Water Splitting by C₆₀-Supported Vanadium Single Atoms

Water splitting is an important source of hydrogen, a promising future carrier for clean and renewable energy. A detailed understanding of the mechanisms of water splitting, catalyzed by supported metal atoms or nanoparticles, is essential to improve the design of efficient catalysts. Here, we report an infrared spectroscopic study of such a water splitting process, assisted by a C₆₀ supported vanadium atom, C₆₀V⁺+H₂O→C₆₀VO⁺+H₂. We probe both the entrance channel complex C₆₀V⁺(H₂O) and the end product C₆₀VO⁺, and observe the formation of H₂ as a result from resonant infrared absorption. Density functional theory calculations exploring the detailed reaction pathway reveal that a quintet-to-triplet spin crossing facilitates the water splitting reaction by C₆₀-supported V⁺, whereas this reaction is kinetically hindered on the isolated V⁺ ion by a high energy barrier. The C₆₀ support has an important role in lowering the reaction barrier with more than 70 kJ mol⁻¹ due to a large orbital overlap of one water hydrogen atom with one carbon atom of the C₆₀ support. This fundamental insight in the water splitting reaction by a C₆₀-supported single vanadium atom showcases the importance of supports in single atom catalysts by modifying the reaction potential energy surface.