Multiphase Heterojunction Nanomaterials for HER
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Solution Overview
Problem
Current heterojunction nanomaterials, particularly those based on transition-metal dichalcogenides like MoSe2, face limitations in stability and catalytic activity due to single-phase constraints, and there is a need for optimizing structures with more than two phases to enhance hydrogen evolution reaction (HER) performance.
Innovation Solution
A method for preparing multiphase heterojunction nanomaterials, specifically tetraphase 1T/2H—MoSe2—H/R—NiSe and triphase 1T/2H—MoSe2—H—NiSe, using a NiMoO4 precursor and selenium in a hydrothermal process, which allows for the formation of nanorods and nanosheets with large double-layer capacitance and low charge transfer resistance, facilitating improved electrocatalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single-phase MoSe2 is used as electrocatalyst, then the structure is simple and cost is low, but the catalytic activity and stability are limited
Solution Approach 1:
The patent constructs multiphase heterojunction nanomaterials combining MoSe2 with NiSe and other components to create composite electrocatalysts. This composite structure synergistically improves catalytic activity and stability while maintaining cost-effectiveness, directly resolving the contradiction between simple structure and high performance.
Solution Approach 2:
The patent creates distinct phases (1T and 2H MoSe2, NiSe, etc.) with different local properties within the heterojunction structure. Each phase contributes specific functionalities (e.g., 1T phase for high activity, 2H phase for stability), allowing the material to overcome the limitations of single-phase structures through localized functional differentiation.
2Reliability
If 1T-MoSe2 phase is used, then the catalytic activity is high, but the thermodynamic stability is poor and it easily converts to 2H phase
Solution Approach 1:
The patent merges the 1T and 2H phases of MoSe2 within a single heterojunction nanomaterial, along with NiSe components. This merging creates a synergistic structure where the high-activity 1T phase is stabilized by the presence of the stable 2H phase and NiSe, preventing unwanted phase transitions while maintaining high catalytic activity.
Solution Approach 2:
By creating a multiphase composite containing both 1T-MoSe2 and 2H-MoSe2 along with NiSe, the patent achieves a balance between activity and stability. The composite structure provides thermodynamic stabilization to the metastable 1T phase while preserving its high catalytic properties.
3Reliability
If more phases are added to heterojunction nanomaterials, then the catalytic performance may improve, but the manufacturing complexity and difficulty increase
Solution Approach 1:
The patent employs a pre-designed precursor structure (NiMoO4 nanorod arrays) that serves as a template for the subsequent formation of the multiphase heterojunction. This preliminary action simplifies the synthesis process by providing a structured framework that guides the formation of multiple phases in a controlled manner, reducing the complexity that would otherwise arise from attempting to assemble multiple phases separately.
Solution Approach 2:
The patent utilizes controlled parameter changes during the hydrothermal process (temperature, time, pH, precursor ratios) to selectively form different phases within the heterojunction. By carefully adjusting these parameters, the patent achieves complex multiphase structures through relatively simple one-step synthesis, making the manufacturing process more feasible despite the complexity of the final material.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting multiphase heterojunction nanomaterials exhibit enhanced activity and stability for hydrogen production, with reduced overpotential and Tafel slope, demonstrating improved performance as non-noble metal-based catalysts for HER in alkaline conditions.
Implementation Method 1
dissolving a selenium powder in hydrazine hydrate, adding water or sodium molybdate aqueous solution, then adding the substrate loaded with a NiMoO4 precursor, and reacting at 180-200° C.
Implementation Method 2
the electronic injection from NiSe to MoSe2 induced the phase transition from 2H—MoSe2 to 1T-MoSe2
Implementation Method 3
the electronic injection from NiSe to MoSe2 induced the phase transition from 2H—MoSe2 to 1T-MoSe2
Implementation Method 4
low charge transfer resistance, thus greatly improving the activity and stability of electrocatalytic hydrogen production
Implementation Method 5
the resulting heterojunctions can compensate for the shortcomings each another, and cause synergistic effects into a single entity, thereby optimizing the inherent active species, active site and conductivity of electrocatalysts, and promoting the HER performance that occurs on the surface or interfaces of catalysts
Data Source
AI summary
The present invention relates to the technical field of nano-materials, and specifically provides a method for preparing multiphase heterojunction nanomaterials. The method comprises the following steps: providing a substrate loaded with a NiMoO4 precursor; dissolving a selenium powder in hydrazine hydrate, adding water or sodium molybdate aqueous solution, then adding the substrate loaded with a NiMoO4 precursor, and reacting at 180-200° C.; and after the reaction, obtaining the multiphase heterojunction nanomaterials. The present invention also provides a tetraphase heterojunction nanomaterial 1T/2H-MoSe2—H/R—NiSe, and a triphase heterojunction nanomaterial 1T/2H-MoSe2—H—NiSe prepared by the method, and use thereof as an electrocatalyst to catalyze a hydrogen evolution reaction under an alkaline condition. The multiphase heterojunction nanomaterials prepared in the present invention possess large double-layer capacitance, large electrochemical active specific area and low charge transfer resistance, thus greatly improving the activity and stability of electrocatalytic hydrogen production.