Enhancing electrocatalytic N-2 reduction via tailoring the electric double layers

Abstract

The electrocatalytic nitrogen reduction reaction (NRR) for NH3 synthesis is still far from being practical and competitive with the common Haber–Bosch process. The rational design of highly selective NRR electrocatalyst is therefore urgently needed, which requires a deep understanding of both the electrode–electrolyte interface and the mass transport of reactants. Here, we develop a theoretical framework that includes electric double layer (EDL), mass transport, and the NRR kinetics. This allows us to evaluate the roles of near-electrode environment and N2 diffusion on the NRR selectivity and activity. The EDL, as the immediate reaction environment, remarkably impedes the diffusion of N2 to the cathode surface at high electrode potentials, which explains experimental observations. This article also gives microscopic insights into the interplay between N2 diffusion and reaction activity under the nano-confinement, providing theoretical guidance for future design of advanced NRR electrocatalytic systems.