【作者】 周鹏；

【导师】 王双印；

【作者基本信息】 湖南大学 ， 化学， 2018， 硕士

【摘要】 电解水是非常有希望应用于能量的储存与转换,但缓慢反应动力学的氧析出反应阻碍了其广泛应用。由于氧析出反应对绿色能源生产和储存的重要性,人们一直在寻找高效、低成本的氧析出电催化剂。贵金属氧析出催化剂的大规模应用受到其高成本和稀缺性的严重制约,而双金属层状氢氧化物(LDHs)由于其独特的层状结构和较好氧析出性能,常被认为有望替代贵金属用于氧析出反应。然而,LDHs的广泛应用受到其电子性质和活性位点的限制。本文主要通过化学刻蚀LDHs来优化结构和电子结构用于增强的氧析出反应,具体内容主要如下:1.作者通过简单有效的酸刻蚀LDHs的方法,在室温下对LDHs成功实现了缺陷的引入和形貌结构的优化。酸刻蚀能够增加无序度、提高导电性和调整表面性质,同步辐射数据和透射电子显微镜图像为酸蚀刻后形成多种空位提供了强有力的证据,这些空位从而导致氧析出催化活性的增强。同时,酸刻蚀使得LDHs纳米片变薄和表小,暴露了更多的活性位点。本研究不仅揭示了空位缺陷对电催化剂的关键作用,而且还开辟了一个简单的路线来优化电子结构和表面性质来设计开发未来的电催化剂。2.基于LDHs的体相形式和导电性差等问题,作者通过简单有效、方便经济的水热合成方法得到了富缺陷多级结构的LDHs,即将LDHs分散在乙二醇并水热从而得到产物。纳米片的变薄和变小以及多级结构,调整了形貌结构,暴露了更多的活性位点,促进了电子传输和离子扩散。而且大量缺陷的产生,优化了电子结构,提高了氧析出催化活性。经过水热反应之后,富缺陷多级结构的LDHs显示出很低的氧析出反应起始电位,实现了氧析出催化性能的巨大提升。此外,富缺陷多级结构的LDHs具有很小的Tafel斜率,进一步证明了缺陷的引入对氧析出反应催化性能的提高。通过缺陷工程来调整结构和电子结构的思路为先进催化剂的开发设计与性能优化打开了新的大门。更多还原

【Abstract】 Water splitting is promising for energy storage and conversion,but the sluggish oxygen evolution reaction（OER）hinders its wide application.The search for efficient and low-cost electrocatalysts for oxygen evolution has been pursued owing to their significance for green energy generation and storage.Noble metals and their oxides have seriously impeded their large-sacle applications because of their scarcity and high cost.Layered double hydroxides（LDHs）have been proposed as the most pro mising alternatives due to their unique layered structure and good intrinsic OER activity.Layered double hydroxides based materials are promising for the OER to improve this weakness.However,the wide application of LDHs is limited by their electronic properties and active sites.Chemical etched LDHs is used to optimize the structure and electronic properties for enhancing oxygen evolution reaction.The detailed research contents are as follows:1.Our work realized the desired product using a simple and effective method where HNO₃ was added to the LDHs suspension for etching,which results in the generation of multiple vacancies and optimization of structure.This can increase the disorder,improve the electronic conductivity and tune the surface propert ies.The XAFS data and TEM images provide strong evidence that multiple vacancies are formed after acid etching,resulting in the enhancement of the OER catalytic activity.Meanwhile,LDHs nanosheets which become thinner and smaller after acid etching exposure more active sites.This study not only demonstrates the key role of multiple vacancies for superior electrocatalysts,but also opens up a simple route to optimize the electronic structure and surface properties for advanced electrocatalytic performanc e in the future.2.Based on the bulk form and poor intrinsic conductivity,LDHs with rich defects and hierarchical structure was obtained by a simple and efficient hydrothermal method which use glycol.The thinner and smaller nanosheets,as well as the hi erarchical structure,tune the morphology and structure,exposure more active sites,and facilitate the electron transport.Moreover,a large number of defects are generated,which optimizes the electronic structure and improves the catalytic activity of o xygen evolution.After the hydrothermal reaction,the LDHs with rich defect s and hierarchical structure showed a very low onset potential of oxygen evolution,which achieved a great improvement in the catalytic performance of oxygen evolution.In addition,the LDHs with rich defects and hierarchical structure has a small Tafel slope,further proving that the introduction of defects improves the catalytic performance of oxygen evolution reaction.The method of tuning the structure and electronic properties b y defect engineering in this work will open a door for design and optimization of advanced catalysts in the future.更多还原