采用以量子力学为基础的半经验计算方法—–自洽和环境依赖的原子轨道线性理论,预测了类α-石墨炔的碳锗炔结构.研究了α-碳锗炔的稳定结构、电子结构以及热力学稳定性,得到其最稳定的构型是Ge原子在六元环的六个顶角处,晶格常数为8.686?的六角原胞构成的单层平面蜂窝状结构.该结构是带隙为1.078 e V的半导体.α-碳锗炔在很高的温度下都可以保持稳定,直到2280 K时其长程有序态才被破坏,当体系低于此温度时,可以通过降温使其恢复到零温时的稳定平面结构.
In this work, we discussed the stochastic thermodynamics of mesoscopic electron transfer reactions between ions and electrodes. With a relationship between the reaction rate con- stant and the electrode potential, we ...
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In this work, we discussed the stochastic thermodynamics of mesoscopic electron transfer reactions between ions and electrodes. With a relationship between the reaction rate con- stant and the electrode potential, we find that the heat dissipation βq equals to the dynamic irreversibility of the reaction system minus an internal entropy change term. The total en- tropy change Ast is defined as the summation of the system entropy change As and the heat dissipation/βq such that △st=△s＋βq. Even though the heat dissipation depends linearly on the electrode potential, the total entropy change is found to satisfy the fluctuation theo- rem 〈e-△st 〉=1, and hence a second law-like inequality reads （△st）≥0. Our study provides a practical methodology for the stochastic thermodynamics of electrochemical reactions, which may find applications in biochemical and electrochemical reaction systems.
在众多能量存储和转化器件中,超级电容器由于具有功率密度高、充放电迅速和优异的循环性能的优点而被广泛研究.然而,较低的比容量和能量密度,限制了超级电容作为大尺度能量存储和转化器件的广泛应用.为了提高超级电容器的比容量,需要增大电极材料和电解质的接触面积,进而促进电极材料俘获/释放电解质中的粒子(例如电子、离子或者小分子).在此,我们通过简单的水热法联合高温退火实验方案能够大规模制备出镍泡沫支撑的Co_3O_4多孔纳米结构.无需借助导电胶和粘合剂,在集流器镍泡沫上"生长"Co_3O_4多孔纳米结构直接作为超级电容的电极材料.这种多孔纳米结构和一体化设计思路不仅能够有效提高电极的导电性,而且能够有效缩短离子和电子的迁移路径.由于多孔的结构特征和优异的导电性能,Co_3O_4电极表现出超高比容量(在电流密度为2.5 m A·cm^(-2)和5.5 m A·cm^(-2)时,比容量分别为1.87 F·cm(-2)(936 F·g-1)和1.80 F·cm^(-2)(907 F·g-1))、较好的倍率性能(电流密度从2.5 m A·cm^(-2)增大到100 m A·cm^(-2)时,保留其48.37%的初始电容)和超高的循环稳定性(经历4000次电流密度为10 m A·cm^(-2)的循环充放电过程,保留其92.3%的比容量).这种多孔纳米结构和一体化设计思路对设计其他高性能储能器件具有重要的指导意义.
Low‐temperature CO oxidation is important for both fundamental studies and practical applica‐tions. Supported gold catalysts are generally regarded as the most active catalysts for low‐temperature CO oxidation. The...
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Low‐temperature CO oxidation is important for both fundamental studies and practical applica‐tions. Supported gold catalysts are generally regarded as the most active catalysts for low‐temperature CO oxidation. The active sites are traditionally believed to be Au nanoclusters or nanoparticles in the size range of 0.5–5 nm. Only in the last few years have single‐atom Au catalysts been proved to be active for CO oxidation. Recent advances in both experimental and theoretical studies on single‐atom Au catalysts unambiguously demonstrated that when dispersed on suitable oxide supports the Au single atoms can be extremely active for CO oxidation. In this mini‐review, recent advances in the development of Au single‐atom catalysts are discussed, with the aim of illus‐trating their unique catalytic features during CO oxidation.
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