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