LAUSR

Developing metal‐nitrogen‐carbon (M‐N‐C)‐based single‐atom electrocatalysts for carbon dioxide reduction reaction (CO2RR) have captured widespread interest because of their outstanding activity and selectivity. Yet, the loss of nitrogen sources during the synthetic process hinders their further development. Herein, an effective strategy using 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM][BF4]) as a liquid nitrogen source to construct a nickel single‐atom electrocatalyst (Ni‐SA) with well‐defined Ni‐N4 sites on a carbon support (denoted as Ni‐SA‐BB/C) is reported. This is shown to deliver a carbon monoxide faradaic efficiency of >95% over a potential of −0.7 to −1.1 V (vs reversible hydrogen electrode) with excellent durability. Furthermore, the obtained Ni‐SA‐BB/C catalyst possesses higher nitrogen content than the Ni‐SA catalyst prepared by conventional nitrogen sources. Importantly, only thimbleful Ni nanoparticles (Ni‐NP) are contained in the large‐scale‐prepared Ni‐SA‐BB/C catalyst without acid leaching, and with only a slight decrease in the catalytic activity. Density functional theory calculations indicate a salient difference between Ni‐SA and Ni‐NP in the catalytic performance toward CO2RR. This work introduces a simple and amenable manufacturing strategy to large‐scale fabrication of nickel single‐atom electrocatalysts for CO2‐to‐CO conversion.