Nitrogen-Doped TiO2 Nanostructures Visible Light Photocatalysis
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Solution Overview
Problem
Existing TiO2 nanostructures require UV activation for photocatalytic activity, limiting their application, and industrial production faces challenges with agglomeration and surface uncontrollability, while the hot injection method struggles with producing homogeneous and monodispersed nanoparticles due to temperature fluctuations.
Innovation Solution
Nitrogen-doped TiO2 nanostructures are produced using the hot injection method with controlled synthesis of Titanium complexes and long chain carboxylic acids and amines, allowing photocatalytic activity in the visible region and achieving high quantum efficiency, with the ability to form both spherical and acicular structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If standard TiO2 nanostructures are used, then UV photocatalytic activity is achieved, but visible light activation is not possible
Solution Approach 1:
The patent applies parameter changes by doping TiO2 with nitrogen, which modifies the electronic structure and band gap of the material. This chemical composition change enables visible light absorption while maintaining photocatalytic activity, directly resolving the contradiction between UV-only activation and visible light responsiveness
Solution Approach 2:
The patent creates a composite material system by incorporating nitrogen-doped TiO2 with specific crystal structures (anatase and rutile phases). This composite approach combines the advantages of different TiO2 polymorphs with nitrogen doping to achieve both visible light activation and sustained photocatalytic reliability
2Manufacturing precision
If bottom up method is used for TiO2 production, then molecular control is achieved, but agglomeration and surface uncontrollability occur
Solution Approach 1:
The patent applies local quality by using specific ligands (carboxylic acids and amines) that selectively bind to TiO2 nanoparticle surfaces. This localized surface modification prevents agglomeration and provides colloidal stability while maintaining the molecular precision of the bottom-up synthesis approach
Solution Approach 2:
The patent uses long-chain carboxylic acids and amines as intermediary molecules that mediate between the TiO2 nuclei and the surrounding medium. These intermediaries control particle growth, prevent uncontrolled aggregation, and enable precise size and shape control during the bottom-up synthesis process
3Manufacturing precision
If hot injection method is used, then quantum particle production is achieved, but temperature fluctuations cause synthesis difficulties
Solution Approach 1:
The patent applies periodic action by using controlled injection cycles where precursors are introduced in periodic pulses rather than continuously. This periodic injection method allows temperature stabilization between injections while maintaining precise quantum particle production, resolving the conflict between hot injection benefits and temperature control challenges
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 nitrogen-doped TiO2 nanostructures exhibit 75% higher photocatalytic activity in the visible region compared to standard TiO2, with controlled particle formation and crystal structure transformation, overcoming the limitations of UV-dependent activation and industrial production challenges.
Implementation Method 1
the electron-hole pair, which is formed by the effect of UV light, which is almost 3% in daylight, the electron transferred from the valence band to the conduction band in accordance with the band gap energy
Implementation Method 2
Obtained nitrogen-doped TiO2 nanostructures show a much more efficient photocatalytic activity and quantum efficiency than standard TiO2 (anatase) structures when quantum efficiencies are compared
Data Source
AI summary
The embodiments relate to visible range active, doped TiO2 nanostructures with the hot injection method in a protected atmosphere showing the enhanced photocatalytic properties in the visible region. It is the production method of TiO2 nanostructures, where obtained nanostructures can be yellow-orange in color, doped with the nitrogen as spectroscopic techniques evidenced. This is the first time observation and detection that hot injection method can be used for the geometry controlled (spherical, elongated or acicular) TiO2 nanostructures starting from a well designed titanium precursors complexed with long chain amine or carboxylic acids.