Constant-potential simulation of electrocatalytic N2 reduction over atomic metal-N-graphene catalysts

Abstract

Charge-neutral method (CNM) is extensively used in investigating the performance of catalysts and the mechanism of N₂ electrochemical reduction (NRR). However, disparities remain between the predicted potentials required for NRR by the CNM methods and those observed experimentally, as the CNM method neglects the charge effect from the electrode potential. To address this issue, we employed the constant electrode potential (CEP) method to screen atomic transition metal-N-graphene (M₁/N-graphene) as NRR electrocatalysts and systematically investigated the underlying catalytic mechanism. Among eight types of M₁/N-graphene (M₁ = Mo, W, Fe, Re, Ni, Co, V, Cr), W₁/N-graphene emerges as the most promising NRR electrocatalyst with a limiting potential as low as −0.13 V. Additionally, the W₁/N-graphene system consistently maintains a positive charge during the reaction due to its Fermi level being higher than that of the electrode. These results better match with the actual circumstances compared to those calculated by conventional CNM method. Thus, our work not only develops a promising electrocatalyst for NRR but also deepens the understanding of the intrinsic electrocatalytic mechanism.