Adsorption of C6H6 and C7H8 onto pristine and metal (Pd, Pt)-mediated ZnO monolayers: Electronic and gas sensing properties

Abstract ZnO monolayers, as typical two-dimensional materials, have attracted considerable interests for gas-sensing applications due to their ultralarge theoretical specific surface area and unique electronic properties. Here, using first-principles calculations, the adsorption behaviors of C6H6 and C7H8 molecules on pristine and metal (Pd, Pt)-mediated ZnO monolayers including the adsorption energy, charge transfer, band structure, and recovery time, are systematically investigated. The results show that C6H6 and C7H8 molecules on pristine and metal (Pd, Pt)-mediated ZnO monolayers are energetically favorable. The adsorption energies for C6H6 and C7H8 molecules on the metal-adsorbed (Pd, Pt) ZnO monolayer range from −2.631 eV to −1.986 eV, while the adsorption energies range from −1.023 eV to −0.785 eV for C6H6 and C7H8 molecules on the metal-doped (Pd, Pt) ZnO monolayer, indicating that metal (Pd, Pt) mediation can greatly enhance the adsorption ability of the ZnO monolayer to C6H6 and C7H8 molecules. Moreover, the band gaps of C6H6 and C7H8 molecules on the ZnO monolayer could be greatly modulated by metal (Pd, Pt) doping. More importantly, the moderate adsorption energies and short recovery time suggest that metal-doped (Pd, Pt) ZnO monolayers are the promising C6H6 and C7H8 sensors with high selectivity and sensitivity, and good reversibility. The current results provide insight into the adsorption behavior of metal-mediated ZnO monolayers upon C6H6 and C7H8 molecules, which could promote the further application of ZnO-based materials in the gas-sensing field.