Wang Yi-Chi, Slater Thomas J A, Leteba Gerard M, Lang Candace I, Wang Zhong Lin, Haigh Sarah J
Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China.
Department of Materials, University of Manchester, Manchester, M13 9PL, UK.
Small. 2024 Mar;20(10):e2302426. doi: 10.1002/smll.202302426. Epub 2023 Oct 31.
Tailoring nanoparticles' composition and morphology is of particular interest for improving their performance for catalysis. A challenge of this approach is that the nanoparticles' optimized initial structure often changes during use. Visualizing the three dimensional (3D) structural transformation in situ is therefore critical, but often prohibitively difficult experimentally. Although electron tomography provides opportunities for 3D imaging, restrictions in the tilt range of in situ holders together with electron dose considerations limit the possibilities for in situ electron tomography studies. Here, an in situ 3D imaging methodology is presented using single particle reconstruction (SPR) that allows 3D reconstruction of nanoparticles with controlled electron dose and without tilting the microscope stage. This in situ SPR methodology is employed to investigate the restructuring and elemental redistribution within a population of PtNi nanoparticles at elevated temperatures. The atomic structure of PtNi is further examined and a heat-induced transition is found from a disordered to an ordered phase. Changes in structure and elemental distribution are linked to a loss of catalytic activity in the oxygen reduction reaction. The in situ SPR methodology employed here can be extended to a wide range of in situ studies employing not only heating, but gaseous, aqueous, or electrochemical environments to reveal in-operando nanoparticle evolution in 3D.
调整纳米颗粒的组成和形态对于提高其催化性能尤为重要。这种方法面临的一个挑战是，纳米颗粒优化后的初始结构在使用过程中常常会发生变化。因此，原位可视化三维（3D）结构转变至关重要，但在实验上往往极其困难。尽管电子断层扫描为三维成像提供了机会，但原位样品架倾斜范围的限制以及电子剂量的考虑因素限制了原位电子断层扫描研究的可能性。在此，我们提出一种使用单颗粒重建（SPR）的原位三维成像方法，该方法能够在控制电子剂量且不倾斜显微镜载物台的情况下对纳米颗粒进行三维重建。利用这种原位SPR方法，我们研究了高温下PtNi纳米颗粒群体内部的结构重组和元素再分布。进一步研究了PtNi的原子结构，发现了从无序相到有序相的热诱导转变。结构和元素分布的变化与氧还原反应中催化活性的丧失有关。这里采用的原位SPR方法不仅可以扩展到广泛的原位研究，包括加热、气态、水性或电化学环境，以揭示纳米颗粒在三维空间中的原位演变。
