In situ production of hydrogen peroxide from Fe, Mo co-doped N@TiO2 for organic pollutant degradation

A Fe/Mo/N multi-element doping modification method is reported, which increases the active sites, adjusts the electronic structure of Ti in TiO 2 , and enhances the electron transfer between the catalyst and reactants, jointly promoting the production of H 2 O 2 from the 2e - ORR process. The in situ generated H 2 O 2 can degrade organic pollutants efficiently by both directly oxidization and the electro-Fenton pathway with addition of Fe 2+ . • FeMoN@TiO 2 is prepared to electro-catalyze 2e - oxygen reduction for H 2 O 2 generation. • Fe doping can improve the electron transfer between the catalyst and reactants. • Mo doping increases active sites within the catalyst. • Fe/Mo co-doping further increases the concentrations of Ti 3+ and chemisorbed O. • FeMoN@TiO 2 shows excellent performance in H 2 O 2 production and dyes degradation. Degradation of organic pollutants by in-situ electrochemically synthetic hydrogen peroxide (H 2 O 2 ) in electro-Fenton (EF) system is important for the treatment of wastewater. In this work, a Fe, Mo co-doped N@TiO 2 electrocatalyst was constructed for H 2 O 2 generation and applied to the degradation of organic dyes. The FeMoN@TiO 2 catalyst in 0.1 M KOH exhibits excellent 2e - Oxygen reduction reaction (ORR) activity and stability, with a yield of up to 1409 mmol gcat -1 h −1 and Faraday efficiency (FE) of 83.4 % at −0.7 V (relative to SCE) for more than 10 h. The in situ generated H 2 O 2 delivers benign organic dyes degradation ability with high methylene blue (MB) removal rate of 98.2 % after 2 h in 0.1 M KOH without adding Fe 2+ . After adding Fe 2+ , the EF process occurs to degrade dyes more efficiently, with Congo red and phenol removal rates of more than 99.0 % and Ciprofloxacin (CIP) removal rate of more than 96.0 % in 0.1 M Na 2 SO 4 solution. It is found that Mo doping increases the active sites of the catalyst, while the dopant of Fe can enhance can improve the electron transfer rate between the catalyst and reactants. Additionally, the synergistic Fe and Mo modulate the electronic structure of Ti, increasing the concentrations of Ti 3+ and chemiadsorbed O. This enhances the electronic conductivity and the reactivity of the catalyst, leading to improved ability for H 2 O 2 generation and organic pollutants degradation. Radical quenching experiments show that the in-situ generated H 2 O 2 reacts with added Fe 2+ to produce a large amount of ·OH, which is the main active substance for organic pollutants degradation. This study provides new insights for non-precious metal oxides to replace precious metals towards in-situ production of H 2 O 2 and degradation of pollutants.