WO3 nanostructures for photoelectrocatalytic emerging pollutants degradation: influence of carboxylic acids on electrochemical anodization

This study investigates the influence of adding different carboxylic acids (citric, tartaric, and aspartic acids) on the anodization of WO 3 nanostructures under hydrodynamic conditions and their performance for the degradation of organic emerging pollutants. A comprehensive physicochemical and electrochemical characterization was performed to correlate these properties with their photoelectrocatalytic (PEC) response. WO 3 nanostructures anodized with tartaric acid exhibited superior PEC behavior, making them the most promising candidates for the degradation of three common organic emerging pollutants: two drugs (trimethoprim and ciprofloxacin) and one pesticide (imidacloprid). The results demonstrated high PEC-degradation efficiencies and kinetic rates for all the pollutants, showing a synergistic effect compared to the individual photo, photocatalytic, and electrocatalytic approaches. Furthermore, removal percentages after 6 hours were higher than those reported in the literature (>90%, >50%, and >80% for ciprofloxacin, trimethoprim, and imidacloprid, respectively). Finally, a degradation mechanism was proposed for the three emerging pollutants, revealing the formation of more polar and simpler products following PEC degradation. • Best photoelectrochemical response for WO3 nanostructures anodized in tartaric acid. • Tartaric and citric acid form nanoplatelets with higher surface area than aspartic acid. • A synergistic effect was observed in the PEC removal of emerging pollutants. • Efficient PEC removals after 6h for ciprofloxacin (>90%), trimetoprim (>50%) and imidacloprid (∼80%).