导　　师： 丁轶

学科专业： G0304

授予学位： 博士

作　　者： ;

机构地区： 山东大学

摘　　要： 20世纪80年代,Hutchings在研究乙炔氢氯化反应的机理时预测负载的金将对这一反应有较高的催化活性。随后,Haruta发现尺寸缩小到纳米量级、并且高度分散在Fe2O3、Co3O4、NiO等载体氧化物上的金,在低至-70℃的温度下,对CO的氧化仍具有很高的催化活性。这两大重要发现,彻底改变了人们一直以来对Au化学惰性的认识,引起了人们的高度关注,在世界范围内掀起了研究金纳米粒子的热潮。随着研究的深入,人们发现Au纳米粒子对很多反应都具有较高的催化活性,如CO的氧化、氮氧化物的还原、不饱和烃的氢化及烃类的燃烧等。同时,人们还研究了制备方法、载体氧化物种类、Au纳米粒子的尺寸、形貌及氧化态等因素对其催化性能的影响。通过这些探索,人们对金纳米材料的催化活性有了一定的认识,但尚不完善。比如,Au纳米粒子高催化活性的起因一直是备受争议的问题,目前人们还没有统一认识。另外,Au纳米粒子催化的CO氧化、H2O2的直接合成等一系列重要反应的机理也没有完全弄清楚。 Pt及Pt基催化剂是所有元素中催化性能最好、选择性最高、应用最为广泛的催化剂。特别值得一提的是,它们在质子交换膜燃料电池中有极高的潜在应用价值,如直接甲醇燃料电池等。然而,Pt电极易被反应生成的副产物CO毒化,导致其失活,加之Pt在全球的储量少、价格昂贵,人们一直在寻求提高Pt催化活性及利用率的方法,并不断开发高性能、低成本的催化剂。许多研究发现Pt-Au二元金属纳米粒子具有很好的抗CO中毒能力,而且对甲醇氧化、甲酸氧化等反应的催化活性较单一纯金属的高。另外,Au的加入使催化剂的成本大为降低,符合人们对“高性能、低成本”催化剂的要求。然而Pt-Au二元金属纳米粒子的微观结构还存在很多争议,有人认为该双金属可以形成均匀混合的合金结构,而� In the 1980's, supported Au has been prognosticated by Hutchings having higher catalytic activity toward the hydrochlorination of acetylene. Subsequently, it was found by Haruta et al that Au can exhibit surprisingly high catalytic activity for CO oxidation as low as-70℃when it is highly dispersed on Fe2O3、Co3O4、NiO. These vital findings make Au nanoparticles attract sustained experimental and theoretical interest and change the traditional impression about its inert activity. Using supported gold nanoparticles as catalysts, many important reactions have been achieved so far, including the oxidation of CO, the direct synthesis of H2O2 from H2 and O2, the reduction of nitrogen oxides, selective hydrogenation of unsaturated hydrocarbon, the combustion of hydrocarbons and so on. In the past decade, many experimental and theoretical studies have been devoted to unveiling the origin of the catalytic activity of Au nanoparticles. The effects of preparation method, support oxides, oxidation state, size and morphology of Au particles have been investigated. However, there is no consensus on the crucial factors that govern the catalytic activity of Au nanoparticles. And our understanding for the mechanisms of CO oxidation and H2O2 formation from H2 and O2 are still far from complete. Pt and Pt-based particles, which have extensive application, are regarded as the most active catalysts with the highest selectivity among the chemical elements. It is worthy to note that they have potential application in proton exchange membrane fuel cell, such as direct methanol fuel cell. However, the Pt electrode can be easily poisoned by the byproduct CO and loss the catalytic activity. Moreover, the scarce world reserves of Pt make it much more expensive than the other noble metals, such as Au. Thus, the enhanced activity and most effective utilization of Pt catalyst are desired. Up to date, much effort has been devoted to develop the 'less expensive and more efficient' Pt-based catalysts. Several groups have consistently obs

关 键 词： 密度泛函理论 团簇 氧化 反应机理 二元金属 微观结构

领　　域： [自动化与计算机技术] [自动化与计算机技术] [电子电信]