▎ 摘　　要

Moving forward from single atom catalysts, here we propose Cu mers coordinated with N atoms in graphene as a potential catalyst for hydrogen evolution reaction (HER) using first-principles calculations. Our study shows that Cu mers (monomer, dimer and trimer) with no N coordination adsorb H too strongly, whereas Cu mers with complete N coordination adsorb H too weakly, indicating that neither is catalytically active for HER. However, these results imply that Cu mers with partial N coordination may exhibit a better catalytic performance. Thus, we further explored all the Cu2Nx complexes with different atomic coordination numbers and spatial distributions and find that one of the Cu2N4 atomic configurations possesses a Delta G(H*) of -0.09 eV, exhibiting a superior catalytic performance for HER. The possible reason might be that this configuration tunes the p-band center to an optimum level. Our study here reveals a promising catalyst for HER and presents a practical route to design catalysts by introducing metal mers and tuning their coordination with high-valence non-metal elements.