The high electron occupation on anti-bond orbital induced by the asymmetric covalent structure of C-S-N enhancing the oxygen reduction reaction

Despite heteroatom doping is a smart approach to facilitate the oxygen reduction reaction (ORR) performances of nanocarbon catalysts, two dominant issues still retain as significant obstacles. One is the relatively low activity compared to benchmark catalysts, the other is the ambiguous elucidation of the catalytic mechanism for dual heteroatom-doped catalysts. Here, nitrogen and sulfur co-doped carbon-dots electrocatalyst (HT-CDs) are simply prepared by means of physical activation with water vapor on the carbon-dots precursor. The material exhibits excellent ORR performance under alkaline conditions, achieving a half-wave potential of 0.91 V (vs RHE), surpassing most metal-free catalysts and Pt/C. Further theoretical studies reveal that N/C-S-N structure fills more electrons in the anti-bond orbitals that promoting the charge transfer from the catalyst to the reactant O 2 , thus enhancing the efficient ORR process.