Heterogeneous Semiconductor Photocatalyst Oxidation Stability
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Solution Overview
Problem
Elemental copper-based photocatalysts suffer from degradation of antibacterial activity and unappealing cosmetic changes due to oxidation, limiting their longevity and applicability in indoor applications such as air purification and self-cleaning surfaces.
Innovation Solution
Development of heterogeneous materials comprising a p-type semiconductor with a mixed valence oxide compound and an n-type semiconductor with a deeper valence band, in ionic charge communication, to enhance photocatalytic activity and durability, maintaining antibacterial and antiviral efficacy over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elemental copper or copper composites are used as photocatalysts, then antibacterial and antiviral activity is achieved, but durability deteriorates due to oxidation causing loss of activity and cosmetic changes
Solution Approach 1:
The patent uses metal oxides (such as CuO, Cu2O, Fe2O3, TiO2, ZnO) as intermediary materials to replace direct elemental copper. These metal oxides serve as stable photocatalysts that maintain antibacterial and antiviral activity without undergoing further oxidation, thus preserving both reliability and longevity throughout the service life of the material
Solution Approach 2:
The patent changes the oxidation state parameter of copper from elemental (Cu0) to oxidized forms (Cu+ in Cu2O, Cu2+ in CuO). This parameter change transforms the material from unstable and prone to further oxidation into a stable form that maintains consistent photocatalytic activity and cosmetic appearance over time
2Reliability
If elemental copper is used to achieve photocatalytic activity, then initial antibacterial efficacy is obtained, but cosmetic appearance deteriorates due to oxidation from copper to black copper oxide
Solution Approach 1:
The patent employs metal oxides as intermediary compounds that provide the necessary photocatalytic function without the cosmetic drawbacks of elemental copper oxidation. These oxides maintain stable color and appearance characteristics while delivering sustained antibacterial and antiviral effects
Solution Approach 2:
The patent utilizes composite materials comprising multiple metal oxides (such as combinations of CuO, Cu2O with TiO2, ZnO, or Fe2O3) to achieve synergistic effects. These composites enhance photocatalytic activity while maintaining stable cosmetic appearance, preventing the unsightly blackening associated with copper oxidation
3Productivity
If visible-light activated photocatalysts are deployed for indoor applications, then air purification and self-cleaning functions are achieved, but material stability deteriorates due to oxidation under normal application conditions
Solution Approach 1:
The patent replaces elemental copper with metal oxide intermediaries that are inherently stable under indoor lighting conditions. These metal oxides (CuO, Cu2O, TiO2, ZnO, Fe2O3) resist further oxidation and degradation, maintaining both photocatalytic productivity and material stability throughout the operational lifetime
Solution Approach 2:
The patent creates an chemically inert environment by using metal oxides that are already in their oxidized state and resistant to further reaction with oxygen. This inert composition prevents degradation under normal indoor air conditions while maintaining active photocatalytic functionality
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 effectively maintains photocatalytic activity and antibacterial efficacy, improving the longevity of photocatalysts and preventing cosmetic changes, making them suitable for indoor applications like air purification and self-cleaning surfaces.
Implementation Method 1
Multivalent heterogeneous materials can be used to enhance the photocatalytic activity of photocatalytic materials
Implementation Method 2
wherein the semiconductors are in ionic charge communication with each other
Implementation Method 3
a method of decomposing a chemical compound comprising exposing the chemical compound to a photocatalyst comprising a homogeneous material described herein in the presence of light
Implementation Method 4
A method of killing a microbe, comprising exposing the microbe to a photocatalyst comprising the homogeneous material of any of embodiments 1-29 in the presence of light
Data Source
AI summary
Described herein are heterogeneous materials comprising a p-type semiconductor comprising two metal oxide compounds of the same metal in two different oxidation states and an n-type semiconductor having a deeper valence band than the p-type semiconductor valence bands, wherein the semiconductor types are in ionic communication with each other. The heterogeneous materials enhance photocatalytic activity.