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 Ag2Se 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 Ag2Se NMs. We demonstrate that the controlled formation of Se0(aq) and its redox reaction with Ag0 on the surface of the Ag2Se 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 Ag2Se NMs were extensively investigated, and the cubic Ag2Se NMs exhibited the highest specific catalytic activities. The M–SC transformation-based synthesis of anisotropic Ag2Se NMs would be highly valuable for expanding the structural diversity of semiconductor NMs and their structure-dependent applications.