催化学报 ›› 2019, Vol. 40 ›› Issue (7): 1035-1056.DOI: 10.1016/S1872-2067(19)63385-1

• 综述 • 上一篇    下一篇

面向贵金属纳米晶的晶相调控策略

陈巧丽, 程天春, 傅红雅, 朱艺涵   

  1. 浙江工业大学化学工程学院, 浙江工业大学绿色化学合成技术国家重点实验室培育基地, 浙江杭州 310014
  • 收稿日期:2019-03-10 修回日期:2019-04-25 出版日期:2019-07-18 发布日期:2019-05-24
  • 通讯作者: 朱艺涵
  • 基金资助:

    国家自然科学基金(21771161,51701181);浙江省自然科学基金(LR18B030003);国家青年千人计划.

Crystal phase regulation in noble metal nanocrystals

Qiaoli Chen, Tianchun Cheng, Hongya Fu, Yihan Zhu   

  1. College of Chemical Engineering and State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China
  • Received:2019-03-10 Revised:2019-04-25 Online:2019-07-18 Published:2019-05-24
  • Supported by:

    This work was supported by Zhejiang Provincial Natural Science Foundation of China (LR18B030003), the National Natural Science Foundation of China (21771161, 51701181), and the Thousand Talents Program for Distinguished Young Scholars.

摘要:

贵金属纳米晶在催化等领域拥有广泛的应用前景.通过调控尺寸、形貌、表面结构和晶型等基本结构参数,能够进一步提升其性能、推动其更有效的催化应用.随着纳米晶合成技术的不断发展,基于尺寸、形貌和表面结构调控对贵金属纳米晶的性能影响研究已较为系统和深入,当前的研究更加关注对其晶相和晶体结构的改变和调控.因而近期有大量成功的晶相调控研究报道,其中具有更高能晶相结构的纳米晶基于独特的原子排布和电子效应,在催化等领域中表现出更为优异的性质.然而,贵金属纳米晶的原子通常采取最稳定的密堆积排列形式,合成热力学不稳定的高能晶相是一个重大的挑战.本综述详细介绍了贵金属及其合金纳米晶晶相调控的最新研究进展,讨论了贵金属纳米晶不同晶相的结构特征、表征手段,微观驱动力、调控原理、合成策略和催化应用.最后,对贵金属纳米晶晶相调控领域的未来发展提出了展望.
具体而言,基于贵金属纳米晶的原子密堆积模式,我们将纳米晶的原子堆积模式分为最紧密堆积的"Barlow堆积型"和非最密堆积的"非Barlow堆积型",并分类详细介绍了其各自的结构特征.其次,我们比较了X射线粉末衍射法、电子衍射法和高分辨透射电镜法在确定晶相结构中的优势和劣势.此外,我们总结了决定贵金属纳米晶原子堆积模式的部分微观驱动力,包括d电子占据、动态稳定性、自旋有序和应变这四种微观驱动力,并从热力学的角度探讨了表面和体相能量对相变的驱动作用,进而进一步介绍了各种晶相转变的机理,包括Bain相变机理、Pitsch相变机理、Kurdjumov-Sachs相变机理、Shockley不全位错滑移机理和重构型有序化机理.基于以上这些决定晶相的微观驱动力,我们总结了各类晶相调控的方法,包括合金诱导相变法、温度诱导晶相调控法、压力诱导晶相调控法、应变诱导晶相调控法、模板诱导晶相调控法和表面吸附诱导晶相调控法.最后,以各类催化反应为例,分别对比了面心立方最密堆积、六方最密堆积、面心四方(体心四方)、体心立方等几种典型晶相的催化性质差异.

关键词: 晶相调控, 贵金属, 纳米晶, 密堆积, 化学合成

Abstract:

Noble metal nanocrystals (NCs) are often densely packed in their most stable forms that are determined by a combination of effects arising from the electronic, magnetic, geometric, and phononic properties of the NCs. These packing modes usually include the densest packed polytypes of Barlow packings and more open or distorted packings with slightly lower atomic packing factors. The structural modulation strategies of NCs towards the better performances for diverse applications are usually limited to the crystal size, shape, and surface control, which have been robustly studied and documented. An exciting emerging field related to structural engineering of noble metal NCs turns out to be the crystal phase control, which allows the chemical synthesis of energetically high-lying phases of NCs and leads to intriguing performances in catalysis and energy conversion. This article provides a comprehensive review of crystal phase regulation that endows both noble metal and noble-metal-based alloy NCs with unique electronic structures and enhanced performances. The basic principles, general design rationale, synthetic approaches, and structural characterizations for a variety of successful case studies related to crystal phase engineering are reviewed and discussed. In the end, the perspectives and challenges associated with the development of a more controllable chemical synthetic strategy towards the high-energy phases of noble metal NCs are put forward.

Key words: Crystal phase, Noble metals, Nanocrystals, Dense packing, Chemical synthesis