G-C3N4/In2O3 composite for effective formaldehyde detection

This paper reports a new type of high-performance formaldehyde gas sensor using g-C3N4 nanosheets to modify the surface of In2O3 nanospheres as the sensing material. SEM and TEM results showed that g-C3N4 nanosheets were uniformly distributed on the surface of In2O3. The samples were characterized by XPS, and it was found that both oxygen defects (Ov) and chemically adsorbed oxygen (Oc) in the composite material were increased. The sensor performance under different loadings of g-C3N4 was systematically studied. Especially for 12 wt% loading the response of the sensor material with to 100 ppm formaldehyde reached 1405, which was 2 times bigger than that of pure In2O3. Importantly, it also had a low operating temperature of 119〬C and a short response time of 1 s. The enhancement of sensing performance could be attributed to the realization of rapid electron transfer and the exposure of high-density active center by constructing a unique n-n heterostructure. This research provides an effective method for preparing a formaldehyde sensor with fast response, high sensitivity and low power consumption.