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具有逐块圆型边界的堆垒域上的--方程的一致估计 被引量:1
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作者 林良裕 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 1999年第2期167-172,共6页
C^n空间中由任意N个圆型域构成的具有逐块圆型边界的堆叠域D,建立了具有离散全纯核的整体Bochner-Martinelli-Norguet积分公式,获得了^-δ-方程^-δu=g的整体解及其一致估计。
关键词 一致估计 逐块圆型边界 ^-δ方程 堆叠域
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Synergy of staggered stacking confinement and microporous defect fixation for high‐density atomic Fe^(Ⅱ)‐N_(4)oxygen reduction active sites 被引量:1
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作者 Menghui Chen Yongting Chen +6 位作者 Zhili Yang Jin Luo Jialin Cai Joey Chung‐Yen Jung Jiujun Zhang Shengli Chen Shiming Zhang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2022年第7期1870-1878,共9页
The development of high‐performance nonprecious metal catalysts(NPMCs)to supersede Pt‐based catalysts for the oxygen reduction reaction(ORR)in polymer electrolyte membrane fuel cells is highly desirable but remains ... The development of high‐performance nonprecious metal catalysts(NPMCs)to supersede Pt‐based catalysts for the oxygen reduction reaction(ORR)in polymer electrolyte membrane fuel cells is highly desirable but remains challenging.In this paper,we present a pyrolysis strategy for spatial confinement and active‐site fixation using iron phthalocyanine(FePc),phthalocyanine(Pc)and Zn salts as precursors.In the obtained carbon‐based NPMC with a hierarchically porous nanostructure of thin‐layered carbon nanosheets,nearly 100%of the total Fe species are Fe^(Ⅱ)‐N_(4) active sites.In contrast,pyrolyzing FePc alone forms Fe‐based nanoparticles embedded in amorphous carbon with only 5.9%Fe^(Ⅱ)‐N_(4) active sites.Both experimental characterization and density functional theory calculations reveal that spatial confinement through the staggeredπ–πstacking of Pc macrocycles effectively prevents the demetallation of Fe atoms and the formation of Fe‐based nanoparticles via aggregation.Furthermore,Zn‐induced microporous defects allow the fixation of Fe^(Ⅱ)‐N_(4) active sites.The synergistic effect of staggered stacking confinement and microporous defect fixation results in a high density of atomic Fe^(Ⅱ)‐N_(4) active sites that can enhance the ORR.The optimal Fe^(Ⅱ)‐N_(4)‐C electro‐catalyst outperforms a commercial Pt/C catalyst in terms of half‐wave potential,methanol toler‐ance,and long‐term stability in alkaline media.This modulation strategy can greatly advance efforts to develop high‐performance NPMCs. 展开更多
关键词 Oxygen reduction reaction Synergy strategy Staggered stacking confinement Microporous defects fixation Fe^(Ⅱ)‐N_(4)
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