Localized surface plasmon resonance effect dominates room temperature formaldehyde gas sensor with ultra-high sensitivity and selectivity

Universal sensitivity and high operating temperature have always been the serious problems faced by semiconductor based gas sensors in practical applications. The use of photoelectric and Localized Surface Plasmon Resonance (LSPR) effects can replace heating to provide energy to electrons. However, the differences between electrons generated by photoelectirc effect and LSPR effect, as well as the impact of these differences on gas sensing performance are still unclear. In this work, gold and silver modified In₂O₃ nanocubes are designed and employed as a gas sensor to study the above issues. The gas sensing characteristics under different wavelengths of light are researched. A room temperature natural light assisted gas sensor with high sensitivity and selectivity has been obtained. The key factors affecting selectivity are discussed in details and it is innovatively discovered that selectivity is closely related to the conduction band edge energy levels of sensitive materials. In addition, it is revealed that the reason why the LSPR effect improves gas sensing performance is that the increased electrons in the conduction band come from metal particles, thereby reducing the electron hole recombination rate. Density functional theory (DFT) is employed to provide theoretical support for the proposal. This work opened up a new strategy for the development of room temperature high performance gas sensors.