evolution reaction is 248mV).

[0074] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A nanotubular bifunctional catalyst for hydrogen and oxygen evolution, characterized in that: The active component is FeNiO nanoparticles x (OH) y The active components of nanotube-shaped Cnts-Ni2O2(OH) are co-loaded on the reticulated nickel foam; Among them, x is 0.5~2, and y is 1~3.

2. A nanotubular bifunctional catalyst for hydrogen and oxygen evolution according to claim 1, characterized in that: The active component nanoparticles FeNiO x (OH) y The loading amount is 0.5 to 10 wt%; The loading amount of the nanotube-shaped Cnts-Ni2O2(OH) active component is 10-30 wt%.

3. A method for preparing a nanotubular bifunctional catalyst for hydrogen and oxygen evolution according to claim 1 or 2, characterized in that: The nickel salt and polyethylene glycol are dissolved and mixed, and then calcined to obtain a Ni2O2(OH) material; the Ni2O2(OH) material is dispersed in a solution and mixed with Cnts to obtain a nano-tubular Cnts-Ni2O2(OH); the nano-tubular Cnts-Ni2O2(OH) is dissolved and then drop-coated on a foamed nickel substrate that has been pre-activated to obtain a Cnts-Ni2O2(OH) / foamed nickel composite material; The Cnts-Ni2O2(OH) / nickel foam composite material is used as a cathode and a platinum electrode is used as an anode to obtain Cnts-Ni2O2(OH) / FeNiO by electro-depositing nickel and iron. x (OH) y / Nickel foam composite material.

4. The method for preparing a nanotubular bifunctional catalyst for hydrogen and oxygen evolution according to claim 3, characterized in that: The nickel salt includes nickel nitrate; The solid-to-liquid ratio of the nickel salt to the polyethylene glycol is 1 g / (6-12) mL; The nickel salt and polyethylene glycol are dissolved and mixed for 1 to 2 hours, the calcination temperature is 500 to 700° C., and the calcination time is 1 to 2 hours.

5. The method for preparing a nanotubular bifunctional catalyst for hydrogen and oxygen evolution according to claim 3, characterized in that: The molar ratio of the Ni2O2(OH) material to Cnts is (7-9):

1.

6. A method for preparing a nanotubular bifunctional catalyst for hydrogen and oxygen evolution according to any one of claims 3 to 5, characterized in that: The drop coating thickness is 100-200 μm.

7. The method for preparing a nanotubular bifunctional catalyst for hydrogen and oxygen evolution according to claim 3, characterized in that: The electroplating of nickel iron uses an electroplating solution including nickel sulfate and iron sulfate, wherein the total concentration of the nickel sulfate and the iron sulfate is 2-10 mmol / L.

8. The method for preparing a nanotubular bifunctional catalyst for hydrogen and oxygen evolution according to claim 7, characterized in that: The molar ratio of the nickel sulfate to the iron sulfate is calculated based on the molar ratio of nickel to iron being (5-1):(1-5).

9. A method for preparing a nanotubular bifunctional catalyst for hydrogen and oxygen evolution according to claim 7 or 8, characterized in that: The electro-deposited nickel iron adopts constant voltage deposition, the voltage range is -1 to -2V, and the deposition time is 15 to 60 minutes.

10. Use of a nanotubular bifunctional catalyst for hydrogen and oxygen evolution according to claim 1 or 2, characterized in that: It is used as an electrocatalyst to catalyze the electrolysis of water to produce hydrogen.

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