Computational studies of electric field effects in CO2 methanation on Ni metal surfaces

Abstract

Non-Faradaic electrochemical modification of catalytic activity (NEMCA) with an electric field (EF) has attracted attention as one of the methods to improve catalyst performance. However, this activation mechanism is not still clear. In this study, we focused on the NEMCA mechanism in CO2 methanation on Ni metal catalyst with solid oxide electrolysis cell (SOEC) and calculated two possible effects of the NEMCA mechanism; direct EF applications and oxygen atom co-adsorptions, using the density functional theory calculations and detailed kinetic simulations. Compared with these effects in terms of kinetic energy changes in the rate-determining steps, it has been revealed that the spillover effect of lattice oxygen toward the catalyst surface is dominant in the NEMCA mechanism. Also, we have found that overall CO2 methanation is promoted in SOEC mode with oxygen atom co-adsorptions in both cases of Ni flat and step sites.