Chemically Tailorable Dissolution Pathways of Individual Cu₃As Nanocrystals

The optical, electronic, and catalytic properties of nanocrystals (NCs) are often determined by their size, shape, and materials. Understanding the underlying mechanisms of shape-controlled synthesis and transformation is crucial for revealing fundamental reaction kinetics, enabling the design of more precisely controlled materials. Liquid cell transmission electron microscopy (LCTEM) enables the observation of individual NC growth and dissolution with millisecond time resolution and subnanometer space resolution. In this study, we harnessed the chemical environment to analyze the single-particle etching trajectories of well-faceted copper arsenide (Cu 3 As) nanocubes. Distinct kinetically controlled dissolution trajectories are identified by adjusting the chemical reactions of Cu or As through pH, coordination, concentration, and oxidative species. These LCTEM observations illustrate how the nanoscale shape transformations in binary semiconductors can be controlled through manipulation of cationic and anionic reactivity within a highly reactive nonequilibrium radiolysis liquid environment.