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

Degradation of organic pollutants by in-situ electrochemically synthetic hydrogen peroxide (H2O2) in electroFenton (EF) system is important for the treatment of wastewater. In this work, a Fe, Mo co-doped N@TiO2 electrocatalyst was constructed for H2O2 generation and applied to the degradation of organic dyes. The FeMoN@TiO2 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-1h- 1 and Faraday efficiency (FE) of 83.4 % at -0.7 V (relative to SCE) for more than 10 h. The in situ generated H2O2 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 Fe2+. After adding Fe2+, 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 Na2SO4 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 Ti3+ and chemiadsorbed O. This enhances the electronic conductivity and the reactivity of the catalyst, leading to improved ability for H2O2 generation and organic pollutants degradation. Radical quenching experiments show that the in-situ generated H2O2 reacts with added Fe2+ to produce a large amount of & sdot;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 H2O2 and degradation of pollutants.