Bias Enhanced Electro-Photocatalysis on TiO2 Nanoporous Materials for Decomposition of Forever Chemicals in Saltwater

In this study, a TiO2-based bias-enhanced photocatalytic system was prepared with the aim of achieving high photocatalytic activity in deionized as well as in saltwater systems. Highly ordered TiO2 nanoporous materials were fabricated via a double-anodization method. A small potential bias was applied that suppresses electron-hole recombination and deters interference from the ions present in the solution while minimizing electrochemical reactions. Photodegradation reactions involving Rhodamine B (RhB) were conducted to evaluate the efficacy of the nanomaterials with and without the applied bias. Our experimental results revealed that the synthesized TiO2 nanomaterials possessed high photochemical activity under UVA light, substantially enhanced with the applied bias. A very significant enhancement was observed when the Bias Enhanced Electrolytic Photocatalysis (BEEP) system was used in saline solutions. Higher photocatalytic efficiency was achieved with the increase in the salinity level in the reaction mixture. These bias-enhanced nanomaterials were successfully tested for the degradation of per- and polyfluorinated substances (PFAS), recognized as a significant threat to the environment and human health. The results indicated that the presented technology could eliminate a wide range of fluorinated molecules. The simplicity, efficacy and scalability of the new BEEP approach described in this study make the use of TiO2-based advanced oxidation process (AOP) possible in designing high-performance water purification technologies applicable to fresh and salt water.