A heterogeneous core-shell structure Ag@AgP2 / Ni2P and its synthesis method
By forming the Ag@AgP2 core-shell structure on the surface of the catalyst Ni2P nanosheet, the problem of slow adsorption and desorption of active hydrogen during the decomposition of water is solved, and efficient electrocatalytic decomposition of water and long-term stability is achieved.
Patent Information
- Application Number
- CN202310594154.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-05-25
- Publication Date
- 2025-05-06
- Estimated Expiration
- 2043-05-25
AI Technical Summary
During the decomposition of water, existing catalysts have problems such as strong adsorption of active hydrogen and slow bubble desorption, resulting in low catalytic activity.
Using the heterogeneous core-shell structure Ag@AgP2/Ni2P, Ni2P nanosheets are synthesized through hydrothermal reaction, and an Ag@AgP2 core-shell structure is formed on its surface, optimizing the reaction barrier and increasing the specific surface area.
The activity of decomposing water catalysis was significantly improved, the catalytic performance during the electrocatalysis process was enhanced, and the stability was maintained for 200 hours under alkaline conditions.
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Figure CN116695164B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of clean and sustainable new energy preparation and application, and particularly relates to heterogeneous core-shell structure Ag@AgP 2 / Ni 2 P and its synthesis method, and its application in electrocatalytic hydrogen evolution. Background Art
[0002] Hydrogen energy can be used for the conversion and storage of various energy sources. Compared with fossil energy, it has many advantages, such as being renewable, cheap, safe and easy to transport. However, the slow kinetics of hydrogen production will increase the actual water electrolysis voltage, resulting in additional energy consumption. The core factor affecting the kinetics is the catalyst. Currently, most commercial catalysts are Pt / C catalysts, but due to the small reserves of Pt, high prices, and poor stability, their large-scale application is limited. Therefore, it is particularly important to find efficient and low-cost platinum-replacing catalysts.
[0003] Transition metal compounds meet this condition, including transition metal sulfides, oxides / hydroxides, carbides, nitrides, borides, phosphides, etc. Among them, metal phosphides have attracted much attention, and their properties are similar to those of metals, with excellent chemical resistance, high thermal stability and good thermal conductivity. However, a comprehensive summary of target-oriented tuning strategies for TMP defects is still lacking. Here, we discuss the electronic structure of metal particles and dialectically analyze the derived activity of metal particles for HER.
[0004] Nickel-based catalysts have the advantages of high conductivity and low price. 2 P electrons are adjustable, but the current Ni 2 Because there are certain deficiencies in the process of water decomposition, such as strong adsorption of active hydrogen, slow bubble desorption, and low catalytic activity. Summary of the invention
[0005] Aiming at the deficiencies of the prior art, the present invention proposes a heterogeneous core-shell structure Ag@AgP 2 / Ni 2 P and its synthesis method.
[0006] The heterogeneous core-shell structure Ag@AgP of the present invention 2 / Ni 2 P includes Ni 2 P nanosheets and from the Ni 2 Ag@AgP deposited on the surface of P nanosheets 2 Core-shell structure, Ag@AgP 2 The diameter of the core-shell structure is between 10-30nm. 2 P and phosphorus-rich phase AgP 2The heterogeneous structure optimizes the reaction barrier in the catalytic process and improves the water splitting performance. 2 The core-shell structure significantly increases the specific surface area during the electrocatalytic process and greatly improves the catalytic activity of water decomposition.
[0007] The heterogeneous core-shell structure Ag@AgP of the present invention 2 / Ni 2 A method for synthesizing P, comprising:
[0008] (1) A substrate is placed in an autoclave lining containing a precursor solution, wherein the precursor solution is: Ni(NO 3 ) 2 .6H 2 O, a mixed aqueous solution of HMT with a concentration of 0.2-0.4 M; after hydrothermal reaction at 100-120 ° C for 10 hours, it was washed with deionized water and ethanol to remove the adsorbed impurities on the surface, and Ni(OH) 2 Nanosheet precursors.
[0009] (2) Ni(OH) 2 Nanosheet precursor immersed in AgNO 3 The concentration of the AgNO nanoparticles was 0.14-0.74 M in a DMF solution for 24 h. After being taken out and dried naturally in the air, the AgNO nanoparticles loaded on the substrate were obtained. 3 / Ni(OH) 2 Precursor.
[0010] (3) AgNO 3 / Ni(OH) 2 The precursor is placed downstream of the tube furnace, and the upstream is NaH 2 PO 2 .H 2 O, the protective gas is argon, the heating rate is 2℃ / min, and the heat treatment is carried out at 300℃ for 2 hours. After the tube furnace is naturally cooled to room temperature, the sample is taken out. Due to the strong interaction between Ag and Ni, the electron distribution around Ni atoms is rearranged to form Ag@AgP 2 Core-shell structure, and phosphorus-poor phase Ni 2 P and phosphorus-rich AgP in the shell 2 Forming a heterogeneous structure.
[0011] In particular, in step 3, NaH 2 PO 2 .H 2 The mass of O is 0.4g. It can better form the heterogeneous core-shell structure Ag@AgP 2 / Ni 2 P.
[0012] In particular, porous nickel can be used as a substrate to provide a three-dimensional network-like framework.
[0013] The beneficial effect of the present invention is that a heterogeneous core-shell structure Ag@AgP is synthesized by co-action of multiple components. 2 / Ni 2 P, and used it for electrocatalytic water decomposition. In terms of catalytic activity, due to the introduction of Ag element, the 2 A large amount of core-shell Ag@AgP was precipitated on the surface of P nanosheets. 2 This new structure has obvious catalytic advantages in both morphology and electronic structure.
[0014] 1. The emergence of nanoparticles greatly increases the number of surface interfaces and active sites on the nanosheets, and the active area in the catalytic process is greatly increased.
[0015] 2. The electron mass transfer between Ag and Ni has a local reconstruction effect on the coordination environment and electronic structure around Ni atoms. 2 P and phosphorus-rich phase AgP 2 The material can greatly reduce the intermediate adsorption barrier in the HER and OER processes, thereby enhancing the intrinsic activity of water splitting and promoting efficient water splitting. This core-shell heterogeneous synthesis method is of great significance for the phase change synthesis of phosphides and the expansion and upgrading of water electrolysis catalysts. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 The Ag@AgP prepared by the present invention 2 / Ni 2 P (Example 1) and Ni 2 P / NF (Comparative Example 1) and Ag@AgP 2 / NF (Comparative Example 2) X-ray diffraction spectrum.
[0017] Figure 2 The present invention prepares Ni 2 P / NF (Comparative Example 1) nanosheets, heterogeneous core-shell structure Ag@AgP 2 / Ni 2 P
[0018] (Example 1) and Ag@AgP 2 SEM images (a, b, c) of / NF (Comparative Example 2).
[0019] Figure 3 The Ag@AgP prepared by the present invention 2 / Ni 2 P (Example 1), Ni 2 P / NF (Comparative Example 1), Ag@AgP2 Comparison of electrochemical polarization curves of / NF (Comparative Example 2) under 1 M KOH conditions.
[0020] Figure 4 The Ag@AgP prepared by the present invention 2 / Ni 2 P (Example 1) Stability test curve of catalytic hydrogen evolution under 1M KOH conditions.
[0021] Figure 5 The Ag@AgP prepared by the present invention 2 / Ni 2 P-200 (Comparative Example 3), Ag@AgP 2 / Ni 2 P-400
[0022] (Comparative Example 4), Ag@AgP 2 / Ni 2 P-500 (Comparative Example 5) and Ag@AgP 2 / Ni 2 P-300 (Example
[0023] 1) Comparison of electrochemical polarization curves.
[0024] Figure 6 The Ag@AgP prepared by the present invention 2 / Ni 2 P-200(a), Ag@AgP 2 / Ni 2 P-300(b),Ag@AgP 2 / Ni 2 P-400(c) and Ag@AgP 2 / Ni 2 SEM image of P-500(d). DETAILED DESCRIPTION
[0025] The present invention starts from the two perspectives of morphology and intrinsic activity, constructs a complex catalytic interface and uses heterogeneous structures to optimize the reaction barriers of nickel phosphide in the HER and OER processes, greatly improving the performance of nickel phosphide in electrocatalytic water decomposition and promoting the application of nickel phosphide series materials in industrial catalysis.
[0026] The technical solution of the present invention is further described below in conjunction with embodiments. These embodiments should not be construed as limiting the technical solution.
[0027] Embodiment 1:
[0028] (1) First, nickel foam (NF) was pretreated to remove the surface oxide layer. It was ultrasonically cleaned with 4M hydrochloric acid, distilled water, and ethanol for 10, 5, and 5 minutes respectively, and dried with a high-speed flow of Ar gas.
[0029] (2)Ni(OH) 2 Synthesis of / NF precursor: 1.45 g Ni(NO 3 ) 2 .6H 2 O and 1.40 g HMT were dissolved in 30 mL of deionized water and stirred vigorously for 15 min, and then the mixture was transferred to a polytetrafluoroethylene autoclave. The nickel foam with a size of 2×3 cm treated by method (1) was immersed in the autoclave liner for hydrothermal synthesis. The autoclave was heat treated at 100°C for 10 hours. After cooling to room temperature, obvious blue-green substances appeared in the solution and on the surface of the nickel foam. It was taken out and ultrasonically treated with deionized water and ethanol, respectively, to remove impurities adsorbed on its surface. Finally, it was dried in a vacuum environment at 60°C for 10 hours.
[0030] (3) AgNO 3 / Ni(OH) 2 Synthesis: 3g AgNO 3 Dissolve in 40 mL DMF solution and place in a beaker. 2 The nanosheet precursor was immersed in the solution for 24 hours. After being taken out, it was naturally dried in the air to obtain AgNO nanoparticles loaded on the nanosheet on the substrate. 3 / Ni(OH) 2 Precursor.
[0031] (4) Ag@AgP 2 / Ni 2 Synthesis of P: AgNO 3 / Ni(OH) 2 The precursor was placed downstream of the tube furnace, and 0.4 g of NaH 2 PO 2 .H 2 O was placed upstream of the tube furnace, the protective gas was argon, the heating rate was 2°C / min, and the heat treatment was performed at 300°C for 2 hours. After the tube furnace was naturally cooled to room temperature, the sample was taken out to obtain the product Ag@AgP 2 / Ni 2 P.
[0032] The core-shell structure grown on the surface of the obtained material nanosheet has a diameter of 10-30nm, which can be observed by scanning electron microscopy and transmission electron microscopy. 2 P nanosheets and from the Ni 2 Core-shell Ag@AgP grown on the surface of P nanosheets2 "The successful synthesis of this structure shows that the catalytic activity of this heterogeneous core-shell structure in the electrocatalytic hydrogen evolution process far exceeds that of the comparative material Ni 2 P nanosheets and other example materials.
[0033] Example 2
[0034] (1) First, nickel foam (NF) was pretreated to remove the surface oxide layer. It was ultrasonically cleaned with 4M hydrochloric acid, distilled water, and ethanol for 10, 5, and 5 minutes respectively, and dried with a high-speed flow of Ar gas.
[0035] (2)Ni(OH) 2 Synthesis of / NF precursor: 1.45 g Ni(NO 3 ) 2 .6H 2 O and 1.40 g HMT were dissolved in 30 mL of deionized water and stirred vigorously for 15 min, and then the mixture was transferred to a polytetrafluoroethylene autoclave. The nickel foam with a size of 2×3 cm treated by method (1) was immersed in the autoclave liner for hydrothermal synthesis. The autoclave was heat treated at 100°C for 10 hours. After cooling to room temperature, obvious blue-green substances appeared in the solution and on the surface of the nickel foam. It was taken out and ultrasonically treated with deionized water and ethanol, respectively, to remove impurities adsorbed on its surface. Finally, it was dried in a vacuum environment at 60°C for 10 hours.
[0036] (3) AgNO 3 / Ni(OH) 2 Synthesis of -1: 1g AgNO 3 Dissolve in 40 mL DMF solution and place in a beaker. 2 The nanosheet precursor was immersed in the solution for 24 hours. After being taken out, it was naturally dried in the air to obtain AgNO nanoparticles loaded on the nanosheet on the substrate. 3 / Ni(OH) 2 Precursor.
[0037] (4) Ag@AgP 2 / Ni 2 Synthesis of P-1: AgNO 3 / Ni(OH) 2 The precursor was placed downstream of the tube furnace, and 0.4 g of NaH 2 PO 2 .H 2 O was placed upstream of the tube furnace, the protective gas was argon, the heating rate was 2°C / min, and the heat treatment was performed at 300°C for 2 hours. After the tube furnace was naturally cooled to room temperature, the sample was taken out to obtain the product Ag@AgP 2 / Ni2 P-1.
[0038] X-ray diffraction spectrum showed that the product had Ni 2 P, Ag and AgP 2 Characteristic peaks. The diameter of the particles precipitated on the surface of the obtained material nanosheets is 10-30 nm, and the number of nanoparticles is less than that of Example 1.
[0039] Embodiment 3:
[0040] (1) First, nickel foam (NF) was pretreated to remove the surface oxide layer. It was ultrasonically cleaned with 4M hydrochloric acid, distilled water, and ethanol for 10, 5, and 5 minutes respectively, and dried with a high-speed flow of Ar gas.
[0041] (2)Ni(OH) 2 Synthesis of / NF precursor: 1.45 g Ni(NO 3 ) 2 .6H 2 O and 1.40 g HMT were dissolved in 30 mL of deionized water and stirred vigorously for 15 min, and then the mixture was transferred to a polytetrafluoroethylene autoclave. The nickel foam with a size of 2×3 cm treated by method (1) was immersed in the autoclave liner for hydrothermal synthesis. The autoclave was heat treated at 100°C for 10 hours. After cooling to room temperature, obvious blue-green substances appeared in the solution and on the surface of the nickel foam. It was taken out and ultrasonically treated with deionized water and ethanol, respectively, to remove impurities adsorbed on its surface. Finally, it was dried in a vacuum environment at 60°C for 10 hours.
[0042] (3) AgNO 3 / Ni(OH) 2 Synthesis of -2: 2 g AgNO 3 Dissolve in 40 mL DMF solution and place in a beaker. 2 The nanosheet precursor was immersed in the solution for 24 hours. After being taken out, it was naturally dried in the air to obtain AgNO nanoparticles loaded on the nanosheet on the substrate. 3 / Ni(OH) 2 Precursor.
[0043] (4) Ag@AgP 2 / Ni 2 Synthesis of P-2: AgNO 3 / Ni(OH) 2 The precursor was placed downstream of the tube furnace, and 0.4 g of NaH 2 PO 2 .H 2O was placed upstream of the tube furnace, the protective gas was argon, the heating rate was 2°C / min, and the heat treatment was performed at 300°C for 2 hours. After the tube furnace was naturally cooled to room temperature, the sample was taken out to obtain the product Ag@AgP 2 / Ni 2 P-2.
[0044] X-ray diffraction spectrum showed that the product had Ni 2 P, Ag and AgP 2 Characteristic peaks. The diameter of the particles precipitated on the surface of the obtained material nanosheets is 10-30 nm, and the number of nanoparticles is more than that of Example 2 and less than that of Example 1.
[0045] Embodiment 4:
[0046] (1) First, nickel foam (NF) was pretreated to remove the surface oxide layer, and then ultrasonically cleaned with 4M hydrochloric acid, distilled water, and ethanol, and dried with a high-speed flow of Ar gas.
[0047] (2)Ni(OH) 2 Synthesis of / NF precursor: 1.45 g Ni(NO 3 ) 2 .6H 2 O and 1.40 g HMT were dissolved in 30 mL of deionized water and stirred vigorously for 15 min, and then the mixture was transferred to a polytetrafluoroethylene autoclave. The nickel foam with a size of 2×3 cm treated by method (1) was immersed in the autoclave liner for hydrothermal synthesis. The autoclave was heat treated at 100°C for 10 hours. After cooling to room temperature, obvious blue-green substances appeared in the solution and on the surface of the nickel foam. It was taken out and ultrasonically treated with deionized water and ethanol, respectively, to remove impurities adsorbed on its surface. Finally, it was dried in a vacuum environment at 60°C for 10 hours.
[0048] (3) AgNO 3 / Ni(OH) 2 Synthesis of -5: 5 g AgNO 3 Dissolve in 40 mL DMF solution and place in a beaker. 2 The nanosheet precursor was immersed in the solution for 24 hours. After being taken out, it was naturally dried in the air to obtain AgNO nanoparticles loaded on the nanosheet on the substrate. 3 / Ni(OH) 2 Precursor.
[0049] (4) Ag@AgP 2 / Ni 2 Synthesis of P-5: AgNO 3 / Ni(OH) 2The precursor was placed downstream of the tube furnace, and 0.4 g of NaH 2 PO 2 .H 2 O was placed upstream of the tube furnace, the protective gas was argon, the heating rate was 2°C / min, and the heat treatment was performed at 300°C for 2 hours. After the tube furnace was naturally cooled to room temperature, the sample was taken out to obtain the product Ag@AgP 2 / Ni 2 P-5.
[0050] X-ray diffraction spectrum showed that the product had Ni 2 P, Ag and AgP 2 Characteristic peaks. The diameter of the particles precipitated on the surface of the obtained material nanosheets is 10-30 nm, the number of nanoparticles is more than that of Example 1, and agglomeration occurs.
[0051] Comparative Example 1:
[0052] (1) First, nickel foam (NF) was pretreated to remove the surface oxide layer. It was ultrasonically cleaned with 4M hydrochloric acid, distilled water, and ethanol for 10, 5, and 5 minutes respectively, and dried with a high-speed flow of Ar gas.
[0053] (2)Ni(OH) 2 Synthesis of / NF precursor: 1.45 g Ni(NO 3 ) 2 .6H 2 O and 1.40 g HMT were dissolved in 30 mL of deionized water and stirred vigorously for 15 min, and then the mixture was transferred to a polytetrafluoroethylene autoclave. The nickel foam with a size of 2×3 cm treated by method (1) was immersed in the autoclave liner for hydrothermal synthesis. The autoclave was heat treated at 100°C for 10 hours. After cooling to room temperature, obvious blue-green substances appeared in the solution and on the surface of the nickel foam. It was taken out and ultrasonically treated with deionized water and ethanol, respectively, to remove impurities adsorbed on its surface. Finally, it was dried in a vacuum environment at 60°C for 15 hours.
[0054] (3)Ni 2 Synthesis of P / NF: Ni(OH) 2 / NF precursor was also placed downstream of the tube furnace. 0.4 gNaH 2 PO 2 .H 2 O was placed upstream of the tube furnace, the protective gas was argon, the heating rate was 2°C / min, and the heat treatment was carried out at 300°C for 2 hours. After the tube furnace was naturally cooled to room temperature, the sample was taken out to obtain the product Ni 2 P.
[0055] Comparative Example 2:
[0056] (1) First, nickel foam (NF) was pretreated to remove the surface oxide layer. It was ultrasonically cleaned with 4M hydrochloric acid, distilled water, and ethanol for 10, 5, and 5 minutes respectively, and dried with a high-speed flow of Ar gas.
[0057] (2) AgNO 3 Synthesis of NF precursor: 3 g of silver nitrate was dissolved in 40 mL of DMF solution and placed in a beaker. The pretreated NF was immersed in the solution for 24 h. After being taken out, it was naturally dried in the air to obtain AgNO loaded with nanoparticles on the substrate. 3 / NF precursor.
[0058] (3) Ag@AgP 2 Synthesis of AgNO 3 / NF precursor was placed downstream of the tube furnace. 0.4 g of NaH 2 PO 2 .H 2 O was placed upstream of the tube furnace, the protective gas was argon, the heating rate was 2°C / min, and the heat treatment was carried out at 300°C for 2 hours. After the tube furnace was naturally cooled to room temperature, the sample was taken out to obtain the product Ag@AgP 2 / NF.
[0059] Figure 1 The Ag@AgP prepared by the present invention 2 / Ni 2 P (Example 1), Ni 2 P / NF (Comparative Example 1) and Ag@AgP 2 / NF (Comparative Example 2) X-ray diffraction spectrum. The precursor is Ni(OH) 2 / NF, Ni only appears at 40.71° and 47.36° after phosphating. 2 P characteristic peaks, corresponding to (1 1 1), (2 1 0) crystal planes (PDF#74-1385). The precursor is AgNO 3 / NF, AgP appeared at 21.49°, 29.44°, and 38.89° after phosphating 2 The characteristic peaks of Ag appear at 38.2°, 64.6°, and 77.59°, corresponding to the (1 1 1), (2 2 0), and (3 1 1) crystal planes (PDF#87-0720). 2 PO 2 .H 2 O and AgNO 3 and Ni(OH) 2 When working together, in the original typical Ni 2 AgP is generated based on P2 and Ag, all the above characteristic peaks appear at the same time.
[0060] Figure 2 The heterogeneous core-shell structure Ag@AgP prepared by the present invention 2 / Ni 2 SEM image (a) of P (Example 1); Ni 2 SEM image (b) of P / NF nanosheets (Comparative Example 1); Ag@AgP 2 SEM (c) of the SEM image of / NF (Comparative Example 2). Through (a), it can be clearly observed that Ni 2 P is in the form of nanosheets. After the introduction of Ag, Ni 2 There are fine nanoparticles precipitated on the surface of P nanosheets, with a diameter between 10-30nm (b). There is no Ni in (c). 2 P nanosheets, nanoparticles tend to agglomerate during the phosphating process, forming nanoparticles with larger particle sizes on the surface of nickel foam.
[0061] Figure 3 The Ag@AgP prepared by the present invention 2 / Ni 2 P (Example 1), Ni 2 P / NF (Comparative Example 1) and Ag@AgP 2 Comparison of electrochemical polarization curves of NF (Comparative Example 2) in 1M KOH electrolyte. Figure 3 As shown, when Ni 2 P nanosheets and Ag@AgP 2 When they exist alone, the catalytic activity of the materials is poor. When a heterogeneous core-shell structure is formed on the surface of the nanosheets, electron transfer occurs between Ni and Ag, making the electrochemical activity of the material even better. -2 The turn-on point is 78mV at this current density.
[0062] Figure 4 The Ag@AgP prepared by the present invention 2 / Ni 2 P (Example 1) Stability test curve of catalytic hydrogen evolution under alkaline conditions. Constant current method was adopted with a current density of 10 mA cm -2 The ultra-long stability experiment is a great challenge to the robustness and durability of the catalyst. The good catalytic activity can still be maintained after 200 hours of continuous stability testing, which is of great significance to the industrial application of the overall hydrolysis catalyst.
[0063] Comparative Example 3:
[0064] This embodiment is the same as embodiment 1, except that in step 4, a heat treatment at 200°C for 2 hours is performed to obtain the product Ag@AgP2 / Ni 2 P-200.
[0065] The diameter of the nanoparticles on the surface of the obtained material nanosheets is small. This is because the heat treatment temperature is relatively low, resulting in incomplete phosphating. The silver nitrate nanoparticles are less aggregated and not completely transformed into silver and silver phosphide. Most of them are transformed into silver nitrite with smaller particle size. The catalytic activity is also weaker than that of Ag@AgP under 300℃ due to the structural changes caused by incomplete phosphating. 2 / Ni 2 P.
[0066] Comparative Example 4:
[0067] This embodiment is the same as embodiment 1, except that in step 2, a heat treatment at 400°C for 2 hours is performed to obtain the product Ag@AgP 2 / Ni 2 P-400.
[0068] The diameter of the particles precipitated on the surface of the obtained material nanosheets is 30-50 nm. The diameter of the nanoparticles is larger than that of Example 1, which weakens the specific surface area and electrochemical activity to a certain extent.
[0069] Comparative Example 5:
[0070] This embodiment is the same as embodiment 1, except that in step 2, a heat treatment at 500°C for 2 hours is performed to obtain the product Ag@AgP 2 / Ni 2 P-500.
[0071] The diameter of the particles precipitated on the surface of the obtained material nanosheets is 50-70nm, and the diameter of the nanoparticles is further increased than that of Example 1, which weakens the specific surface area and electrochemical activity. 2 The P nanosheet structure was destroyed to some extent.
[0072] Figure 5 The Ag@AgP prepared by the present invention 2 / Ni 2 P-200 (Comparative Example 3), Ag@AgP 2 / Ni 2 P-400 (Comparative Example 4), Ag@AgP 2 / Ni 2 P-500 (Comparative Example 5) and Ag@AgP 2 / Ni 2 Comparison of electrochemical polarization curves of P-300 (Example 1) in 1M KOH electrolyte. It can be seen that the samples obtained at 200℃, 400℃ and 500℃ are inferior to those at 300℃ in catalytic performance, which further shows the importance of surface heterogeneous core-shell structure in the catalytic hydrogen production process.
[0073] Figure 6 The Ag@AgP prepared by the present invention 2 / Ni 2 P-200 (Comparative Example 3), Ag@AgP 2 / Ni 2 P-400 (Comparative Example 4) and Ag@AgP 2 / Ni 2 SEM image of P-500 (Comparative Example 5). At 200°C, due to insufficient phosphating, the morphology basically maintains the main characteristics of the precursor, the nanoparticles are silver nitrite, and the particle size is small. At 400°C and 500°C, the nanoparticles grow excessively. At 300°C, the original small nanoparticles contact and merge to form super large nanoparticles, and Ni 2 The P nanosheets are destroyed to some extent by high temperature, which greatly reduces the relative active area of the material.
[0074] This method realizes the synthesis of a heterogeneous core-shell structure Ag@AgP by a multi-component co-action thermal treatment method. 2 / Ni 2 P and used for alkaline electrocatalytic hydrogen evolution. Ag@AgP 2 / Ni 2 The core-shell structure on the surface of P nanosheets maximizes the catalytic active area, and the heterogeneous structure realizes the electron transfer between Ag and Ni. The electron polarization causes a significant change in the binding characteristics of the active sites, and the electrocatalytic hydrogen evolution ability is greatly enhanced in all aspects. 2 P nanosheets for Ag@AgP 2 The strong confinement of Ag@AgP prevents 2 The material is stable at 10 mA cm -2 The turn-on point is only 78 mV at a current density of 10 mA cm -2 It can maintain excellent stability for 200 hours at the current density, making subsequent industrial production possible.
Claims
1. A heterogeneous core-shell structure Ag@AgP2 / Ni2P, comprising Ni2P nanosheets and Ag@AgP2 core-shell structures grown from the surfaces of the Ni2P nanosheets, wherein the diameter of the Ag@AgP2 core-shell structure is between 10-30 nm.
2. A method for synthesizing a heterogeneous core-shell structure Ag@AgP2 / Ni2P, characterized in that: The following steps are involved: (1) placing a substrate in an autoclave liner containing a precursor solution, wherein the precursor solution is a mixed aqueous solution of Ni(NO3)2·6H2O with a concentration of 0.1-0.2 M and hexamethylenetetramine with a concentration of 0.2-0.4 M; after hydrothermal reaction at 100-120°C for 10 hours, washing with deionized water and ethanol to remove adsorbed impurities on the surface, thereby obtaining a Ni(OH)2 nanosheet precursor on the substrate; (2) Immersing the Ni(OH)2 nanosheet precursor in a DMF solution with a AgNO3 concentration of 0.14-0.74 M for 24 h to obtain a AgNO3 / Ni(OH)2 precursor loaded with nanoparticles on the substrate; (3) Synthesis of Ag@AgP2 / Ni2P: The AgNO3 / Ni(OH)2 precursor was placed downstream of a tube furnace with NaH2PO2·H2O upstream. The protective gas was argon. The heating rate was 2 °C / min and the heat treatment was carried out at 300 °C for 2 h. After the tube furnace was naturally cooled to room temperature, the sample was taken out to obtain a heterogeneous core-shell structure of Ag@AgP2 / Ni2P on the substrate.
3. The synthesis method according to claim 2, characterized in that In step 3, the mass of NaH2PO2·H2O is 0.4 g.
4. The synthesis method according to claim 2, characterized in that The substrate is porous nickel.