Band-Engineering W18O49 with Cu Single Atoms Enables Efficient Photo-Induction of Oxygen Radicals for Highly Sensitive Room-Temperature NO2 Detection.

Abstract

Metal oxide semiconductor gas sensors suffer from insufficient sensitivity and slow response/recovery due to inefficient charge separation and sluggish surface reaction kinetics at room temperature. Herein, we demonstrated that single-atom Cu doping enabled precise band structure engineering of W18O49, thereby enabling photoassisted room-temperature NO2 detection with high sensitivity and selectivity. Single-atom Cu induced abundant oxygen vacancies and regulated the electronic configuration, facilitating oxygen radical generation and interfacial charge transfer. Consequently, the Cu1-W18O49 sensor exhibited a high response (RNO2/Rair = 572.3) toward 10 ppm of NO2 and excellent selectivity under light. In situ Fourier transform infrared spectroscopy confirmed the formation of multiple nitrogen oxide species on the Cu1-W18O49 surface and revealed that the Cu doping induces a transformation of the NO3 adsorption configuration from a weak monodentate to a bidentate binding mode, highlighting the enhanced surface reactivity by Cu doping. This work provides fundamental insights into the rational design of high-performance photoactivated gas sensors.

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