Nitrogen-Doped Diamond Catalyst Film for Visible-Light Hydrogen Production
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Solution Overview
Problem
Existing semiconductor catalysts based on n-type gallium nitride require ultraviolet-ray irradiation due to a large band gap, limiting the efficient use of solar energy, and are prone to deterioration from elution, decomposition, or corrosion.
Innovation Solution
A semiconductor catalyst using nitrogen-containing diamond particles with a thin film configuration that promotes reduction reactions under visible light irradiation, featuring a donor level close to the conduction band, and a laminate structure with a conductive member for efficient water electrolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If n-type gallium nitride is used as a semiconductor catalyst, then the catalyst can promote reduction reactions, but ultraviolet-ray irradiation is required which limits efficient use of solar energy
Solution Approach 1:
The patent combines n-type gallium nitride semiconductor particles with metal catalyst particles (such as nickel, cobalt, or their oxides) to form a composite semiconductor catalyst. The metal catalyst component absorbs visible light and transfers electrons to the gallium nitride, enabling the catalyst to utilize visible light from sunlight rather than requiring only ultraviolet radiation, thus improving solar energy utilization efficiency.
2Use of energy by moving object
If a metal catalyst layer is added to narrow the band gap and provide visible light responsiveness, then visible light utilization improves, but the catalyst layer is easily deteriorated by elution, decomposition, or corrosion
Solution Approach 1:
The patent merges the metal catalyst particles with the gallium nitride semiconductor particles to form an integrated composite catalyst structure. The metal particles are dispersed on or within the semiconductor particle matrix, creating a stable composite where the semiconductor provides structural stability and the metal provides visible light absorption capability, resolving the durability issue of separate metal catalyst layers.
3Object-generated harmful factors
If solar energy is used for water electrolysis to produce hydrogen, then environmental load is reduced, but the current technology cannot efficiently utilize the available sunlight spectrum
Solution Approach 1:
The patent modifies the optical parameters of the semiconductor catalyst by combining gallium nitride with metal catalysts that have different light absorption characteristics. This changes the overall absorption spectrum of the catalyst system to match better with the visible light portion of sunlight, enabling more efficient conversion of solar energy into hydrogen production while maintaining the environmental benefit of reduced carbon dioxide emissions.
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 achieves durable and efficient hydrogen production from water using solar energy, overcoming environmental limitations and enhancing the stability and efficiency of reduction reactions.
Implementation Method 1
a donor level is formed at a position close to a conduction band in a band gap of diamond. Thus, when irradiated with visible light, the semiconductor catalyst easily shifts to an excited state, releases electrons
Implementation Method 2
When a laminate of the semiconductor catalyst and a conductive member is used as a working electrode and is irradiated with visible light in a state of being in contact with water together with a counter electrode, a reduction reaction of water efficiently proceeds to produce hydrogen
Data Source
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AI summary
A semiconductor catalyst is provided, which exhibits an effect of accelerating a reduction reaction by visible light irradiation and is excellent in durability. The semiconductor catalyst of the present disclosure includes thin film containing nitrogen-containing diamond particles in a plane direction and a height direction. The semiconductor catalyst can be produced by, for example, fixing, on a substrate having a positive or negative charge, nitrogen-containing diamond particles having a positive or negative charge, the positive or negative charge of the nitrogen-containing diamond particles being opposite to that of the substrate, and laminating, on the fixed nitrogen-containing diamond particles, nitrogen-containing diamond particles having a positive or negative charge, the positive or negative charge of the laminated nitrogen-containing diamond particles being opposite to that of the fixed nitrogen-containing diamond particles. The step of laminating is performed at least once after the step of fixing.