Alleviating hydroxyl poisoning on Ru through competitive adsorption regulation using anatase-rutile TiO₂ heterostructures in alkaline hydrogen oxidation reaction

Jie Gao^a, Jing Liu^a*, Mengdi Wang^a, Nuo Sun^a, Hao Hu^a, Xuejing Cui^a, Xin Zhou^b,c*, Luhua Jiang^a*

^aCollege of Materials Science & Engineering, Qingdao University of Science & Technology, Qingdao, 266042, P.R. China

^bInterdisciplinary Research Center for Biology and Chemistry, Liaoning Normal University, Dalian 116029, P. R. China

^cCollege of Environment and Chemical Engineering, Dalian University, Dalian 116622, P. R. China

*Corresponding authors. Email: liuj955@qust.edu.cn (J. Liu); luhuajiang@qust.edu.cn (L. Jiang); zhouxin@dlu.edu.cn (X. Zhou).

Abstract: Ruthenium (Ru) is a promising electrocatalyst for the alkaline hydrogen oxidation reaction (HOR), yet it suffers from deactivation at higher potentials due to excessive oxophilicity, which leads to hydroxyl adsorption poisoning. Here, we report a tri-phase heterostructured catalyst (Ru-P25-TiO₂) comprising Ru with anatase (A-) and rutile (R-) TiO₂. This catalyst exhibits remarkable HOR activity, delivering 0.82 mA mg_Ru^-1 along with superior electrochemical stability up to 0.9 V vs. RHE, positioning it as the state-of-the-art electrocatalyst for HOR. This enhanced performance is attributed to the optimized electron distribution and a tailored d band structure at the Ru surface, enabled by strong metal and support interaction, which weakens both hydrogen binding energy and hydroxyl binding energy. The highly oxophilic P25-TiO₂ facilitates hydroxyl adsorption and establishes a continuous hydrogen-bond network at the catalyst/electrolyte interface, thereby promoting OH⁻ transport and alleviating competitive OH adsorption on the Ru surface. The synergistic interplay between anatase and rutile TiO₂ ideally endows Ru with both superior activity and excellent electrochemical stability. This work not only unravels the intrinsic role of biphasic TiO₂ in tailoring Ru electrocatalysis but also provides a generalizable synergistic heterostructure design strategy for developing efficient and durable electrocatalysts.

Keywords: Anatase TiO₂, Rutile TiO₂, Ruthenium, Synergistic interplay, Hydrogen oxidation reaction