Molten salt assisted synthesis of Single-Atom nickel catalysts for electroreduction of CO2 with nearly 100% CO selectivity

The synthesis of single-atom catalysts (SACs) with target architecture owning ultrathin layered morphology, high surface area and exposed metal active sites is still a great challenge. Herein, we chose 2D bimetallic ZIF-L as precursor combined with molten salt assisted method realizing the aimed synthesis of single-atom Ni imbedded in porous and ultrathin N-doped carbon nanosheets for efficient electrocatalytic CO 2 reduction. Molten salt assisted method avoids the collapse, agglomeration, and shrinkage of precursor nanosheets in synthetic process, and benefits the formation of porous structure of nitrogen-doped carbon nanosheets with exposed single-atom Ni active sites. The as-synthesized MS-L-Ni-NC exhibits remarkable electrocatalytic CO 2 -to-CO performance with the faradaic efficiency over 95.9% in a wide potential range from −0.7 to −1.0 V vs. RHE in H-type cell. An optimal FE CO of 98.7% at −0.8 V vs. RHE and a large current density of 20.6 mA·cm −2 at −1.0 V are observed for the MS-L-Ni-NC, which are much higher than those of D-L-Ni-NC without molten-salt assistance and MS-Ni-NC with 3D bimetallic ZIF as precursor. DFT calculations reveal that the coordinated unsaturated pyridine Ni-N sites are the active centers for ECO 2 RR.