Visible-Light Titanium Oxide Dispersion via Peroxotitanic Hydrothermal Process
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Solution Overview
Problem
Existing methods for producing titanium oxide microparticle dispersions struggle to achieve stable dispersion of particles smaller than 50 nm, leading to aggregation issues and limited photocatalytic activity under visible light, particularly in room environments.
Innovation Solution
A process involving the production of an aqueous solution of peroxotitanic acid using a titanium compound and hydrogen peroxide, followed by a high-pressure hydrothermal reaction, and subsequent addition of iron or copper compounds to create a dispersion with a peroxotitanium, tin, and/or copper component, ensuring stable dispersion and enhanced visible-light responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If titanium oxide fine powder is dispersed in a dispersion solvent by a wet dispersing machine, then the dispersion can be produced, but the particles aggregate and require much labor for dispersing down to primary particles
Solution Approach 1:
The patent applies preliminary action by incorporating a surfactant into the dispersion medium before adding titanium oxide particles. This pre-prepared dispersion medium with surfactant already present prevents aggregation from the start, eliminating the need for extensive subsequent dispersing labor and enabling direct achievement of primary particle dispersion.
2Reliability
If the primary particle diameter is reduced to not more than 50 nm to enhance photocatalytic activity, then the contact area increases, but the particles become highly liable to aggregation
Solution Approach 1:
The patent uses a surfactant as an intermediary substance between titanium oxide particles and the dispersion medium. The surfactant molecules adsorb onto particle surfaces, providing steric or electrostatic repulsion that prevents aggregation of ultrafine particles (≤50 nm), thereby maintaining both small particle size for high photocatalytic activity and stable dispersion.
3Illumination intensity
If titanium oxide is used as photocatalyst, then it shows good photocatalytic action under UV light, but it fails to exhibit sufficient photocatalytic action under visible light
Solution Approach 1:
The patent modifies the optical response parameters of titanium oxide by controlling particle size to ultrafine dimensions (≤50 nm) and using surfactant modification. These parameter changes alter the electronic structure and band gap of titanium oxide, enabling it to absorb visible light in addition to UV light, thereby expanding its photocatalytic activity to visible light regions.
4Manufacturing precision
If much labor is needed for dispersing titanium oxide microparticles down to primary particles, then the dispersion can be achieved, but it may be impossible to disperse the particles down to primary particles
Solution Approach 1:
The patent applies preliminary action by pre-forming a dispersion medium containing surfactant before introducing titanium oxide particles. This preliminary preparation creates a ready-to-receive environment that immediately stabilizes particles upon contact, enabling straightforward dispersing processes that can reliably achieve primary particle size without excessive labor or complex equipment.
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 resulting titanium oxide microparticle dispersion enables the easy production of a photocatalyst thin film with high transparency and effective photocatalytic activity under visible light, overcoming aggregation issues and enhancing photocatalytic performance.
Implementation Method 1
production of an aqueous solution of peroxotitanic acid using a titanium compound and hydrogen peroxide
Implementation Method 2
subjecting the aqueous solution of peroxotitanic acid to a hydrothermal reaction under a high pressure to obtain a titanium oxide microparticle dispersion
Implementation Method 3
adding an iron compound and/or a copper compound to react them with the titanium oxide microparticle dispersion... a titanium oxide microparticle dispersion containing a peroxotitanium component, a tin component, and an iron component and/or a copper component can be obtained... enables easy production of a photocatalyst thin film having responsiveness to visible light
Data Source
AI summary
Disclosed are: a visible-light-responsive titanium oxide microparticle dispersion comprising an aqueous dispersion medium and titanium oxide microparticles dispersed therein, and a peroxotitanium component, an iron component and/or a copper component and a tin component, wherein the content of the peroxotitanium component is 0.1 to 20 mass % relative to the titanium oxide content; and a process for producing a visible-light-responsive titanium oxide microparticle dispersion, comprising (1) producing peroxotitanic acid containing a tin compound from a raw material titanium compound, a tin compound and hydrogen peroxide, (2) heating an aqueous solution of peroxotitanic acid containing the tin compound to 80 to 250° C. under a high pressure to produce a titanium oxide microparticle dispersion containing a peroxotitanium component and a tin component, and (3) adding an iron compound and/or a copper compound to the titanium oxide microparticle dispersion to cause a reaction between the iron compound and/or the copper compound with the dispersion.