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·g_cat^–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.