Rational design of single-metal atom sites in carbon substrates by a flexible strategy is highly desired for the preparation of high-performance catalysts for metal-air batteries.In this study,biomass hydrogel reactor...Rational design of single-metal atom sites in carbon substrates by a flexible strategy is highly desired for the preparation of high-performance catalysts for metal-air batteries.In this study,biomass hydrogel reactors are utilized as structural templates to prepare carbon aerogels embedded with single iron atoms by controlled pyrolysis.The tortuous and interlaced hydrogel chains lead to the formation of abundant nanowrinkles in the porous carbon aerogels,and single iron atoms are dispersed and stabilized within the defective carbon skeletons.X-ray absorption spectroscopy measurements indicate that the iron centers are mostly involved in the coordination structure of FeN_(4),with a minor fraction(ca.1/5)in the form of FeN_(3)C.First-principles calculations show that the FeN_(x) sites in the Stone-Wales configurations induced by the nanowrinkles of the hierarchically porous carbon aerogels show a much lower free energy than the normal counterparts.The resulting iron and nitrogen-codoped carbon aerogels exhibit excellent and reversible oxygen electrocatalytic activity,and can be used as bifunctional cathode catalysts in rechargeable Zn-air batteries,with a performance even better than that based on commercial Pt/C and RuO_(2) catalysts.Results from this study highlight the significance of structural distortions of the metal sites in carbon matrices in the design and engineering of highly active single-atom catalysts.展开更多
基金Y.Z.acknowledges support from the National Natural Science Foundation of China(21972169,21773311,and 21473257)Hunan Provincial Science and Technology Plan Project(2017TP1001)+2 种基金The authors thank Dr.Yongfeng Hu of the Canadian Light Source(Saskatoon)and Dr.JengLung Chen of the National Synchrotron Radiation Research Center(Taiwan)for their assistance in the acquisition of XANES and EXAFS data,and Dr.Yi Peng(UCSC)for helpful discussion.T.H.is supported by a research fellowship from the China Scholarship Council(201806370027)J.V.J.acknowledges support from the Army Research Office under contract W911NF-17-1-0473S.W.C.acknowledges support from the National Science Foundation(CHE-1710408 and CHE-1900235).
文摘Rational design of single-metal atom sites in carbon substrates by a flexible strategy is highly desired for the preparation of high-performance catalysts for metal-air batteries.In this study,biomass hydrogel reactors are utilized as structural templates to prepare carbon aerogels embedded with single iron atoms by controlled pyrolysis.The tortuous and interlaced hydrogel chains lead to the formation of abundant nanowrinkles in the porous carbon aerogels,and single iron atoms are dispersed and stabilized within the defective carbon skeletons.X-ray absorption spectroscopy measurements indicate that the iron centers are mostly involved in the coordination structure of FeN_(4),with a minor fraction(ca.1/5)in the form of FeN_(3)C.First-principles calculations show that the FeN_(x) sites in the Stone-Wales configurations induced by the nanowrinkles of the hierarchically porous carbon aerogels show a much lower free energy than the normal counterparts.The resulting iron and nitrogen-codoped carbon aerogels exhibit excellent and reversible oxygen electrocatalytic activity,and can be used as bifunctional cathode catalysts in rechargeable Zn-air batteries,with a performance even better than that based on commercial Pt/C and RuO_(2) catalysts.Results from this study highlight the significance of structural distortions of the metal sites in carbon matrices in the design and engineering of highly active single-atom catalysts.
