Nanoconfined Crystal Growth of Copper-Intercalated Graphene Oxide Interlayers

Recently, graphene oxide (GO) has been taken as a host for ultra-fast self-assembly of metal nanoparticles [Nat. Commun. 2016, 7, 12332] or synthesis of ultrathin and mechanically robust lithium foils [Nat. Energy 2021, 6, 790–798]. However, the main factors dominating preparations of these nanoconfined metals are still not clear. In this study, the crystal growth mechanism of copper (Cu) nanosheet-intercalated GO interlayers has been revealed by combining theoretical models with molecular dynamics simulations. Both the interlayer spacing and oxidation degree of GO play key roles in crystal growth velocities, which increase with increasing interlayer spacings but decrease with increasing oxidation degrees. The phenomenon is found to be a consequence of crystal growth being energetically favorable and a small ratio of interfacial van der Waals-affected zones for larger crystal thicknesses and strong hydrophilic properties of GO with higher oxidation degrees. In addition, more smooth surfaces have been observed for nanoconfined metals. These insights provide an effective method for generating nanocrystalline metals in a nanoconfined environment.