Ternary Z-Scheme Ag/TiO₂/g-C₃N₄ Nanocomposite for Enhanced Visible-Light Photocatalytic Reduction of p-Nitrophenol

In this study, a novel biphasic anatase/brookite TiO₂ was successfully deposited onto g-C₃N₄ via an impregnation method, followed by the photodeposition of Ag nanoparticles to construct a ternary Ag/TiO₂/g-C₃N₄ nanocomposite. Detailed physicochemical characterizations confirmed the successful immobilization of Ag nanoparticles on the TiO₂/g-C₃N₄ surface, contributing to a significantly enhanced surface area, broadened visible light absorption, and improved charge carrier separation. The photocatalytic performance of the resulting nanocomposites was evaluated through the reduction of p-nitrophenol (PNP) to p-aminophenol (PAP), revealing a remarkable enhancement in activity with increasing Ag content. Notably, the 2% Ag/TiO₂/g-C₃N₄ nanocomposite achieved complete (98%) conversion of PNP to PAP within just 6.5 min under visible light irradiation. This performance was approximately three times higher than that of 0.5% Ag/TiO₂/g-C₃N₄, twice that of 2% Ag/TiO₂ (commercial)/g-C₃N₄, and significantly superior to bare TiO₂/g-C₃N₄. The outstanding photocatalytic efficiency of the 2% Ag/TiO₂/g-C₃N₄ system is attributed to its superior light-harvesting ability and efficient charge separation via a Z-scheme mechanism. These findings present a promising and scalable strategy for engineering advanced ternary nanocomposite photocatalysts with enhanced environmental remediation capabilities.

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