Photoelectrochemical mineralization of emerging contaminants at porous WO3 interfaces

Nanocrystalline WO3 absorbs visible light up to 470 nm and generates OH•radicals via valence bandinjection. Therefore, it promotes the OH•mediated oxidation of organic pollutants, when applied tothe near UV–vis photodegradation of environmentally relevant target molecules like atenolol and car-bamazepine. They both represent potentially hazardous recalcitrant contaminants of emerging concern(CEC) in waters. In the case of WO3electrodes, a considerable acceleration of the degradation kinetics (upto 4–5 times) occurs through the application of a 1.5 V potential bias, which is instrumental to optimize thecharge separation within the thin films and to maximize holes transfer rate to the electrolyte. Moreover,after sufficiently long irradiation, the complete mineralization of the organics is obtained. Interestingly,the photo-electrochemical degradation process (applied bias condition) maintains its effectiveness anda large efficiency margin over conventional open circuit conditions. Photoelectrocatalysis is observedeven in diluted supporting electrolyte conditions, representing the average salinity of natural freshwatersamples, demonstrating the advantageous practical feasibility of the photo-electrochemical approach.