Biomimetic synthesis of C3N4/TiO2/Ag nanosheet composites with high visible-light photocatalytic performance

Abstract

In order to more efficiently utilize solar energy, semiconductor-based nanocomposites with high visible-light responses have attracted much interest in recent years. In this study, a C₃N₄/TiO₂/Ag nanosheet with a high visible-light photocatalytic performance has been synthesized via a biomimetic strategy under mild conditions. Firstly, TiO₂ nanoparticles (NPs) about 10 nm in diameter are loaded on a C₃N₄ nanosheet by the arginine-enabled biomimetic mineralization. Then, Ag NPs about 5 nm in size nucleate and grow on the TiO₂ surface using 3-(3,4-dihydroxyphenyl)propionic acid as an anchor and a reducer to form the TiO₂–Ag heterojunction. The resultant C₃N₄/TiO₂/Ag nanosheet exhibits significantly higher photoelectric conversion efficiency and photodegradation activity than pure C₃N₄ and C₃N₄/TiO₂ under visible-light irradiation. Moreover, the loading amount of Ag nanocrystals can be readily regulated by changing the AgNO₃ concentration. Both TiO₂ and Ag play critical roles for the enhanced photocatalytic activity of C₃N₄/TiO₂/Ag nanosheets. The band match of TiO₂ with C₃N₄ is in favour of the separation of photo-generated carriers in C₃N₄, and the surface plasmon resonance effect of Ag nanocrystals induces the electron excitation in TiO₂ NPs under visible light. This study offers a facile approach for the cost-effective and environmentally benign synthesis of high-efficiency photocatalysts.