Aqueous Transformation of Ag to Anisotropic Ag₂Se Nanostructures with Facet-Specific Catalytic Reduction of Cr⁶⁺ and Degradation of Amaranth

The universal strategies for the anisotropic synthesis of Ag 2 Se nanomaterials (NMs) have been rarely investigated, despite their unique thermoelectric and luminescent properties. Here, we present the metal-to-semiconductor (M–SC) transformation of anisotropic Ag NMs with sphere, plate, cube, rod, and wire structures to synthesize anisotropic Ag 2 Se NMs. We demonstrate that the controlled formation of Se 0 (aq) and its redox reaction with Ag 0 on the surface of the Ag 2 Se NMs are the keys to preserving the initial shapes. The reaction mechanism involving the gradual migration of Se from the surface to the core of the Ag NMs was simulated and supported by density functional theory. The structure-dependent catalytic properties of the Ag 2 Se NMs were extensively investigated, and the cubic Ag 2 Se NMs exhibited the highest specific catalytic activities. The M–SC transformation-based synthesis of anisotropic Ag 2 Se NMs would be highly valuable for expanding the structural diversity of semiconductor NMs and their structure-dependent applications.