The
introduction of heteroatoms (such as B, P, S and Se) into M-N-C
catalysts provides a useful strategy to further enhance its catalytic
activity due to the optimized electronic
structure[11-14]. For example, Yang et al.
developed S doped NiNC catalyst for robust CO2RR due to
the formation of low-valent Ni(I)[15]. Besides, P
doped FeNC catalyst also exhibited impressive performance owing to the
moderate adsorption energy[16]. According to the
previous reports, the formation of *COOH intermediate via the
proton-electron transfer process is the rate-determining step (RDS) for
CO2RR to CO[17, 18]. However, few
studies have scrutinized the water activation and proton transfer.
In this work, we develop a Co1-SNC catalyst with S doped
in the first shell of CoN4. The Co1-SNC
exhibits superior CO2RR performance compared to
Co1-NC. In situ ATR-SEIRAS and KIE studies
indicate that Co1-SNC owns better water affinity and
superior capability for water activation. Theoretical analyses further
show that S doping can upshift the d-band center of Co active site and
reduce the free energy of *COOH intermediate formation. This work
enriches the understanding of CO2RR chemistry over
heteroatom doping M-N-C SACs and offers new insights for developing
high-performance catalysts for various important electrochemical
reactions.
Results and Discussion