title: DFT simulations of water adsorption and activation on low-index α-Ga2O3 surfaces.
abstract: Density functional theory (DFT) calculations are used to explore water adsorption and activation on different α-Ga2O3 surfaces, namely (001), (100), (110), and (012). The geometries and binding energies of molecular and dissociative adsorption are studied as a function of coverage. The simulations reveal that dissociative water adsorption on all the studied low-index surfaces are thermodynamically favorable. Analysis of surface energies suggests that the most preferentially exposed surface is (012). The contribution of surface relaxation to the respective surface energies is significant. Calculations of electron local density of states indicate that the electron-energy band gaps for the four investigated surfaces appears to be less related to the difference in coordinative unsaturation of the surface atoms, but rather to changes in the ionicity of the surface chemical bonds. The electrochemical computation is used to investigate the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) on α-Ga2O3 surfaces. Our results indicate that the (100) and (110) surfaces, which have low stability, are the most favorable ones for HER and OER, respectively.
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, 457 Zhongshan Road, Dalian, 116023 (P.R. China).
authors.forename: Xin
authors.initials: X
authors.lastname: Zhou
authors.forename: Emiel J M
authors.initials: EJ
authors.lastname: Hensen
authors.forename: Rutger A
authors.initials: RA
authors.lastname: van Santen
authors.forename: Can
authors.initials: C
authors.lastname: Li
keywords: density functional calculations; gallium; photocatalysis; surfaces; water adsorption