Engineering Cr-Ru oxide catalysts on TiO2 support for high-efficiency proton exchange towards electrocatalytic water splitting

Proton exchange membrane water electrolysis (PEMWE) is a promising technology for sustainable hydrogen production, nevertheless it faces challenges related to the high cost and scarcity of noble metal-based anodic catalysts. Herein, we report a low-cost, high-performance acidic oxygen evolution electrocatalyst, Cr 0.66 Ru 0.34 O 2 /TiO 2 , consisting of chromium-ruthenium mixed oxides supported on a TiO 2 substrate. The catalyst was synthesized through sol-gel and hydrothermal methods, enabling controlled crystallinity and uniform dispersion. By tuning the Cr/Ru ratio, we elucidated the synergistic interaction between Cr and Ru, which modulates the electronic structure and morphological characteristics of the catalyst, thereby promoting the lattice oxygen mechanism (LOM) and enhancing catalytic activity. TiO 2 was employed as a support due to its high specific surface area and excellent chemical stability under acidic conditions, which helps stabilize oxygen vacancies and facilitates the oxygen vacancy site mechanism (OVSM), ultimately improving the catalytic stability. The optimized Cr 0.66 Ru 0.34 O 2 /TiO 2 catalyst delivers a low overpotential of 179 mV at 10 mA cm −2 in 0.5 M H 2 SO 4 and demonstrates excellent stability under constant current operation. When applied in a PEM single-cell electrolyzer, the catalyst achieves a low cell voltage of 1.633 V at 1 A cm −2 and stable operation over 180 h at 60 °C, outperforming commercial IrO 2 . These results highlight the potential of Cr-doped Ru-based oxides supported on TiO 2 as efficient and durable anode catalysts for next-generation PEM water electrolyzers with reduced noble metal usage.