Hybrid aligned zinc oxide nanowires array on CVD graphene for hydrogen sensing

A novel seedless floating growth scheme has been developed to grow vertically aligned ZnO nanowires array on single layer CVD graphene in solution at low temperatures (<;100 °C). The obtained hybrid ZnO-graphene nanostructures are ideal for chemical and gas sensing applications considering the advantages of high sensitivity due to large sensing surface area on the ZnO nanowire array and fast response and recovery due to high charge mobility of graphene. High-quality single-crystallinity of ZnO nanowires, a key parameter for high-performance sensors, has been confirmed using transmission electron microscopy. In addition, the well-formed interface between graphene and ZnO obtained is important to achieve high signal-to-noise ratio. Hydrogen sensors were fabricated using the hybrid ZnO-graphene nanostructure on interdigitated electrodes, and responses to hydrogen with different concentration were characterized. This floating growth process provides a low-cost and robust scheme for large-scale fabrication of semiconductor nanostructures on graphene for chemical and gas sensing applications.