Accelerated hydrogen gas sensing of ZnO nanosphere at room temperature by photoactivation

High performance Hydrogen (H₂) sensors often suffer from reliability issues in terms of baseline drift, poor response/recovery time. Normally, the sensors are often realized on microheaters to facilitate the redox reaction (temperature of the sensing layer should be high for desorption of generated water molecules) to avoid the baseline drift which leads to structural instability and large power consumption. In this work we report an UV (400nm Light Emitting Diode at 400μW optical power (P_o) and 18 mW input power (P_i)) excited ZnO nanosphere based H₂ sensor with minimum base line drift. The ZnO nanospheres used as sensing layer are synthesized by microwave assisted technique and dropcasted. Here, in this report it can be observed that the UV irradiated sensor is getting sufficient activation energy to enable the current modulation (Redox reaction). By exploiting the UV radiation, a negligible baseline drift H₂ sensor is demonstrated with enhanced sensitivity (39%) and fast response (15 s) /recovery time (10 s) at room temperature. Theoretical reasoning for sensing characteristic is attempted to explain the sensing behavior with the help of SEM (Scanning Electron Microscopy), XRD and Photoluminescence spectrum (PL).