H$_2$ + H$_2$O -> H$_4$O: Synthesizing Hyper-hydrogenated Water in Small-Sized Fullerenes?

Nanoscale confinement provides an ideal platform to rouse some exceptional reactions which cannot happen in the open space. Intuitively, H2 and H$_2$O cannot react. Herein, through utilizing small-sized fullerenes (C$_{24}$, C$_{26}$, C$_{28}$, and C$_{30}$) as nanoreactors, we demonstrate that a hyperhydrogenated water species, H$_4$O, can be easily formed using H2 and H$_2$O under ambient conditions by ab initio molecular dynamics simulations.The H$_4$O molecule rotates freely in the cavity of the cages and maintains its structure during the simulations. Further theoretical analysis indicates that H$_4$O in the fullerene possesses high stability thermodynamically and chemically, which can be rationalized by the electron transfer between H$_4$O and the fullerene. This work highlights the possibility of utilizing fullerene as a nanoreactor to provide confinement constraints for unexpected chemistry.