Theoretical prediction by DFT and experimental observation of heterocation-doping effects on hydrogen adsorption and migration over the CeO2(111) surface

Hydrogen (H) atom adsorption and migration over the CeO2-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 CeO2-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 CeO2(111) surface using density functional theory (DFT) calculations. Results revealed that the electron-deficient lattice oxygen (O-lat) and the flexible CeO2 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 CeO2 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 (NH3 synthesis in an electric field). Results confirmed clear correlation between H atom adsorption energy and surface protonics.

Automated summary

This study investigated H atom adsorption and migration over CeO2-based materials surfaces through density functional theory calculations. The results showed that electron-deficient lattice oxygen and flexible CeO2 matrix played crucial roles in strong H atom adsorption, while smaller valence and ionic radius heterocations induced electron-deficient lattice oxygen and enhanced the flexibility of the CeO2 matrix. Furthermore, the influence of doping-controlled H atom adsorption on surface proton migration and catalytic reactions involving surface protonics was confirmed, showing a clear correlation between H atom adsorption energy and surface protonics.