Automated room temperature optical absorbance CO sensor based on In-doped ZnO nanorod

Metal oxide based optical absorbance gas sensor (MOAGS) exhibits underlying potential to be the most promising energy-saving device with long-term stability and excellent sensing performance. In this work, a self-customized automated MOAGS setup was employed to study the carbon monoxide (CO) gas sensing performance between the hydrothermal synthesized ZnO nanorod (ZNR) and Indium-doped ZnO nanorod (IZNR) operating at room temperature of (25 ± 1)°C. Specifically, it was found that the In3+ was evenly doped into ZnO lattice which in turn increased the defect density and generated an impurity state within the energy band structure of ZnO. The results showed that 0.04 mol% IZNR exhibited an optimum sensing performance with absolute optical absorbance change (OAC) of 0.067 a.u. under the 10 ppm of CO gas testing environment with fastest respond and recovery time. The dependency of sensing performances to the optical band gap energy alteration and the defect state was evaluated. This work provides a simple and feasible route to develop the room temperate operating MOAGS for hazardous gas detection.