Nonequilibrium ab initio modeling of electrocatalysis

We present a nonequilibrium ab initio approach for modeling electrocatalysis using steady-state density functional theory (SS-DFT), where nonequilibrium effects are incorporated through Hershfield quantum statistics. In the equilibrium limit, where the working electrode potential U equals the potential of zero charge U PZC , our SS-DFT approach reduces to the constant-charge DFT (DFT-CC). When | U - U PZC | is small, the linear response approximation (LRA) simplifies the SS-DFT effective energy to a quadratic form on electrode potential U . Although analogous to the constant-potential DFT (DFT-CP) formulation, the resulting expression contains a distinct prefactor that incorporates nonequilibrium effects. Using N 2 adsorption on an Au(310) cathode as an example, our calculations for adsorption free energies show that the SS-DFT approach accurately reproduces the DFT-CC results at U = U PZC , exhibits quadratic -dependence in excellent agreement with the LRA for | U - U PZC | < 0.5 V , and predicts significant nonequilibrium effects for | U - U PZC | > 0.5 V . Further calculations for electrochemical N 2 reduction reaction (NRR) reveal that potential-dependent nonequilibrium effects, which are not captured in standard DFT approaches, are essential for explaining the experimentally reported high electrocatalytic activity of Au(310) for NRR.