Supported bimetallic nanoparticles (BNPs) are promising catalysts, but study on their compositional and structural changes under reaction conditions remains a challenge. In this work, the structure of PtNi BNPs supported on UiO-67 metal–organic framework (MOF) catalyst (i.e., PtNi@UiO-67) was investigated by in situ by near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS). The results showed differences in the reduction behaviour of Ni species in PtNi BNPs and monometallic Ni supported on UiO-67 catalysts (i.e., PtNi@UiO-67 and Ni@UiO-67), suggesting charge transfer between metallic Pt and Ni oxides in PtNi@UiO-67. Under CO oxidation conditions, Ni oxides segregated to the outer surface of the BNPs forming a thin layer of NiO_x on top of the metallic Pt (i.e., a NiO_x-on-Pt structure). This resulted in a core-shell structure which was confirmed by high-resolution scanning transmission electron microscopy (HR-STEM). Accordingly, the layer of NiO_x on PtNi BNPs, which is stabilised by charge transfer from metallic Pt, was proposed as the possible active phase for CO oxidation, being responsible for the enhanced catalytic activity observed in the bimetallic PtNi@UiO-67 catalyst.

负载型双金属纳米粒子（BNP）是很有前途的催化剂，但是研究在反应条件下其组成和结构变化仍然是一个挑战。在这项工作中，通过近环境压力X射线光电子能谱（NAP-XPS）原位研究了UiO-67金属-有机骨架（MOF）催化剂（即PtNi @ UiO-67）上负载的PtNi BNP的结构。。结果表明，PtNi BNPs中的Ni物种和UiO-67催化剂上负载的单金属Ni（即PtNi @ UiO-67和Ni @ UiO-67）的还原行为存在差异，表明PtNi中金属Pt和Ni氧化物之间的电荷转移@ UiO-67。在CO氧化条件下，Ni氧化物偏析于BNP的外表面，从而在金属Pt（即NiO）的顶部形成一层NiO _x薄层_x -on-Pt结构）。这产生了核-壳结构，其通过高分辨率扫描透射电子显微镜（HR-STEM）得到了证实。因此，提出了通过从金属Pt转移电荷而稳定的PtNi BNPs上的NiO _x层可能作为CO氧化的活性相，这是在双金属PtNi @ UiO-67催化剂中观察到的催化活性增强的原因。