In Situ Liquid Cell Electron Microscopy of the Solution\nGrowth of Au–Pd Core–Shell Nanostructures

Abstract

Using in situ liquid cell electron\nmicroscopy we investigate Pd\ngrowth in dilute aqueous Pd salt solutions containing Au nanoparticle\nseeds. Au–Pd core–shell nanostructures are formed via\ndeposition of Pd⁰, generated by the reduction of chloropalladate\ncomplexes by radicals, such as hydrated electrons (e_aq^–) induced by the electron beam in the solution. The\nsize and shape of the Au seeds determine the morphology of the Pd\nshells, via preferential Pd incorporation in low-coordination sites\nand avoidance of extended facets. Analysis of the Pd incorporation\non Au particles at different distances from a focused electron beam\nprovides a quantitative picture of the growth process and shows that\nthe growth is limited by the diffusion of e_aq^– in the solution.