Tungsten oxide clusters decorated ultrathin In2O3 nanosheets for selective detecting formaldehyde

Abstract To guarantee the human health, it is important to monitor the amount of formaldehyde in air. However, it is difficult to detect formaldehyde at low concentration level. Here, WO x clusters decorated In 2 O 3 nanosheets were synthesized for the first time via a simple and convenient impregnating method. The sensors based on the above WO x /In 2 O 3 composites show excellent sensing performance to trace formaldehyde gas at a relative low operating temperature (170 °C). The gas sensor based on 4 wt% WO x /In 2 O 3 exhibits the lowest detection limit ( i.e. 0.1 ppm), short response time (1 s) and acceptable recovery time (67 s). Furthermore, the response value of 4 wt% WO x /In 2 O 3 composite sensor is about twice as high as that of the sensor based on pure In 2 O 3 . It is believed that the enhanced sensing performance can be predominantly attributed to the additional active sites induced by the formation of WO x -In 2 O 3 heterojunction between WO x nano-clusters and In 2 O 3 nanosheets.