The surface reactivity of silver nanoparticles doped with TiO2 nanorod like crystals for enhancing photocatalytic degradation of harmful water pollutants under visible - light irradiations

A novel and highly efficient photocatalytic system was successfully engineered through the initial synthesis of TiO₂ nanoparticles, followed by their morphological transformation into one-dimensional TiO₂ nanorod-like crystals (TiO₂ NRCs) via a hydrothermal strategy. To further tailor the surface and interfacial properties, the TiO₂ NRCs were functionalized with Ag nanoparticles through a chemical reduction process, leading to the formation of TiO₂–Ag nanorod like composites (NRCs) with significantly enhanced photocatalytic performance. To elucidate the fundamental origin of the enhanced photocatalytic activity, an extensive physicochemical investigation was performed using advanced characterization techniques, including high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), UV–visible spectroscopy, Raman spectroscopy, and Brunauer–Emmett–Teller (BET) surface area analysis. Nitrogen adsorption–desorption isotherm measurements of TiO₂ nanoparticles and TiO₂–Ag nanocomposites revealed characteristic type-IV isotherms, confirming the mesoporous nature of both materials. HRTEM analysis verified the successful construction of heterojunction interfaces, demonstrating intimate interfacial coupling and homogeneous distribution of Ag nanoparticles over the TiO₂ nanorod-like crystal surface. XRD results further confirmed the highly crystalline nature of the synthesized nanostructures, whereas EIS studies revealed enhanced interfacial charge separation and accelerated transport of photogenerated charge carriers. The improved charge-transfer dynamics are primarily attributed to the efficient migration of conduction-band electrons from TiO₂ to Ag a nanoparticle, which effectively suppresses electron–hole recombination and prolongs the lifetime of photogenerated holes within the TiO₂ NRC framework. The photocatalytic performance of the TiO₂–Ag NRCs was systematically assessed through the degradation of methylene blue (MB) dye in aqueous solution under UV–visible spectroscopic monitoring and compared with pristine TiO₂ nanoparticles. The one-dimensional TiO₂–Ag nanorod-like crystals demonstrated outstanding photocatalytic activity, achieving a remarkable MB degradation efficiency of 96.7%. These findings clearly demonstrate the exceptional potential of TiO₂–Ag NRCs as advanced photocatalytic materials for efficient environmental remediation and the degradation of organic contaminants in wastewater systems.