Minimizing the Efficiency Loss in Thin Films Using the Biopolymeric Complexation Approach for Advanced Aqueous Phase Photocatalysis

The efficiency loss in the case of photocatalytic thin films due to reduced surface exposure of the immobilized catalysts is a persisting concern limiting their potential. This study proposes a unique biopolymeric complexation approach to resolve this intricate problem. A chitosan/cellulose-based (CN/CL) hybrid immobilizing surface has been designed and meticulously explored to demonstrate the restoration of photocatalytic efficiency. The efficiency restoration is primarily a repercussion of the interactive forces operating between CN and CL, which has been adequately verified by the DFT studies. These interactions lead to an intense negative charging of the CN/CL surface, which enhances the surface activity, resulting in the increased adsorption of the model cationic pollutant (tetracycline hydrochloride). This surge in activity is found to be a counterbalancing factor for the reduced surface area of the immobilized catalyst (ZnO-CuO), thereby preserving the efficiency (95%). As opposed to the CN/CL surface, bare CN-based thin films are unable to restore the activity, and a huge efficiency drop from 97% of powdered ZnO-CuO to 64% is recorded for them, which reaffirms the critical role of CN/CL complexation in preserving the efficiency of films. This property of efficiency restoration is tested for a range of complex pollutant systems, and a detailed mechanistic outlook based on the obtained results has been proposed.