Preparation method of co-p3 / s-tio2 nanowire array material, product and application thereof

Abstract

This invention discloses a method for preparing Co-P3 / S-TiO2 nanowire array materials, along with their products and applications. Through a hydrothermal-etching-phosphating method, Co single atoms coordinated with P were successfully anchored on the surface of a TiO2 nanowire array rich in step defects, resulting in the Co-P3 / S-TiO2 nanowire array material. Under the dual regulation of the special step structure and the suitable electronegativity of P, the Co metal atom becomes an electron-rich center, exhibiting superior adsorption capacity and a unique coordination environment, thus possessing excellent electrocatalytic hydrogen evolution performance. The preparation process is simple, and the raw materials are inexpensive. This invention provides inspiration for the design and synthesis of single-atom catalysts and their application in the field of electrocatalytic water electrolysis.

Description

Technical Field

[0001] This invention relates to the field of energy materials, and in particular to a method for preparing P-coordinated metal single atoms and a method for surface modification of single-atom catalyst substrates. Background Technology

[0002] The increasingly serious problems of resource depletion and environmental pollution are forcing people to rapidly advance the development of clean and pollution-free water electrolysis hydrogen production technology. Finding efficient electrocatalysts is a breakthrough issue for this technology. However, currently commercially available mature catalysts are still made from precious metals such as Pt and Ru, which are costly to produce and scarce, greatly limiting the development of water electrolysis hydrogen production technology. To reduce production costs, scientists are currently using methods such as developing non-precious metal-based electrocatalysts or continuously shrinking catalyst size, from nanoparticles to nanoclusters and even single atoms. Among these, single-atom catalysts, which shrink the catalyst size to the extreme, can undoubtedly maximize the utilization of metal atoms and significantly reduce the production cost. Currently, various single-atom catalysts (SACs) for the electrocatalytic hydrogen evolution reaction (HER) have been developed, among which non-precious metal-based single-atom catalysts, such as Co, Ni, Fe, Mo, and Cu-based SACs, are the most economical. Although these catalysts already possess good catalytic activity, they still do not meet the baseline requirements. Therefore, there is an urgent need to develop catalysts that are inexpensive, highly efficient, and stable.

[0003] Typically, SACs are supported on solid substrates to prevent agglomeration. However, the low conductivity and instability of reported metal oxide-supported SACs under harsh electrolytic environments (strong acids and strong bases) remain problems that need to be addressed. Summary of the Invention

[0004] Objectives of this invention: The first objective is to provide a method for preparing a Co-P3 / S-TiO2 nanowire array material, which anchors phosphorus-coordinated Co single-atom materials on a stepped TiO2 array, providing insights into the selection of substrates and the regulation of coordination environment for single-atom catalysts. The second objective is to provide the Co-P3 / S-TiO2 nanowire array material obtained by this method. The third objective is to provide the application of this Co-P3 / S-TiO2 nanowire array material in electrocatalytic hydrogen evolution.

[0005] Technical solution: The preparation method of Co-P3 / S-TiO2 nanowire array material of the present invention includes the following steps:

[0006] (1) Place the titanium mesh in NaOH solution and perform a hydrothermal reaction to obtain a pretreated titanium mesh;

[0007] (2) The pretreated titanium mesh was calcined at high temperature to obtain a titanium mesh for growing TiO2 nanowires;

[0008] (3) Place the titanium mesh on which TiO2 nanowires are grown in an acid solution and perform a hydrothermal reaction to obtain a titanium mesh with a stepped structure of TiO2 nanowires.

[0009] (4) Impregnate the stepped TiO2 nanowires with a titanium mesh in Co 2+ In solution, a titanium mesh with Co single atoms anchored on a stepped TiO2 nanowire array was obtained;

[0010] (5) Phosphate the titanium mesh anchored with Co single atoms on the stepped TiO2 nanowire array to obtain a material with phosphorus-coordinated Co single atoms anchored on the stepped TiO2 nanowire array, namely Co-P3 / S-TiO2 nanowire array material.

[0011] In step (1), the concentration of the NaOH solution is 1-3M.

[0012] In step (1), the ratio of the volume of the NaOH solution to the area of ​​the titanium mesh is 3–8 mL / cm². 2 .

[0013] In step (1), the aperture of the titanium mesh is 40-60 mesh.

[0014] In step (1), the temperature of the hydrothermal reaction is 150℃~170℃ and the time of the hydrothermal reaction is 5~7h.

[0015] In step (2), the high-temperature calcination temperature is 450-600℃ and the holding time is 1-3h.

[0016] In step (3), the acid solution is hydrochloric acid or nitric acid. Based on the interaction effect of the acid solution with TiO2, its oxidizing properties and toxicity, hydrochloric acid solution is preferred.

[0017] In step (3), the concentration of the acid solution is 1 to 2.5 M.

[0018] In step (3), the ratio of the acid solution volume to the area of ​​the titanium mesh on which the TiO2 nanowires are grown is 6–10 mL / cm². 2 .

[0019] In step (3), the temperature of the hydrothermal reaction is 100-130°C and the time of the hydrothermal reaction is 1-3 hours.

[0020] In step (3), the titanium mesh on which TiO2 nanowires are grown is placed in an acid solution for hydrothermal reaction and etching is performed by the acid solution. The etching degree and step size are adjusted by adjusting the concentration of the acid solution.

[0021] In step (4), the Co 2+ The solution is Co(NO3)2·6H2O.

[0022] In step (4), the Co 2+ The optimal Co concentration is 0.025–0.075 M. 2+ The concentration of the solution is 0.05M.

[0023] In step (4), the Co 2+ The ratio of solution volume to the area of ​​the titanium mesh containing the stepped TiO2 nanowires is 10–40 mL / cm². 2 .

[0024] In step (4), the impregnation process involves impregnating for 0.5 to 2 minutes, drying at 50 to 80°C, repeating this process 2 to 6 times, and finally drying at 50 to 80°C for 2 to 6 hours.

[0025] In step (4), as Co 2+ Different solution concentrations can form single atoms and nanoclusters on the surface of TiO2 nanowires, respectively.

[0026] In step (5), during the phosphating process, a titanium mesh with Co single atoms anchored on a stepped TiO2 nanowire array is placed downstream of a tube furnace, and sodium hypophosphite is placed upstream of the tube furnace as the phosphorus source. Phosphating is carried out at 300-350°C for 1-3 hours under an argon atmosphere.

[0027] In step (5), the mass ratio of the titanium mesh anchoring Co single atoms on the stepped TiO2 nanowire array to sodium hypophosphite is 1 to 6:10.

[0028] The Co-P3 / S-TiO2 nanowire array material obtained by the preparation method described in this invention.

[0029] The present invention also includes the application of the Co-P3 / S-TiO2 nanowire array material in electrocatalytic hydrogen evolution.

[0030] This invention designs TiO2 with step defects as a substrate for SACs. TiO2 with a surface rich in step defects possesses numerous unsaturated sites, which can not only better trap metal atoms but also modulate the electronic structure of metal atoms. By coordinating with P and using the step-type TiO2 to adjust the valence state of Co, the material exhibits improved HER activity and stability, and this also provides insights into broadening the design strategies for SACs.

[0031] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0032] The preparation method described in this invention anchors Co ions on the step-defect-rich TiO2 surface and successfully coordinates Co atoms with P element via phosphating. This method is then used for the electrocatalytic hydrogen evolution reaction, and results confirm that this application exhibits good electrocatalytic performance and high reaction stability. This invention fully utilizes the strong ion-trapping ability of TiO2 step defects and the suitable electronegativity of P element to prepare a novel high-performance single-atom electrocatalyst. The process is simple, the raw materials are inexpensive, and it provides insights into the design and synthesis of single-atom catalysts and their application in the field of electrocatalytic water electrolysis. Attached Figure Description

[0033] Figure 1 This is a scanning electron microscope image of the Co-P3 / S-TiO2 nanowire array material prepared in Example 1;

[0034] Figure 2 This is a high-resolution transmission electron microscope image of the Co-P3 / S-TiO2 nanowire array material prepared in Example 1;

[0035] Figure 3 This is the EDX spectrum of the Co-P3 / S-TiO2 nanowire array material prepared in Example 1;

[0036] Figure 4 This is a scanning electron microscope image of the Co-P3 / S-TiO2 nanowire array material prepared in Example 2;

[0037] Figure 5 This is a transmission electron microscope (TEM) image of the Co-P3 / S-TiO2 nanowire array material prepared in Example 2;

[0038] Figure 6 This is a high-resolution transmission electron microscope image of the Co-P3 / S-TiO2 nanowire array material prepared in Example 2;

[0039] Figure 7 This is a scanning electron microscope image of the nanowire array material prepared in Comparative Example 1;

[0040] Figure 8 This is a high-resolution transmission electron microscope image of the nanowire array material prepared in Comparative Example 1;

[0041] Figure 9 The image shows the EDX spectrum of the nanowire array material prepared in Comparative Example 1.

[0042] Figure 10 These are the XRD patterns of the Co-P3 / S-TiO2 nanowire array material prepared in Example 1 and the nanowire array material prepared in Comparative Example 1.

[0043] Figure 11These are the electrocatalytic hydrogen evolution LSV curves of the nanowire array materials prepared in Examples 1, 2, and Comparative Example 1;

[0044] Figure 12 This is a high-resolution transmission electron microscope image of the stepped structure TiO2 nanowire array material prepared in step 4;

[0045] Figure 13 This is a high-resolution transmission electron microscope image of the stepped structure TiO2 nanowire array material prepared in step 5;

[0046] Figure 14 This is a high-resolution transmission electron microscope image of the Co-P3 / S-TiO2 nanowire array material prepared in step 6;

[0047] Figure 15 This is a high-resolution transmission electron microscope image of the Co-P3 / S-TiO2 nanowire array material prepared in step 7;

[0048] Figure 16 Electrocatalytic hydrogen evolution LSV curves of the Co-P3 / S-TiO2 nanowire array materials prepared in Examples 4, 5, 6 and 7. Detailed Implementation

[0049] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0050] Example 1

[0051] A cut titanium mesh (2.6 x 4 cm, 50 mesh) was placed in a reactor containing 35 mL of deionized water and 35 mL of concentrated hydrochloric acid. The mixture was hydrothermally reacted at 100 °C for 30 min. After natural cooling, the titanium mesh was removed, rinsed with deionized water, and then dried at room temperature to obtain a clean titanium mesh. Then, 3 g of NaOH was weighed and dissolved in 35 mL of deionized water. After complete dissolution, the dissolved NaOH was transferred to a 50 mL reactor along with the cleaned titanium mesh. The mixture was hydrothermally reacted at 160 °C for 6 h to obtain a pretreated titanium mesh. After natural cooling, the pretreated titanium mesh was removed, washed with 0.96 M dilute hydrochloric acid solution to remove residual NaOH, and dried. The pretreated titanium mesh was then placed in a tube furnace and calcined in air at 500 °C for 2 h (heating rate 5 °C / min) to obtain a titanium mesh for growing TiO2 nanowires. The titanium mesh from which TiO2 nanowires were grown was then placed in a 25 mL reactor along with 10 mL of 1.5 M HCl solution and subjected to a hydrothermal reaction at 120 °C for 2 h. After natural cooling, it was soaked in deionized water for 35 min and dried overnight at 60 °C to obtain a titanium mesh with stepped TiO2 nanowires. Then, 40 mL of 0.05 M Co(NO3)2·6H2O solution was prepared, and the titanium mesh with the stepped TiO2 nanowires was vertically inserted into it for 1 min. It was then removed and dried at 60 °C for 5 min, repeated five times. Finally, it was dried at 60 °C for 2 h to obtain a titanium mesh with Co single atoms anchored on the stepped TiO2 nanowire array. Subsequently, 0.3 g of sodium hypophosphite was weighed out and placed in a titanium mesh anchored with Co single atoms on a stepped TiO2 nanowire array. The mesh was placed downstream of a tube furnace, and sodium hypophosphite was placed upstream of the tube furnace as the phosphorus source. Phosphating was carried out for 2 h at 320 °C in a slow argon gas flow with a heating rate of 2 °C / min to obtain the sample Co-P3 / S-TiO2 nanowire array material.

[0052] The Co-P3 / S-TiO2 nanowire array material prepared in this embodiment was analyzed by scanning electron microscopy, and the results are as follows: Figure 1 As shown. Figure 1 These are scanning electron microscope (SEM) images of the Co-P3 / S-TiO2 nanowire array material prepared in Example 1. Figure 1 It can be seen that acid etching did not destroy the basic morphology of TiO2.

[0053] The Co-P3 / S-TiO2 nanowire array material prepared in this embodiment was analyzed by high-resolution transmission electron microscopy, and the results are as follows: Figure 2 As shown. Figure 2 This is a high-resolution transmission electron microscope (TEM) image of the Co-P3 / S-TiO2 nanowire array material prepared in Example 1. Figure 2 It can be seen that the surface of the TiO2 nanowires has become uneven, with obvious step defects.

[0054] The Co-P3 / S-TiO2 nanowire array material prepared in this embodiment was subjected to EDX energy dispersive spectroscopy analysis, and the results are as follows: Figure 3 As shown. Figure 3 This is the EDX spectrum of the Co-P3 / S-TiO2 nanowire array material prepared in Example 1. Figure 3 It can be seen that the Co-P3 / S-TiO2 nanowire array material contains Co, P, Ti, and O elements, with an atomic ratio of Co to P of approximately 1:3. Figure 2 No particles were observed in the high-resolution transmission image, which suggests that Co and P are doped into the stepped TiO2 nanowires in the form of single atoms.

[0055] Example 2

[0056] A cut titanium mesh (2.6 x 4 cm, 50 mesh) was placed in a reaction vessel containing 35 mL of deionized water and 35 mL of concentrated hydrochloric acid. The mixture was hydrothermally reacted at 100 °C for 30 min. After natural cooling, the titanium mesh was removed, rinsed with deionized water, and then dried at room temperature to obtain a clean titanium mesh. Then, 3 g of NaOH was weighed and dissolved in 35 mL of deionized water. After complete dissolution, the dissolved NaOH was transferred to a 50 mL reaction vessel along with the cleaned titanium mesh. The mixture was hydrothermally reacted at 160 °C for 6 h to obtain a pretreated titanium mesh. After natural cooling, the pretreated titanium mesh was removed, washed with 0.96 M dilute hydrochloric acid solution to remove residual NaOH, and dried. The pretreated titanium mesh was then placed in a tube furnace and calcined in air at 500 °C for 2 h (heating rate 5 °C / min) to obtain a titanium mesh for growing TiO2 nanowires. The titanium mesh from which TiO2 nanowires were grown was then placed in a 25 mL reactor along with 10 mL of 1.5 M HCl solution and subjected to a hydrothermal reaction at 120 °C for 2 h. After natural cooling, it was soaked in deionized water for 35 min and dried overnight at 60 °C to obtain a titanium mesh with stepped TiO2 nanowires. Then, 40 mL of 0.075 M Co(NO3)2·6H2O solution was prepared, and the titanium mesh with the stepped TiO2 nanowires was vertically inserted into it for 1 min. It was then removed and dried at 60 °C for 5 min, repeated five times. Finally, it was dried at 60 °C for 2 h to obtain a titanium mesh with Co single atoms anchored on the stepped TiO2 nanowire array. Subsequently, 0.3 g of sodium hypophosphite was weighed out and placed in a titanium mesh anchored with Co single atoms on a stepped TiO2 nanowire array. The mesh was placed downstream of a tube furnace, and sodium hypophosphite was placed upstream of the tube furnace as the phosphorus source. Phosphating was carried out for 2 h at 320 °C in a slow argon gas flow with a heating rate of 2 °C / min to obtain the sample Co-P3 / S-TiO2 nanowire array material.

[0057] The Co-P3 / S-TiO2 nanowire array material prepared in this embodiment was analyzed by scanning electron microscopy, and the results are as follows: Figure 4As shown. Figure 4 This is a scanning electron microscope (SEM) image of the Co-P3 / S-TiO2 nanowire array material prepared in Example 2. Figure 4 As can be seen, the TiO2 nanowire array remains intact. This indicates that acid etching did not damage the basic morphology of TiO2.

[0058] The Co-P3 / S-TiO2 nanowire array material prepared in this embodiment was analyzed by transmission electron microscopy, and the results are as follows: Figure 5 As shown. Figure 5 This is a transmission electron microscope (TEM) image of the Co-P3 / S-TiO2 nanowire array material prepared in Example 2. As can be seen from image 5, a distinct granular texture can be observed on the surface of the TiO2 nanowires. This indicates that with the increase of metal ion concentration, Co atoms no longer exist in the form of single atoms on the TiO2 surface, but rather aggregate to form nanoclusters.

[0059] The Co-P3 / S-TiO2 nanowire array material prepared in this embodiment was analyzed by high-resolution transmission electron microscopy, and the results are as follows: Figure 6 As shown. Figure 6 This is a high-resolution transmission electron microscope (TEM) image of the Co-P3 / S-TiO2 nanowire array material prepared in Example 2. Figure 6 Further observation reveals that these nanoclusters possess a distinct phosphide lattice.

[0060] Comparative Example 1

[0061] A pre-cut titanium mesh (2.6 x 4 cm) was placed in a reactor containing 35 mL of deionized water and 35 mL of concentrated hydrochloric acid. The mixture was hydrothermally reacted at 100 °C for 30 min. After natural cooling, the titanium mesh was removed, rinsed with deionized water, and then dried at room temperature to obtain a clean titanium mesh. Then, 3 g of NaOH was weighed and dissolved in 35 mL of deionized water. After complete dissolution, the dissolved NaOH was transferred to a 50 mL reactor along with the cleaned titanium mesh. The mixture was hydrothermally reacted at 160 °C for 6 h to obtain a pretreated titanium mesh. After natural cooling, the pretreated titanium mesh was removed, washed with 0.96 M dilute hydrochloric acid solution to remove residual NaOH, and dried. The pretreated titanium mesh was then placed in a tube furnace and calcined in air at 500 °C for 2 h (heating rate 5 °C / min) to obtain a titanium mesh for growing TiO2 nanowires. Then, 40 mL of 0.05 M Co(NO3)2·6H2O solution was prepared, and the titanium mesh with grown TiO2 nanowires was vertically inserted into it and soaked for 1 min. It was then removed and dried at 60 °C for 5 min, repeated 5 times. Finally, it was dried at 60 °C for 2 h to obtain a titanium mesh anchored with Co single atoms. Subsequently, 0.3 g of sodium hypophosphite was weighed, and the titanium mesh anchored with Co single atoms was placed downstream of a tube furnace. Sodium hypophosphite, as the phosphorus source, was placed upstream of the tube furnace. Phosphating was carried out at 320 °C for 2 h in a slow argon gas flow, with a heating rate of 2 °C / min, to obtain a nanowire array material without etched steps.

[0062] The unetched step nanowire array material prepared in this comparative example was analyzed by scanning electron microscopy, and the results are as follows: Figure 7 As shown. Figure 7 This is a scanning electron microscope image of the nanowire array material prepared in Comparative Example 1. Figure 7 It can be seen that the material obtained in Comparative Example 1 is a nanowire array.

[0063] The unetched step nanowire array material prepared in this comparative example was analyzed by high-resolution transmission electron microscopy, and the results are as follows: Figure 8 As shown. Figure 8 This is a high-resolution transmission electron microscope image of the nanowire array material prepared in Comparative Example 1, by... Figure 8 It can be seen that TiO2 nanowires have a smooth surface, an ordered lattice, and a diameter of approximately 10–20 nm.

[0064] The nanowire array material prepared in this comparative example was subjected to EDX energy dispersive spectroscopy analysis, and the results are as follows: Figure 9 As shown. Figure 9 The image shows the EDX spectrum of the nanowire array material prepared in Comparative Example 1. Figure 9 It can be seen that the sample contains Co, P, Ti, and O elements, with an atomic ratio of Co to P of approximately 1:3. Figure 8No particles were observed in the high-resolution transmission image, which suggests that Co and P are doped into TiO2 nanowires in the form of single atoms.

[0065] The Co-P3 / S-TiO2 nanowire array material prepared in Example 1 and the nanowire array material prepared in Comparative Example 1 were subjected to XRD pattern analysis, and the results are as follows: Figure 10 As shown. Figure 10 These are the XRD patterns of the Co-P3 / S-TiO2 nanowire array material prepared in Example 1 and the nanowire array material prepared in Comparative Example 1. Figure 10 It can be seen that only the reaction peaks of TiO2 and the titanium mesh substrate are observed, with no other impurity peaks appearing. This indicates that the Co content in the sample is very low and has not formed a crystalline compound, confirming that it exists in the sample in a single-atom form. Furthermore, from... Figure 3 As can be seen from the energy dispersive spectroscopy (EDS) spectrum, the Co and P contents of the stepped TiO2 surface in Example 1 are both higher than those of the smooth TiO2 surface in Comparative Example 1. Therefore, it can be concluded that the stepped TiO2 increases the Co content. 2+ The anchor point.

[0066] Example 3

[0067] Electrochemical measurements were performed using a three-electrode system connected to a CHI 660D electrochemical workstation. A saturated calomel electrode (SCE) was used as the reference electrode, and platinum wire as the counter electrode. Materials prepared in Examples 1, 2, and 1 (all cut to 0.5 cm × 0.5 cm) were used as working electrodes, with 1 M NaOH as the electrolyte solution. All measurements were taken at 5 mV s⁻¹. -1 The scan rate was used to record linear scan voltammetry (LSV) data. The potential was referenced to the reversible hydrogen electrode (RHE), and the formula was E. RHE =E SCE +0.059pH+0.242, where E RHE E represents the electrode potential of the reversible hydrogen electrode. SCE The electrode potential represents the saturated calomel electrode, and pH represents the pH value of the electrolyte solution. All obtained electrochemical data must be corrected using the iR correction formula: E corrected =E measured -iR. Where E corrected E represents the correction potential. measured iR represents the measured experimental potential, and iR represents the real-time current.

[0068] The results are as follows Figure 11 As shown. Figure 11 These are the LSV curves of the electrocatalytic hydrogen evolution performance of the nanowire array materials prepared in Examples 1, 2, and 1 (Comparative Example 1). Figure 11As can be seen, the nanowire array material prepared in Example 1 exhibits the best electrocatalytic performance. At 100 mA cm⁻¹ -1 At the current density, the overpotential is 189mV.

[0069] Compared to Comparative Example 1, the importance of step defects for performance optimization can be seen; compared to Example 2, the superiority of single-atom anchoring can be observed. The presence of particulate structures may lead to a reduction in the active surface area of ​​the catalyst, thereby reducing electrocatalytic performance.

[0070] Example 4

[0071] A cut titanium mesh (2.6 x 4 cm, 50 mesh) was placed in a reactor containing 35 mL of deionized water and 35 mL of concentrated hydrochloric acid. The mixture was hydrothermally reacted at 100 °C for 30 min. After natural cooling, the titanium mesh was removed, rinsed with deionized water, and then dried at room temperature to obtain a clean titanium mesh. Then, 3 g of NaOH was weighed and dissolved in 35 mL of deionized water. After complete dissolution, the dissolved NaOH was transferred to a 50 mL reactor along with the cleaned titanium mesh. The mixture was hydrothermally reacted at 160 °C for 6 h to obtain a pretreated titanium mesh. After natural cooling, the pretreated titanium mesh was removed, washed with 0.96 M dilute hydrochloric acid solution to remove residual NaOH, and dried. The pretreated titanium mesh was then placed in a tube furnace and calcined in air at 500 °C for 2 h (heating rate 5 °C / min) to obtain a titanium mesh for growing TiO2 nanowires. The titanium mesh from which TiO2 nanowires were grown was then placed in a 25 mL reactor along with 10 mL of 1 M HCl solution. The reactor was subjected to a hydrothermal reaction at 120 °C for 2 h to obtain a stepped TiO2 nanowire array material. After natural cooling, the material was immersed in deionized water for 35 min and dried overnight at 60 °C to obtain a titanium mesh containing stepped TiO2 nanowires. Then, 40 mL of 0.075 M Co(NO3)2·6H2O solution was prepared, and the titanium mesh containing the stepped TiO2 nanowires was vertically inserted into it for 1 min. It was then removed and dried at 60 °C for 5 min, repeated five times. Finally, it was dried at 60 °C for 2 h to obtain a titanium mesh with Co single atoms anchored on the stepped TiO2 nanowire array. Subsequently, 0.3 g of sodium hypophosphite was weighed out and placed in a titanium mesh anchored with Co single atoms on a stepped TiO2 nanowire array. The mesh was placed downstream of a tube furnace, and sodium hypophosphite was placed upstream of the tube furnace as the phosphorus source. Phosphating was carried out for 2 h at 320 °C in a slow argon gas flow with a heating rate of 2 °C / min to obtain the sample Co-P3 / S-TiO2 nanowire array material.

[0072] Scanning electron microscopy analysis was performed on the stepped structure TiO2 nanowire array material of this embodiment, and the results are as follows: Figure 12 As shown. Figure 12 This is a high-resolution transmission electron microscope image of the stepped structure TiO2 nanowire array material prepared by method 4. Figure 12 It can be observed that only slight unevenness appears on the surface of TiO2 nanowires, indicating that the step defects are insufficient.

[0073] Example 5

[0074] A cut titanium mesh (2.6 x 4 cm, 50 mesh) was placed in a reactor containing 35 mL of deionized water and 35 mL of concentrated hydrochloric acid. The mixture was hydrothermally reacted at 100 °C for 30 min. After natural cooling, the titanium mesh was removed, rinsed with deionized water, and then dried at room temperature to obtain a clean titanium mesh. Then, 3 g of NaOH was weighed and dissolved in 35 mL of deionized water. After complete dissolution, the dissolved NaOH was transferred to a 50 mL reactor along with the cleaned titanium mesh. The mixture was hydrothermally reacted at 160 °C for 6 h to obtain a pretreated titanium mesh. After natural cooling, the pretreated titanium mesh was removed, washed with 0.96 M dilute hydrochloric acid solution to remove residual NaOH, and dried. The pretreated titanium mesh was then placed in a tube furnace and calcined in air at 500 °C for 2 h (heating rate 5 °C / min) to obtain a titanium mesh for growing TiO2 nanowires. The titanium mesh from which TiO2 nanowires were grown was then placed in a 25 mL reactor along with 10 mL of 2 M HCl solution. The reactor was subjected to a hydrothermal reaction at 120 °C for 2 h to obtain a stepped TiO2 nanowire array material. After natural cooling, the material was soaked in deionized water for 35 min and then dried overnight at 60 °C to obtain a titanium mesh containing stepped TiO2 nanowires. Next, 40 mL of 0.075 M Co(NO3)2·6H2O solution was prepared, and the titanium mesh containing the stepped TiO2 nanowires was vertically inserted into it for 1 min. It was then removed and dried at 60 °C for 5 min, and this process was repeated 5 times. Finally, it was dried at 60 °C for 2 h to obtain a titanium mesh with Co single atoms anchored on the stepped TiO2 nanowire array. Subsequently, 0.3 g of sodium hypophosphite was weighed out and placed in a titanium mesh anchored with Co single atoms on a stepped TiO2 nanowire array. The mesh was placed downstream of a tube furnace, and sodium hypophosphite was placed upstream of the tube furnace as the phosphorus source. Phosphating was carried out for 2 h at 320 °C in a slow argon gas flow with a heating rate of 2 °C / min to obtain the sample Co-P3 / S-TiO2 nanowire array material.

[0075] Scanning electron microscopy analysis was performed on the stepped structure TiO2 nanowire array material of this embodiment, and the results are as follows: Figure 13 As shown. Figure 13 This is a high-resolution transmission electron microscope image of the stepped structure TiO2 nanowire array material prepared by method 5. Figure 13 It can be observed that the lattice on the surface of TiO2 nanowires begins to become disordered, indicating that the etching degree is too high.

[0076] Example 6

[0077] A cut titanium mesh (2.6 x 4 cm, 50 mesh) was placed in a reactor containing 35 mL of deionized water and 35 mL of concentrated hydrochloric acid. The mixture was hydrothermally reacted at 100 °C for 30 min. After natural cooling, the titanium mesh was removed, rinsed with deionized water, and then dried at room temperature to obtain a clean titanium mesh. Then, 3 g of NaOH was weighed and dissolved in 35 mL of deionized water. After complete dissolution, the dissolved NaOH was transferred to a 50 mL reactor along with the cleaned titanium mesh. The mixture was hydrothermally reacted at 160 °C for 6 h to obtain a pretreated titanium mesh. After natural cooling, the pretreated titanium mesh was removed, washed with 0.96 M dilute hydrochloric acid solution to remove residual NaOH, and dried. The pretreated titanium mesh was then placed in a tube furnace and calcined in air at 500 °C for 2 h (heating rate 5 °C / min) to obtain a titanium mesh for growing TiO2 nanowires. The titanium mesh from which TiO2 nanowires were grown was then placed in a 25 mL reactor along with 10 mL of 1.5 M HCl solution and subjected to a hydrothermal reaction at 120 °C for 2 h. After natural cooling, the mesh was soaked in deionized water for 35 min and dried overnight at 60 °C to obtain a titanium mesh with stepped TiO2 nanowires. Then, 40 mL of 0.05 M Co(NO3)2·6H2O solution was prepared, and the titanium mesh sample with the stepped TiO2 nanowires was vertically inserted into it for 1 min. It was then removed and dried at 60 °C for 5 min, repeated five times. Finally, it was dried at 60 °C for 2 h to obtain a titanium mesh with Co single atoms anchored on the stepped TiO2 nanowire array. Subsequently, 0.3 g of sodium hypophosphite was weighed out and placed in a titanium mesh anchored with Co single atoms on a stepped TiO2 nanowire array. The mesh was placed downstream of a tube furnace, and sodium hypophosphite was placed upstream of the tube furnace as the phosphorus source. Phosphating was carried out for 2 h at 300 °C in a slow argon gas flow with a heating rate of 2 °C / min to obtain the sample Co-P3 / S-TiO2 nanowire array material.

[0078] The Co-P3 / S-TiO2 nanowire array material obtained in this embodiment was analyzed by scanning electron microscopy, and the results are as follows: Figure 14 As shown.

[0079] Example 7

[0080] A cut titanium mesh (2.6 x 4 cm, 50 mesh) was placed in a reactor containing 35 mL of deionized water and 35 mL of concentrated hydrochloric acid. The mixture was hydrothermally reacted at 100 °C for 30 min. After natural cooling, the titanium mesh was removed, rinsed with deionized water, and then dried at room temperature to obtain a clean titanium mesh. Then, 3 g of NaOH was weighed and dissolved in 35 mL of deionized water. After complete dissolution, the dissolved NaOH was transferred to a 50 mL reactor along with the cleaned titanium mesh. The mixture was hydrothermally reacted at 160 °C for 6 h to obtain a pretreated titanium mesh. After natural cooling, the pretreated titanium mesh was removed, washed with 0.96 M dilute hydrochloric acid solution to remove residual NaOH, and dried. The pretreated titanium mesh was then placed in a tube furnace and calcined in air at 500 °C for 2 h (heating rate 5 °C / min) to obtain a titanium mesh for growing TiO2 nanowires. The titanium mesh from which TiO2 nanowires were grown was then placed in a 25 mL reactor along with 10 mL of 1.5 M HCl solution and subjected to a hydrothermal reaction at 120 °C for 2 h. After natural cooling, the mesh was soaked in deionized water for 35 min and dried overnight at 60 °C to obtain a titanium mesh with stepped TiO2 nanowires. Then, 40 mL of 0.05 M Co(NO3)2·6H2O solution was prepared, and the titanium mesh sample with the stepped TiO2 nanowires was vertically inserted into it for 1 min. It was then removed and dried at 60 °C for 5 min, repeated five times. Finally, it was dried at 60 °C for 2 h to obtain a titanium mesh with Co single atoms anchored on the stepped TiO2 nanowire array. Subsequently, 0.3 g of sodium hypophosphite was weighed out and placed in a titanium mesh anchored with Co single atoms on a stepped TiO2 nanowire array. The mesh was placed downstream of a tube furnace, and sodium hypophosphite was placed upstream of the tube furnace as the phosphorus source. Phosphating was carried out at 350 °C for 2 h in a slow argon gas flow with a heating rate of 2 °C / min to obtain the sample Co-P3 / S-TiO2 nanowire array material.

[0081] The Co-P3 / S-TiO2 nanowire array material obtained in this embodiment was analyzed by scanning electron microscopy, and the results are as follows: Figure 15 As shown.

[0082] Depend on Figure 14 and Figure 15 It can be seen that changing the phosphating temperature did not alter the morphological characteristics of the sample, but it did affect the electrochemical performance.

[0083] The electrocatalytic hydrogen evolution performance of the Co-P3 / S-TiO2 nanowire array materials obtained in Examples 4-7 was tested. The experimental procedure was the same as in Example 3, and the results are as follows. Figure 16 As shown. Figure 16The LSV curves for the electrocatalytic hydrogen evolution of Co-P3 / S-TiO2 nanowire array materials prepared in Examples 4, 5, 6, and 7 are shown. Comparing the LSV curves of Examples 1, 4, and 5, it can be seen that the etching degree achieves the best performance at an acid concentration of 1.5 M, indicating that the etching in Example 4 is the optimal result. tower Insufficient step defects may reduce the anchoring sites for Co ions, affecting the performance of the final material. In Example 5, excessive etching can damage the crystal structure of TiO2 nanowires, leading to a decrease in the performance of the final material. Comparing the LSV curves of Examples 1, 6, and 7 shows that the phosphating temperature of 320℃ yields the best catalytic performance. This indicates that the phosphating temperature affects the ability of P to regulate the electronic structure of Co atoms, and that the material exhibits higher catalytic performance within the phosphating temperature range of 300–350℃.

Claims

1. A preparation method of a Co-P3 / S-TiO2 nanowire array material, characterized by, Includes the following steps: (1) Place the titanium mesh in NaOH solution and perform a hydrothermal reaction to obtain a pretreated titanium mesh; (2) The pretreated titanium mesh was calcined at high temperature to obtain a titanium mesh for growing TiO2 nanowires; (3) Place the titanium mesh on which TiO2 nanowires are grown in an acid solution and perform a hydrothermal reaction to obtain a titanium mesh with a stepped structure of TiO2 nanowires. (4) The titanium mesh of the stepped TiO2 nanowire is immersed in Co 2+ solution to obtain a titanium mesh anchoring Co monatomic atoms on the stepped structure TiO2 nanowire array. (5) Phosphate the titanium mesh anchored with Co single atoms on the stepped TiO2 nanowire array to obtain a material with phosphorus-coordinated Co single atoms anchored on the stepped TiO2 nanowire array, namely Co-P3 / S-TiO2 nanowire array material.

2. The method for preparing the Co-P3 / S-TiO2 nanowire array material according to claim 1, characterized in that, In step (1), the concentration of the NaOH solution is 1–3 M, and the volume ratio of the NaOH solution to the area of ​​the titanium mesh is 3–8 mL / cm². 2 The titanium mesh has a pore size of 40-60 mesh, the hydrothermal reaction temperature is 150℃~170℃, and the hydrothermal reaction time is 5~7h.

3. The method for preparing the Co-P3 / S-TiO2 nanowire array material according to claim 1, characterized in that, In step (2), the high-temperature calcination temperature is 450-600℃ and the holding time is 1-3h.

4. The method of claim 1, wherein the Co-P3 / S-TiO2 nanowire array material is prepared by the steps of: In step (3), the acid solution is a hydrochloric acid solution or a nitric acid solution, the concentration of the acid solution is 1-2.5M, and the ratio of the volume of the acid solution to the area of ​​the titanium mesh on which the TiO2 nanowires are grown is 6-10 mL / cm². 2 The hydrothermal reaction temperature is 100-130℃, and the hydrothermal reaction time is 1-3h.

5. The method for preparing the Co-P3 / S-TiO2 nanowire array material according to claim 1, characterized in that, In step (4), the Co 2+ The solution is Co(NO3)2·6H2O, Co 2+ The concentration of the solution is 0.025–0.075 M, and the Co 2+ The ratio of solution volume to the area of ​​the titanium mesh containing the stepped TiO2 nanowires is 10–40 mL / cm². 2 . 6.The method of claim 1, wherein the Co-P3 / S-TiO2 nanowire array material is prepared by the steps of, In step (4), the impregnation is performed for 0.5 to 2 minutes, followed by drying at 50 to 80°C. This process is repeated 2 to 6 times, and finally dried at 50 to 80°C for 2 to 6 hours.

7. The method for preparing the Co-P3 / S-TiO2 nanowire array material according to claim 1, characterized in that, In step (5), during the phosphating process, a titanium mesh with Co single atoms anchored on a stepped TiO2 nanowire array is placed downstream of a tube furnace, and sodium hypophosphite is placed upstream of the tube furnace as the phosphorus source. Phosphating is carried out at 300-350°C for 1-3 hours under an argon atmosphere.

8. The method for preparing the Co-P3 / S-TiO2 nanowire array material according to claim 7, characterized in that, In step (5), the mass ratio of the titanium mesh anchoring Co single atoms on the stepped TiO2 nanowire array to sodium hypophosphite is 1 to 6:

10.

9. The Co-P3 / S-TiO2 nanowire array material obtained by the preparation method according to any one of claims 1-8.

10. The application of the Co-P3 / S-TiO2 nanowire array material according to claim 9 in electrocatalytic hydrogen evolution.

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