Zno nanorods provided with orthogonal oxidized copper nanoplates and corresponding gas sensor
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Solution Overview
Problem
Existing ZnO/CuO composite materials exhibit limited gas sensitivity and selectivity, particularly at room temperature or controlled temperatures below 200°C.
Innovation Solution
A metal oxide heterostructure comprising ZnO nanorods with transversally attached oxidized copper nanoplates, where the nanoplates are perpendicular or inclined up to 45° relative to the ZnO nanorods, with a density of 10-100 per µm of ZnO nanorod length, and a method of synthesis involving pH adjustment and annealing to convert Cu2(OH)3Cl nanoplates to CuO nanoplates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CuO particles are grown on ZnO nanorods, then gas sensitivity to H2S is improved, but gas sensitivity at room temperature and below 200°C remains limited
Solution Approach 1:
The patent applies local quality by creating specific orientations of CuO nanoplates relative to ZnO nanorods. The nanoplates are positioned with their normals parallel or inclined up to 45° relative to the nanorod longitudinal axis, creating localized active sites with enhanced gas sensitivity that function at lower temperatures
Solution Approach 2:
The patent uses composite materials by combining ZnO nanorods with CuO nanoplates in a heterostructure. This composite structure leverages the complementary properties of both materials to achieve enhanced gas sensitivity and expanded operating temperature range, particularly improving performance at room temperature and below 200°C
2Shape
If CuO nanoparticles are attached to ZnO matrix, then hierarchical structure is formed, but gas sensitivity and selectivity remain limited
Solution Approach 1:
The patent enhances the hierarchical structure by imposing specific orientational order on CuO nanoplates relative to ZnO nanorods. The nanoplates are positioned with their normals parallel or inclined up to 45° relative to the nanorod axis, creating locally optimized active sites that significantly improve gas sensitivity and selectivity beyond what random hierarchical structures achieve
Solution Approach 2:
The patent introduces asymmetry by creating a preferred orientation relationship between the CuO nanoplates and ZnO nanorods. The specific angular relationship (normals parallel or inclined ≤45°) creates asymmetric active sites that enhance gas interaction, improving sensitivity and selectivity compared to isotropic hierarchical structures
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
Enhances chemiresistive gas sensitivity and selectivity by increasing the contact surface area with gases, demonstrating improved response to various gases including O2, H2, CO, and NO2 at elevated temperatures.
Implementation Method 1
a method of synthesis involving pH adjustment and annealing to convert Cu2(OH)3Cl nanoplates to CuO nanoplates
Implementation Method 2
demonstrating improved response to various gases including O2, H2, CO, and NO2 at elevated temperatures
Data Source
Figure 1~2c
Figure 3~4
Figure 5
AI summary
The invention is directed to a metal oxide material comprising ZnO nanorods (2) and oxidized copper nanoplates (4; 6) extending transversally to the ZnO nanorod (2); a method for synthetizing the metal oxide material; and a gas sensor comprising a substrate; at least two electrodes deposited on the substrate; a gas sensing layer comprising ZnO nanorods deposited on the at least two electrodes and on the substrate between said at least two electrodes, said gas sensing layer showing an electrical resistivity that varies when contacted by the gas; wherein the ZnO nanorods are provided with transversal nanoplates of CuO so as to confer sensitivity of the gas sensing layer to the gas being at least one of O2, H2, CO, ethanol and NO2.