Performance Improvement of n-ZnO/p-rGO Heterojunction Based Room Temperature Hydrogen Gas Sensor

This letter reports a room-temperature hydrogen gas sensor based on the nanohybrid structure of ZnO nanorods (NRs) and reduced graphene oxide (rGO) with better sensitivity. In this nanohybrid structure, ZnO NRs were grown up by the chemical bath deposition technique followed by the electrochemical exfoliation of rGO layer. The collaborative hybridization of these two dissimilar sensing elements revealed much better response at room temperature, which could hardly be achieved by the individual ones. The sensing was carried out at room temperature at ~40% RH, with hydrogen as a target gas with fastest response and recovery times (17.02 and 27.06 s), which have not been achieved earlier. The physics behind it is the high carrier mobility of rGO. A very high response magnitude (586.93% at 100 ppm) was found due to the increased number of gas-interaction sites and availability of free surface energy provided by ZnO NRs and rGO. A comparative discussion elucidating the role of ZnO NRs-rGO junctions has also been presented correlating the experimental findings.