Ab Initio Study of ZnO-Based Gas-Sensing Mechanisms: Surface Reconstruction and Charge Transfer

Density functional theory (DFT) calculations were employed to explore the gas-sensing mechanisms of zinc oxide (ZnO) with surface reconstruction taken into consideration. Mix-terminated (101̅0) ZnO surfaces were examined. By simulating the adsorption process of various gases, i.e., H2, NH3, CO, and ethanol (C2H5OH) gases, on the ZnO (101̅0) surface, the changes of configuration and electronic structure were compared. Based on these calculations, two gas-sensing mechanisms were proposed and revealed that both surface reconstruction and charge transfer result in a change of electronic conductance of ZnO. Also, the calculations were compared with existing experiments.