Insight into the Activity of Atomically Dispersed Cu Catalysts for Semihydrogenation of Acetylene: Impact of Coordination Environments

Atomically dispersed metal catalysts (ADMCs), which offer maximized atom-use efficiency and catalytic performance enhancements for many catalytic systems, have received increasing attention in the catalysis field. Additionally, ADMCs with well-defined architectures are promising for providing valuable information to derive structure-performance relationships. Here, we immobilized Cu-1 on a defective nanodiamond-graphene (ND@G) and N-doped nanodiamond-graphene (ND@NG). By changing the coordination environments (Cu-C or Cu-N), the electronic state of Cu ADMCs can be tailored. The highly oxidized Cu atoms in Cu-N AMDCs present distinctively different acetylene hydrogenation activity compared to that in Cu-C AMDCs (i.e., with high conversion (100%), high selectivity (93%), and good stability (more than for 100 h)). Density functional theory and H-2-D-2 exchange experiments reveal that Cu-C bond anchoring favors H-2 dissociative adsorption, which is a rate-limiting step. In addition, the facile desorption of the target product C2H4 over Cu-C ADMCs ensures the outstanding activity and selectivity of the catalyst. This work thus helps to bring perspectives for linking activity and structures of ADMCs and designing active ADMCs for hydrogenation applications.