Development of SnO2 functionalized In2O3 porous microrods for trace level detection of formaldehyde at room temperature

Room temperature detection is a crucial objective in semiconductor sensor research, given its inherent benefits including reduced energy consumption, extended sensor lifespan, and significant reduction of safety hazards. Herein, novel room temperature sensing materials, SnO2-modified In2O3 porous microrods were synthesized, which exhibited exceptional sensing capability towards formaldehyde at room temperature. Specifically, the 5%-SnO2/In2O3 porous microrods demonstrate an impressive sensing response across varying formaldehyde concentrations, even at sub-ppm levels (0.1 ppm, 5.22), with a theoretical detection limit of 5.47 ppb, thereby enabling the detection of trace amounts of formaldehyde. Moreover, the sensors exhibit superior formaldehyde selectivity, rapid response characteristic, as well as good stability and reproducibility. The exceptional formaldehyde sensing ability of the SnO2/In2O3 sensor primarily arises from the creation of n-n heterojunctions at the SnO2/In2O3 interface, effectively modulating the interfacial potential. Additionally, the presence of SnO2 enhances the amount of surface-adsorbed oxygen species and active sites, thereby boosting sensing response. The porous rod-like structures further facilitate gas adsorption and diffusion, enhancing gas sensing capabilities. This work presents a novel strategy for constructing SnO2-In2O3 heterojunctions to achieve room-temperature formaldehyde detection.