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Well‐Dispersed ZIF‐Derived Co,N‐Co‐doped Carbon Nanoframes through Mesoporous‐Silica‐Protected Calcination as Efficient Oxygen Reduction Electrocatalysts 下载免费PDF全文
Lu Shang Huijun Yu Xing Huang Tong Bian Run Shi Yufei Zhao Geoffrey I. N. Waterhouse Li‐Zhu Wu Chen‐Ho Tung Tierui Zhang 《Advanced materials (Deerfield Beach, Fla.)》2016,28(8):1668-1674
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Co‐N‐Doped Mesoporous Carbon Hollow Spheres as Highly Efficient Electrocatalysts for Oxygen Reduction Reaction 下载免费PDF全文
Feng Hu Hongchao Yang Changhong Wang Yejun Zhang Huan Lu Qiangbin Wang 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(3)
Rational design of cost‐effective, nonprecious metal‐based catalysts with desirable oxygen reduction reaction (ORR) performance is extremely important for future fuel cell commercialization, etc. Herein, a new type of ORR catalyst of Co‐N‐doped mesoporous carbon hollow sphere (Co‐N‐mC) was developed by pyrolysis from elaborately fabricated polystyrene@polydopamine‐Co precursors. The obtained catalysts with active Co sites distributed in highly graphitized mesoporous N‐doped carbon hollow spheres exhibited outstanding ORR activity with an onset potential of 0.940 V, a half‐wave potential of 0.851 V, and a small Tafel slope of 45 mV decade?1 in 0.1 m KOH solution, which was comparable to that of the Pt/C catalyst (20%, Alfa). More importantly, they showed superior durability with little current decline (less than 4%) in the chronoamperometric evaluation over 60 000 s. These features make the Co‐N‐mC one of the best nonprecious‐metal catalysts to date for ORR in alkaline condition. 相似文献
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Pseudocapacitive Ni‐Co‐Fe Hydroxides/N‐Doped Carbon Nanoplates‐Based Electrocatalyst for Efficient Oxygen Evolution 下载免费PDF全文
Wu‐Jun Liu Xiao Hu Hong‐Chao Li Han‐Qing Yu 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(34)
The oxygen evolution reaction (OER) catalytic activity of a transition metal oxides/hydroxides based electrocatalyst is related to its pseudocapacitance at potentials lower than the OER standard potential. Thus, a well‐defined pseudocapacitance could be a great supplement to boost OER. Herein, a highly pseudocapacitive Ni‐Fe‐Co hydroxides/N‐doped carbon nanoplates (NiCoFe‐NC)‐based electrocatalyst is synthesized using a facile one‐pot solvothermal approach. The NiCoFe‐NC has a great pseudocapacitive performance with 1849 F g?1 specific capacitance and 31.5 Wh kg?1 energy density. This material also exhibits an excellent OER catalytic activity comparable to the benchmark RuO2 catalysts (an initiating overpotential of 160 mV and delivering 10 mA cm?2 current density at 250 mV, with a Tafel slope of 31 mV dec?1). The catalytic performance of the optimized NiCoFe‐NC catalyst could keep 24 h. X‐ray photoelectron spectroscopy, electrochemically active surface area, and other physicochemical and electrochemical analyses reveal that its great OER catalytic activity is ascribed to the Ni‐Co hydroxides with modular 2‐Dimensional layered structure, the synergistic interactions among the Fe(III) species and Ni, Co metal centers, and the improved hydrophily endowed by the incorporation of N‐doped carbon hydrogel. This work might provide a useful and general strategy to design and synthesize high‐performance metal (hydr)oxides OER electrocatalysts. 相似文献
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Kun Gao Bin Wang Li Tao Benjamin V. Cunning Zhipan Zhang Shuangyin Wang Rodney S. Ruoff Liangti Qu 《Advanced materials (Deerfield Beach, Fla.)》2019,31(13)
N‐doped carbon nanomaterials have rapidly grown as the most important metal‐free catalysts in a wide range of chemical and electrochemical reactions. This current report summarizes the latest advances in N‐doped carbon electrocatalysts prepared by N mono‐doping and co‐doping with other heteroatoms. The structure–performance relationship of these materials is subsequently rationalized and perspectives on developing more efficient and sustainable electrocatalysts from carbon nanomaterials are also suggested. 相似文献
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Biomass Derived N‐Doped Porous Carbon Supported Single Fe Atoms as Superior Electrocatalysts for Oxygen Reduction 下载免费PDF全文
Zhengping Zhang Xinjin Gao Meiling Dou Jing Ji Feng Wang 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(22)
Exploring sustainable and high‐performance electrocatalysts for the oxygen reduction reaction (ORR) is the crucial issue for the large‐scale application of fuel cell technology. A new strategy is demonstrated to utilize the biomass resource for the synthesis of N‐doped hierarchically porous carbon supported single‐atomic Fe (SA‐Fe/NHPC) electrocatalyst toward the ORR. Based on the confinement effect of porous carbon and high‐coordination natural iron source, SA‐Fe/NHPC, derived from the hemin‐adsorbed bio‐porphyra‐carbon by rapid heat‐treatment up to 800 °C, presents the atomic dispersion of Fe atoms in the N‐doped porous carbon. Compared with the molecular hemin and nanoparticle Fe samples, the as‐prepared SA‐Fe/NHPC exhibits a superior catalytic activity (E 1/2 = 0.87 V and J k = 4.1 mA cm?2, at 0.88 V), remarkable catalytic stability (≈1 mV negative shift of E 1/2, after 3000 potential cycles), and outstanding methanol‐tolerance, even much better than the state‐of‐the‐art Pt/C catalyst. The sustainable and effective strategy for utilizing biomass to achieve high‐performance single‐atom catalysts can also provide an opportunity for other catalytic applications in the atomic scale. 相似文献
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The increasing interest in fuel cell technology encourages the development of efficient and low‐cost electrocatalysts to replace the Pt based materials for catalyzing the cathodic oxygen reduction reaction (ORR). In the present work, a nitrogen and phosphorus co‐coordinated manganese atom embedded mesoporous carbon composite (MnNPC‐900) is successfully prepared via a polymerization of o‐phenylenediamine followed by calcination at 900 °C. The MnNPC‐900 composite shows a high ORR activity in alkaline media, offering an onset potential of 0.97 V, and a half‐wave potential of 0.84 V (both vs reversible hydrogen electrode) with a loading of 0.4 mg cm?2. This performance not only exceeds its phosphorus‐free counterpart (MnNC‐900), but also is comparable to the Pt/C catalyst under identical measuring conditions. The significantly enhanced ORR performance of MnNPC‐900 can be ascribed to: i) the introduction of phosphorus assists the generation of mesopores during the pyrolysis and endows the MnNPC‐900 composite with large surface area and pore volume, thus facilitating the mass transfer process and increases the number of exposed active sites. ii) The formation of N,P co‐coordinated atomic‐scale Mn sites (MnNxPy), which modifies the electronic configuration of the Mn atoms and thereby boosts the ORR catalytic activity. 相似文献
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ZIF‐8/ZIF‐67‐Derived Co‐Nx‐Embedded 1D Porous Carbon Nanofibers with Graphitic Carbon‐Encased Co Nanoparticles as an Efficient Bifunctional Electrocatalyst 下载免费PDF全文
Wenming Zhang Xiuyun Yao Shengnan Zhou Xiaowei Li Ling Li Ze Yu Lin Gu 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(24)
Herein, an approach is reported for fabrication of Co‐Nx‐embedded 1D porous carbon nanofibers (CNFs) with graphitic carbon‐encased Co nanoparticles originated from metal–organic frameworks (MOFs), which is further explored as a bifunctional electrocatalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Electrochemical results reveal that the electrocatalyst prepared by pyrolysis at 1000 °C (CoNC‐CNF‐1000) exhibits excellent catalytic activity toward ORR that favors the four‐electron ORR process and outstanding long‐term stability with 86% current retention after 40 000 s. Meanwhile, it also shows superior electrocatalytic activity toward OER, reaching a lower potential of 1.68 V at 10 mA cm?2 and a potential gap of 0.88 V between the OER potential (at 10 mA cm?2) and the ORR half‐wave potential. The ORR and OER performance of CoNC‐CNF‐1000 have outperformed commercial Pt/C and most nonprecious‐metal catalysts reported to date. The remarkable ORR and OER catalytic performance can be mainly attributable to the unique 1D structure, such as higher graphitization degree beneficial for electronic mobility, hierarchical porosity facilitating the mass transport, and highly dispersed CoNxC active sites functionalized carbon framework. This strategy will shed light on the development of other MOF‐based carbon nanofibers for energy storage and electrochemical devices. 相似文献
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Bifunctional Electrocatalysts: ZIF‐8/ZIF‐67‐Derived Co‐Nx‐Embedded 1D Porous Carbon Nanofibers with Graphitic Carbon‐Encased Co Nanoparticles as an Efficient Bifunctional Electrocatalyst (Small 24/2018) 下载免费PDF全文
Wenming Zhang Xiuyun Yao Shengnan Zhou Xiaowei Li Ling Li Ze Yu Lin Gu 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(24)
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Controllable Construction of Core–Shell Polymer@Zeolitic Imidazolate Frameworks Fiber Derived Heteroatom‐Doped Carbon Nanofiber Network for Efficient Oxygen Electrocatalysis 下载免费PDF全文
Yingxuan Zhao Qingxue Lai Junjie Zhu Jia Zhong Zeming Tang Yan Luo Yanyu Liang 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(19)
Designing rational nanostructures of metal–organic frameworks based carbon materials to promote the bifunctional catalytic activity of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is highly desired but still remains a great challenge. Herein, an in situ growth method to achieve 1D structure‐controllable zeolitic imidazolate frameworks (ZIFs)/polyacrylonitrile (PAN) core/shell fiber (PAN@ZIFs) is developed. Subsequent pyrolysis of this precursor can obtain a heteroatom‐doped carbon nanofiber network as an efficient bifunctional oxygen electrocatalyst. The electrocatalytic performance of derived carbon nanofiber is dominated by the structures of PAN@ZIFs fiber, which is facilely regulated by efficiently controlling the nucleation and growth process of ZIFs on the surface of polymer fiber as well as optimizing the components of ZIFs. Benefiting from the core–shell structures with appropriate dopants and porosity, as‐prepared catalysts show brilliant bifunctional ORR/OER catalytic activity and durability. Finally, the rechargeable Zn‐air battery assembled from the optimized catalyst (CNF@Zn/CoNC) displays a peak power density of 140.1 mW cm?2, energy density of 878.9 Wh kgZn?1, and excellent cyclic stability over 150 h, giving a promising performance in realistic application. 相似文献
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James A. Behan Eric Mates‐Torres Serban N. Stamatin Carlota Domínguez Alessandro Iannaci Karsten Fleischer Md. Khairul Hoque Tatiana S. Perova Max García‐Melchor Paula E. Colavita 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(48)
Metal‐free carbon electrodes with well‐defined composition and smooth topography are prepared via sputter deposition followed by thermal treatment with inert and reactive gases. X‐ray photoelectron spectroscopy (XPS) and Raman spectroscopy show that three carbons of similar N/C content that differ in N‐site composition are thus prepared: an electrode consisting of almost exclusively graphitic‐N (NG), an electrode with predominantly pyridinic‐N (NP), and one with ≈1:1 NG:NP composition. These materials are used as model systems to investigate the activity of N‐doped carbons in the oxygen reduction reaction (ORR) using voltammetry. Results show that selectivity toward 4e‐reduction of O2 is strongly influenced by the NG/NP site composition, with the material possessing nearly uniform NG/NP composition being the only one yielding a 4e‐reduction. Computational studies on model graphene clusters are carried out to elucidate the effect of N‐site homogeneity on the reaction pathway. Calculations show that for pure NG‐doping or NP‐doping of model graphene clusters, adsorption of hydroperoxide and hydroperoxyl radical intermediates, respectively, is weak, thus favoring desorption prior to complete 4e‐reduction to hydroxide. Clusters with mixed NG/NP sites display synergistic effects, suggesting that co‐presence of these sites improves activity and selectivity by achieving high theoretical reduction potentials while facilitating retention of intermediates. 相似文献
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Metal–organic framework (MOF) composites have recently been considered as promising precursors to derive advanced metal/carbon‐based materials for various energy‐related applications. Here, a dual‐MOF‐assisted pyrolysis approach is developed to synthesize Co–Fe alloy@N‐doped carbon hollow spheres. Novel core–shell architectures consisting of polystyrene cores and Co‐based MOF composite shells encapsulated with discrete Fe‐based MOF nanocrystallites are first synthesized, followed by a thermal treatment to prepare hollow composite materials composed of Co–Fe alloy nanoparticles homogeneously distributed in porous N‐doped carbon nanoshells. Benefitting from the unique structure and composition, the as‐derived Co–Fe alloy@N‐doped carbon hollow spheres exhibit enhanced electrocatalytic performance for oxygen reduction reaction. The present approach expands the toolbox for design and preparation of advanced MOF‐derived functional materials for diverse applications. 相似文献
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Carbon Nanosheets: Nitrogen‐Doped Porous Carbon Nanosheets Templated from g‐C3N4 as Metal‐Free Electrocatalysts for Efficient Oxygen Reduction Reaction (Adv. Mater. 25/2016) 下载免费PDF全文
Huijun Yu Lu Shang Tong Bian Run Shi Geoffrey I. N. Waterhouse Yufei Zhao Chao Zhou Li‐Zhu Wu Chen‐Ho Tung Tierui Zhang 《Advanced materials (Deerfield Beach, Fla.)》2016,28(25):5140-5140
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Networking Pyrolyzed Zeolitic Imidazolate Frameworks by Carbon Nanotubes Improves Conductivity and Enhances Oxygen‐Reduction Performance in Polymer‐Electrolyte‐Membrane Fuel Cells 下载免费PDF全文
Chao Zhang Yu‐Cheng Wang Bing An Ruiyun Huang Cheng Wang Zhiyou Zhou Wenbin Lin 《Advanced materials (Deerfield Beach, Fla.)》2017,29(4)
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Electrocatalysts: Bottom‐Up Construction of Triazine‐Based Frameworks as Metal‐Free Electrocatalysts for Oxygen Reduction Reaction (Adv. Mater. 20/2015) 下载免费PDF全文
Long Hao Shuangshuang Zhang Rongji Liu Jing Ning Guangjin Zhang Linjie Zhi 《Advanced materials (Deerfield Beach, Fla.)》2015,27(20):3189-3189