Photodoping-Inspired Room-Temperature Gas Sensing by Anatase TiO₂ Quantum Dots

Detection of volatile organic compounds (VOCs) at room temperature in an ambient environment is highly desired, but still a distant function for gas sensor materials. Here, we are demonstrating a photodoping-inspired gas sensing approach based on a thin solid film made of ultrasmall (<5 nm) TiO2 nanoparticles. The gas sensing material has been activated by UV light-generating electrons and holes. In the presence of VOCs acting as scavengers of photogenerated holes, the electrical resistance of the sensor element significantly decreases because of electron accumulation. The material shows a 1 order of magnitude higher response toward ethanol under UV light than in the absence of light. The proposed concept enables a selective sensor material design.