image: Spin-State Modulation of the Co3O4 Support in a Single-Atom Ru-Doped Co3O4 Catalyst for Industrial-Level Hydrogen Production via Water Splitting
Credit: Chao Meng, China University of Petroleum (East China)
Electrolytic hydrogen production through water splitting is a crucial technology for achieving carbon neutrality. The core processes involved are the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), both of which rely on the adsorption behavior of hydroxyl intermediates (OH*). This adsorption behavior directly impacts the activity and stability of electrocatalysts, thereby determining the efficiency of the overall water splitting process. In ruthenium single-atom catalysts supported on (hydro)oxides, precise control of the spin state of the support is vital for optimizing OH* adsorption and enhancing water splitting efficiency. However, under conditions of low ruthenium loading, traditional strategies often fail to effectively regulate the spin state of the support, thereby limiting the overall performance of the water splitting reaction.
To address this challenge, a research team led by China University of Petroleum (East China) has proposed an innovative solution. By leveraging strong atomic and electronic synergistic effects, the team has designed and synthesized a novel single-atom ruthenium-doped Co3O4 catalyst (a-Ru-Co3O4). This catalyst is enriched with high-spin Co3+ species, which not only serve as robust OH* adsorption sites, significantly promoting the dissociation of water molecules, but also enhance the supply of H* intermediates to ruthenium sites, thereby accelerating the Volmer–Tafel pathway of the HER. Moreover, the high-spin Co3+ facilitates the formation and stabilization of O*–Ru–O–Co–OH* intermediates, providing a more kinetically favorable oxide path mechanism for the OER. As a result, a-Ru-Co3O4 exhibits excellent bifunctional catalytic activity, with its mass and cost-normalized performance being approximately 30 times higher than that of commercial Ru/C. When integrated into an anion exchange membrane electrolyzer, a-Ru-Co3O4 achieves an industrial-level current density of 1.46 A cm⁻2 at a cell voltage of 2.0 V and demonstrates robust durability.