Preparation of luminescent graphitic C3N4 NS and their composites with RGO for property controlling

Abstract

Thin graphitic C₃N₄ nanosheets (g-C₃N₄ NS) with bright blue photoluminescence were prepared through an acid and alkali corrosion and ultrasonic-assisted method. g-C₃N₄ NS/reduced graphene oxide (RGO) sample which was prepared through a hydrothermal synthesis offered high separation and transfer efficiency of photogenerated carriers because of the thin g-C₃N₄ NS attached closely to the RGO. The introduction of RGO sheets provided prominent advantages for enhanced light absorption and promoted the transfer rate of photogenerated carriers from g-C₃N₄ NS. A g-C₃N₄ NS/RGO (3 : 2) composite not only functions as a sensor to detect Pb²⁺ and Cd²⁺ in an aqueous solution but also exhibits efficient visible-light photocatalytic performance. The application in a sensor is ascribed to the intercalation impact between thin g-C₃N₄ NS and heavy metal ions. Owing to the presence of more active functional groups (e.g., carboxyl and amino groups) on the surface of the g-C₃N₄ NS compared with the bulk form, the ions can be easily adsorbed onto g-C₃N₄ NS. The g-C₃N₄ NS/RGO composites are highly sensitive and selective in ion sensing, as well as having superior photocatalytic activity.