Doped TiO2 Photocatalytic Coating for Visible Light Air Purification
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Solution Overview
Problem
Current photocatalytic materials are limited in their ability to effectively clean pollutants from ambient air, particularly under visible light, and require improvement for commercial viability, durability, and cost-effectiveness, with a need for water-soluble and UV-absorbing materials that can be easily applied to various articles.
Innovation Solution
A water-soluble photocatalytic material composed of doped metal oxide substrates, specifically TiO2 in the anatase phase, with particle sizes between 18-35 nanometers, combined with a polymeric adhesive for improved adhesion, allowing for effective photocatalytic activity under visible light and easy application to articles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional photocatalytic materials are used, then they can clean pollutants from ambient air, but they require UV radiation and cannot effectively utilize visible light
Solution Approach 1:
The patent modifies the band gap parameters of TiO2 by doping it with transition metals (Fe, Co, Ni, Cu, Mn, Zn) and non-metals (N, C, S, P). This changes the optical properties of the material, enabling it to absorb visible light while maintaining photocatalytic activity. The doping introduces intermediate energy levels within the band gap, allowing electron excitation by visible light photons.
Solution Approach 2:
The patent creates composite photocatalytic materials by combining TiO2 with doped metal oxides and polymeric adhesives. This composite structure integrates the high photocatalytic activity of TiO2 with the visible light absorption capabilities of the doped components, achieving both UV and visible light utilization for pollutant degradation.
2Reliability
If photocatalytic materials are applied to articles, then they can purify air in enclosed spaces, but the adhesion and durability of the coating is insufficient
Solution Approach 1:
The patent develops a composite coating system consisting of photocatalytic powder particles embedded in a polymeric adhesive matrix. This composite structure ensures strong adhesion to various substrates while maintaining the photocatalytic activity of the powder particles. The polymeric binder provides mechanical durability and coating integrity.
Solution Approach 2:
The patent utilizes porous photocatalytic powder particles with high surface area to volume ratio. This porous structure increases the active sites for photocatalytic reactions while the small particle size allows for better penetration and adhesion within the polymeric matrix, enhancing both activity and durability of the coating.
3Ease of manufacture
If water-soluble photocatalytic materials are developed, then they can be easily applied by conventional processes, but the cost and manufacturing complexity increases
Solution Approach 1:
The patent employs water-based slurry formulation for the photocatalytic coating. The water-soluble polymeric adhesive creates a liquid suspension that can be easily applied to articles using conventional coating methods such as dip coating, spray coating, or brush application. The water-based system simplifies the application process compared to organic solvent-based systems.
Solution Approach 2:
The patent optimizes the particle size of photocatalytic powder to 1-10 micrometers, which provides the right balance between photocatalytic activity and ease of handling in water-based slurries. This size parameter change ensures the particles remain suspended in water without excessive settling while maintaining high surface area for catalysis.
4Productivity
If TiO2 particle size is reduced to enhance photocatalytic activity, then the cleaning rate improves, but the particle stability and handling difficulty worsens
Solution Approach 1:
The patent combines ultra-fine TiO2 particles (1-10 micrometers) with polymeric adhesive binders to create a stable composite coating. The polymeric matrix prevents particle aggregation and provides mechanical stability, while the small particle size within the composite maintains high photocatalytic activity through increased surface area.
Solution Approach 2:
The patent utilizes porous structured TiO2 particles with controlled pore sizes. This porous morphology provides high surface area for photocatalysis while the porous structure allows for better light penetration and reactant diffusion. The porosity also helps in anchoring the particles within the polymeric matrix, improving 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 enables high photocatalytic activity and effective adhesion to various surfaces, enhancing air purification and de-odourization capabilities while being non-toxic, durable, and inexpensive, with applications in enclosed spaces like homes and vehicles.
Implementation Method 1
a doped metal oxide substrate capable of exhibiting photocatalytic behavior on being exposed to visible light
Implementation Method 2
The electron of the valence band of titanium dioxide becomes excited when illuminated by light. The excess energy of this excited electron promotes the electron to the conduction band of titanium dioxide
Implementation Method 3
there is a need of having photocatalytic materials capable of absorbing the ultra violet light from the visible light spectrum, thereby neutralizing the bad effects of ultra violet light
Implementation Method 4
the photocatalytic material includes a polymeric adhesive for improving the adhering property of the doped metal oxide substrate on the article
Implementation Method 5
the free radicals are able to react with organic contaminants to decompose them. Therefore, such a reaction has an ability to clean air
Data Source
AI summary
A water soluble photocatalytic material capable of being adhered to an article by a conventional coating process is described. The photocatalytic material includes a doped metal oxide substrate capable of exhibiting photocatalytic behavior on being exposed to visible light, wherein particle size of doped metal oxide substrate ranges from about 18 nanometer (nm) to about 35 nm. Further, the photocatalytic material includes a polymeric adhesive for improving the adhering property of the doped metal oxide substrate on the article. In addition, a process for producing the water soluble photocatalytic material is described. Further, an air purifying article, such as a sheet, on which the said photocatalytic material is applied to is also described.