Maximizing Surface Single-Ni Sites on Hollow Carbon Sphere for Efficient CO<sub>2</sub> Electroreduction
Dan Ping, Yi-Chen Feng, Shi-De Wu, Feng Yi, Siyuan Cheng, Shiwen Wang, Junfeng Tian, Heng Wang, Xu-Zhao Yang, Dongjie Guo, Shaoming Fang
Abstract
Single-atom catalysts show great application potential due to their high catalytic efficiency but suffer from insufficient active site density and utilization. Herein, a robust single-atomic Ni catalyst anchored on porous hollow carbon spheres (Ni–N–HCS) was successfully synthesized via a pyrolysis approach employing SiO 2 -templated HCS, dicyandiamide, and Ni(CH 3 COO) 2 ·4H 2 O as raw materials. Profiting from the abundant (3.47 wt %) and accessible single-Ni active sites and the robust hollow carbon architecture, this catalyst showed superior performance for electrochemical CO 2 reduction reaction in an H-type cell. A prominent Faradaic efficiency for CO (95.04%) can be achieved at a −0.70 V vs a reversible hydrogen electrode (RHE) and the value can even be kept at >80% over a broad voltage range (−0.62 to −0.87 V vs RHE) with a desirable CO current density (10.88 mA·cm –2 ). In addition, the FE CO was kept almost unchanged during continuous electrolysis for 40 h. Significantly, Ni–N–HCS also exhibits an excellent CO selectivity of >95% over the whole investigated potential window in the flow cell. We believe this work will provide a new possibility to build single-atom catalysts with maximized utilization for improving electrochemical performance.