双组元金属-类金属合金纳米晶生长的光谱学动态过程研究

Controllable growth of nanocrystalline is the fundamental science for the further development and practical applications of nanomaterials. Metal and semimetal-based nanoparticles with unique atomic and electronic structures have attracted broad attention for their particular optic, electronic and catalytic properties. Detection and elucidation of the dynamical nucleation and growth on the nano- even atomic scale is the common scientific problems in the topic of nanoparticles. Solution chemical method is the main process for preparation of nanoparticles, however, the rapid ions-by-ions reaction for nanocrystalline growth and the complex solution environments impede the possible dynamical detection at the atomic scale from current techniques, in contrast, the relative slow interaction and assemble processes among small particles or clusters promise the possible capture of the transit state for nanocrystalline growth. Laser ablation in liquids, developed in our group, is a powerful and unique technique for the efficient fabrication of highly reactive, surface clean and metastable charged clusters. Motivation by above challenges and our beforehand achievements, in this program, we aim for the controllable preparation of noble metal-based nanoalloy catalyst and metalloid-based topological insulators or thermoelectric materials nanocrystalline. On the basis of optical responses of monomer nanoparticles in dependent of size, shape, microstructure and constituents, we will employ in-situ and time-resolved optical spectroscopy together with ex-situ fine characterization, to detect the real dynamical processes and mechanisms of dissolution, fusion, nucleation and growth of bimetallic nanoparticles. Those efforts are pushed to provide favorable scientific insights for controllable growth of nanoparticles.

纳米晶的精确生长调控是纳米材料科学的基础，金属、类金属纳米晶由于其具有独特的原子电子结构，以及优异的光、电、磁和催化等性能，受到广泛的重视。在纳米以至原子尺度上探测、诠释纳米晶的成核与生长动态过程是此领域的共性技术与科学问题。溶液化学法是获取纳米颗粒的主要手段，但基于离子反应的快速生长过程与复杂的溶液环境难以实现原子尺度的动态探测，相对缓慢的团簇间反应与组装动力学过程为捕捉纳米晶生长中瞬态的结构与物性提供了独特的机遇，课题组发展的液相激光熔蚀是获取高活性、表面洁净、亚稳态团簇的独特手段。项目将围绕贵金属基的合金催化剂与类金属基热电合金两类材料体系，基于单组元颗粒结构、尺寸、成分依赖的光谱响应特征，采用原位动态的时间分辨光谱学系统结合去位的精细结构表征，系统分析液相体系中，激光诱导双组元纳米颗粒的溶解、融合、形核与生长动力学机制，为实现纳米晶的精确生长调控提供关键科学依据。

考虑到相对缓慢的团簇间反应与组装动力学过程是捕捉纳米晶生长中瞬态结构与物性变化的独特机遇，在这个前提下，项目利用课题组长期发展的液相激光加工与制备技术，优势的设计和制备了具有高活性、表面洁净的亚稳态团簇级合金前驱体体系，开展了异质组元合金化相关的基础与应用研究。得益于单组元颗粒结构、尺寸、成份依赖的光谱响应特征，项目利用原位动态时间分辨的光谱学系统结合去位的精细结构表征，探索了激光诱导双组元纳米晶溶解、融合、形核与生长的动力学机制。截至项目结题，项目组基于液相激光加工与制备技术获得了一系列不同液相体系和尺寸结构的高活性单组元合金前驱体颗粒，发现其液相体系的组成及异质前驱体的选择对后续的自发诱导及外场干预下的合金化均具有重要的影响。上述研究，确立了合金纳米结构的组分-微结构-性能的关联机制。同时，项目组在总结异质纳米颗粒之间的相互作用及合金纳米颗粒的生长动力学过程和机制的基础上，探索了应用于工业催化、电催化和能源相关纳米材料的制备与结构的组装。项目的顺利进行，发展了激光辅助一步法合金化的途径，为相关科研人员的合金纳米材料的精准控制制备、合金化过程及机制分析和性能拓展提供了新的思路，推动了液相激光技术辅助不同组元合金纳米材料合成领域的发展。