Copper-Doped TiO2 Nanoparticle Dispersion for Visible Light Photocatalysis
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Solution Overview
Problem
Existing photocatalytic titanium oxide fine particle dispersions face challenges in maintaining long-term dispersion stability and visible-light-responsive activity without the use of organic dispersing agents or surfactants, which can inhibit activity, and they are not durable against heat or UV exposure.
Innovation Solution
A visible-light-responsive photocatalytic fine particle dispersion is created using copper-containing titanium oxide fine particles obtained by heating a peroxotitanic acid aqueous solution under high pressure, incorporating a copper component in solid solution form within titanium oxide particles, along with a peroxotitanium and tin components, to enhance stability and activity under visible light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If copper-containing titanium oxide is used to enhance visible light photocatalytic activity, then photocatalytic activity under visible light is improved, but dispersion stability during long-term storage deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating specific metal elements (copper, zinc, aluminum, or silicon) at controlled concentrations (0.01-5 wt%) within the titanium oxide lattice. This compositional modification enables visible light absorption while the patent addresses stability through controlled storage conditions (indoor cold dark place) and optimal particle size (5-50 nm), which prevent aggregation and maintain dispersion stability over time.
Solution Approach 2:
The patent creates composite titanium oxide materials by integrating multiple elements (Ti with Cu/Zn/Al/Si) to form a multi-component system. This composite structure combines the photocatalytic properties of titanium oxide with the visible light absorption capabilities of the added metals, achieving both improved visible light activity and enhanced structural stability through the synergistic interaction of components.
2Use of energy by moving object
If copper component is incorporated to enhance visible light response, then photocatalytic activity is improved, but durability against heat or UV exposure deteriorates
Solution Approach 1:
The patent optimizes the concentration parameter of copper and other metal elements to 0.01-5 wt%, which is sufficient to provide visible light absorption centers but low enough to prevent excessive structural distortion that would compromise thermal and UV stability. This precise parameter control allows the material to maintain both high visible light responsiveness and durability under harsh conditions.
Solution Approach 2:
The patent introduces metal elements at specific local sites within the titanium oxide lattice rather than uniform distribution, creating localized active centers for visible light absorption. This localized modification preserves the overall robust titanium oxide structure, maintaining durability against heat and UV while providing enhanced visible light response at the modified sites.
3Stability of the object's composition
If organic dispersing agents or surfactants are used to maintain dispersion stability, then dispersion stability is improved, but photocatalytic activity is inhibited
Solution Approach 1:
The patent completely removes organic dispersing agents and surfactants from the system, achieving dispersion stability through alternative means: optimized particle size (5-50 nm) that prevents aggregation, controlled metal element composition that enhances surface stability, and proper storage conditions (indoor cold dark place). This extraction of harmful organic substances eliminates activity inhibition while maintaining stability through physical and compositional optimization.
Solution Approach 2:
The titanium oxide particles themselves provide self-stabilization through their controlled composition and size, without requiring external organic stabilizers. The metal elements incorporated into the lattice and the small particle size create inherent stability in the dispersion, allowing the system to maintain itself without substances that would interfere with photocatalytic function.
4Use of energy by moving object
If particle size is reduced to increase contact area for enhancing photocatalytic activity, then photocatalytic activity is improved, but transparency of the film deteriorates
Solution Approach 1:
The patent optimizes the particle size parameter to a specific range of 5-50 nm, which is small enough to provide large surface area for high photocatalytic activity but small enough to allow light transmission through the film. This precise parameter control resolves the contradiction by finding the optimal size where both activity and transparency requirements are satisfied simultaneously.
Data Source
AI summary
It is possible to obtain a visible light-responsive photocatalytic nanoparticle dispersion liquid containing copper-containing titanium oxide nanoparticles by subjecting an aqueous peroxotitanic acid solution containing a copper compound to hydrothermal reaction for crystallizing the aqueous solution by means of heat under high pressure. The visible light-responsive photocatalytic nanoparticle dispersion liquid thus obtained exhibits excellent dispersion stability of titanium oxide nanoparticles within a water-based dispersion medium even when left in a cold and dark indoor area for a long period of time, expresses photocatalytic activity even in visible light (400 to 800 nm) alone, and can easily create a photocatalytic thin film which is extremely transparent and exhibits excellent durability, and in which the state of copper coordination when exposed to heat or ultraviolet rays is stable and cannot be easily modified.