Semi-sacrificial template synthesis of single-atom Ni sites supported on hollow carbon nanospheres for efficient and stable electrochemical CO2 reduction

Abstract

Facile synthesis of single-atom catalytic sites on various supports for the electrochemical carbon dioxide reduction reaction (CO₂RR) has attracted increasing attention. Herein, atomically dispersed Ni species supported on nitrogen-doped hollow carbon spheres (SA-Ni/N-CS) were fabricated by using a semi-sacrificial template strategy. The obtained SA-Ni/N-CS was employed as an electrocatalyst for the CO₂RR. We found that the SA-Ni/N-CS displayed ultra-high efficiency and selectivity for CO₂ conversion into CO with a faradaic efficiency (FE) of 95.1%. Moreover, the SA-Ni/N-CS also exhibited an excellent stability with current density and FE maintained over 99% and 95%, respectively, after 24 h of the CO₂RR test. Furthermore, density functional theory (DFT) calculations revealed that the CO₂ activation process with an activation energy barrier of 2.16 eV is the reaction control step when using SA-Ni/N-CS as a CO₂RR catalyst. This work will open up the opportunity for the hard-template synthesis of novel single-atom catalysts for application in electrocatalysis, and suggests that promoting the CO₂ activation process could be a crucial approach to boosting the CO₂RR.