FIRST-PRINCIPLES INVESTIGATIONS ON ELECTROCHEMICAL CATALYSTS FOR CARBON-FREE ENERGY FUELS

Abstract

H2 and NH3 have recognized as potential carbon-free energy fuels to replace dominant fossil fuels. They can be produced by hydrogen/oxygen evolution reaction (HER/OER) and nitrogen reduction reaction (NRR) coupled with renewable energies, where the catalysts play significant roles. In this thesis, first-principles calculations have been performed to understand recent experimental phenomena and predict potential catalysts. In the first work, we proposed two-dimensional Mo6S4 as a potential structure of the experimentally synthesized sub-stoichiometric molybdenum sulfide. The HER activity of this phase was predicted theoretically and verified experimentally. In the second work, an insight was gained for the experimentally observed facet-dependent OER activity of alpha-Fe2O3: (012)&gt(104)&gt(110) and the experimental-theoretical contradiction between the latter two facets. In the third work, the Mo single atom anchored on the Mo top site of MoS2 was identified as the most promising NRR catalyst candidate among a series of transition metal single atoms.