Synthesizing nickel single atom catalyst via SiO 2 protection strategy for efficient CO 2 electroreduction to CO in a wide potential range

At present, electrochemical CO 2 reduction has been developed towards industrial current density, but the high faradaic efficiency at wide potential range or large current density is still an arduous task. Therefore, in this work, the highly exposed Ni single atoms (Ni - N - C - R-0.72) was synthesized through simple metal organic frameworks (MOFs)-derived method with SiO 2 protection strategy. The obtained catalyst keeps CO faradaic efficiency (FE CO ) above 91 % under the wide potential range, and achieves a high FE CO of 96.0 % and large CO partial current density of-206.8 mA cm-2 at-0.7 V in flow cell. The experimental results and theoretical calculation disclose that Ni - N - C - R-0.72 possesses the robust structure with rich mesopore and more highly exposed Ni-N active sites under SiO 2 protection, which could facilitate CO 2 transportation, lower energy barrier of CO 2 reduction, and raise difficulty of hydrogen evolution reaction. The protection strategy is instructive to the synthesis of other MOFs-derived metal single atoms.