▎ 摘　　要

Single atom catalysis has recently become the most active frontier in heterogeneous catalysis, however, its performance is practically limited by the exposure of single atoms to reactants. Herein, we synthesized a vertically aligned N-doped graphene nanomesh array (VNGNMA) with a high density of in-plane surface holes and out-of-plane interconnected, vertically aligned structures to facilitate the diffusion of reactants and maximize the utility of single atoms in the liquid phase. Pd and Pt single atom catalysts supported on a 3D graphene nanomesh outperformed benchmark Pt/C and conventional single atom catalysts for the hydrogen evolution reaction due to rapid mass transport.