Electrocatalytic hydrogen reduction reaction design method based on AlAs / ZrS2 Van der Waals heterojunction

Abstract

The invention discloses an electro-catalytic hydrogen reduction reaction design method based on an AlAs / ZrS2 Van der Waals heterojunction, and belongs to the technical field of hydrogen production through electro-catalytic decomposition of water. According to the method, an AlAs / ZrS2 heterojunction model is calculated and constructed through a first principle, and 20 vacuum layers are arranged; four stacking configurations are formed based on single-layer AlAs translation; screening a stable structure based on binding energy; and calculating the hydrogen adsorption Gibbs free energy. Researches find that compared with noble metal catalysts such as Pt and the like and traditional heterojunction catalysts, the noble metal-free two-dimensional AlAs / ZrS2 van der Waals heterojunction catalyst has the characteristics of low cost, low lattice mismatch and the like, and results show that adsorption on AZ-2 configuration Al atoms with the most negative binding energy has relatively low hydrogen adsorption free energy, and also prove that the catalyst has good HER catalytic activity.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic water splitting for hydrogen production technology, specifically relating to a design method for electrocatalytic hydrogen reduction reaction based on AlAs / ZrS2 van der Waals heterojunction. Background Technology

[0002] Due to the finite and non-renewable nature of fossil fuels, and the environmental problems caused by their combustion, pollution-free and clean hydrogen energy holds promise as a new energy source to replace traditional fossil fuels. In recent years, various types of catalysts have been extensively explored and prepared for electrocatalytic water splitting to produce hydrogen. Currently, platinum (Pt)-based noble metal materials remain the recognized highly efficient HER catalysts, but their high cost and scarcity severely limit their large-scale application. Traditional heterojunction catalysts (such as metal / semiconductor composite structures) require chemical bonding at the interface, which is prone to structural defects due to lattice mismatch, reducing catalytic stability. Therefore, developing a HER catalyst that combines high stability and low cost while avoiding interfacial lattice mismatch is of great significance.

[0003] In recent years, two-dimensional (2D) materials (such as transition metal sulfides and nitrides) have been regarded as potential candidates to replace noble metals due to their high specific surface area and tunable electronic structure. Van der Waals heterostructures, on the other hand, avoid lattice mismatch problems because there are no interlayer chemical bonds. Therefore, two-dimensional ZrS2 with good thermodynamic stability, environmental friendliness, and low production cost was chosen to construct AlAs / ZrS2 van der Waals heterostructures. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a design method for electrocatalytic hydrogen reduction reaction (HER) based on AlAs / ZrS2 van der Waals heterostructures.

[0005] To achieve the above technology, the following steps are included: S1. Single-layer structure optimization: The crystal structures of monolayer AlAs and ZrS2 were optimized by calling the CASTEP module in Materials Studio, a first-principles calculation software. Using the initial crystal structures of monolayer AlAs and monolayer ZrS2 as inputs, the optimized lattice constants and angles are output as follows: a=b=4.06Å, γ=120° and a=b=3.65Å, γ=120°, respectively; where a represents the side length of the unit cell along the x-axis, b represents the side length of the unit cell along the y-axis, Å represents the unit (Angstrom), and γ represents the interaxial angle of the unit cell.

[0006] S2. Construct a two-dimensional AlAs / ZrS2 van der Waals heterostructure; Based on the optimized monolayer AlAs and ZrS2 crystal structures, heterojunctions were constructed using 3×3 (AlAs) and 2√3×2√3 (ZrS2) supercells via the Build Layers tool, resulting in a two-dimensional AlAs / ZrS2 van der Waals heterojunction. The constructed AlAs / ZrS2 van der Waals heterojunction has a lattice constant and angles of a=b=12.41 Å and γ=120°. Meanwhile, a vacuum layer of 20 Å was set to prevent periodic interactions in the structure.

[0007] S3. Construct four stacking configurations; Based on the heterojunction model constructed using S2, four two-dimensional heterostructures were constructed by translating a single AlAs layer, including: AZ-1: The S atom corresponds to the center of the AlAs layer; AZ-2: Zr atoms correspond to the center of the AlAs layer; AZ-3: As atoms correspond to S atoms in the ZrS2 layer; AZ-4: Al atoms correspond to S atoms in the ZrS2 layer; Four different stacked AlAs / ZrS2 heterojunction models (AZ-1~AZ-4) were obtained.

[0008] S4. Geometric optimization and energy calculation; Based on the four heterostructures obtained from S3, geometry optimization was performed using the CASTEP module. After optimization, the interlayer spacing of the four configurations were 3.29 Å, 3.21 Å, 3.27 Å and 3.29 Å, respectively. Energy calculations were performed on the optimized structure to obtain the total energy for each of the four configurations.

[0009] S5, Single-layer energy calculation; Based on the four optimized configurations of S4, monolayer structures are extracted from heterojunctions, and the energies of monolayer AlAs and monolayer ZrS2 are calculated respectively, providing monolayer energy input for the binding energy formula.

[0010] S6. Combining calculations with stable configuration screening; Using the total energy of the four configurations obtained in S4, the energy of the monolayer AlAs and monolayer ZrS2 obtained in S5, and the heterojunction area as inputs, the binding energy values ​​of the four configurations are calculated using the binding energy formula, and the stable configurations are selected by preset conditions. Furthermore, the formula for binding energy is expressed as follows: In the formula, Indicates binding energy; This represents the total energy of the AlAs / ZrS2 van der Waals heterojunction; This represents the total energy of a heterojunction monolayer AlAs; This represents the total energy of a single layer of ZrS2 in the heterojunction; S is the area of ​​the AlAs / ZrS2 van der Waals heterojunction. The preset condition is set to: -21 meV / Ų < <-13 meV / Ų; The binding energies for the four configurations were obtained as -12.67 meV / Å. 2 -13.13meV / Å 2 -13.08meV / Å 2 and -12.72 meV / Å 2 A more negative binding energy value means higher structural stability. The binding energies of all four configurations are negative, and the binding energy of AZ-2 is the most negative, indicating that the AZ-2 structure is the most stable. In addition, the binding energies of AZ-2 and AZ-3 configurations are both less than -13meV / Å2. Therefore, the AZ-2 and AZ-3 configurations are selected for H atom adsorption calculations.

[0011] S7. Construct a hydrogen adsorption structure model; Based on the results of S6, the optimized AZ-2 and AZ-3 two-dimensional heterostructures from S4 were used as the substrate, i.e., the heterojunction substrate. With the AlAs side as the adsorption side, H adsorption structures at different types of sites on the substrate were constructed. According to the stacking of the upper AlAs and ZrS2 monolayer materials in the heterojunction, there are two adsorption modes: adsorption on Al atoms and adsorption on As atoms. The adsorption distance for the two adsorption modes was set to 1.23 Å, providing a structural model for calculating hydrogen adsorption energy.

[0012] S8, Hydrogen adsorption structure optimization and energy calculation; Based on the hydrogen adsorption model constructed using S7, the CASTEP module was used for structural optimization, and the total energy after adsorption was calculated. Among them, the adsorption distances of AZ-2 after optimization for the two adsorption methods were 1.61 Å and 1.52 Å, respectively, and the adsorption distances of AZ-3 were 1.61 Å and 1.53 Å, respectively.

[0013] S9. Vibration rating calculation; Based on the S8-optimized hydrogen adsorption structure, vibrational rating analysis was performed using the CASTEP module, outputting the zero-point energy and entropy value of each H adsorption structure, providing a thermal correction term for Gibbs free energy calculation.

[0014] S10, Gibbs free energy calculation; Based on the total energy after adsorption obtained from S8 and the zero-point energy and entropy value obtained from S9, the Gibbs free energy formula is used to obtain the Gibbs free energy of hydrogen adsorption at different types of sites. Furthermore, the Gibbs free energy expression is as follows: ΔG=ΔE H +ΔE ZPE -TΔS In the formula, ΔEH represents the adsorption energy of H atoms; ΔEZPE represents the zero-point energy between adsorbed H and gaseous H; T represents the temperature, with a value of 298 K; and ΔS represents the entropy difference between adsorbed H and gaseous H. The optimal result is obtained by using the Gibbs free energy and the most negative binding energy.

[0015] Beneficial effects of the present invention This invention uses first-principles calculations to screen for highly stable catalyst structures, solving the problems of high cost and lattice mismatch in traditional catalysts.

[0016] This invention utilizes an AlAs / ZrS22 van der Waals heterojunction as a catalyst for the electrocatalytic hydrogen reduction reaction. Compared with traditional noble metals and traditional heterojunction catalysts, the two-dimensional van der Waals heterojunction catalyst of this invention has the following advantages: First, the heterojunction catalyst has good structural stability, which is beneficial for the continuous and stable catalysis of the hydrogen reduction reaction; second, the catalyst does not involve noble metal elements, resulting in low cost; and third, as a van der Waals heterojunction, it avoids lattice mismatch problems. Attached Figure Description

[0017] Figure 1 This is a flowchart of the steps of the present invention; Figure 2 This is a schematic diagram of the structure of the AlAs / ZrS2 van der Waals heterojunction of the present invention, wherein, Figure 2 (a) is a schematic diagram of the structure of AZ-1; Figure 2 (b) is a schematic diagram of the structure of AZ-2; Figure 2 (c) is a schematic diagram of the structure of AZ-3; Figure 2 (d) is a schematic diagram of the structure of AZ-4; Figure 3 This is a schematic diagram of the structure of H adsorbed at various points in the AlAs / ZrS2 van der Waals heterojunction of the present invention, wherein, Figure 3 (a) is a schematic diagram of the structure of AZ-2 Al; Figure 3 (b) is a schematic diagram of the structure of AZ-3Al; Figure 3 (c) is a schematic diagram of the structure of AZ-2As; Figure 3 (d) is a schematic diagram of the structure of AZ-3As; Figure 4 This is the Gibbs free energy reaction spectrum of H adsorption according to the present invention. Detailed Implementation The present invention will be further described in detail below with reference to specific embodiments.

[0018] like Figure 1As shown, a design method for electrocatalytic hydrogen reduction reaction (HER) based on AlAs / ZrS2 van der Waals heterostructure includes the following steps: S1. Single-layer structure optimization; The crystal structures of monolayer AlAs and ZrS2 were optimized by calling the CASTEP module in Materials Studio, a first-principles calculation software. Using the initial crystal structures of monolayer AlAs and monolayer ZrS2 as inputs, the optimized lattice constants and angles are output as follows: a=b=4.06Å, γ=120° and a=b=3.65Å, γ=120°, respectively; where a represents the side length of the unit cell along the x-axis, b represents the side length of the unit cell along the y-axis, Å represents the unit (Angstrom), and γ represents the interaxial angle of the unit cell.

[0019] S2. Construct a two-dimensional AlAs / ZrS2 van der Waals heterostructure; Based on the optimized monolayer AlAs and ZrS2 crystal structures, heterojunctions were constructed using 3×3 (AlAs) and 2√3×2√3 (ZrS2) supercells via the Build Layers tool, resulting in a two-dimensional AlAs / ZrS2 van der Waals heterojunction. The constructed AlAs / ZrS2 van der Waals heterojunction has a lattice constant and angles of a=b=12.41 Å and γ=120°. Meanwhile, a vacuum layer of 20 Å was set to prevent periodic interactions in the structure.

[0020] S3. Construct four stacking configurations; Based on the heterojunction model constructed using S2, four two-dimensional heterostructures were constructed by translating a single AlAs layer, including: AZ-1: The S atom corresponds to the center of the AlAs layer; AZ-2: Zr atoms correspond to the center of the AlAs layer; AZ-3: As atoms correspond to S atoms in the ZrS2 layer; AZ-4: Al atoms correspond to S atoms in the ZrS2 layer; Four different stacked AlAs / ZrS2 heterojunction models (AZ-1~AZ-4) were obtained, such as Figure 2 middle Figure 2 (a) Figure 2 (b) Figure 2 (c) and Figure 2 As shown in (d).

[0021] S4. Geometric optimization and energy calculation; Based on the four heterostructures obtained from S3, geometry optimization was performed using the CASTEP module. After optimization, the interlayer spacing of the four configurations were 3.29 Å, 3.21 Å, 3.27 Å and 3.29 Å, respectively. Energy calculations were performed on the optimized structure to obtain the total energy for each of the four configurations.

[0022] S5, Single-layer energy calculation; Based on the four optimized configurations of S4, monolayer structures are extracted from heterojunctions, and the energies of monolayer AlAs and monolayer ZrS2 are calculated respectively, providing monolayer energy input for the binding energy formula.

[0023] S6. Combining calculations with stable configuration screening; Using the total energy of the four configurations obtained in S4, the energy of the monolayer AlAs and monolayer ZrS2 obtained in S5, and the heterojunction area as inputs, the binding energy values ​​of the four configurations are calculated using the binding energy formula, and the stable configurations are selected by preset conditions. Furthermore, the formula for binding energy is expressed as follows: In the formula, Indicates binding energy; This represents the total energy of the AlAs / ZrS2 van der Waals heterojunction; This represents the total energy of a heterojunction monolayer AlAs; This represents the total energy of a single layer of ZrS2 in the heterojunction; S is the area of ​​the AlAs / ZrS2 van der Waals heterojunction. The preset condition is set to: -21 meV / Ų < <-13 meV / Ų; The binding energies for the four configurations were obtained as -12.67 meV / Å. 2 -13.13meV / Å 2 -13.08meV / Å 2 and -12.72 meV / Å 2 A more negative binding energy value indicates higher structural stability. All four configurations have negative binding energies, with AZ-2 having the most negative binding energy, indicating that the AZ-2 structure is the most stable. Furthermore, the binding energies of both the AZ-2 and AZ-3 configurations are less than -13 meV / Å. 2 Therefore, the AZ-2 and AZ-3 configurations were chosen for H atom adsorption calculations.

[0024] S7. Construct a hydrogen adsorption structure model; Based on the results of S6, the optimized AZ-2 and AZ-3 two-dimensional heterostructures from S4 were used as the substrate, i.e., the heterojunction substrate. With the AlAs side as the adsorption side, H adsorption structures at different types of sites on the substrate were constructed. Due to the stacking of the upper AlAs and ZrS2 monolayer materials in the heterojunction, two adsorption modes exist: adsorption on Al atoms and adsorption on As atoms. The adsorption distance for both modes was set to 1.23 Å, providing a structural model for calculating hydrogen adsorption energy. Figure 3 middle Figure 3 (a) Figure 3 (b) Figure 3 (c) and Figure 3 As shown in (d).

[0025] S8, Hydrogen adsorption structure optimization and energy calculation; Based on the hydrogen adsorption model constructed using S7, the CASTEP module was used for structural optimization, and the total energy after adsorption was calculated. Among them, the adsorption distances of AZ-2 after optimization for the two adsorption methods were 1.61 Å and 1.52 Å, respectively, and the adsorption distances of AZ-3 were 1.61 Å and 1.53 Å, respectively.

[0026] S9. Vibration rating calculation; Based on the S8-optimized hydrogen adsorption structure, vibrational rating analysis was performed using the CASTEP module, outputting the zero-point energy and entropy value of each H adsorption structure, providing a thermal correction term for Gibbs free energy calculation.

[0027] S10, Gibbs free energy calculation; Based on the total energy after adsorption obtained from S8 and the zero-point energy and entropy value obtained from S9, the Gibbs free energy formula is used to obtain the Gibbs free energy of hydrogen adsorption at different types of sites. Furthermore, the Gibbs free energy expression is as follows: ΔG=ΔE H +ΔE ZPE -TΔS In the formula, ΔEH represents the adsorption energy of H atoms; ΔEZPE represents the zero-point energy between adsorbed H and gaseous H; T represents the temperature, with a value of 298 K; and ΔS represents the entropy difference between adsorbed H and gaseous H. like Figure 4 As shown, calculations show that both AZ-2 and AZ-3 configurations tend to adsorb onto Al atoms, with free energies of -0.24 eV and -0.29 eV, respectively. AZ-2, which has the most negative binding energy (-13.13 meV / Å2), has the smallest absolute free energy (-0.24 eV), making it the optimal result.

[0028] This invention provides an AlAs / ZrS2 van der Waals heterojunction design for electrocatalytic hydrogen reduction reaction (HER). Stable structures were screened based on binding energy -21 meV / Ų < Eb < -13 meV / Ų, and the Gibbs free energy of hydrogen adsorption for each structure was calculated. The results show that the AZ-2 configuration, with the most negative binding energy (-14.89 meV / Ų), exhibits a low hydrogen adsorption free energy (-0.24 eV) on Al atoms, demonstrating its excellent HER catalytic activity.

[0029] Methods for efficient hydrogen reduction based on two-dimensional van der Waals heterostructures as electrocatalysts include, but are not limited to, the examples above.

[0030] The above description is merely an embodiment of the present invention and does not limit the scope of this patent. Any equivalent structures and methods made using the contents of this invention and its drawings are similarly included within the patent protection scope of this invention.

Claims

1. A design method for electrocatalytic hydrogen reduction reaction based on AlAs / ZrS2 van der Waals heterostructure, characterized in that, Includes the following steps: S1. Optimize the crystal structures of monolayer AlAs and ZrS2 by calling the CASTEP module in Materials Studio, a first-principles calculation software; S2. Based on S1, construct a two-dimensional AlAs / ZrS2 van der Waals heterostructure; S3. Based on S2, four stacking configurations are constructed by translating the AlAs monolayer, including: AZ-1: S atoms correspond to the center of the AlAs layer; AZ-2: Zr atoms correspond to the center of the AlAs layer; AZ-3: As atoms correspond to S atoms in the ZrS2 layer; AZ-4: Al atoms correspond to S atoms in the ZrS2 layer. S4. Based on S3, the CASTEP module is used to perform geometry optimization, and energy calculations are performed on the optimized structure to obtain the total energy for each of the four configurations. The geometric interlayer spacings of the four optimized configurations are 3.29 Å, 3.21 Å, 3.27 Å, and 3.29 Å, respectively. S5. Based on S4, perform energy calculations for single-layer AlAs and single-layer ZrS2. S6. Based on S4 and S5, perform combined calculations and stable configuration screening; S7. Based on S4 and S6, construct a hydrogen adsorption structure model; S8. Based on S7, perform hydrogen adsorption structure optimization and energy calculation; S9. Based on the optimized hydrogen adsorption structure of S8, the vibrational rating analysis is performed using the CASTEP module to output the zero-point energy and entropy value of each H adsorption structure. Based on S8 and S9, the Gibbs free energy is calculated using S10, and the optimal result is obtained.

2. The design method for electrocatalytic hydrogen reduction reaction based on AlAs / ZrS2 van der Waals heterojunction according to claim 1, characterized in that: In S1, the initial crystal structures of monolayer AlAs and monolayer ZrS2 are used as inputs, and the optimized lattice constants and angles are output as follows: a=b=4.06Å, γ=120° and a=b=3.65Å, γ=120°, respectively; where a represents the side length of the unit cell on the x-axis, b represents the side length of the unit cell on the y-axis, Å represents the unit, and γ represents the interaxial angle of the unit cell.

3. The design method for an electrocatalytic hydrogen reduction reaction based on an AlAs / ZrS2 van der Waals heterojunction according to claim 2, characterized in that: In S2, based on the optimized monolayer AlAs and ZrS2 crystal structure, a heterojunction is constructed using 3×3 and 2√3×2√3 supercells through the Build Layers tool to obtain a two-dimensional AlAs / ZrS2 van der Waals heterojunction. The lattice constant and angle of the constructed AlAs / ZrS2 van der Waals heterojunction are a=b=12.41 Å and γ=120°. At the same time, the vacuum layer is set to 20 Å to prevent periodic interactions in the structure.

4. The method for designing an electrocatalytic hydrogen reduction reaction based on an AlAs / ZrS2 van der Waals heterojunction according to claim 1, characterized in that: In S6, the total energy of the four configurations obtained in S4, the energy of the monolayer AlAs and monolayer ZrS2 obtained in S5, and the heterojunction area are used as inputs. The binding energy formula is used to calculate and output the binding energy values ​​of the four configurations. Stable configurations are selected by preset conditions. The formula for binding energy is expressed as follows: In the formula, Indicates binding energy; This represents the total energy of the AlAs / ZrS2 van der Waals heterojunction; This represents the total energy of a heterojunction monolayer AlAs; This represents the total energy of a single layer of ZrS2 in the heterojunction; S is the area of ​​the AlAs / ZrS2 van der Waals heterojunction. The preset condition is set to: -21 meV / Ų < <-13 meV / Ų; Adsorption calculations for H atoms were performed using the AZ-2 and AZ-3 configurations.

5. The design method for an electrocatalytic hydrogen reduction reaction based on an AlAs / ZrS2 van der Waals heterojunction according to claim 4, characterized in that: In S7, based on the results of S6, the optimized two-dimensional heterostructures AZ-2 and AZ-3 from S4 are used as substrates to construct hydrogen adsorption models on Al atoms and As atoms on the AlAs side, respectively. The adsorption distance for the two adsorption modes is set to 1.23 Å.

6. The method for designing an electrocatalytic hydrogen reduction reaction based on an AlAs / ZrS2 van der Waals heterojunction according to claim 5, characterized in that: In S8, based on the hydrogen adsorption model constructed in S7, the CASTEP module is used for structural optimization to calculate the total energy after adsorption; among them, after optimization of the two adsorption methods, the adsorption distances of AZ-2 are 1.61 Å and 1.52 Å, respectively, and the adsorption distances of AZ-3 are 1.61 Å and 1.53 Å, respectively.

7. The method for designing an electrocatalytic hydrogen reduction reaction based on an AlAs / ZrS2 van der Waals heterojunction according to claim 1, characterized in that: In S10, based on the total energy after adsorption obtained in S8 and the zero-point energy and entropy value obtained in S9, the Gibbs free energy formula is used to obtain the hydrogen adsorption Gibbs free energy at different types of sites. The Gibbs free energy expression is as follows: ΔG=ΔE H +ΔE ZPE -TΔS In the formula, ΔE H The adsorption energy represents the H atom; ΔE ZPE This represents the zero-point energy between the adsorbed H and the gas phase H; T represents temperature, with a value of 298 K; ΔS represents the entropy difference between adsorbed H and gaseous H; calculations show that AZ-2 yields the best result.

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