A high sensitive and low detection limit of formaldehyde gas sensor based on hierarchical flower-like CuO nanostructure fabricated by sol–gel method

The hierarchical flower-like CuO nanostructure was synthesized by a facile sol–gel method without template. Indirectly-heated sensors are fabricated by coating the sol–gel on ceramic tubes with signal electrodes and subsequent annealing. The obtained nanostructures are analyzed by X-ray diffraction and scanning electron microscopy. Their gas sensing performances were investigated. The results indicated that the sensor based on hierarchical flower-like CuO exhibited excellent sensing properties towards ethanol, formaldehyde, acetone and dimethylbenzene. The sensor based on the CuO exhibited the optimal gas sensing performance, giving a ppb-level detection limit and a high response (R_g/R_a) of 1.378 to 50 ppb formaldehyde at 250 °C. The response and recovery time of the flower-like CuO nanostructure sensor are 11.9 and 8.4 s, respectively. The significantly enhanced sensing properties to formaldehyde could be attributed to the changes in crystallite size and specific surface area. The results indicate that the hierarchical flower-like CuO nanostructure gas sensor can be a simple and useful platform for formaldehyde and other volatile organic compounds sensing application.