Steering the oxygen reduction reaction pathways of N-carbon hollow spheres by heteroatom doping

An original strategy was reported to manipulate ORR selectivity of N-doped hollow mesoporous carbon spheres (N-HMCS) via heteroatom (P and S) doping. Heteroatom doping can not only modulate electronic structure of N-HMCS and proportion/configuration of doped N, but also regulate ORR pathway. Specifically, rich-graphitic N sites and electron-rich C-P bond domains in N,P-HMCS act as electron donors, making *OOH more unstable and easier to desorb into H2O2. This severely distorts the sp2 lattice of graphene, catalyzing a two-electron ORR synergistically. Conversely, a strong interaction between electron-deficient C-S bond domain and *OOH inter-mediate due to the introduction of highly electronegative S hinders the desorption of *OOH, leading to the breakage of the O-O bond and promoting four-electron ORR along with the rich-pyridinic N receptor site. The reaction activity and kinetics mechanism present a positive correlation with proportion of graphitic N, revealing graphitic N is the primary active site with a much faster electron transfer capacity.

Automated summary

An original strategy of heteroatom (P and S) doping was reported to manipulate ORR selectivity of N-doped hollow mesoporous carbon spheres (N-HMCS). Heteroatom doping can modulate the electronic structure and the proportion/configuration of doped N in N-HMCS, as well as regulate the pathway of ORR. The presence of rich-graphitic N sites and electron-rich C-P bond domains in N,P-HMCS act as electron donors, making *OOH more unstable and easier to desorb into H2O2. Conversely, the introduction of highly electronegative S hinders the desorption of *OOH through a strong interaction with the electron-deficient C-S bond domain, leading to the breakage of the O-O bond and promoting four-electron ORR along with the rich-pyridinic N receptor site. The activity and kinetics mechanism of the reaction show a positive correlation with the proportion of graphitic N, indicating that graphitic N is the primary active site with a much faster electron transfer capacity.