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