Targeted Topological Routine Regulation of RuNiO_x Precursors for Excellent Alkaline Overall Water Splitting

Designing efficient and stable electrocatalysts for the hydrogen and oxygen evolution reactions (HER and OER) is crucial for green hydrogen production via the water-splitting system. The bifunctional electrocatalyst offers a promising strategy due to the simplified preparation process and reduced expenses. However, the single-component bifunctional catalysts often struggle to match the redox potential of water and to achieve proper adsorption/desorption of Gibbs free energy for both hydrogen and oxygen intermediates simultaneously. Herein, through precisely controlling the topological transformation path of the RuNiO_x precursor, we successfully prepared high-performance RuNi/Ni and Ru/NiO heterostructure electrocatalysts for the HER and OER, respectively. The energy level matching between the fabricated electrocatalyst and water oxidation/reduction potential confirms the feasibility of HER and OER. The synergistic effect between the active sites ensures rapid intermediate adsorption/desorption kinetics. As a result, the assembled alkaline overall water splitting setup achieves a current density of 1 A cm⁻² at 2 V and maintains stable operation at 100 mA cm⁻² for 100 hours. © 2024 Wiley-VCH GmbH.