Enhanced Nitric Oxide Detection Performance of Layer-like Ni-Doped WO3-Based Photoinduced Gas Sensor at Room Temperature

Nitric oxide (NO) detection at low concentrations was of significant practical importance for the screening and monitoring of certain respiratory diseases, driving the demand for gas sensors with enhanced performance and reduced power consumption. This study presented a photoinduced NO gas sensor based on layer-like Ni-doped WO3 nanomaterials operating at room temperature (RT). The synergistic effect of Ni doping and photoactivation enabled remarkable gas sensitivity across a low concentration range (10~100 ppb), achieving rapid response/recovery times (28 s/50 s) at 50 ppb under RT. The limit of detection (LOD) for NO molecule could reach below 8.29 ppb. A good linear correlation between the response value and NO concentration was demonstrated under a wide relative humidity range (20~90%). Ni doping induced oxygen vacancies while simultaneously facilitating photoinduced electron transfer for surface oxygen activation. The optimized sensor maintained good response stability after three months of ambient storage, demonstrating excellent operational durability. In situ experimental results further elucidated that the doped Ni site enhanced electron transfer from the surface to adsorbed oxygen molecules, generating superoxide radicals. This work provided fundamental insights into surface engineering strategies for developing optically modulated gas sensors and proposed a viable pathway for constructing energy-efficient exhalation monitoring systems.