摘要
Single-site metal atoms(SMAs)on supports are attracting extensive interest as new catalytic systems because of maximized atom utilization and superior performance.However,rational design of configuration-optimized SMAs with high activity from the perspectives of fundamental electron spin is highly challenging.Herein,N-coordinated Fe single atoms are successfully distributed over axial carbon micropores to form dangling-FeN4 centers(d-FeN4).This unique d-FeN4 demonstrates much higher intrinsic activity toward oxygen reduction reaction(ORR)in HClO4 than FeN4 without micropore underneath and commercial Pt/C.Both theoretical calculation and electronic structure characterization imply that d-FeN4 endows central Fe with medium spin(t2g 4 eg 1),which provides a spin channel for electron transition compared with FeN4 with low spin.This leads to the facile formation of the singlet state of oxygen-containing species from triplet oxygen during the ORR,thus showing faster kinetics than FeN4.This work provides an in-depth understanding of spin tuning on SMAs for advanced energy catalysis.
基金
support from the National Natural Science Foundation of China(grants 92163117,52072389,and 52172058)
State Key Laboratory of ASIC&Sys-tem(grant 2020KF002)
J.W.thanks the Program of Shanghai Academic Research Leader(grant 20XD1424300)for financial support.LL.acknowledges support from the Discovery Program of the Natural Sciences and Engineering Research Council of Canada(NSERC,grant DG RGPIN-2020-06675)
Use of the Advanced Photon Source was supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,under contract DE-AC02-06CH11357
Technical support from APS beamline scientists Dr.George E.Ster-binsky and Dr.Tianpin Wu,and from TLS beamline scientist Dr.Lo-Yueh Chang,is greatly appreciated.
