Tuning the coordination environment in single-atom catalysts to achieve highly efficient oxygen reduction reactions

Designing atomically dispersed metal catalysts for oxygen reduction reaction (ORR) is a promising approach to achieve efficient energy conversion. Herein, we develop a template-assisted method to synthesize a series of single metal atoms anchored on porous N, S co-doped carbon (NSC) matrix as highly efficient ORR catalysts to investigate the correlation between the structure and their catalytic performance. The structure analysis indicates that identical synthesis method results in distinguished structural differences between Fe-centred single-atom catalyst (Fe-SAs/NSC) and Co-centred/Ni-centred single-atom catalysts (Co-SAs/NSC and Ni-SAs/NSC) because of the different trends of each metal ion in forming a complex with the N, S-containing precursor during the initial synthesis process. The Fe-SAs/NSC mainly consists of well-dispersed FeN4S2 centre site where S atoms form bonds with the N atoms. The S atoms in Co-SAs/NSC and Ni-SAs/NSC, on the other hand, form metal-S bonds, resulting in CoN3S1 and NiN3S1 ...