排序方式: 共有75条查询结果,搜索用时 0 毫秒
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Young Jin Sa Chiyoung Park Hu Young Jeong Seok‐Hee Park Zonghoon Lee Kyoung Taek Kim Gu‐Gon Park Sang Hoon Joo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(16):4186-4190
A facile, scalable route to new nanocomposites that are based on carbon nanotubes/heteroatom‐doped carbon (CNT/HDC) core–sheath nanostructures is reported. These nanostructures were prepared by the adsorption of heteroatom‐containing ionic liquids on the walls of CNTs, followed by carbonization. The design of the CNT/HDC composite allows for combining the electrical conductivity of the CNTs with the catalytic activity of the heteroatom‐containing HDC sheath layers. The CNT/HDC nanostructures are highly active electrocatalysts for the oxygen reduction reaction and displayed one of the best performances among heteroatom‐doped nanocarbon catalysts in terms of half‐wave potential and kinetic current density. The four‐electron selectivity and the exchange current density of the CNT/HDC nanostructures are comparable with those of a Pt/C catalyst, and the CNT/HDC composites were superior to Pt/C in terms of long‐term durability and poison tolerance. Furthermore, an alkaline fuel cell that employs a CNT/HDC nanostructure as the cathode catalyst shows very high current and power densities, which sheds light on the practical applicability of these new nanocomposites. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(26):7604-7607
Polymer electrolyte membranes employed in contemporary fuel cells severely limit device design and restrict catalyst choice, but are essential for preventing short‐circuiting reactions at unselective anode and cathode catalysts. Herein, we report that nickel sulfide Ni3S2 is a highly selective catalyst for the oxygen reduction reaction in the presence of 1.0 m formate. We combine this selective cathode with a carbon‐supported palladium (Pd/C) anode to establish a membrane‐free, room‐temperature formate fuel cell that operates under benign neutral pH conditions. Proof‐of‐concept cells display open circuit voltages of approximately 0.7 V and peak power values greater than 1 mW cm−2, significantly outperforming the identical device employing an unselective platinum (Pt) cathode. The work establishes the power of selective catalysis to enable versatile membrane‐free fuel cells. 相似文献
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Jiawei Zhu Yupeng Huang Wencen Mei Chenyang Zhao Chengtian Zhang Jian Zhang Ibrahim Saana Amiinu Shichun Mu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):3899-3904
Theoretical calculations reveal that intrinsic pentagons in the basal plane can contribute to the local electronic redistribution and the contraction of band gap, making the carbon matrix possess superior binding affinity and electrochemical reactivity. To experimentally verify this, a pentagon‐defect‐rich carbon nanomaterial was constructed by means of in situ etching of fullerene molecules (C60). The electrochemical tests show that, relative to hexagons, such a carbon‐based material with abundant intrinsic pentagon defects makes much greater contribution to the electrocatalytic oxygen reduction activity and electric double layer capacitance. It shows a four‐electron‐reaction mechanism similar to commercial Pt/C and other transition‐metal‐based catalysts, and a higher specific capacitance than many reported metal‐free carbon materials. These results show the influence of intrinsic pentagon defects for developing carbon‐based nanomaterials toward energy conversion and storage devices. 相似文献
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Jin Xie Bo‐Quan Li Hong‐Jie Peng Yun‐Wei Song Jia‐Xing Li Ze‐Wen Zhang Qiang Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(15):5017-5021
The preparation of carbon materials usually involves the decomposition of precursors and the reorganization of the as‐generated fragments. However, the cleavage of bonds and the simultaneous formation of new bonds at nearly the same positions prevents effective yet precise fabrication. Herein, a supramolecular precursor, cucurbit[6]uril, that contains multiple bonds with distinct bond strengths is proposed to decouple the twin problem of simultaneous bond cleavage and formation, allowing multistage transformations to hierarchical porous carbon and metal‐doped carbon in a single yet effective pyrolysis step without the need of a template or additional purification. As a proof‐of‐concept, the Fe‐doped carbon electrocatalysts realized a Pt/C‐like half‐wave potential of 0.869 V vs. RHE and small Tafel slope of 51.3 mV dec?1 in oxygen reduction reaction. 相似文献