Ligand-dependent energetics for dehydrogenation: Implications in Li-ion battery electrolyte stability and selective oxidation catalysis of hydrogen-containing molecules

The hydrogen adsorption energetics on the surface of inorganic compounds can be used to predict electrolyte stability in Li-ion batteries and catalytic activity for selective oxidation of small molecules such as H2 and CH4. Using first-principles density functional theory (DFT), the hydrogen adsorption was found to be unfavorable on high band-gap insulators, which could be attributed to lower energy level associated with adsorbed hydrogen relative to the bottom of conduction band. In contrast, the hydrogen adsorption was shown the most favorable on metallic and semiconducting compounds, which results from an electron transfer from adsorbed hydrogen to the Fermi level or the bottom of conduction band. Of significance, computed hydrogen adsorption energetics on insulating, semiconducting and metallic oxides, phosphates, fluorides, and sulfides were decreased by lowering the ligand p band center while the ligand vacancy formation energy penalty was increased, indicative of decreased surface reducibility. A s...