Atomically Dispersed Transition Metals on Carbon Nanotubes with Ultrahigh Loading for Selective Electrochemical Carbon Dioxide Reduction

Abstract Single‐atom catalysts (SACs) are the smallest entities for catalytic reactions with projected high atomic efficiency, superior activity, and selectivity; however, practical applications of SACs suffer from a very low metal loading of 1–2 wt%. Here, a class of SACs based on atomically dispersed transition metals on nitrogen‐doped carbon nanotubes (MSA‐N‐CNTs, where M = Ni, Co, NiCo, CoFe, and NiPt) is synthesized with an extraordinarily high metal loading, e.g., 20 wt% in the case of NiSA‐N‐CNTs, using a new multistep pyrolysis process. Among these materials, NiSA‐N‐CNTs show an excellent selectivity and activity for the electrochemical reduction of CO 2 to CO, achieving a turnover frequency (TOF) of 11.7 s −1 at −0.55 V (vs reversible hydrogen electrode (RHE)), two orders of magnitude higher than Ni nanoparticles supported on CNTs.