Maximizing the utilization of single-atom sites on carbon-based catalysts for efficient CO2 electroreduction with ultrahigh turnover frequency

Abstract

Increasing the amount of accessible active sites to reactants is an effective way to enhance electrocatalytic activity. Although single-atom catalysts are claimed to be capable of achieving 100% atomic utilization, there may be abundant single-atom sites buried and inaccessible to reactants in practice. Herein, two Ni, N-doped carbon catalysts with Ni-Nx atomic sites are comparatively studied for CO2 electroreduction. In contrast to the Ni-Nx/Carbon nanosheets with Ni loading of 2.42 wt%, the Ni-Nx/Carbon black with lower Ni loading of 0.16 wt% excitingly exhibits higher activity for CO production. The atomically dispersed Ni-Nx sites over carbon black surface benefit the exposure and utilization of single-atom sites, leading to a significant increase of TOF from 2140 to 100,347 h−1 at − 0.8 V. Particularly, an extraordinarily high current density up to 300 mA cm−2 with CO selectivity of ∼100 % are achieved for Ni-Nx/CB in the flow cell. This work demonstrates the significance of increasing single-atom site utilization.