Adsorption of NO2 and H2S on ZnGa2O4(111) Thin Films: A First-Principles Density Functional Theory Study

Featured Application This work offers a detailed description of gas-sensing performance of ZnGa2O4-based gas sensors. We performed first-principles total-energy density functional calculations to study the reactions of NO2 and H2S molecules on Ga-Zn-O-terminated ZnGa2O4(111) surfaces. The adsorption reaction and work functions of eight NO2 and H2S adsorption models were examined. The bonding of the nitrogen atom from a single NO2 molecule to the Ga atom of the Ga-Zn-O-terminated ZnGa2O4(111) surfaces exhibited a maximum work function change of +0.97 eV. The bond joining the sulfur atom from a single H2S molecule and the Ga atom of Ga-Zn-O-terminated ZnGa2O4(111) surfaces exhibited a maximum work function change of -1.66 eV. Both results concur with previously reported experimental observations for ZnGa2O4-based gas sensors.