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1.
Conjugated microporous polymers (CMPs) as emerging porous materials with diverse structures and tunable building‐units have attracted much attention in the electrochemical field. Herein, we designed phthalocyanine‐porphyrin‐based conjugated microporous polymers as precursors for fabrication of Co, Fe, N tri‐doped graphene composites towards oxygen reduction and evolution reaction (ORR/OER). As expected, the elements cobalt and iron are well dispersed in graphene carbon and interact with the nitrogen sites, thereby providing extra electrocatalytic active sites and enhancing its overall conductivity. Benefiting from its unique design and structure, the obtained catalyst affords a superior bifunctional catalytic activity with a positive onset potential of 0.957 V for ORR, and a low overpotential of 0.36 V for OER. More attractively, the CoFeNG is employed as an air cathode catalyst in Zn‐air batteries, showing a maximum current density of 215 mA cm?2 and good cycle stability for 20000 s. The rational design of phthalocyanine‐porphyrin‐based derivatives provides a feasible route for the construction of high‐performance ORR/OER catalysts. 相似文献
2.
Shunyao Yan Zixun Yu Chang Liu Ziwen Yuan Chaojun Wang Junsheng Chen Li Wei Yuan Chen 《化学:亚洲杂志》2020,15(12):1881-1889
Cost‐effective and high‐performance electrocatalysts for oxygen reduction reactions (ORR) are needed for many energy storage and conversion devices. Here, we demonstrate that whey powder, a major by‐product in the dairy industry, can be used as a sustainable precursor to produce heteroatom doped carbon electrocatalysts for ORR. Rich N and S compounds in whey powders can generate abundant catalytic active sites. However, these sites are not easily accessible by reactants of ORR. A dual‐template method was used to create a hierarchically and interconnected porous structure with micropores created by ZnCl2 and large mesopores generated by fumed SiO2 particles. At the optimum mass ratio of whey power: ZnCl2 : SiO2 at 1 : 3 : 0.8, the resulting carbon material has a large specific surface area close to 2000 m2 g?1, containing 4.6 at.% of N with 39.7% as pyridinic N. This carbon material shows superior electrocatalytic activity for ORR, with an electron transfer number of 3.88 and a large kinetic limiting current density of 45.40 mA cm?2. They were employed as ORR catalysts to assemble primary zinc‐air batteries, which deliver a power density of 84.1 mW cm?2 and a specific capacity of 779.5 mAh g?1, outperforming batteries constructed using a commercial Pt/C catalyst. Our findings open new opportunities to use an abundant biomaterial, whey powder, to create high‐value‐added carbon electrocatalysts for emerging energy applications. 相似文献
3.
Thangavelu Palaniselvam Bishnu P. Biswal Dr. Rahul Banerjee Dr. Sreekumar Kurungot 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(28):9335-9342
The facile synthesis of a porous carbon material that is doped with iron‐coordinated nitrogen active sites (FeNC‐70) is demonstrated by following an inexpensive synthetic pathway with a zeolitic imidazolate framework (ZIF‐70) as a template. To emphasize the possibility of tuning the porosity and surface area of the resulting carbon materials based on the structure of the parent ZIF, two other ZIFs, that is, ZIF‐68 and ZIF‐69, are also synthesized. The resulting active carbon material that is derived from ZIF‐70, that is, FeNC‐70, exhibits the highest BET surface area of 262 m2 g?1 compared to the active carbon materials that are derived from ZIF‐68 and ZIF‐69. The HR‐TEM images of FeNC‐70 show that the carbon particles have a bimodal structure that is composed of a spherical macroscopic pore (about 200 nm) and a mesoporous shell. X‐ray photoelectron spectroscopy (XPS) reveals the presence of Fe‐N‐C moieties, which are the primary active sites for the oxygen‐reduction reaction (ORR). Quantitative estimation by using EDAX analysis reveals a nitrogen content of 14.5 wt. %, along with trace amounts of iron (0.1 wt. %), in the active FeNC‐70 catalyst. This active porous carbon material, which is enriched with Fe‐N‐C moieties, reduces the oxygen molecule with an onset potential at 0.80 V versus NHE through a pathway that involves 3.3–3.8 e? under acidic conditions, which is much closer to the favored 4 e? pathway for the ORR. The onset potential of FeNC‐70 is significantly higher than those of its counterparts (FeNC‐68 and FeNC‐69) and of other reported systems. The FeNC‐based systems also exhibit much‐higher tolerance towards MeOH oxidation and electrochemical stability during an accelerated durability test (ADT). Electrochemical analysis and structural characterizations predict that the active sites for the ORR are most likely to be the in situ generated N? FeN2+2/C moieties, which are distributed along the carbon framework. 相似文献
4.
Dr. Ying Xiao Dr. Chuangang Hu Prof. Liangti Qu Prof. Changwen Hu Prof. Minhua Cao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(42):14271-14278
A facile and low‐cost strategy is developed to prepare three‐dimensional (3D) macroporous NiCo2O4 sheets, which can be used as a highly efficient non‐noble metal electrocatalyst for the oxygen reduction reaction (ORR) in alkaline conditions. The as‐obtained sheets have a thickness of about 150 nm and feature a typical 3D macroporous structure with pore volumes of up to 0.23 cm3 g?1, which could decrease the mass transport resistance and allow easier access of the reactants to the active surface sites. The as‐prepared macroporous NiCo2O4 sheets exhibit high electrocatalytic activity for ORR with a four‐electron pathway, good long‐term stability and high tolerance against methanol. The unique 3D macroporous structure and intrinsic properties may be responsible for their high performance. 相似文献
5.
Pyrolysis of Animal Bones with Vitamin B12: A Facile Route to Efficient Transition Metal–Nitrogen–Carbon (TM‐N‐C) Electrocatalysts for Oxygen Reduction
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Dr. Meiling Dou Duanpeng He Wenhao Shao Dr. Haijing Liu Prof. Feng Wang Prof. Liming Dai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):2896-2901
By pyrolyzing cattle bones, hierarchical porous carbon (HPC) networks with a high surface area (2520 m2 g?1) and connected pores were prepared at a low cost and large scale. Subsequent co‐pyrolysis of HPC with vitamin B12 resulted in the formation of three‐dimensional (3D) hierarchically structured porous cobalt–nitrogen–carbon (Co‐N‐HPC) electrocatalysts with a surface area as high as 859 m2 g?1 as well as a higher oxygen reduction reaction (ORR) electrocatalytic activity, better operation stability, and higher tolerance to methanol than the commercial Pt/C catalyst in alkaline electrolyte. 相似文献
6.
High‐Rate Oxygen Electroreduction over Graphitic‐N Species Exposed on 3D Hierarchically Porous Nitrogen‐Doped Carbons
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Wenhui He Chunhuan Jiang Jiabo Wang Prof. Lehui Lu 《Angewandte Chemie (International ed. in English)》2014,53(36):9503-9507
Nitrogen‐doped species (NDs) are theoretically accepted as a determinant of the catalytic activity of metal‐free N‐doped carbon (NC) catalysts for oxygen reduction reaction (ORR). However, direct relationships between ND type and ORR activity have been difficult to extract because the complexity of carbon matrix impairs efforts to expose specific NDs. Herein, we demonstrate the fabrication of a 3D hierarchically porous NC catalyst with micro‐, meso‐, and macroporosity in one structure, in which sufficient exposure and availability of inner‐pore catalytic sites can be achieved due to its super‐high surface area (2191 cm2 g?1) and interconnected pore system. More importantly, in‐situ formation of graphitic‐N species (GNs) on the surface of NC stimulated by KOH activation enables us to experimentally reveal the catalytic nature of GNs for ORR, which is of great significance for the design and development of advanced metal‐free NC electrocatalysts. 相似文献
7.
Hyperporous‐Carbon‐Supported Nonprecious Metal Electrocatalysts for the Oxygen Reduction Reaction
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《化学:亚洲杂志》2018,13(18):2671-2676
Highly porous carbonaceous nonprecious metal catalysts for the oxygen reduction reaction are prepared by carbonization of low‐cost metalloporphyrin‐based hyper‐crosslinked polymers (MPH‐X). With high surface area (2768 m2 g−1), hierarchical porous structure, and high metal loading (9.97 wt %), the obtained hyperporous carbon MPH‐Fe/C catalyst exhibits high oxygen reduction reaction (ORR) activity with a half‐wave potential (0.816 V) that is comparable to the 0.819 V of commercial Pt/C. Stability tests reveal that MPH‐Fe/C also exhibits outstanding long‐term durability and methanol tolerance. Our findings may offer an alternative approach to produce nonprecious metal ORR catalysts on a large scale owing to the low‐cost MPH‐X precursors with diverse metal types. 相似文献
8.
Platinum Multicubes Prepared by Ni2+‐Mediated Shape Evolution Exhibit High Electrocatalytic Activity for Oxygen Reduction
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Liang Ma Dr. Chengming Wang Dr. Bao Yu Xia Keke Mao Jiawei He Prof. Xiaojun Wu Prof. Yujie Xiong Prof. Xiong Wen Lou 《Angewandte Chemie (International ed. in English)》2015,54(19):5666-5671
Pt(100) facets are generally considered less active for the oxygen reduction reaction (ORR). Reported herein is a unique Pt‐branched structure, a multicube, whose surface is mostly enclosed by {100} facets but contains high‐index facets at the small junction area between the adjacent cubic components. The synthesis is accomplished by a Ni2+‐mediated facet evolution from high‐index {311} to {100} facets on the frameworks of multipods. Despite the high {100} facet coverage, the Pt multicubes exhibit impressive ORR activity in terms of half‐wave potential and current density nearly to the level of the most active Pt‐based catalysts, while the durability of catalysts is well retained. The facet evolution creates a set of samples with tunable ratios of high‐index to low‐index facets. The results reveal that the excellent ORR performance of Pt multicubes is a combined result of active sites by high‐index facets and low resistance by flat surface. It is anticipated that this work will offer a new approach to facet‐controlled synthesis and ORR catalysts design. 相似文献
9.
Nitrogen and Phosphorus Dual‐Doped Hierarchical Porous Carbon Foams as Efficient Metal‐Free Electrocatalysts for Oxygen Reduction Reactions
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Dr. Hongliang Jiang Prof. Yihua Zhu Dr. Qian Feng Dr. Yunhe Su Prof. Xiaoling Yang Prof. Chunzhong Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):3106-3112
Despite tremendous progress in developing doped carbocatalysts for the oxygen reduction reaction (ORR), the ORR activity of current metal‐free carbocatalysts is still inferior to that of conventional Pt/C catalysts, especially in acidic media and neutral solution. Moreover, it also remains a challenge to develop an effective and scalable method for the synthesis of metal‐free carbocatalysts. Herein, we have developed nitrogen and phosphorus dual‐doped hierarchical porous carbon foams (HP‐NPCs) as efficient metal‐free electrocatalysts for ORR. The HP‐NPCs were prepared for the first time by copyrolyzing nitrogen‐ and phosphorus‐containing precursors and poly(vinyl alcohol)/polystyrene (PVA/PS) hydrogel composites as in situ templates. Remarkably, the resulting HP‐NPCs possess controllable nitrogen and phosphorus content, high surface area, and a hierarchical interconnected macro‐/mesoporous structure. In studying the effects of the HP‐NPCs on the ORR, we found that the as‐prepared HP‐NPC materials exhibited not only excellent catalytic activity for ORR in basic, neutral, and acidic media, but also much better tolerance for methanol oxidation and much higher stability than the commercial, state‐of‐the‐art Pt/C catalysts. Because of all these outstanding features, it is expected that the HP‐NPC material will be a very suitable catalyst for next‐generation fuel cells and lithium–air batteries. In addition, the novel synthetic method described here might be extended to the preparation of many other kinds of hierarchical porous carbon materials or porous carbon that contains metal oxide for wide applications including energy storage, catalysis, and electrocatalysis. 相似文献
10.
Ionic Liquids as Precursors for Efficient Mesoporous Iron‐Nitrogen‐Doped Oxygen Reduction Electrocatalysts
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Dr. Zelong Li Dr. Guanglan Li Prof. Luhua Jiang Jinlei Li Prof. Gongquan Sun Prof. Chungu Xia Prof. Fuwei Li 《Angewandte Chemie (International ed. in English)》2015,54(5):1494-1498
A ferrocene‐based ionic liquid (Fe‐IL) is used as a metal‐containing feedstock with a nitrogen‐enriched ionic liquid (N‐IL) as a compatible nitrogen content modulator to prepare a novel type of non‐precious‐metal–nitrogen–carbon (M‐N‐C) catalysts, which feature ordered mesoporous structure consisting of uniform iron oxide nanoparticles embedded into N‐enriched carbons. The catalyst Fe10@NOMC exhibits comparable catalytic activity but superior long‐term stability to 20 wt % Pt/C for ORR with four‐electron transfer pathway under alkaline conditions. Such outstanding catalytic performance is ascribed to the populated Fe (Fe3O4) and N (N2) active sites with synergetic chemical coupling as well as the ordered mesoporous structure and high surface area endowed by both the versatile precursors and the synthetic strategy, which also open new avenues for the development of M‐N‐C catalytic materials. 相似文献
11.
Haixia Zhong Khoa Hoang Ly Mingchao Wang Yulia Krupskaya Xiaocang Han Jichao Zhang Jian Zhang Vladislav Kataev Bernd Büchner Inez M. Weidinger Stefan Kaskel Pan Liu Mingwei Chen Renhao Dong Xinliang Feng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(31):10787-10792
Layered two‐dimensional (2D) conjugated metal–organic frameworks (MOFs) represent a family of rising electrocatalysts for the oxygen reduction reaction (ORR), due to the controllable architectures, excellent electrical conductivity, and highly exposed well‐defined molecular active sites. Herein, we report a copper phthalocyanine based 2D conjugated MOF with square‐planar cobalt bis(dihydroxy) complexes (Co‐O4) as linkages (PcCu‐O8‐Co) and layer‐stacked structures prepared via solvothermal synthesis. PcCu‐O8‐Co 2D MOF mixed with carbon nanotubes exhibits excellent electrocatalytic ORR activity (E1/2=0.83 V vs. RHE, n=3.93, and jL=5.3 mA cm?2) in alkaline media, which is the record value among the reported intrinsic MOF electrocatalysts. Supported by in situ Raman spectro‐electrochemistry and theoretical modeling as well as contrast catalytic tests, we identified the cobalt nodes as ORR active sites. Furthermore, when employed as a cathode electrocatalyst for zinc–air batteries, PcCu‐O8‐Co delivers a maximum power density of 94 mW cm?2, outperforming the state‐of‐the‐art Pt/C electrocatalysts (78.3 mW cm?2). 相似文献
12.
Enhanced Electrocatalytic Performance of a Porous g‐C3N4/Graphene Composite as a Counter Electrode for Dye‐Sensitized Solar Cells
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Prof. Guiqiang Wang Dr. Juan Zhang Dr. Shuai Kuang Dr. Wei Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11763-11769
A porous graphitic carbon nitride (g‐C3N4)/graphene composite was prepared by a simple hydrothermal method and explored as the counter electrode of dye‐sensitized solar cells (DSCs). The obtained g‐C3N4/graphene composite was characterized by XRD, SEM, TEM, FTIR spectroscopy, and X‐ray photoelectron spectroscopy. The results show that incorporating graphene nanosheets into g‐C3N4 forms a three‐dimensional architecture with a high surface area, porous structure, efficient electron‐transport network, and fast charge‐transfer kinetics at the g‐C3N4/graphene interfaces. These properties result in more electrocatalytic active sites and facilitate electrolyte diffusion and electron transport in the porous framework. As a result, the as‐prepared porous g‐C3N4/graphene composite exhibits an excellent electrocatalytic activity. In I?/I3? redox electrolyte, the charge‐transfer resistance of the porous g‐C3N4/graphene composite electrode is 1.8 Ω cm2, which is much lower than those of individual g‐C3N4 (70.1 Ω cm2) and graphene (32.4 Ω cm2) electrodes. This enhanced electrocatalytic performance is beneficial for improving the photovoltaic performance of DSCs. By employing the porous g‐C3N4/graphene composite as the counter electrode, the DSC achieves a conversion efficiency of 7.13 %. This efficiency is comparable to 7.37 % for a cell with a platinum counter electrode. 相似文献
13.
Xiao‐Tong Wang Ting Ouyang Ling Wang Jia‐Huan Zhong Zhao‐Qing Liu 《Angewandte Chemie (International ed. in English)》2020,59(16):6492-6499
Herein, we highlight redox‐inert Zn2+ in spinel‐type oxide (ZnXNi1?XCo2O4) to synergistically optimize physical pore structure and increase the formation of active species on the catalyst surface. The presence of Zn2+ segregation has been identified experimentally and theoretically under oxygen‐evolving condition, the newly formed VZn?O?Co allows more suitable binding interaction between the active center Co and the oxygenated species, resulting in superior ORR performance. Moreover, a liquid flow Zn–air battery is constituted employing the structurally optimized Zn0.4Ni0.6Co2O4 nanoparticles supported on N‐doped carbon nanotube (ZNCO/NCNTs) as an efficient air cathode, which presents remarkable power density (109.1 mW cm?2), high open circuit potential (1.48 V vs. Zn), excellent durability, and high‐rate performance. This finding could elucidate the experimentally observed enhancement in the ORR activity of ZnXNi1?XCo2O4 oxides after the OER test. 相似文献
14.
Gaopeng Liu Bin Wang Li Xu Penghui Ding Pengfei Zhang Jiexiang Xia Huaming Li Junchao Qian 《催化学报》2018,39(4):790-799
The oxygen reduction reaction (ORR) is a vitally important process in fuel cells. The development of high-performance and low-cost ORR electrocatalysts with outstanding stability is essential for the commercialization of the electrochemical energy technology. Herein, we report a facile synthesis of cobalt (Co) and nitrogen (N) co-doped carbon nanotube@porous carbon (Co/N/CNT@PC-800) electrocatalyst through a one-step pyrolysis of waste paper, dicyandiamide, and cobalt(II) acetylacetonate. The surface of the hierarchical porous carbon supported a large number of carbon nanotubes (CNTs), which were derived from dicyandiamide through the catalysis of Co. The addition of Co resulted in the formation of a hierarchical micro/mesoporous structure, which was beneficial for the exposure of active sites and rapid transportation of ORR-relevant species (O2, H+, OH?, and H2O). The doped N and Co formed more active sites to enhance the ORR activity of the electrocatalyst. The Co/N/CNT@PC-800 material exhibited optimal ORR performance with an onset potential of 0.005 V vs. Ag/AgCl and a half-wave potential of –0.173 V vs. Ag/AgCl. Meanwhile, the electrocatalyst showed an excellent methanol tolerance and a long-term operational durability than that of Pt/C, as well as a quasi-four-electron reaction pathway. The low-cost and simple synthesis approach makes the Co/N/CNT@PC-800 a prospective electrocatalyst for the ORR. Furthermore, this work provides an alternative approach for exploring the use of biomass-derived electrocatalysts for renewable energy applications. 相似文献
15.
Xiaoxia Lv Xue Xue Xingyu Gan Chenhao Lv Xiaochen Sun Yun Wang Liangjun Li Hua Wang 《化学:亚洲杂志》2020,15(3):432-439
High‐performance non‐noble electrocatalysts for oxygen reduction reaction (ORR) are the prerequisite for large‐scale utilization of fuel cells. Herein, a type of sandwiched‐like non‐noble electrocatalyst with highly dispersed FeNx active sites embedded in a hierarchically porous carbon/graphene heterostructure was fabricated using a bottom‐up strategy. The in situ ion substitution of Fe3+ in a nitrogen‐containing MOF (ZIF‐8) allows the Fe‐heteroatoms to be uniformly distributed in the MOF precursor, and the assembly of Fe‐doped ZIF‐8 nano‐crystals with graphene‐oxide and in situ reduction of graphene‐oxide afford a sandwiched‐like Fe‐doped ZIF‐8/graphene heterostructure. This type of heterostructure enables simultaneous optimization of FeNx active sites, architecture and interface properties for obtaining an electron‐catalyst after a one‐step carbonization. The synergistic effect of these factors render the resulting catalysts with excellent ORR activities. The half‐wave potential of 0.88 V vs. RHE outperforms most of the none‐noble metal catalyst and is comparable with the commercial Pt/C (20 wt %) catalyst. Apart from the high activity, this catalyst exhibits excellent durability and good methanol‐tolerance. Detailed investigations demonstrate that a moderate content of Fe dopants can effectively increase the intrinsic activities, and the hybridization of graphene can enhance the reaction kinetics of ORR. The strategy proposed in this work gives an inspiration towards developing efficient noble‐metal‐free electrocatalysts for ORR. 相似文献
16.
《化学:亚洲杂志》2017,12(1):60-66
We prepared a non‐precious‐metal tungsten nitride‐cobalt (WN‐Co) electrocatalyst anchored in nitrogen‐doped ordered porous carbon (NOPC) through an in situ method. The WN‐Co/NOPC electrocatalyst possesses good oxygen reduction reaction (ORR) capability in alkaline media, including a high onset potential of −132 mV, a dominant four‐electron process, and a superior stability (onset potential and limiting current density were almost unchanged after 5000 cycles in 0.1 m KOH). The improved ORR performance was comparable to that of WN/NOPC and Co/NOPC with regard to three aspects: the even dispersion and uniform size of electrocatalyst particles provide more reactive sites; the nitrogen doping, high specific surface area and highly ordered mesoporous channel of catalyst support (NOPC) are conducive to the infiltration of the electrolyte; the existence of WN reinvests the catalyst with good stability, and the anchored configuration of WN and Co in the NOPC will prevent the particles from agglomerating after a long‐term cycle, thereby improving the stability of the catalyst particles. 相似文献
17.
Nitrogen‐Doped Carbon Nanosheets with Size‐Defined Mesopores as Highly Efficient Metal‐Free Catalyst for the Oxygen Reduction Reaction
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Wei Wei Dr. Haiwei Liang Khaled Parvez Dr. Xiaodong Zhuang Prof. Xinliang Feng Prof. Klaus Müllen 《Angewandte Chemie (International ed. in English)》2014,53(6):1570-1574
Nitrogen‐doped carbon nanosheets (NDCN) with size‐defined mesopores are reported as highly efficient metal‐free catalyst for the oxygen reduction reaction (ORR). A uniform and tunable mesoporous structure of NDCN is prepared using a templating approach. Such controlled mesoporous structure in the NDCN exerts an essential influence on the electrocatalytic performance in both alkaline and acidic media for the ORR. The NDCN catalyst with a pore diameter of 22 nm exhibits a more positive ORR onset potential than that of Pt/C (?0.01 V vs. ?0.02 V) and a high diffusion‐limited current approaching that of Pt/C (5.45 vs. 5.78 mA cm?2) in alkaline medium. Moreover, the catalyst shows pronounced electrocatalytic activity and long‐term stability towards the ORR under acidic conditions. The unique planar mesoporous shells of the NDCN provide exposed highly electroactive and stable catalytic sites, which boost the electrocatalytic activity of metal‐free NDCN catalyst. 相似文献
18.
Accelerating Oxygen‐Reduction Catalysts through Preventing Poisoning with Non‐Reactive Species by Using Hydrophobic Ionic Liquids
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Dr. Gui‐Rong Zhang Dr. Macarena Munoz Prof.Dr. Bastian J. M. Etzold 《Angewandte Chemie (International ed. in English)》2016,55(6):2257-2261
Developing cost‐effective electrocatalysts for the oxygen reduction reaction (ORR) is a prerequisite for broad market penetration of low‐temperature fuel cells. A major barrier stems from the poisoning of surface sites by nonreactive oxygenated species and the sluggish ORR kinetics on the Pt catalysts. Herein we report a facile approach to accelerating ORR kinetics by using a hydrophobic ionic liquid (IL), which protects Pt sites from surface oxidation, making the IL‐modified Pt intrinsically more active than its unmodified counterpart. The mass activity of the catalyst is increased by three times to 1.01 A mg?1Pt@0.9 V, representing a new record for pure Pt catalysts. The enhanced performance of the IL‐modified catalyst can be stabilized after 30 000 cycles. We anticipate these results will form the basis for an unprecedented perspective in the development of high‐performing electrocatalysts for fuel‐cell applications. 相似文献
19.
Coordination Chemistry of [Co(acac)2] with N‐Doped Graphene: Implications for Oxygen Reduction Reaction Reactivity of Organometallic Co‐O4‐N Species
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Jongwoo Han Young Jin Sa Yeonjun Shim Min Choi Prof. Dr. Noejung Park Prof. Dr. Sang Hoon Joo Prof. Dr. Sungjin Park 《Angewandte Chemie (International ed. in English)》2015,54(43):12622-12626
Hybridization of organometallic complexes with graphene‐based materials can give rise to enhanced catalytic performance. Understanding the chemical structures within hybrid materials is of primary importance. In this work, archetypical hybrid materials are synthesized by the reaction of an organometallic complex, [CoII(acac)2] (acac=acetylacetonate), with N‐doped graphene‐based materials at room temperature. Experimental characterization of the hybrid materials and theoretical calculations reveal that the organometallic cobalt‐containing species is coordinated to heterocyclic groups in N‐doped graphene as well as to its parental acac ligands. The hybrid material shows high electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline media, and superior durability and methanol tolerance to a Pt/C catalyst. Based on the chemical structures and ORR experiments, the catalytically active species is identified as a Co‐O4‐N structure. 相似文献
20.
Peiqun Yin Tao Yao Yuen Wu Lirong Zheng Yue Lin Wei Liu Huanxin Ju Junfa Zhu Xun Hong Zhaoxiang Deng Gang Zhou Shiqiang Wei Yadong Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(36):10958-10963
A new strategy for achieving stable Co single atoms (SAs) on nitrogen‐doped porous carbon with high metal loading over 4 wt % is reported. The strategy is based on a pyrolysis process of predesigned bimetallic Zn/Co metal–organic frameworks, during which Co can be reduced by carbonization of the organic linker and Zn is selectively evaporated away at high temperatures above 800 °C. The spherical aberration correction electron microscopy and extended X‐ray absorption fine structure measurements both confirm the atomic dispersion of Co atoms stabilized by as‐generated N‐doped porous carbon. Surprisingly, the obtained Co‐Nx single sites exhibit superior ORR performance with a half‐wave potential (0.881 V) that is more positive than commercial Pt/C (0.811 V) and most reported non‐precious metal catalysts. Durability tests revealed that the Co single atoms exhibit outstanding chemical stability during electrocatalysis and thermal stability that resists sintering at 900 °C. Our findings open up a new routine for general and practical synthesis of a variety of materials bearing single atoms, which could facilitate new discoveries at the atomic scale in condensed materials. 相似文献