A combination of biomass-derived carbon quantum dots and metal-doped TiO₂ for enhanced visible light photodegradation

Aquatic effluent from industrial sources, particularly the textile industry, is a major source of environmental pollution and is in dire need of a global scientific initiative for its sustainable removal. Among these, solar-driven photocatalysis has emerged as a potential solution for promoting sustainable energy generation with minimal water pollution. We have developed a novel titanium dioxide (TiO2)-based photocatalyst to address environmental concerns by modifying its crystalline structure by doping with transition metals such as Mn, Fe, and Co. Hetero junction photocatalysts were generated by integrating the catalyst with carbon quantum dots (CQDs) fabricated from widely available agricultural biomass (banana peel) and have a blue fluorescence. Because of their combined properties, the CQDs/doped-TiO2 composites had a noticeably higher visible light absorption than both the doped-TiO2 and pure TiO2 NPs. Photocatalytic batch experiments showed that the synthesized composites had a high degradation efficiency towards the Rhodamine B dye. Among them, Fe-doped TiO2/CQDs derived from yellow banana peel had the highest efficiency of 84%, which is ~2.5 times that of pristine anatase TiO2. Upon comparing the degradation efficiencies of the doped-TiO2 samples without the CQDs, Fe-TiO2 exhibited the highest performance with 65% degradation, followed by Co-TiO2 and Mn-TiO2 at 64% and 61.2%, respectively. The results suggest that modifying TiO2 composites with biomass-derived CQDs produces good degradation performance while converting bio-waste into functional materials.