Porous Core-Shell Monolithic Catalyst for Hydrogen Evolution Kinetics
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Solution Overview
Problem
Existing electrocatalysts for hydrogen production by electrolyzed water suffer from poor stability, low catalytic activity, and inefficient multi-electron transfer processes, particularly in oxygen evolution reactions, limiting hydrogen production rates and catalyst durability.
Innovation Solution
A preparation method for an integral catalyst with a porous core-shell structure is developed, involving the growth of cobalt oxalate micron wires on a metal cobalt substrate, followed by high-temperature calcination and reduction to form a cobalt-nickel nano structure, enhancing stability and catalytic activity through epitaxial growth and air calcination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a catalyst with simple structure is used, then the manufacturing cost is reduced, but the catalytic activity and stability are insufficient
Solution Approach 1:
The patent employs a core-shell composite structure where a cobalt-based oxalate microstructure forms the core and a nickel-based oxide nanowire network forms the shell. This composite architecture combines the advantages of both materials: the cobalt core provides structural stability and conductivity, while the nickel shell offers high catalytic activity for oxygen evolution reaction. The epitaxial growth of nickel oxide nanowires on the cobalt oxalate microstructure creates a synergistic effect that simultaneously improves catalytic performance and structural stability without requiring precious metals.
Solution Approach 2:
The patent applies local quality by creating a core-shell structure where different regions of the catalyst have different functions. The inner cobalt oxalate core provides structural framework and electrical conductivity, while the outer nickel oxide shell provides the active catalytic sites. This spatial differentiation of material properties allows each component to optimize its specific function, achieving high stability from the core and high activity from the shell, thereby resolving the contradiction between simple structure and high performance.
2Area of stationary object
If the specific surface area of the catalyst is increased, then the catalytic activity is improved, but the structural stability is reduced
Solution Approach 1:
The patent utilizes porous materials by constructing a three-dimensional hierarchical structure consisting of cobalt oxalate micro-wires or micro-plates as the core framework, with nickel oxide nanowires grown epitaxially on the surface. This porous architecture provides extensive specific surface area for catalytic reactions while the interconnected micro-nano structure maintains mechanical integrity. The porous structure allows efficient mass transport of reactants and products, and the hierarchical organization from micro to nano scale ensures both high surface area and structural stability.
Solution Approach 2:
The patent applies segmentation by dividing the catalyst structure into hierarchical levels: micro-scale cobalt oxalate wires or plates form the primary framework, while nano-scale nickel oxide wires form the secondary structure on the surface. This multi-scale segmentation increases the specific surface area at each level, providing numerous active sites for catalysis. Simultaneously, the segmented hierarchical structure maintains structural stability through the robust micro-framework that supports the nanostructures, preventing collapse or aggregation.
3Productivity
If a multi-electron transfer process is used for oxygen evolution reaction, then the hydrogen production efficiency is improved, but the reaction kinetics becomes slow
Solution Approach 1:
The patent applies parameter changes by optimizing the oxidation state and surface properties of the nickel oxide nanowires through controlled synthesis conditions. By adjusting the calcination temperature and atmosphere, the nickel oxide is maintained in an optimal oxidation state that facilitates multi-electron transfer. The epitaxial growth of nickel oxide on cobalt oxalate creates favorable electronic interactions that lower the activation energy for the oxygen evolution reaction, accelerating the multi-electron transfer kinetics while maintaining high hydrogen production efficiency.
Solution Approach 2:
The patent uses the cobalt oxalate microstructure as an intermediary between the electrical conductor and the nickel oxide catalytic sites. The cobalt-based core acts as a mediator that facilitates electron transfer to the nickel oxide shell, where the multi-electron transfer process for oxygen evolution occurs. This intermediary structure enables efficient charge separation and transfer, accelerating the reaction kinetics of the multi-electron process while maintaining high overall hydrogen production efficiency.
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 catalyst exhibits improved structural stability, increased specific surface area, and high catalytic activity, enabling efficient hydrogen evolution and biomass oxidation, with high current density and selectivity for high-purity bio-based platform compounds.
Implementation Method 1
performing high-temperature calcination on the cobalt oxalate precursor in an air atmosphere to obtain a tricobalt tetraoxide precursor with porous structure
Implementation Method 2
placing the tricobalt tetraoxide precursor into a high-temperature hydrogen atmosphere for reduction to obtain a cobalt intermediate with stable porous structure
Implementation Method 3
epitaxially growing a cobalt-nickel nano structure on a surface of the cobalt micron wire or micron rod to obtain an integral catalyst with porous core-shell structure
Data Source
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AI summary
The present disclosure discloses an integral catalyst with porous core-shell structure and a preparation method and an application thereof. With a transition metal as active material, a stable bifunctional catalyst capable of performing hydrogen evolution and biomass oxidation at the same time is prepared by epitaxial growth and air calcination; and, the process efficiencies of internal diffusion, external diffusion, adsorption, reaction and desorption of reactive molecules and product molecules and so on can be increased by the porous structure of the catalyst, realizing increase of the catalyst activity.