NANOCARBON ORGANISATION UNDER FLOW IN THE VORTEX FLUIDIC DEVICE (VFD)

Abstract

The development of tuneable carbon nanostructures has garnered considerable attention due to their advantageous chemical and physical properties, such as high electrical conductivity, robust mechanical strength, and favourable optical and thermal characteristics. A variety of fabrication strategies both top-down and bottom-up have been established to enable precise control over key parameters including size, shape, morphology, and surface functionality of the particles. These engineered nanomaterials have demonstrated broad applicability across numerous technological domains. Despite significant progress in their synthesis, several challenges remain. These include low production yields, reliance on chemical stabilisers, prolonged and complex processing protocols, elevated manufacturing costs, and the use of high molecular weight reagents. The challenges and constraints previously outlined may be effectively addressed through the implementation of thin film microfluidic technologies, which have recently exhibited notable progress particularly in the development of simplified, single-step methodologies for synthesising zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D) nanomaterials. These innovations are pivotal in advancing sustainable and cost-effective manufacturing processes. Thin film microfluidics confer distinct advantages in chemical synthesis, including an elevated surface-to-volume ratio, reduced reaction durations, precise regulation of residence time and thermal conditions, improved operational safety, and most importantly the inherent potential to factor in scalability at the inception of the research. This dissertation aims to initiate a paradigm shift in nanoscience through the application of a thin-film microfluidic platform, the vortex fluidic device (VFD) to precisely control the fabrication of nanocarbon materials. The VFD has demonstrated versatility across a range of applications, including but not limited to: the transformation of zero-dimensional (0D) fullerenes into two-dimensional (2D) sheets; the exfoliation and v functionalisation of graphene sheets with nanodiamonds exhibit promising performance in electrochemical applications, particularly in the two-electron oxygen reduction reaction (2e-ORR); the unzipping of multiwalled carbon nanotubes under continuous flow conditions; and the controlled synthesis of composite nanocarbon structures from graphene oxide and fullerene C₇₀. Furthermore, the VFD has enabled the encapsulation and decoration of single-walled carbon nanotubes (SWCNTs) with 0D fullerenes, these fabricated nanocarbon composites are currently under investigation for their electrochemical applications. Notably, the high shear fluid dynamics within the VFD have been shown to induce chirality within flow of the liquids, contingent on the direction of tube rotation, with the process further influenced by the Earth's magnetic field. The primary advantage of the VFD lies in its capacity to fabricate nanomaterials without utilising toxic and harsh chemicals, employing straightforward one-step methods that exclude chemical stabilisers and surfactants, while also ensuring scalability of the processing.