Tungsten Oxide Photocatalyst with Titanium Oxide Shell for Alkaline Resistance
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Solution Overview
Problem
Tungsten oxide-based photocatalyst materials face issues with alkaline resistance and poisoning effects, leading to degradation and reduced photocatalytic activity, especially when exposed to basic environments or gases like ammonia.
Innovation Solution
A photocatalyst material comprising core particles of tungsten oxide with a promoter layer and a complete shell layer of titanium oxide, which enhances alkaline resistance and prevents poisoning by covering the entire surface, including the promoter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If tungsten oxide is used as the photocatalyst material to enable visible light absorption, then the photocatalyst can respond to visible light, but the material dissolves easily in alkaline solutions leading to degradation and loss of photocatalytic activity
Solution Approach 1:
The invention creates a composite structure where tungsten oxide core particles are coated with a shell layer comprising titanium oxide and promoter particles. This composite structure allows the tungsten oxide core to provide visible light absorption while the titanium oxide shell provides alkaline resistance, resolving the contradiction between visible light responsiveness and alkaline stability
Solution Approach 2:
A shell layer is formed around the tungsten oxide core particles, creating a protective barrier that prevents direct contact between the alkaline environment and the tungsten oxide surface. This shell structure maintains the photocatalytic functionality while protecting against alkaline dissolution
2Productivity
If promoter particles are added to enhance photocatalytic activity by suppressing electron-hole recombination, then the photocatalytic activity increases, but the promoter particles are susceptible to poisoning effects from adsorbed substances
Solution Approach 1:
The shell layer structure creates different functional zones: the inner tungsten oxide core provides visible light absorption, the promoter particles dispersed in the shell enhance photocatalytic activity at specific sites, while the titanium oxide matrix provides protection. This local differentiation allows promoters to function effectively while being protected from poisoning
Solution Approach 2:
The titanium oxide shell acts as an intermediary that protects the promoter particles from direct contact with poisoning substances in the environment, while still allowing the promoters to perform their electron-hole separation function. The shell mediates between the promoters and the external environment
3Reliability
If titanium oxide coating is applied to protect tungsten oxide from alkaline dissolution, then alkaline resistance improves, but the coating may not fully cover the surface leading to eroded portions
Solution Approach 1:
The invention extracts the protective function from a simple coating and implements it through a composite shell structure with titanium oxide and promoter particles. This structure provides more uniform and complete coverage compared to simple coating, ensuring full protection against alkaline dissolution while maintaining compositional stability
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 solution provides a tungsten oxide-based photocatalyst with improved alkaline resistance and sustained photocatalytic activity, effectively decomposing pollutants under visible light while preventing poisoning effects.
Implementation Method 1
Tungsten oxide has a smaller band gap than titanium oxide and can absorb visible light
Implementation Method 2
photocatalyst materials that adsorb and decompose environmental pollutants under solar light or indoor light
Implementation Method 3
the recombination of electrons excited in the conduction band under irradiation with light and holes generated in the valence band is suppressed
Implementation Method 4
a shell layer made of titanium oxide and covering the entire surface of both the core particles and the promoter
Implementation Method 5
reactive oxygen species are generated by the oxidation reaction of water by holes generated in the valence band and these reactive oxygen species oxidize and decompose organic materials
Data Source
AI summary
To provide a photocatalyst material having alkaline resistance and showing less deterioration in photocatalyst performance due to a poisoning effect and to provide a method for producing the photocatalyst material, a photocatalyst material (1A) according to one embodiment of the present invention includes: core particles (2) containing tungsten oxide; a promoter (4) formed on the surface of the core particles (2); and a shell layer (3) made of titanium oxide and covering the entire surface of both the core particles (2) and the promoter (4).