Regulating Spin Polarization by a Ru Single Atoms to Promote Hydrogen Evolution Reaction in a Spin Catalytic Behavior

To solve the global environment problems caused by burning fossil fuels, hydrogen has been considered as a promising energy carrier for the future. Guided by the carbon neutrality strategy, “green hydrogen”, which is generated from water splitting driven by renewable energy, has attracted great attention. Hydrogen evolution reaction (HER) is a basic reaction for water splitting, but the high cost of Pt electrocatalysts severely restricts its industrial application. To reduce the use of precious metals without sacrificing performance, single atom catalysts (SACs) are emerging as an ideal candidate. This study reports a Ru SA -CoVP SAC, which shows impressive HER activity in alkaline medium. In situ XPS investigations combined with density functional theory calculations reveal that the CoV binary site instead of the Ru site plays a dominate role in H 2 O dissociation and H adsorption. Magnetic investigations find that the loading of Ru SAs reduces the net spin magnetic moment, leading to restructured spin texture. As a result, the Gibbs free energy of H shows a volcanic trend with the spin polarization of d xz, among which the middle spin polarized CoV binary site sits on the most favorable position. A spin-related electron transfer scheme is presented, showing that a moderate spin polarization is efficient for the transport of both spin-up and spin-down electrons in the bridge site. This study highlights the intrinsic spin property in the electron transfer process, which is a commonality in electrocatalysts. The presented spin-related HER mechanism can serve as a trigger to boost the development of spin-catalysis.