Atomic-Dispersed Coordinated Unsaturated Nickel-Nitrogen Sites in Hollow Carbon Spheres for the Efficient Electrochemical CO2 Reduction

Reducing carbon dioxide to high value-added chemicals is of high importance due to its vital role in mitigating CO2 emission and energy crisis. However, seeking for robust catalysts with low overpotential, high selectivity, and stability is extremely challenging. Herein, a single Ni atom anchored on an N-doped carbon (Ni-N-C) catalyst was designed and prepared via a facile synthesis method to embed highly and evenly dispersed, coordinated unsaturated nickel-nitrogen active sites into a hollow carbon matrix with abundant micropores. The prepared Ni-N-C catalysts possess a unique electronic structure, coordination environment, and maximized atomic utilization, which accordingly show a higher intrinsic activity and remarkable selectivity for the electrochemical reduction of CO2. Additionally, the coordination structure and content of Ni can be easily modulated by changing the calcination temperature, which plays a vital role for the catalytical performance. As a result, the Ni-N-C catalysts achieve over 90% for CO at a wide potential window from -0.6 to -1.0 V with a maximum value of 97% at -0.8 V. This paper paves a facile way to develop high-performance single atomic catalysts with a tunable Ni-N coordination structure for CO2 reduction.