Construction of CuO nanoparticles decorated In2O3 hierarchical structure for ultrasensitive and rapid trace detection formaldehyde at low temperature

The reasonable build of a highly efficient formaldehyde (HCHO) gas sensor with excellent performance and low concentration detection ability is an urgent requirement for environmental surveillance and human health protection. Herein, a HCHO sensing structure composed of nanoflower In2O3/CuO self-assembly was fabricated using a facile solvothermal route and characterized accordingly. The gas-sensing test data exhibited that the 3 wt% In2O3/CuO sensor presented remarkable HCHO detection performance with a large response value (Ra/Rg = 231.2, 100 ppm), which is around 4 times larger than that bare In2O3 sensor. The optimum operating temperature decreases from 260℃ to 140℃. Meanwhile, the 3 wt% In2O3/CuO sensor displayed shorter response and recovery times (9 and 17 s), outstanding selectivity, better moisture resistance, recyclability and strong stability. It is commendable that the sensor has achieved ppb level detection for HCHO. The brilliant sensing properties were ascribed to the formation of more active sites with the 3 wt% In2O3/CuO flower-like hierarchical structure. Besides, the gas-sensing improvement mechanism of the composite was explored in detail through the analysis of band structure, adsorption energy and total density of states. Thus, 3 wt% In2O3/CuO sensor open up a new perspective for detecting trace amounts of HCHO gas.