Tungsten Oxide Photocatalyst Alkali Resistance via Zinc Composite
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Solution Overview
Problem
Tungsten oxide photocatalysts are unstable under alkaline conditions, limiting their application in environments like kitchens and bathrooms where they are exposed to detergents and bleaching agents, and existing solutions compromise photocatalytic activity by coating the surface, reducing reactivity.
Innovation Solution
Improving the environmental resistance of tungsten oxide by impregnating it with a metal coating solution of lanthanum, bismuth, or calcium, followed by burning, which enhances stability under alkaline conditions without sacrificing photocatalytic function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If tungsten oxide is used as a visible light-responsive photocatalyst, then photocatalytic activity under visible light is improved, but environmental stability under alkaline conditions deteriorates
Solution Approach 1:
The patent creates a composite material by combining tungsten oxide with zinc oxide through co-precipitation. The zinc oxide component provides alkaline resistance while tungsten oxide maintains visible light photocatalytic activity. This composite structure resolves the contradiction by integrating two materials with complementary properties - ZnO for chemical stability and WO3 for optical-catalytic function.
Solution Approach 2:
The patent modifies the chemical composition parameters of the photocatalyst by controlling the molar ratio of zinc to tungsten during co-precipitation. By optimizing this compositional parameter, the material achieves both adequate alkaline resistance and maintained photocatalytic activity, resolving the stability-activity trade-off through precise parameter control.
2Reliability
If a protective coating is applied to improve alkali resistance, then environmental stability is improved, but photocatalytic activity deteriorates
Solution Approach 1:
Instead of applying a separate protective coating that would block photocatalytic sites, the patent merges the protective function directly into the photocatalyst material itself by forming a ZnO-WO3 composite. The zinc oxide becomes an integral part of the photocatalytic system, providing protection while allowing charge transfer, thus eliminating the trade-off between protection and activity.
Solution Approach 2:
The zinc oxide acts as an intermediary component that mediates between the harsh alkaline environment and the tungsten oxide photocatalyst. It provides a protective interface that resists alkaline degradation while facilitating charge separation and transfer, enabling both protection and photocatalytic function to coexist.
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 method provides a tungsten oxide photocatalyst that is stable under both acidic and alkaline conditions, maintaining photocatalytic activity and enabling effective self-cleaning in indoor environments, such as sinks and bathrooms, where traditional photocatalysts fail.
Implementation Method 1
visible light-responsive semiconductor compounds such as tungsten oxide have a smaller bandgap than that of titanium oxide and can absorb visible light
Implementation Method 2
tungsten oxide visible light-responsive photocatalyst
Implementation Method 3
impregnating a tungsten oxide powder with a metal coating solution of at least one element to form a powder sample
Implementation Method 4
burning the powder sample or the coated film to form a tungsten oxide photocatalyst
Data Source
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AI summary
To provide a novel visible light-responsive photocatalyst or tungsten oxide visible light-responsive semiconductor improved in environmental resistance under an alkaline condition. The tungsten oxide visible light-responsive semiconductor unstable under an alkaline condition is improved in environmental resistance without losing photocatalytic function thereof by adding thereto at least one element selected from the group consisting of copper, tantalum, niobium, lanthanum, bismuth, calcium, chromium, manganese and zinc. The obtained environmental resistant visible light-responsive photocatalyst is subjected to an alkaline treatment to thereby be improved in photocatalytic activity.