**Acknowledgements**

investigated the componential influences of heteroatoms doping (B, P, and S) in graphitic

from 1 to 8, while C atoms are numbered from 9 to 14. Top views of the optimized structures of the energetically most favorable (c) B-CN, (d) P-CN, and (e) SCN, in which the B and P atoms substitute the bay carbon C13, while S atom replaces the pyridinic nitrogen N7. In each structure, the largest value of charge and spin densities on carbon atoms are indicated by black and red colors, respectively; additionally, the related carbon atoms are illustrated by green arrows.

)-based electrocatalysts (**Figure 6**) [50]. They found that S-doped C3

smallest charge-transfer resistance dramatically boosted the reaction kinetics and activities

Recently, Xu et al. designed Fe-N-, Fe-S-, and Fe-N-S-based model catalysts to investigate heteroatom induced performance differences in ORR [51]. Pyrrole-derived and thiophene-

Crafts reaction catalyst, acts as both a metal dopant and a porogen. Interestingly, Fe1−xS and

acts as a higher catalytic active site than S/Fe1−xS. The possible reason is that the strong electronegativity of N generates more charged active sites, while the electronegativity of S is similar

Although state-of-the-art Pt-based ORR catalysts are applicable in fuel cell vehicles, source scarcity limits their mass application. M-N-C materials are still far from satisfaction for commercialization. Presently, design and synthesis of novel ORR catalysts with various structures were at the center of research. Furthermore, to experimentally and theoretically explore the relationship between component structure-properties has attracted extensive interest.

nanoparticles formed in the S-doped and N-doped carbon, respectively. In fact, N/Fe<sup>3</sup>

derived hypercrosslinked polymers were selected as carbon precursors. FeCl<sup>3</sup>

N4

Reproduced with permission from Ref. [50]. Copyright 2017, American Chemical Society.

to that of carbon. However, the synergistic effect between Fe1−xS/Fe<sup>3</sup>

carbon showed superior ORR performance.

**Figure 6.** Optimized structure of pristine g-C3

N4

and the N, S-doped

O4

as (a) top view and (b) side view, in which the N atoms are numbered

with the

, a Friedel-

O4

C3 N4 (g-C3 N4

Fe<sup>3</sup> O4

**3. Conclusions**

of ORR.

88 Chalcogen Chemistry

This work was supported by the National Nature Science Foundation of China (No. 21603156), Jiangsu Province Science Foundation for Youths (No. BK20170331).
