Water splitting by C${}_{60}$-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 C${}_{60}$ supported vanadium atom, C${}_{60}$V${}^{+}$+H${}_2$O$\to$C${}_{60}$VO${}^{+}$+H${}_2$. We probe both the entrance channel complex C${}_{60}$V${}^{+}$(H${}_2$O) and the end product C${}_{60}$VO${}^{+}$, and observe the formation of H${}_2$ 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 C${}_{60}$-supported V${}^{+}$, whereas this reaction is kinetically hindered on the isolated V${}^{+}$ ion by a high energy barrier. The C${}_{60}$ 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 C${}_{60}$ support. This fundamental insight in the water splitting reaction by a C${}_{60}$-supported single vanadium atom showcases the importance of supports in single atom catalysts by modifying the reaction potential energy surface. (© 2021 Wiley‐VCH GmbH)