Water electrolysis to produce hydrogen has broad prospects due to its pollution-free feature, yet its electrolysis efficiency is limited by the slow kinetics of the anodic oxygen evolution reaction (OER). In this study, we develop a synergistic catalyst which integrates MXene/TiO₂-supported Ru nanoparticles and oxygen-coordinated Co single atoms (RuCo-MXene/TiO₂) for efficient OER. This double-tuned structure enables both high-density active sites and precise microenvironment control. Moreover, the interaction between metals during annealing process provides the generation of metallic-bonded Ru-Co pairs between Ru nanoparticles and Co single atoms, facilitating Ru nanoparticles-to-support charge transfer, resulting in optimized electronic properties of the catalyst. As expected, the as-synthesized RuCo-MXene/TiO₂ catalyst at 10 mA·cm⁻² current density exhibits 208 mV low overportential and a long-term stability of up to 500 h, which is superior to Ru-MXene/TiO₂ and Co-MXene/TiO₂. This work provides a promising strategy for designing efficient and stable electrocatalysts for renewable energy applications.

The employment of spin polarization under an external magnetic field holds great potential for the improvements of photocatalytic performance. However, owing to the huge difference in dielectric properties between ferromagnetic oxide and polymers, the photogenerated excitons with spin states are often limited to the ferromagnetic oxide wells, which leads to unsatisfactory activity. In this paper, a single-atom Co-doped C₃N₄ photocatalyst is successfully synthesized for photocatalytic water splitting and simultaneous oxidation of benzylamine. Under a tiny external magnetic field (24.5 mT), the hydrogen production rate could reach at 3979.0 μmol·g⁻¹·h⁻¹, which is about 340 times that of C₃N₄. Experimental results and theoretical calculations indicate that the interaction of Co d and N p orbital changes the symmetry center of C₃N₄, resulting in an increase in dielectric constant and spin polarization. Moreover, magnetic fields further promote parallel electron spin, and the increased number of charges with the parallel spin-down state is likely to dissociate under the action of an external magnetic field. On the other hand, the Co–N bond provides a huge built-in electric field and active site for strengthening the charge transfer and surface reaction. This work not only deepens the understanding of spin polarization, but also enriches methods to accelerate electron–hole separation.