NiOOH / Ti-P-O nanotube array photoanode, preparation method and application thereof

Abstract

The application relates to a NiOOH / Ti-P-O nanotube array photoanode and a preparation method and application thereof. The preparation method comprises the following steps: S1, pretreated Ti sheets are sequentially subjected to anodic oxidation treatment and crystallization treatment to obtain a Ti-O nanotube array photoanode; S2, the Ti-O nanotube array photoanode is subjected to phosphating treatment, and a Ti-P-O nanotube array photoanode is obtained after cooling; and S3, the Ti-P-O nanotube array photoanode is immersed in a mixed solution containing a nickel source and urea for thermal deposition to obtain a NiOOH / Ti-P-O nanotube array photoanode. The NiOOH / Ti-P-O nanotube array photoanode can be widely applied to the field of photoelectrocatalytic water splitting. Compared with the prior art, the application provides a controllable preparation method with short time consumption, and the prepared product significantly enhances photoelectrochemical activity and improves photoelectrocatalytic efficiency.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of photoelectrocatalysis, in particular to a NiOOH / Ti-P-O nanotube array photoanode and a preparation method and application thereof. BACKGROUND

[0002] Among all the energy, solar energy, wind energy, tidal energy, water energy and hydrogen energy are pollution-free and new renewable energy gifted by nature. Among all the energy, hydrogen energy is a very outstanding green clean energy, and the generated product in the use process is water, which obviously does not cause any harm to the environment, and the hydrogen energy itself also has a relatively high energy density. The preparation methods of hydrogen energy include electrocatalysis, photocatalysis and photoelectrocatalysis, among which, the technology of using a semiconductor as a catalyst base to prepare hydrogen by water splitting is the most promising technology at present.

[0003] The most common semiconductor materials are BiVO4, TiO2, ZnO, MnO2 and WO3, and TiO2 can be used to prepare hydrogen by water splitting and is used by researchers for various in-depth discussions because it is discovered by Fujishima and Honda. TiO2 is low in price, stable in nature and good in light response, and is a relatively ideal raw material for photoelectrocatalytic water splitting for hydrogen. However, it has a large band gap and a high degree of recombination of photo-generated carriers and holes, which greatly limits its development.

[0004] Inorganic non-metallic ion doping is an effective strategy to improve the visible light catalytic performance of the matrix material, and can expand the narrow interval of TiO2 responding to ultraviolet light to the visible light interval. After element doping, the band gap value can be reduced to a certain extent, greatly promoting the transmission of electrons and holes and promoting electron transition. Generally, non-metallic ions replace the position of oxygen, causing the valence band of TiO2 to move upwards, or introducing new energy levels in the forbidden band, thereby reducing the conduction band position of TiO2. Phosphorus element will replace the position of titanium ion and produce certain oxygen defects during doping, which will reduce the band gap of TiO2 and cause charge imbalance between Ti and O. 4+ and O 2- Compared with non-metallic elements such as nitrogen, sulfur and boron, the atomic radius of phosphorus element is larger, which can promote the distribution of charge density and form a hydrophilic polar surface, thereby promoting electron transfer and inhibiting electron-hole recombination, and thus enhancing the visible light absorption capacity and improving the photoelectrocatalytic performance.

[0005] While non-metallic doping can improve the separation efficiency of photogenerated carriers in TiO2 photoanodes, the resulting photoanodes often exhibit high onset potentials and poor fill factors. This is because the water oxidation kinetics on the TiO2 surface are relatively slow, and carrier recombination is prone to occur at low potentials. Loading an oxygen evolution co-catalyst onto the TiO2 surface can accelerate the surface water oxidation kinetics. Oxygen evolution co-catalysts have numerous active sites, can significantly reduce the onset potential, and are stable and efficient. By growing them on the TiO2 photoanode surface, they can improve the injection efficiency of the photogenerated carrier phase electrolyte solution at the interface, enhance electrode conductivity and electron transfer, and thus promote oxygen evolution activity. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects in the prior art, such as the high onset potential of the photoanode caused by non-metallic doping, and to provide a NiOOH / Ti-PO nanotube array photoanode, its preparation method, and its application.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] One of the technical solutions of the present invention is to provide a method for preparing a NiOOH / Ti-PO nanotube array photoanode, comprising the following steps:

[0009] S1. The pretreated Ti sheet is subjected to anodic oxidation and crystallization treatment in sequence to obtain Ti-O nanotube array photoanode;

[0010] S2. Phosphate the Ti-O nanotube array photoanode obtained in step S1, and then cool it to obtain the Ti-PO nanotube array photoanode.

[0011] S3. The Ti-PO nanotube array photoanode obtained in step S2 is immersed in a mixed solution containing nickel source and urea for thermal deposition to obtain NiOOH / Ti-PO nanotube array photoanode.

[0012] Furthermore, in step S1, the pretreatment process is as follows: the Ti wafer is first sanded with wet sandpaper until the surface is free of scratches, then ultrasonically cleaned in acetone, anhydrous ethanol, and deionized water for 10 minutes each, and finally dried at room temperature.

[0013] Furthermore, in step S1, the anodic oxidation process is as follows: first, a mixed solution of 0.4wt% NH4F and 2vol% H2O in ethylene glycol is prepared as the electrolyte, the pretreated Ti sheet is used as the anode, and the graphite plate is used as the cathode, and the reaction is carried out for 1-2 hours under a DC voltage of 35-45V.

[0014] Further, in step S1, the crystallization process is as follows: the anodized Ti-O nanotube array is calcined at 525-575℃ for 1-3 hours, and after cooling, the anatase phase Ti-O nanotube array photoanode is obtained.

[0015] Further, in step S2, the phosphating process is as follows: the Ti-O nanotube array photoanode is heated and reacted with the phosphorus source NaHPO2·H2O, wherein the mass of the phosphorus source NaHPO2·H2O is 1-3g, the temperature of the phosphorus source region is 525-575℃, the temperature of the Ti-O nanotube array photoanode placement region is 350-450℃, and the heating time is 3-5h.

[0016] Furthermore, in step S3, the nickel source is NiCl2·6H2O.

[0017] Furthermore, in step S3, the concentration of the nickel source in the mixed solution is 30-40 mmol, and the concentration of urea is 30-50 mmol.

[0018] Furthermore, in step S3, the thermal deposition process is as follows: the Ti-PO nanotube array photoanode is immersed in a mixed solution at a temperature of 80-95℃ for 1-3 hours, then washed with deionized water, and vacuum dried at 60℃ for 6 hours.

[0019] The second technical solution of the present invention is to provide a NiOOH / Ti-PO nanotube array photoanode, based on the preparation method described in one of the above technical solutions.

[0020] The third technical solution of the present invention is to provide an application of a NiOOH / Ti-PO nanotube array photoanode, wherein the NiOOH / Ti-PO nanotube array photoanode is used in the field of photoelectrocatalytic water splitting.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention provides a time-efficient method for the controllable fabrication of nanotube arrays. P doping replaces Ti. 4+ The position of doping will reduce the band gap of TiO2 and cause Ti to... 4+ and O 2-The charge imbalance between elements, coupled with the larger atomic radius of phosphorus (P), promotes charge density distribution, forming a hydrophilic polar surface. This facilitates electron transfer and inhibits charge recombination, thereby enhancing visible light absorption and improving photoelectrochemical performance. Nickel significantly lowers the onset potential and accelerates surface water oxidation kinetics. Solution thermal deposition allows for the uniform and efficient loading of NiOOH onto the surface of Ti-PO nanotube arrays. The NiOOH / Ti-PO nanotube array photoanode prepared using this method exhibits a negative shift in onset potential, effectively suppressing the recombination of photogenerated electron-hole pairs and significantly enhancing photoelectrochemical activity. Attached Figure Description

[0023] Figure 1 The graph shows a comparison of linear scanning voltammetry for Example 2, Comparative Example 2, and Comparative Example 4.

[0024] Figure 2 The graph shows a comparison of transient photocurrents in Example 2, Comparative Example 2, and Comparative Example 4. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0026] Unless otherwise specified, the raw materials or processing techniques used in the following embodiments and comparative examples are all conventional commercially available raw materials or conventional processing techniques in the art.

[0027] Example 1:

[0028] A method for preparing a NiOOH / Ti-PO nanotube array photoanode is as follows:

[0029] The first step is pretreatment: A pure titanium sheet with a size of 10mm×20mm×1mm is polished with 240 grit, 400 grit, 800 grit, 1000 grit and 1500 grit water sandpaper in sequence until the surface is smooth. Then, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 10 minutes respectively to remove surface impurities.

[0030] The second step is anodizing: the pretreated pure titanium sheet is used as the anode and the graphite plate as the cathode. A mixed solution of 0.4wt% NH4F and 2vol% H2O in ethylene glycol is used as the electrolyte. The oxidation is carried out for 1 hour under a DC voltage of 40V. Then, the surface impurities are cleaned with deionized water and dried with N2 to obtain a titanium dioxide nanotube array.

[0031] The third step is to perform crystallization treatment. The Ti-O nanotube array obtained after the above anodizing treatment is placed in a muffle furnace and calcined at 550°C for 2 hours. After cooling to room temperature with the furnace, it is taken out to obtain anatase phase Ti-O nanotube array photoanode.

[0032] The fourth step is to perform tube furnace phosphating treatment. Weigh 3,000 g of NaHPO2·H2O and place it in the reagent zone. Transfer the anatase phase Ti-O nanoarray photoanode obtained in the third step to the dual-temperature zone tube furnace for phosphating treatment. The reagent zone is set to 550℃, the temperature zone where the Ti-O nanotube array is placed is set to 400℃, the holding time is set to 4 hours, and it is naturally cooled to room temperature to obtain the Ti-PO nanotube array photoanode.

[0033] The fifth step involves solution thermal deposition. Weigh 0.3556g of NiCl2·6H2O and 0.1350g of urea, dissolve them in 50mL of deionized water, stir well, and then transfer them to an oven set at 90℃ for 1.5h. After cooling to room temperature, remove the material, wash it with deionized water about 3 times, and dry it in a vacuum drying oven at 60℃ for 6h to obtain the NiOOH / Ti-PO nanotube array photoanode electrode material.

[0034] Three-electrode testing was performed using a Chenhua CHI660E electrochemical workstation employing different LSV, IT, VOPT, EIS, and MOTT methods. A NiOOH / Ti-PO nanotube array photoanode electrode was selected as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode. A xenon lamp was used as the light source. The working electrode, counter electrode, and reference electrode were connected to the electrochemical workstation, and the test was conducted at a 1 mol L... -1 The photoelectrochemical properties of the electrode material were measured in KOH solution.

[0035] Example 2:

[0036] A method for preparing a NiOOH / Ti-PO nanotube array photoanode is as follows:

[0037] The first step is pretreatment: A pure titanium sheet with a size of 10mm×20mm×1mm is polished with 240 grit, 400 grit, 800 grit, 1000 grit and 1500 grit water sandpaper in sequence until the surface is smooth. Then, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 10 minutes respectively to remove surface impurities.

[0038] The second step is anodizing: the pretreated pure titanium sheet is used as the anode and the graphite plate as the cathode. A mixed solution of 0.4wt% NH4F and 2vol% H2O in ethylene glycol is used as the electrolyte. The oxidation is carried out for 1 hour under a DC voltage of 40V. Then, the surface impurities are cleaned with deionized water and dried with N2 to obtain a Ti-O nanotube array.

[0039] The third step is to perform crystallization treatment. The Ti-O nanotube array obtained after the above anodizing treatment is placed in a muffle furnace and calcined at 550°C for 2 hours. After cooling to room temperature with the furnace, it is taken out to obtain anatase phase Ti-O nanotube array photoanode.

[0040] The fourth step is to perform tube furnace phosphating treatment. Weigh 3.000g of NaHPO2·H2O and transfer the anatase phase Ti-O nanoarray photoanode obtained in the third step to a dual-temperature zone tube furnace for phosphating treatment. The chemical zone is set to 550℃, the temperature zone for placing the Ti-O nanotube array is set to 400℃, the holding time is set to 4h, and it is naturally cooled to room temperature to obtain the Ti-PO nanotube array photoanode.

[0041] The fifth step involves solution thermal deposition. Weigh 0.3556g of NiCl2·6H2O and 0.1350g of urea, dissolve them in 50mL of deionized water, stir well, and then transfer them to an oven set at 90℃ for 2 hours. After cooling to room temperature, remove the material, wash it with deionized water about 3 times, and dry it in a vacuum drying oven at 60℃ for 6 hours to obtain the NiOOH / Ti-PO nanotube array photoanode electrode material.

[0042] Using the Chenhua CHI660E electrochemical workstation, three-electrode testing was conducted using different LSV, IT, VOPT, EIS, and MOTT methods. NiOOH / Ti-PO nanotube array photoanode electrode material was selected as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode. A xenon lamp was used as the light source. The working electrode, counter electrode, and reference electrode were connected to the electrochemical workstation, and the test was performed at 1 mol L... -1 The photoelectrochemical properties of the electrode material were measured in KOH solution.

[0043] Example 3:

[0044] A method for preparing a NiOOH / Ti-PO nanotube array photoanode is as follows:

[0045] The first step is pretreatment: A pure titanium sheet with a size of 10mm×20mm×1mm is polished with 240 grit, 400 grit, 800 grit, 1000 grit and 1500 grit water sandpaper in sequence until the surface is smooth. Then, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 10 minutes respectively to remove surface impurities.

[0046] The second step is anodizing: the pretreated pure titanium sheet is used as the anode and the graphite plate as the cathode. A mixed solution of 0.4wt% NH4F and 2vol% H2O in ethylene glycol is used as the electrolyte. The oxidation is carried out for 1 hour under a DC voltage of 40V. Then, the surface impurities are cleaned with deionized water and dried with N2 to obtain a Ti-O nanotube array.

[0047] The third step is crystallization treatment. The titanium dioxide nanotube array obtained after the above anodizing treatment is placed in a muffle furnace and calcined at 550°C for 2 hours. After cooling to room temperature with the furnace, it is taken out to obtain anatase phase Ti-O nanotube array photoanode.

[0048] The fourth step is to perform tube furnace phosphating treatment. Weigh 3.000g of NaHPO2·H2O and transfer the anatase phase Ti-O nanoarray photoanode obtained in the third step to a dual-temperature zone tube furnace for phosphating treatment. The chemical zone is set to 550℃, the temperature zone for placing the Ti-O nanotube array is set to 400℃, the holding time is set to 4h, and it is naturally cooled to room temperature to obtain the Ti-PO nanotube array photoanode.

[0049] The fifth step involves solution thermal deposition. Weigh 0.3556g NiCl2·6H2O and 0.1350g urea, dissolve them in 50mL of deionized water, stir well, and then transfer the solution to an oven set at 90℃ for 2.5h. After cooling to room temperature, remove the solution, wash it with deionized water about three times, and then dry it in a vacuum drying oven at 60℃ for 6h to obtain the NiOOH / Ti-PO nanotube array photoanode electrode material.

[0050] Using the Chenhua CHI660E electrochemical workstation, three-electrode testing was conducted using different LSV, IT, VOPT, EIS, and MOTT methods. NiOOH / Ti-PO nanotube array photoanode electrode material was selected as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode. A xenon lamp was used as the light source. The working electrode, counter electrode, and reference electrode were connected to the electrochemical workstation, and the test was performed at 1 mol L... -1 The photoelectrochemical properties of the electrode material were measured in KOH solution.

[0051] Comparative Example 1:

[0052] A method for preparing a Ti-PO nanotube array photoanode is as follows:

[0053] The first step is pretreatment: A pure titanium sheet with a size of 10mm×20mm×1mm is polished with 240 grit, 400 grit, 800 grit, 1000 grit and 1500 grit water sandpaper in sequence until the surface is smooth. Then, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 10 minutes respectively to remove surface impurities.

[0054] The second step is anodizing: the pretreated pure titanium sheet is used as the anode and the graphite plate as the cathode. A mixed solution of 0.4wt% NH4F and 2vol% H2O in ethylene glycol is used as the electrolyte. The oxidation is carried out for 1 hour under a DC voltage of 40V. Then, the surface impurities are cleaned with deionized water and dried with N2 to obtain a Ti-O nanotube array.

[0055] The third step is crystallization treatment. The titanium dioxide nanotube array obtained after the above anodizing treatment is placed in a muffle furnace and calcined at 550°C for 2 hours. After cooling to room temperature with the furnace, it is taken out to obtain anatase phase Ti-O nanotube array photoanode.

[0056] The fourth step is to perform tube furnace phosphating treatment. Weigh 3.000g of NaHPO2·H2O and transfer the anatase phase Ti-O nanoarray photoanode obtained in the third step to a dual-temperature zone tube furnace for phosphating treatment. The reagent zone is set to 550℃, the temperature zone for placing the Ti-O nanotube array is set to 400℃, the holding time is set to 3.5h, and it is naturally cooled to room temperature to obtain the Ti-PO nanotube array photoanode.

[0057] Using the Chenhua CHI660E electrochemical workstation, three-electrode electrochemical experiments were conducted using different LSV, IT, VOPT, EIS, and MOTT methods. Ti-PO nanotube array photoanode material was selected as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode. A xenon lamp was used as the light source. The working electrode, counter electrode, and reference electrode were connected to the electrochemical workstation, and the experiment was conducted at 1 mol L... -1 The photoelectrochemical properties of the electrode material were measured in KOH solution.

[0058] Comparative Example 2:

[0059] A method for preparing a Ti-PO nanotube array photoanode is as follows:

[0060] The first step is pretreatment: A pure titanium sheet with a size of 10mm×20mm×1mm is polished with 240 grit, 400 grit, 800 grit, 1000 grit and 1500 grit water sandpaper in sequence until the surface is smooth. Then, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 10 minutes respectively to remove surface impurities.

[0061] The second step is anodizing: the pretreated pure titanium sheet is used as the anode and the graphite plate as the cathode. A mixed solution of 0.4wt% NH4F and 2vol% H2O in ethylene glycol is used as the electrolyte. The oxidation is carried out for 1 hour under a DC voltage of 40V. Then, the surface impurities are cleaned with deionized water and dried with N2 to obtain a Ti-O nanotube array.

[0062] The third step is crystallization treatment. The titanium dioxide nanotube array obtained after the above anodizing treatment is placed in a muffle furnace and calcined at 550°C for 2 hours. After cooling to room temperature with the furnace, it is taken out to obtain anatase phase Ti-O nanotube array photoanode.

[0063] The fourth step is to perform tube furnace phosphating treatment. Weigh 3.000g of NaHPO2·H2O and transfer the anatase phase Ti-O nanoarray photoanode obtained in the third step to a dual-temperature zone tube furnace for phosphating treatment. The chemical zone is set to 550℃, the temperature zone for placing the Ti-O nanotube array is set to 400℃, the holding time is set to 4h, and it is naturally cooled to room temperature to obtain the Ti-PO nanotube array photoanode.

[0064] Using the Chenhua CHI660E electrochemical workstation, three-electrode testing was performed using different LSV, IT, VOPT, EIS, and MOTT methods. Ti-PO nanotube array photoanode electrode material was selected as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode. A xenon lamp was used as the light source. The working electrode, counter electrode, and reference electrode were connected to the electrochemical workstation, and the test was conducted at 1 mol L... - 1 The photoelectrochemical properties of the electrode material were measured in KOH solution.

[0065] Comparative Example 3:

[0066] A method for preparing a Ti-PO nanotube array photoanode is as follows:

[0067] The first step is pretreatment: A pure titanium sheet with a size of 10mm×20mm×1mm is polished with 240 grit, 400 grit, 800 grit, 1000 grit and 1500 grit water sandpaper in sequence until the surface is smooth. Then, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 10 minutes respectively to remove surface impurities.

[0068] The second step is anodizing: the pretreated pure titanium sheet is used as the anode and the graphite plate as the cathode. A mixed solution of 0.4wt% NH4F and 2vol% H2O in ethylene glycol is used as the electrolyte. The oxidation is carried out for 1 hour under a DC voltage of 40V. Then, the surface impurities are cleaned with deionized water and dried with N2 to obtain a Ti-O nanotube array.

[0069] The third step is to perform crystallization treatment. The mixed-phase titanium dioxide nanotube array obtained after the above anodizing treatment is placed in a muffle furnace and calcined at 550°C for 2 hours. After cooling to room temperature with the furnace, it is taken out to obtain anatase phase Ti-O nanotube array photoanode.

[0070] The fourth step is to perform tube furnace phosphating treatment. Weigh 3.000g of NaHPO2·H2O and transfer the anatase phase Ti-O nanoarray photoanode obtained in the third step to a dual-temperature zone tube furnace for phosphating treatment. The chemical zone is set to 550℃, the temperature zone for placing the Ti-O nanotube array is set to 400℃, the holding time is set to 4.5h, and it is naturally cooled to room temperature to obtain the Ti-PO nanotube array photoanode.

[0071] Using the Chenhua CHI660E electrochemical workstation, three-electrode testing was performed using different LSV, IT, VOPT, EIS, and MOTT methods. Ti-PO nanotube array photoanode electrode material was selected as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode. A xenon lamp was used as the light source. The working electrode, counter electrode, and reference electrode were connected to the electrochemical workstation, and the test was conducted at 1 mol L... - 1 The photoelectrochemical properties of the electrode material were measured in KOH solution.

[0072] Comparative Example 4:

[0073] A method for preparing a Ti-O nanotube array photoanode is as follows:

[0074] The first step is pretreatment: A pure titanium sheet with a size of 10mm×20mm×1mm is polished with 240 grit, 400 grit, 800 grit, 1000 grit and 1500 grit water sandpaper in sequence until the surface is smooth. Then, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 10 minutes respectively to remove surface impurities.

[0075] The second step is anodizing: the pretreated pure titanium sheet is used as the anode and the graphite plate as the cathode. A mixed solution of 0.4wt% NH4F and 2vol% H2O in ethylene glycol is used as the electrolyte. The oxidation is carried out for 1 hour under a DC voltage of 40V. Then, the surface impurities are cleaned with deionized water and dried with N2 to obtain a Ti-O nanotube array.

[0076] The third step is crystallization treatment. The titanium dioxide nanotube array obtained after the above anodizing treatment is placed in a muffle furnace and calcined at 550°C for 2 hours. Then it is cooled to room temperature with the furnace and taken out to obtain anatase phase Ti-O nanotube array photoanode.

[0077] Using the Chenhua CHI660E electrochemical workstation, three-electrode testing was performed using different LSV, IT, VOPT, EIS, and MOTT methods. A Ti-O nanotube array photoanode was selected as the working electrode, AgC / AgCl as the reference electrode, a platinum sheet as the counter electrode, and a xenon lamp as the light source. The working electrode, counter electrode, and reference electrode were connected to the electrochemical workstation, and the test was conducted at 1 mol L... -1The photoelectrochemical properties of the electrode material were measured in KOH solution.

[0078] Table 1. Photoelectrochemical properties of the photoanode materials prepared in the examples and comparative examples.

[0079]

[0080] As can be seen from the table, the photocurrent density of the NiOOH / Ti-PO nanotube array photoanodes prepared in Examples 1-3 is higher than that of the Ti-PO nanotube array photoanodes prepared in Comparative Examples 1-3 and the Ti-O nanotube array photoanode prepared in Comparative Example 4. Specifically, Example 2, compared to Comparative Example 2, added the step of "thermal deposition of Ti-PO in a mixed solution containing a nickel source and urea," demonstrating that the addition of the oxygen evolution co-catalyst NiOOH can enhance its photoelectrochemical performance. Compared to Comparative Example 4, Example 2 added the steps of "phosphating the Ti-O nanotube array photoanode" and "thermal deposition of Ti-PO in a mixed solution containing a nickel source and urea." The photocurrent density of the NiOOH / Ti-PO nanotube array photoanode was significantly improved compared to the Ti-O nanotube array, indicating that the scheme of elemental doping of the original Ti-O nanotube array and then loading an oxygen evolution co-catalyst on this basis is feasible.

[0081] Figure 1 The graph shows a comparison of linear scanning voltammetry results for Example 2, Comparative Example 2, and Comparative Example 4. As can be seen from the graph, the photocurrent density of the NiOOH / Ti-PO nanotube array photoanode prepared in Example 2 is significantly improved compared to the Ti-PO nanotube array photoanode prepared in Comparative Example 2 and the Ti-O nanotube array photoanode prepared in Comparative Example 4.

[0082] Figure 2 The graph shows a comparison of transient photocurrents for Example 2, Comparative Example 2, and Comparative Example 4. As can be seen from the graph, the photocurrent density of the NiOOH / Ti-PO nanotube array photoanode prepared in Example 2 is significantly improved compared to the Ti-PO nanotube array photoanode prepared in Comparative Example 2 and the Ti-O nanotube array photoanode prepared in Comparative Example 4.

[0083] The foregoing description of the embodiments and comparative examples is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments and comparative examples, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a NiOOH / Ti-PO nanotube array photoanode, characterized in that, Includes the following steps: S1. The pretreated Ti sheet is subjected to anodic oxidation and crystallization treatment in sequence to obtain Ti-O nanotube array photoanode; S2. Phosphate the Ti-O nanotube array photoanode obtained in step S1, and then cool it to obtain the Ti-PO nanotube array photoanode. The phosphating process is as follows: the Ti-O nanotube array photoanode is heated and reacted with the phosphorus source NaHPO2·H2O, wherein the mass of the phosphorus source NaHPO2·H2O is 1-3g, the temperature of the phosphorus source region is 525-575℃, the temperature of the Ti-O nanotube array photoanode placement region is 350-450℃, and the heating time is 3-5h. S3. The Ti-PO nanotube array photoanode obtained in step S2 is immersed in a mixed solution containing nickel source and urea for thermal deposition to obtain NiOOH / Ti-PO nanotube array photoanode. The thermal deposition process is as follows: the Ti-PO nanotube array photoanode is immersed in a mixed solution at a temperature of 80-95℃ for 1-3 hours, then washed with deionized water, and vacuum dried at 60℃ for 6 hours.

2. The method for preparing a NiOOH / Ti-PO nanotube array photoanode according to claim 1, characterized in that, In step S1, the pretreatment process is as follows: the Ti wafer is first sanded with wet sandpaper until the surface is free of scratches, then ultrasonically cleaned in acetone, anhydrous ethanol, and deionized water for 10 minutes each, and finally dried at room temperature.

3. The method for preparing a NiOOH / Ti-PO nanotube array photoanode according to claim 1, characterized in that, In step S1, the anodic oxidation process is as follows: first, a mixed solution of 0.4wt% NH4F and 2vol% H2O in ethylene glycol is prepared as the electrolyte, the pretreated Ti sheet is used as the anode, and the graphite plate is used as the cathode, and the reaction is carried out for 1-2 hours under a DC voltage of 35-45V.

4. The method for preparing a NiOOH / Ti-PO nanotube array photoanode according to claim 1, characterized in that, In step S1, the crystallization process is as follows: the anodized Ti-O nanotube array is calcined at 525-575℃ for 1-3 hours, and after cooling, the anatase phase Ti-O nanotube array photoanode is obtained.

5. The method for preparing a NiOOH / Ti-PO nanotube array photoanode according to claim 1, characterized in that, In step S3, the nickel source is NiCl2·6H2O.

6. The method for preparing a NiOOH / Ti-PO nanotube array photoanode according to claim 1, characterized in that, In step S3, the concentration of nickel source in the mixed solution is 30-40 mmol, and the concentration of urea is 30-50 mmol.

7. A NiOOH / Ti-PO nanotube array photoanode, characterized in that, Based on the preparation method according to any one of claims 1-6.

8. An application of the NiOOH / Ti-PO nanotube array photoanode as described in claim 7, characterized in that, The NiOOH / Ti-PO nanotube array photoanode is used in the field of photoelectrocatalytic water splitting.

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