An overview of the recent advances of carbon quantum dots/metal oxides in the application of heterogeneous photocatalysis in photodegradation of pollutants towards visible-light and solar energy exploitation

Since the discovery of carbon quantum dots (CQDs), their potential applications in the fields of chemical sensing, bio-imaging, drug delivery and photocatalysis have been enormously developed. In particular, CQDs have received immense attention in visible-light-driven heterogeneous photocatalysis for the sake of their excellent aqueous solubility, outstanding electron transfer and efficient light-harvesting ability that enable the full utilization of solar spectrum. Recently, green CQDs have attracted considerable interest in this burgeoning field due to their non-toxic nature, high sustainability, outstanding photostability and their innate photoluminescence properties. By virtue of the high biocompatibility and tunable optical properties, the applications of CQDs alone or in combination with other bulk semiconductors in the photocatalytic degradation of organic pollutants have been reported in many studies. This review aims to provide a comprehensive overview of the recent progress and breakthroughs made in the development of diverse CQDs/semiconductor hybrid photocatalysts. The detailed information regarding their photocatalytic degradation performances and the mechanisms underlying the interaction of CQDs in photocatalytic system are highlighted. The current review also presents the strategies employed in the design of efficient photocatalyst with greater emphasis on the experimental condition, surface modification, facet control, charge transfer mode and the construction of ternary heterostructures. The resulting impact on the physiochemical properties and catalytic performance of hybrid photocatalysts could provide readers an insight into the recent advances made and stimulate innovative techniques which ultimately lead to significant enhancement of photocatalytic activity in solar energy conversion.