Recent progress in carbon quantum dots: synthesis, properties and applications in photocatalysis

Carbon quantum dots (CQDs) as a rising star of carbon nanomaterials, by virtue of their unique physicochemical, optical and electronic properties, have displayed tremendous momentum in numerous fields such as biosensing, bioimaging, drug delivery, optoelectronics, photovoltaics and photocatalysis. In particular, the rich optical and electronic properties of CQDs including efficient light harvesting, tunable photoluminescence (PL), extraordinary up-converted photoluminescence (UCPL) and outstanding photoinduced electron transfer have attracted considerable interest in different photocatalytic applications for the sake of full utilization of the solar spectrum. This review aims to demonstrate the recent progress in the synthesis, properties and photocatalytic applications of CQDs, particularly highlighting the fundamental multifaceted roles of CQDs in photoredox processes. Furthermore, we discuss the challenges and future direction of CQD-based materials in this booming research field, with a perspective toward the ultimate achievement of highly efficient and long-term stable CQD-based photocatalysts.