Theoretical prediction by DFT and experimental observation of heterocation-doping effects on hydrogen adsorption and migration over the CeO(111) surface

Hydrogen (H) atom adsorption and migration over the CeO 2 -based materials surface are of great importance because of its wide applications to catalytic reactions and electrochemical devices. Therefore, comprehensive knowledge for controlling the H atom adsorption and migration over CeO 2 -based materials is crucially important. For controlling H atom adsorption and migration, we investigated irreducible divalent, trivalent, and quadrivalent heterocation-doping effects on H atom adsorption and migration over the CeO 2 (111) surface using density functional theory (DFT) calculations. Results revealed that the electron-deficient lattice oxygen (O lat ) and the flexible CeO 2 matrix played key roles in strong adsorption of H atoms. Heterocations with smaller valence and smaller ionic radius induced the electron-deficient O lat . In addition, smaller cation doping enhanced the CeO 2 matrix flexibility. Moreover, we confirmed the influence of H atom adsorption controlled by doping on surface proton migration ( i.e. surface protonics) and catalytic reaction involving surface protonics (NH 3 synthesis in an electric field). Results confirmed clear correlation between H atom adsorption energy and surface protonics. The addition of dopants with a small ionic radius led to strong binding of H atoms, and the balance of H + reactivity (mobility) and H + coverage was fundamentally important for high H + conductivity and catalysis involving surface protonics.