Core–shell g-C3N4/Pt/TiO2 nanowires for simultaneous photocatalytic H2 evolution and RhB degradation under visible light irradiation

Abstract

Core–shell g-C₃N₄/Pt/TiO₂ nanowire structures were successfully synthesized through a facile two-step synthetic methodology, involving photodepositing Pt nanoparticles on the surface of TiO₂ nanowires and subsequent growth of g-C₃N₄ (CN) layers via thermal evaporation of urea. The as-prepared CN/Pt/TiO₂ composites show a higher photocurrent density compared to CN/TiO₂. The CN/Pt/TiO₂ photocatalysts exhibit an enhanced H₂ evolution rate of 8.93 μmol h⁻¹ under visible light irradiation, which is 1.25 times higher than that of CN/TiO₂ (7.15 μmol h⁻¹), while Pt/TiO₂ and TiO₂ nanowires do not show any visible light responses. Our experiments demonstrate for the first time that CN/Pt/TiO₂ with a unique core–shell nanowire structure of semiconductor–metal–semiconductor enables concurrent hydrogen evolution through photo-induced water splitting and RhB degradation by photo-oxidation in the visible range. This result is probably attributable to the formation of a heterojunction and the Pt nanoclusters in CN/Pt/TiO₂, facilitating the electron transfer from the LUMO of g-C₃N₄ to that of TiO₂ and generating different active sites upon photo-absorption in the CN layers. Our work provides a feasible way to obtain H₂ while treating sewage using photocatalysis.