The advancement of modern theoretical calculation together with experimental characterization techniques has played a crucial role in the development of heterogenous catalysis for electrochemical energy conversion reactions. Among the recent improvement of theoretical chemistry, first principles density functional theory (DFT) simulation provides an excellent methodology to calculate catalysts intrinsic activity towards energy conversion reactions based on the materials electronic properties. In this study, we applied DFT calculation in order to choose highly active and efficient nonprecious transition metals based single atom catalysts (SACs) for hydrogen evolution reaction (HER). We derived an activity correlation with catalysts electronic structure and found that the energy states of...[ Read more ]

The advancement of modern theoretical calculation together with experimental characterization techniques has played a crucial role in the development of heterogenous catalysis for electrochemical energy conversion reactions. Among the recent improvement of theoretical chemistry, first principles density functional theory (DFT) simulation provides an excellent methodology to calculate catalysts intrinsic activity towards energy conversion reactions based on the materials electronic properties. In this study, we applied DFT calculation in order to choose highly active and efficient nonprecious transition metals based single atom catalysts (SACs) for hydrogen evolution reaction (HER). We derived an activity correlation with catalysts electronic structure and found that the energy states of antibonding state orbital are neither completely empty nor fully filled makes ideal catalysts for HER, strongly supported by the experimental study. Later, we developed a potential based macroscopic theory called the grand canonical potential kinetics (GCP-K) methods to modify density functional theory from fixed number of electrons to fixed potential based calculation in order to account experimental electrochemical conditions at a specified applied voltage. The GCP-K method utilizes the Legendre transformation of the Gibbs free energy obtained from fixed charged quantum mechanical calculation to constant potential calculation. To demonstrate this method, we applied GCP-K theory to elucidate the reaction mechanism and kinetics for the electroreduction of CO₂ over different Ni sites (Ni-N₂C₂, Ni-N₃C₁, and Ni-N₄) on graphene-supported Ni-SACs and hydrogen evolution reaction (HER) on Te vacant site of 2H- and 1T′-MoTe₂ basal plane. This new method describes the electron transfer accompanying proton or hydrogen transfer as a continuous process, rather than as a discrete electron jump as in the PCET formulation of traditional Butler-Volmer kinetics. We believe that this constant potential based GCP-K approach can be used for various electrochemical energy conversion systems and opened a new era to guide further developments in electrochemistry.