Interface Coupled Deep Eutectic Solvents as Functionally Active Photocatalytic Components for Aqueous Phase Elimination of Organic Contaminants

Band gap engineering is an intricate aspect in the domain of photocatalysis which vastly impacts the performance of catalysts. This study demonstrates how solvents can be incorporated in photocatalytic schemes to play the role of functionally active components to enhance the performance. Herein, a series of DESs with different metallic entities (Zn, Cu, Ni and Ce) were designed and strategically hybridized with a model photocatalyst, g-C₃N₄. The g-C₃N₄/Zn system showed the best structural and morphological traits compared to other developed systems, which rendered it with the best photocatalytic attributes. It exhibited the best photocatalytic performance toward both the model pollutants, tetracycline hydrochloride (TC) and methylene blue (MB). Precisely, activity enhancement of 30% and 33% was obtained with the g-C₃N₄/Zn system for MB and TC compared to unmodified g-C₃N₄. The electronic structure investigation of the developed catalytic systems pointed toward an intricate coordination. For instance, in the best performing g-C₃N₄/Zn system, a Z-scheme type mechanism was deduced between DES and the g-C₃N₄. Based on the investigations, a plausible mechanism has been proposed to holistically explain the role of DESs in enhancing the photocatalytic performance of the system.