'Autophagy' and unique aerial oxygen harvesting properties exhibited by highly photocatalytic carbon quantum dots. (30th August 2021)

• Record Type: Journal Article
• Authors: Mondal, Sanjit; Vinod, C.P.; Gautam, Ujjal K.
• Is Part Of: Carbon. Volume 181(2021)
• Page Start: 16
• Page End: 27
• Publication Date: 2021-08-30
• Subjects: Carbon dots -- Oxygen-enrichment -- Photocatalytic oxidation -- Self-sensitized photo-oxidation; Carbon -- Periodicals; Carbone -- Périodiques; Koolstof; Toepassingen; Electronic journals; 546.681
• DOI: 10.1016/j.carbon.2021.04.054
• Languages: English
• ISSNs: 0008-6223

Abstract

Abstract: Plastic pollution is a serious threat to the environment as they are not bio-degradable. Herein using waste-polyethylene, we report two inter-related important findings. First that they can be converted economically and completely into highly photocatalytic carbon quantum-dots (CQDs) using H2 O2 as a residue-free oxidant in an acid medium, and they have the ability to enrich a reaction medium with an extraordinary amount of molecular oxygen harvested from the air so that no separate oxygen source is needed while carrying out facile photocatalytic oxidation reactions. Second, when they are not performing any photocatalytic reaction, they exhibit self-sensitized photo-oxidation to convert themselves completely to CO2 in the presence of sunlight, a phenomenon that we term as 'CQD-autophagy' by drawing parallels to the death of useless-cells in the body. Such extinction from the reaction media is unique as no other material is known to do so and advantageous because the removal of carbon-dots from a solution is rather inefficient from an industry-viewpoint due to their high solubility. Instead, the inexpensive CQDs can be discarded casually with the notion that they will gradually get eliminated from the environment. Graphical abstract: Image 1 Highlights: Green, residue-free synthesis of carbon quantum dots (CQDs) from waste-plastics. CQDs for molecular O2 harvesting from the air as the cheapest oxidant for carrying out highly efficient photocatalytic oxidation reactions. CQD 'autophagy' i. e. their self-sensitized photo-oxidation forming CO2 for a complete and automated removal from a solution. 'CQD-autophagy' becomes prominent only in the absence of reactants but stable otherwise.