In-situ engineered RuTiO_x nanorods for synergistic AEM-LOM pathways enabling overall water splitting

Exploring efficient bifunctional catalysts for pH-universal water splitting is pivotal for sustainable hydrogen production. This study reports the in-situ synthesis of RuTiO_x nanorods on Ti mesh (RuTiO_x@TM) as a self-supported bifunctional electrocatalyst. The nanorod architecture maximized active site exposure, while strategic oxygen vacancies promoted electron transfer and triggered lattice oxygen activation. Combined experimental and theoretical analyses revealed a synergistic adsorbate evolution mechanism (AEM) and the lattice oxygen mechanism (LOM). RuTiO_x@TM exhibited excellent bifunctional performance with low overpotentials of 248 mV for oxygen evolution reaction (OER) and 46 mV for hydrogen evolution reaction (HER) at 10 mA cm^-2 in 0.5 mol L^-1 H₂SO₄, maintaining operational stability for 400 h. Notably, this performance persisted across a wide pH range, underscoring its potential for practical water splitting applications. In a two-electrode configuration, RuTiO_x@TM||RuTiO_x@TM sustained stable operation for 100 h at 50 and 300 mA cm^-2. In a proton exchange membrane (PEM) electrolyzer, the catalyst maintained continuous operation for 200 h at 300 mA cm^-2, with an estimated electricity-cost-based hydrogen production cost of US$1.02 kg^-1. These results demonstrate a significant advance in electrocatalytic efficiency and pave the way for scalable, pH-universal water splitting technologies.