Effect of fluorine doping on the electrocatalytic properties of Nb2O5 for H2O2 electrogeneration

The oxygen reduction reaction (ORR) via the 2-electron mechanism is an efficient way to produce hydrogen peroxide (H₂O₂) under mild conditions. This study examines the modification of Vulcan XC72 carbon with fluorine (F)-doped niobium oxide (Nb₂O₅) nanoparticles at varying molar ratios (0, 0.005, 0.01, 0.02). The F-doped Nb₂O₅ nanoparticles were synthesized using the oxidizing peroxide method and then incorporated into Vulcan XC72 carbon via impregnation. Characterization techniques included X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle measurements, and X-ray photoelectron spectroscopy (XPS). Electrochemical evaluation using the rotating ring disk electrode method revealed that Vulcan XC72 modified with 1.0 % F-doped Nb₂O₅ exhibited the best ORR performance. When used as a gas diffusion electrode, this electrocatalyst produced more H₂O₂ at all applied potentials than the pure and Nb₂O₅-modified Vulcan XC72 carbon. At potentials of −0.7 V and −1.3 V, the proposed electrocatalyst achieved H₂O₂ yields 65 % and 98 % higher than the Nb₂O₅-modified electrocatalyst. Furthermore, it presented lower energy consumption and higher current efficiency than the other electrocatalysts compared in this study. The enhanced performance is attributed to F doping, which increased Nb₂O₅ lattice distortion and disorder, improving electron availability for ORR. Additionally, F-doped electrocatalysts exhibited more oxygenated species and greater hydrophilicity, facilitating O₂ adsorption, transport, and electron transfer. These properties significantly enhanced H₂O₂ electrogeneration efficiency while reducing energy consumption.