Light-Induced Room-Temperature Gas Sensing by Donor-Doped Anatase TiO2 Ultrasmall Nanoparticles

Gas sensors that detect volatile organic compounds (VOCs) at room temperature are highly attractive for low-power devices and safety. One of the best alternatives to thermal activation is the UV-A light, which allows gas sensor room-temperature operation. Here, we demonstrate how the doping of TiO2 via transition metals (Nb5+, Ta5+ and Hf4+) can increase the gas sensing performance of UV-activated VOC gas sensors prepared from these particles. Doping increased the gas sensing response by more than an order of magnitude, while the response time decreased by as much as 38%, compared to the undoped TiO2 sample. The effect was attributed to additional electron accumulation facilitated by the introduced dopants.