Application of carbon quantum dots to increase the activity of conventional photocatalysts: A systematic review

Photocatalysis, a green technique is widely applied in the fields of environmental remediation for the removal of many pollutant constituents. It is known that major problems related to the present photocatalytic system, which significantly limit their photocatalysis efficiency, are low-usage of visible light, fast recombination and also the low migration ability of the photo-generated electrons and holes. To solve the problem associated with conventional photocatalytic systems, recently hybrid photocatalysts containing carbon quantum dots (CQDs) have been proposed. The tunable photocatalytic characteristics of CQDs are widely mentioned. Moreover, the excellent photocatalytic activity of CQDs alone and in combination with photoactive species in the photo-degradation of organic pollutants was confirmed in the many reports. This work presents a comprehensive view of the application of CQDs to improve conventional photocatalytic systems in those studies which considered organic dyes as sample pollutants. In addition to providing detailed information regarding important roles of CQDs in photocatalytic activity enhancement, this review provides the comprehensive details about findings of the photocatalytic degradation of dyes using CQD-based photocatalysts and the best CQD-based composites photocatalysts are highlighted.