Shape-dependent activity of anisotropic Ag nanostructures supported on TiO₂ for the photoelectrocatalytic water oxidation

Herein, we report shape-dependent photoelectrocatalytic activity of Ag/Ag₂O nanostructures supported on pristine or nitrogen-doped TiO₂ (NTiO₂). Isotropic (spherical) and anisotropic (cubic and triangular) nanocrystals of Ag/Ag₂O nanocrystals were fabricated using complexing and surface directing agents. Microscopic images confirmed the formation of nanospheres (∼ 50–60 nm), nanocubes (∼ 50–70 nm), triangular nanoplates (∼ 40–60 nm). The X-ray photoelectron spectroscopy indicated the presence of metallic silver (Ag⁰) and oxidized silver (Ag⁺). The as-prepared photoelectrodes were illuminated by Ultraviolet–Visible (λ = 300–600 nm) or visible radiations (λ = > 420 nm), and photoelectrochemical oxidation of water was examined. The findings indicate a significant correlation in the shape of Ag/Ag₂O nanostructures, the incident wavelength, and the photoelectrochemical performance. In addition, different performance trend was discerned under Ultraviolet–Visible and visible excitations with respect to the amount of deposited Ag/Ag₂O. The variation in activity observed with different shapes of Ag/Ag₂O was correlated to enhanced optical property, arising due to the anisotropic structure, and electrical conductivity.