Visible Light Titanium Oxide Photocatalyst Mixture
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Solution Overview
Problem
Existing photocatalysts using titanium oxide struggle to exhibit high visible light activity, particularly in indoor settings illuminated with visible-spectrum light, where conventional materials fail to effectively decompose organic pollutants like acetaldehyde at low concentrations.
Innovation Solution
A visible light-responsive photocatalytic titanium oxide fine particle mixture is developed by combining titanium oxide fine particles with tin and a transition metal in solid solution with those containing an iron-group and chromium-group element in solid solution, enhancing photocatalytic activity under visible light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional titanium oxide photocatalysts are used, then the material is stable and widely available, but the visible light activity is insufficient for indoor air purification
Solution Approach 1:
The patent creates a composite photocatalyst system by combining titanium oxide fine particles with iron-group elements (Fe, Co, Ni) and chromium-group elements (Cr, Mo, W) doped into the crystal lattice. This composite structure enables the material to maintain the stability of titanium oxide while gaining visible light responsiveness through the added elements, achieving both reliability and improved productivity in indoor air purification applications
Solution Approach 2:
The patent modifies the chemical composition parameters of titanium oxide by doping it with specific transition metals (iron-group and chromium-group elements) at controlled concentrations (0.01-10 wt% each). This parameter change alters the band gap structure of titanium oxide, enabling it to absorb visible light while maintaining structural stability, thus resolving the contradiction between stability and visible light activity
2Productivity
If metal-doped titanium oxide is used to enhance visible light activity, then photocatalytic performance improves, but material stability and resistance to deterioration decrease
Solution Approach 1:
The patent optimizes the doping concentration parameters of iron-group and chromium-group elements within specific ranges (0.01-10 wt% each) to achieve the right balance between visible light activity and stability. This controlled parameter adjustment ensures sufficient visible light absorption while preventing excessive metal content that would cause deterioration, thus resolving the stability-activity trade-off
Solution Approach 2:
The patent creates a synergistic composite where titanium oxide serves as the stable matrix and iron-group/chromium-group elements provide visible light responsiveness. The titanium oxide lattice structure maintains overall stability while the dopant elements create visible light absorption centers, achieving both durability and enhanced photocatalytic activity under visible light
3Productivity
If tungsten oxide photocatalyst is used for visible light response, then visible light activity is achieved, but the scarcity and cost of tungsten increase device complexity
Solution Approach 1:
The patent substitutes scarce tungsten with more abundant iron-group (Fe, Co, Ni) and chromium-group (Cr, Mo, W) elements that can be obtained more easily and at lower cost. By adjusting the doping concentration parameters of these alternative elements, the patent achieves comparable visible light photocatalytic activity without the material scarcity and cost issues associated with tungsten, thereby reducing device complexity
Solution Approach 2:
The patent employs abundant, low-cost transition metals (iron, cobalt, nickel, chromium, molybdenum) as dopants instead of scarce expensive metals like tungsten. These common elements provide sufficient visible light photocatalytic activity at much lower material costs, making the photocatalyst system more economically viable and easier to manufacture
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 mixture achieves high decomposition activity for acetaldehyde, reducing concentrations to 0.03 ppm or below, meeting indoor air quality guidelines, and maintains transparency, outperforming prior art under visible light exposure.
Implementation Method 1
Photocatalytic reaction refers to a reaction caused by excited electrons and holes generated due to the absorption of light by titanium oxide
Implementation Method 2
the absorption of light by titanium oxide
Implementation Method 3
titanium oxide fine particles containing in solid solution an iron-group element constituent and a chromium-group element constituent
Data Source
AI summary
Provided are the following: a mixture of visible light-responsive photocatalytic titanium oxide fine particles which can conveniently produce a photocatalyst thin film that exhibits photocatalyst activity even with only visible light (400-800 nm) and that exhibits high transparency; a dispersion liquid of the fine particles; a method for producing the dispersion liquid; a photocatalyst thin film; and a member having the photocatalyst thin film on a surface thereof. The mixture of visible light-responsive photocatalytic titanium oxide fine particles is characterized by containing two kinds of titanium dioxide fine particles: first titanium oxide fine particles, in which a tin component and a transition metal component (excluding an iron group element component) that increases visible light response properties form a solid solution, and second titanium oxide fine particles, in which an iron group element component and a chromium group element component form a solid solution.