In situ growth of Ag/Ag2O nanoparticles on g-C3N4 by a natural carbon nanodot-assisted green method for synergistic photocatalytic activity

Abstract

Novel visible-light-driven Ag/Ag₂O@g-C₃N₄ (AAC) hybrid materials were synthesized successfully via a green, facile hydrothermal treatment approach by reducing AgNO₃ using carbon nanodots as reducing agent for the first time. Natural leaves were used as precursors to prepare carbon nanodots. By adjusting the feed mass ratio of AgNO₃ to carbon nanodots, the average diameter of Ag/Ag₂O can be modulated from 8 to 33 nm. The effects of Ag/Ag₂O deposition on the optical and photocatalytic performance of AAC in the degradation of rhodamine B (RhB) under visible light irradiation were systematically investigated. It was found that the Ag/Ag₂O content greatly influences the photocatalytic activity of AAC nanocomposites. A suitable amount of Ag/Ag₂O in the AAC system could obtain the best photocatalytic activity. The experimental results indicated that all the AAC nanocomposites showed higher photocatalytic activities compared with that of pure g-C₃N₄. The remarkable visible-light photocatalytic activity of AAC heterostructures could be attributed to their absorption in the visible region and low recombination rate of the electron–hole pairs because of the heterojunction formed between Ag₂O and g-C₃N₄. In addition, Ag nanoparticles are believed to play an essential role in affecting the photoreactivity because they are able to trap electrons, further separate the electron–hole pairs, and prolong the life of electron–hole pairs. In other words, it can be concluded that the increased photocatalytic activity of AAC was attributed to the synergic effect between g-C₃N₄, Ag₂O and Ag. It is believed that the present work could render useful information for steering the design and application of noble nanoparticle loaded g-C₃N₄-based heterojunction composites with high photocatalytic activity.