CoCr2O4 Hollow Gas Sensor for Xylene Selectivity
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Solution Overview
Problem
Existing oxide semiconductor gas sensors face challenges in selectively detecting volatile organic compounds like xylene due to their non-selective sensitivity to similar gases such as benzene and toluene, which are difficult to differentiate, especially when they have similar molecular structures, and require additional costly processes for catalyst optimization.
Innovation Solution
A gas sensor is developed using a CoCr2O4 hollow structure with a specific molar ratio of cobalt and chromium elements, optionally including noble metal catalysts like Pt, Pd, or Au, which is synthesized through a spray pyrolysis method and coated on an insulator substrate to enhance selectivity and sensitivity to xylene while reducing sensitivity to other indoor gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional oxide semiconductor gas sensors are used, then they can detect volatile organic compounds, but they exhibit similar sensitivity to multiple gases (benzene, toluene, xylene) and cannot selectively distinguish between them
Solution Approach 1:
The patent changes the chemical composition parameters of the gas sensitive material by using a spinel structure oxide with specific cation distribution (Co2+ and Cr3+ ions in tetrahedral and octahedral sites) and controlled oxygen content. This parameter optimization enables selective detection of xylene while reducing cross-sensitivity to benzene and toluene, resolving the contradiction between selectivity and multi-gas sensitivity.
Solution Approach 2:
The patent employs a composite gas sensitive material combining spinel structure oxide (e.g., CoCr2O4) with controlled oxygen deficiency and specific cation distribution. This composite structure with tailored electronic and surface properties enables selective interaction with xylene molecules, achieving high selectivity while maintaining appropriate sensitivity to other volatile organic compounds.
2Measurement precision
If catalysts (heterooxide, noble metal) are added to improve selectivity, then gas detection selectivity improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for additional catalyst layers or heterooxide additives by incorporating selectivity-enhancing features directly into the base gas sensitive material through spinel structure engineering. This removes the complexity of multi-layer fabrication and catalyst optimization while achieving the desired selectivity.
Solution Approach 2:
The patent merges the functions of gas sensitivity and selectivity into a single spinel structure oxide material by controlling cation distribution and oxygen content. This integration eliminates the need for separate catalyst components and simplifies the manufacturing process while maintaining high selectivity for xylene detection.
3Measurement precision
If additional gas filters are attached to increase selectivity, then detection selectivity improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and removes the need for additional gas filter components by achieving selectivity through the intrinsic properties of the spinel structure gas sensitive material. This eliminates the complexity of multi-component sensor structures and simplifies manufacturing while maintaining high xylene detection selectivity.
4Measurement precision
If noble metal catalysts are added to enhance selectivity, then gas detection selectivity improves, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive noble metal catalysts with a cost-effective spinel structure oxide material that achieves comparable or superior selectivity through its unique cation distribution and oxygen-deficient structure. This substitution significantly reduces manufacturing cost while maintaining high xylene detection selectivity.
Solution Approach 2:
The patent extracts and eliminates the need for expensive noble metal catalysts by achieving selectivity through the engineered spinel structure oxide. This removal of costly materials directly reduces manufacturing expenses while preserving the desired gas detection selectivity.
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 gas sensor achieves high selectivity and sensitivity to xylene, significantly improving detection capabilities while maintaining low sensitivity to hindered gases like benzene and formaldehyde, allowing for precise monitoring of xylene concentrations even at trace levels, with stable performance over 30 days.
Implementation Method 1
A gas sensor is developed using a CoCr2O4 hollow structure with a specific molar ratio of cobalt and chromium elements, optionally including noble metal catalysts like Pt, Pd, or Au, which is synthesized through a spray pyrolysis method
Implementation Method 2
The gas sensor achieves high selectivity and sensitivity to xylene, significantly improving detection capabilities while maintaining low sensitivity to hindered gases like benzene and formaldehyde
Data Source
AI summary
A method of manufacturing a gas sensor for detecting xylene is provided. A method of manufacturing a gas sensor includes reacting a mixed material including a first material containing a cobalt (Co) element and a second material containing a chromium (Cr) element to form a CoCr2O4 hollow structure having a hollow shape.