Fe-Doped TiO2 for Efficient Electrochemical Hydrogen Peroxide Production: Electronic Structure Modulation and Defect-Mediated Selectivity Enhancement

The electrochemical synthesis of hydrogen peroxide through two-electron oxygen reduction (2e– ORR) presents a sustainable alternative to conventional synthesis methods, such as the anthraquinone method. TiO2-based materials are promising candidates due to their stability and tunable electronic properties, but their intrinsic 2e– ORR activity and selectivity are insufficient for practical applications. Here, we report that strategic Fe doping significantly enhances the 2e– ORR performance of TiO2. The optimized Fe-TiO2 catalyst exhibits remarkable activity and selectivity, achieving a 30% increase in H2O2 selectivity (from 47% to 77%) while reducing the electron transfer number from 3.05 to 2.45 in 0.1 M KOH electrolyte. Notably, the material shows substantially improved electrochemical active surface area (ECSA) and ORR kinetics, culminating in an exceptional H2O2 production rate of 406 mmol·gcat–1·h–1 with 97.5% Faraday efficiency at 0 V vs RHE in an H-cell configuration. Density functional theory (DFT) calculations reveal the mechanistic origins of this enhancement: Fe doping effectively narrows the band gap and lowers the oxygen vacancy formation energy, thereby boosting electrical conductivity as confirmed by experimental characterization; and the modified electronic structure increases Bader charge accumulation on the terminal oxygen of adsorbed *OOH intermediates, facilitating protonation at this site and consequently promoting the 2e– pathway. These dual effects synergistically enhance both ORR activity and H2O2 selectivity. This study not only presents Fe-TiO2 as an efficient, earth-abundant catalyst for sustainable H2O2 production but also establishes fundamental design principles for developing advanced metal oxide electrocatalysts through targeted heteroatom doping.