Tunable Conformal Graphene Growth on Oxide Nanotube scaffolds: Towards Superwettable Hierarchical 2D-3D Architectures
Hierarchical hybrid nanoarchitectures that integrate vertically oriented graphene nanowalls, GNWs, with metal oxide, MeOx, nanotube scaffolds offer versatile platform for smart surfaces, nanoelectronics, and electrochemical technologies. Herein we present rapid, dry, plasma-assisted fabrication route that enables direct and conformal growth of GNWs on mechanically robust MeOx nanoforests. The method combines supported single-crystalline organic nanowires as a 1D soft template with sequential plasma-enabled oxide deposition and GNW growth, all performed under mild temperature, power, and vacuum conditions. This approach yields an unprecedented 2D-3D hierarchical architecture consisting of tunable-thickness MeOx nanotubes uniformly decorated with radially oriented graphene nanosheets, forming re-entrant, multiscale surface. Resulting hierarchical roughness imparts fluorine-free, long-term omniphobicity, with contact angles exceeding 170 degree for water, bovine serum, and other complex fluids. GNWs dominate the wetting response across TiO2, Al2O3, and SiO2 nanotube scaffolds, effectively decoupling surface behavior from intrinsic oxide chemistry and maintaining robust repellency under UV irradiation and water condensation. Comprehensive SEM, TEM, XPS, angle-resolved NEXAFS, and Raman analyses elucidate growth mechanism and confirm preservation of the sp2 graphitic framework, together with controlled degree of edge functionalization. Overall, this work establishes universal, substrate-compatible, low-temperature, and scalable route for the fabrication of tunable graphene-metal oxide nano-microstructured multifunctional surfaces.