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Effect of doping order on metal-free heteroatoms dual-doped carbon as oxygen reduction electrocatalyst

Chinese Chemical Letters 2021年第2期32卷 745-749页

作者： Hui-Juan Zhang Jing Geng Chunlei Cai Zi-Feng Ma Zhong Ma Wenli Yao Junhe Yang School of Materials Science and Engineering University of Shanghai for Science and TechnologyShanghai 200093China Department of Chemical and Biomolecular Engineering.University of Illinois at Urbana-Champaign UrbanaIllinois 61801United States Department of Chemical Engineering Shanghai Jiaotong UniversityShanghai 200240China Department of Chemical Engineering Waterloo Institute for Nanotechnology(WIN)University of WaterlooWaterlooOntario N2L3G1Canada Jiangxi Key Laboratory of Power Battery and Material Faculty of Materials Metallurgy and ChemistryJiangxi University of Science and TechnologyGanzhou 341000China

metal-free heteroatoms dual-doped carbon has been recognized as one of the most promising Pt/C-substitutes for oxygen reduction reaction(ORR).Herein,we optimize the preparation process by doping order of metal-free heteroatoms to obtain the best electrocatalytic performance through three types of dual-doped carbon,including XC-N(first X doping then N doping),NC-X(first N doping then X doping) and NXC(N and X doping)(X=P,S and F).XC-N has more defect than the other two indicated by Raman spectra.X-ray photoelectron spectrom(XPS) measurements indicate that N and X have been dual-doped into the carbon matrix with different doping contents and modes,Electrocatalytic results,including the potential of ORR peak(Ep),the half-wave potential,the diffusion-limiting current density mainly follows the order of XC-N>NC-X> NXC,Furthermore,the synergistic effect of second atom doping are also compared with the single doped carbon(NC,PC,SC and FC).The differences in electronegativity and atomic radius of these metal-free heteroatoms can affect the defect degree,the doping content and mode of hete roatoms on carbon matrix,induce polarization effect and space effect to affect O2 adsorption and product desorption,ultimately to the ORR electrocatalytic performance.

关键词： Oxygen reduction reaction metal-free electrocatalyst Heteroatoms dual-doped carbon Doping order N P S and F

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Quasi-Three-Dimensional Cyclotriphosphazene-Based Covalent Organic Framework Nanosheet for Efficient Oxygen Reduction

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Nano-Micro Letters 2023年第9期15卷 550-561页

作者： Jianhong Chang Cuiyan Li Xiaoxia Wang Daohao Li Jie Zhang Xiaoming Yu Hui Li Xiangdong Yao Valentin Valtchev Shilun Qiu Qianrong Fang State Key Laboratory of Inorganic Synthesis and Preparative Chemistry Jilin UniversityChangchun 130012People’s Republic of China State Key Laboratory of Bio-Fibers and Eco-Textiles College of Materials Science and EngineeringQingdao UniversityQingdao 266071People’s Republic of China Qingdao Institute of Bioenergy and Bioprocess Technology Chinese Academy of Sciences189 Song Ling RdQingdao 266101ShandongPeople’s Republic of China Laboratoire Catalyse et Spectrochimie CNRSENSICAENUNICAENNormandie Univ6 Marechal Juin14050 CaenFrance

metal-free carbon-based materials are considered as promising oxygen reduction reaction(ORR)electrocatalysts for clean energy conversion,and their highly dense and exposed carbon active sites are crucial for efficient ORR.In this work,two unique quasi-three-dimensional cyclotriphosphazene-based covalent organic frameworks(Q3CTP-COFs)and their nanosheets were successfully synthesized and applied as ORR electrocatalysts.The abundant electrophilic structure in Q3CTP-COFs induces a high density of carbon active sites,and the unique bilayer stacking of[6+3]imine-linked backbone facilitates the exposure of active carbon sites and accelerates mass diffusion during ORR.In particular,bulk Q3CTP-COFs can be easily exfoliated into thin COF nanosheets(NSs)due to the weak interlayerπ-πinteractions.Q3CTP-COF NSs exhibit highly efficient ORR catalytic activity(half-wave potential of 0.72 V vs.RHE in alkaline electrolyte),which is one of the best COF-based ORR electrocatalysts reported so far.Furthermore,Q3CTP-COF NSs can serve as a promising cathode for Zn-air batteries(delivered power density of 156 mW cm-2 at 300 mA cm^(-2)).This judicious design and accurate synthesis of such COFs with highly dense and exposed active sites and their nanosheets will promote the development of metal-free carbon-based electrocatalysts.

关键词： Covalent organic framework Quasi-three-dimensional structures Oxygen reduction reaction metal-free electrocatalyst

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Pyrazine-nitrogen-rich exfoliated C4N nanosheets as efficient metal-free polymeric catalysts for oxygen reduction reaction

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Journal of Energy Chemistry 2020年第10期29卷 243-247页

作者： Yuan Li Chunshao Mo Jing Li Dingshan Yu Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education Key Laboratory of High Performance Polymer-based Composites of Guangdong ProvinceSchool of ChemistrySun Yat-sen UniversityGuangzhou 510275GuangdongChina

Herein,we for the first time demonstrate the synthesis of exfoliated C4N nanosheets via a top-down approach and exploit their use as a new class of organic polymeric catalyst for the oxygen reduction reaction(ORR).The obtained C4N nanosheets are semi-conductive with a small band gap of 1.41 eV and contain abundant pyrazine-nitrogen moieties uniformly distributed throughout C4N.Density function theory calculations reveal that the intramolecular charge transfer induced by pyrazine-nitrogen in C4N enables effective charge redistribution to activate the conjugated structure and facilitate the oxygen adsorption,while the exfoliated sheet-like C4N formation renders improved electrochemical active surface area and results in high exposure of active sites.As a result,despite the bulk C4N is not active,the sheet-like C4N yield markedly improved ORR performance,even on a par with the commercial Pt/C catalyst.Our recent findings not only enrich the family members of two-dimensional conjugated polymer nanosheets but also open up new opportunity to explore new metal-free organic polymeric materials for efficient oxygen reduction catalysis and beyond.

关键词： Oxygen reduction reaction metal-free electrocatalyst Polymeric electrocatalysts C4N nanosheets Pyrazine-nitrogen

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Ten years of carbon-based metal-free electrocatalysts

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Carbon Energy 2019年第1期1卷 19-31页

作者： Rajib Paul Quanbin Dai Chuangang Hu Liming Dai Department of Macromolecular Science and Engineering Case Western Reserve UniversityClevelandOhio The UNSW-CWRU International Joint Laboratory School of Chemical EngineeringUniversity of New South WalesSydneyAustralia

Since the discovery of the first carbon-based metal-free electrocatalysts(C-MFECs,i.e.,N-doped carbon nanotubes)for the oxygen reduction reaction in 2009,the field of C-MFECs has grown enormously over the last 10 years.C-MFECs,as alternatives to nonprecious transition metals and/or precious noble metal-based electrocatalysts,have been consistently demonstrated as efficient catalysts for oxygen reduction,oxygen evolution,hydrogen evolution,carbon dioxide reduction,nitrogen reduction,and many other(electro-)chemical reactions.Recent research and development of C-MFECs have indicated their potential applications in fuel cells,metal-air batteries,and hydrogen generation through water oxidation as well as electrochemical production of various commodity chemicals,such as ammonia,alcohols,hydrogen peroxide,and other useful hydrocarbons.Further research and development of C-MFECs would surely revolutionize traditional energy conversion and storage technologies with minimal environmental impact.In this short review article,we summarize the journey of C-MFECs over the past 10 years with an emphasis on materials development and their structure-property characterization for applications in fuel cells and metal-air batteries.Current challenges and future prospects of this emerging field are also discussed.

关键词： carbon electrocatalysis energy conversion energy storage metal-free electrocatalyst

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