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Correlating the electronic structure of perovskite La_(1-x)SrxCoO_(3) with activity for the oxygen evolution reaction:The critical role of Co 3d hole state

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Journal of Energy Chemistry 2022年第2期31卷 637-645页

作者： Zechao Shen Mei Qu jueli shi Freddy E.Oropeza Victor A.de la Peña O’Shea Giulio Gorni C.M.Tian Jan P.Hofmann Jun Cheng Jun Li Kelvin H.L.Zhang State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005FujianChina Photoactivated Processes Unit IMDEA Energy InstituteParque Tecnológico de MóstolesAvda.Ramón de la Sagra 328935 MóstolesMadridSpain CELLS-ALBA Synchrotron Carrer de la Llum 2-2608290 Cerdanyola del VallèsSpain Surface Science Laboratory Department of Materials and Earth SciencesTechnical University of Darmstadt Otto-Berndt-Strasse 364287 DarmstadtGermany

Perovskite LaCoO_(3) is being increasingly explored as an effective low-cost electrocatalyst for the oxygen evolution reaction(OER).Sr doping in LaCoO_(3)(La1-xSrxCoO_(3))has been found to substantially increase its catalytic activity.In this work,we report a detailed study on the evolution of the electronic structure of La1-xSrxCoO_(3) with 0≤x≤1 and its correlation with electrocatalytic activity for the OER.A combination of X-ray photoemission spectroscopy(XPS)and X-ray absorption spectroscopy(XAS)was used to unravel the electronic density of states(DOS)near the Fermi level(EF),which provide insights into the key electronic structure features for the enhanced OER catalytic activity.Detailed analysis on the Co L-edge XAS suggest that LaCoO_(3) has a low spin state with t_(2g)^(6) e_(g)^(0) configuration at room temperature.This implies that the high OER catalytic activity of LaCoO_(3) should not be rationalized by the occupancy of eg=1 descriptor.Substituting Sr^(2+) for La^(3+) in LaCoO_(3) induces Co4+oxidation states and effectively dopes hole states into the top of valence band.A semiconductor-to-metal transition is observed for x>0.2,due to the holeinduced electronic DOS at the EF and increased hybridization between Co 3 d and O 2 p.Such an electronic modulation enhances the surface adsorption of the*OH intermediate and reduces the energy barrier for interfacial charge transfer,thus improving the OER catalytic activity in La_(1-x)Sr_(x)CoO_(3).In addition,we found that the La_(1-x)Sr_(x)CoO_(3) surface undergoes amorphization after certain period of OER measurement,leading to a partial deactivation of the electrocatalyst.High Sr doping levels accelerated the amorphization process.

关键词： Perovskite oxide Oxygen evolution Cobalt Electronic structure

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Solvent-dependent evolution of cyclic penta-twinned rhodium icosahedral nanocrystals and their enhanced catalytic properties

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Nano Research 2018年第2期11卷 656-664页

作者： Yanan Yang Jiawei Zhang Yajing Wei Qiaoli Chen Zhenming Cao Huiqi Li Jiayu Chen jueli shi Zhaoxiong Xie Lansun Zheng State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen China

Cyclic penta-twinned noble metal nanocrystals exhibit promising properties due to their unique geometric and electronic structures. However, the controlled synthesis of cyclic penta-twinned nanostructures, especially of noble metals with a high cohesive energy （e.g., Rh）, is very difficult, and the corresponding growth mechanism is not fully understood. Herein, we report a facile one-pot hydrothermal approach for the synthesis of cyclic penta-twinned Rh icosahedral nanocrystals. It was found that apart from regulating the surface free energy by changing the concentration or category of the capping agents, the solvent might influence the adsorption ability of the surfactant on the Rh crystal surface, which results in a change in the surface free energy and thus allows the formation of Rh cyclic penta-twinned nanostructures. In addition, due to their unique electronic and geometric structures, the Rh icosahedral nanocrystals exhibit superior catalytic activity and stability for the electrooxidation of ethanol as compared to single-crystal Rh tetrahedral nanocrystals and commercial Rh black.

关键词： Rhrcrystal growth,icosahedron,tetrahedron,electrocatalysis

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玄武岩纤维用于国内摩擦材料的可行性研究

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玻璃纤维 2005年第6期 5-7,11页

作者：熊松炉陈阳李振伟石珏李中材科技股份有限公司双威事业部南京210012

将试制的玄武岩短切纤维进行了配方试验和性能测试。分析玄武岩纤维在国内摩擦材料中的应用前景,介绍了玄武岩纤维在摩擦材料中的应用。通过对玄武岩短切纤维增强制动片的检测认为其适合作为摩擦材料的增强材料。

关键词：玄武岩纤维摩擦材料可行性研究增强材料

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