金属纳米催化剂表面应力调控及其催化性能研究

Metal nanocrystals are of great importance to modern science and technology, with their wide applications ranging from industry to biology. Most recently, researchers have shown that the strong relationship between the surface lattice strain of metal nanocrystals and their properties, thus mastery over the lattice strain enables enhancement of their usefulness for a given applications. In the case of catalysis, it is well-established that the activity and selectivity of a metal nanocrystal can be tuned by manipulating its surface lattice strian. Therefore, synthesis of metal nanocrystals with controllable lattice strain has attracted numerous attentions during the past decades, and many significant progresses have been made by far. How to establish a facile and robust tailoring strategy to control the surface lattice strain so as to improve their catalytic properties is still an urgent topic and a focus of current nanometerials research. In this project, we propose a novel tailoring strategy based on the insertion of nonmetallic atoms into the surface lattice of metal nanocrystals, thus tailoring the distance between metal atoms, so as to manipulate the lattice strain of metal nanocrystals. Based on these metal nanocrystals with well-controlled surface lattice strains, their unique physical and chemical properties and potential applications will be further studied. We plan to perform solution phase synthesis, which based on the addition of the original metal nanocrystals and the nonmetallic atom precursors. Through tuning the reaction parameters, the high quality of metal nanocrystals with well controlled surface lattice strains will be prepared, followed by the study of their catalytci properties toward different reactions. This ressearch results can provide the new principles and methods to tailor the surface lattice strains of metal nanocatalysts, thus optimize the catalytic properties of metal nanocrystals through tuning surface lattice strains.

金属纳米材料由于其优越的催化活性在现代工业催化中起着至关重要的作用。近期，大量研究表明金属纳米晶体的表面晶格应力直接决定了材料的某些物理化学性质乃至催化活性和选择性。如何建立简单普适的调控策略，有效调控金属纳米晶体的表面应力是目前金属纳米材料研究中面临的焦点问题。本课题提出在纳米尺度下，利用非金属原子嵌入金属纳米晶体表面，通过调控嵌入原子浓度，连续大范围调控金属纳米晶体的表面应力，实现金属纳米催化剂表面应力的精细调控，并探索表面应力对材料催化性能的影响和潜在的催化应用前景。拟采用液相法，在含有金属纳米晶体和嵌入原子前驱体的溶液中，通过控制反应条件，获得表面应力得到精确调控的单分散、表面结构均一的高质量金属纳米材料，并对其电催化性能进行深入研究，最终获得高效的金属纳米催化剂。本课题研究成果将有助于提供构建高性能金属纳米催化剂的新途径，进一步拓展金属纳米晶体在催化领域的实际应用。

能源的高效、有序转化是推动能源可持续发展的关键所在。催化转化是实现能源转化的重要方式。传统催化剂在催化能源转化过程中存在能量无序释放、转化效率低、能耗大及易对环境造成污染等问题，已成为制约我国能源可持续发展战略的瓶颈。对现有催化体系的优化刻不容缓。“应变调控”技术通过改变原子间距调节能源转化过程中关键物种在材料表面的吸附强度和吸附位点，为现有催化体系的优化提供了重要手段。然而现有的技术皆因无法对材料表面进行连续、精准应变调控而难以取得令人满意的效果。在本项目的支持下，本课题组通过系统研究提出了崭新的“应变调控”策略，通过构建核壳体系，利用内核的膨胀和收缩在材料表面实现广泛可调的晶格应变；结合系统的材料制备、表征技术和理论计算揭示 “应变调控”通过调节关键物种在材料表面的吸附能及优化物种吸附位点提升能源转化效率的机制；基于“应变调控”技术提升铂材料能源转化效率，应变优化后铂材料表面的电催化甲醇氧化和产氢反应活性分别提升2.5和1.5倍以上。“应变调控”技术可以优化现有催化体系，为能源高效转化提供了原创变革性技术。