A large-diameter FCCVD reactor approach for scalable CNT sheet fabrication

The direct spinning of carbon nanotube (CNT) aerogels via floating catalyst chemical vapour deposition (FCCVD) provides a robust pathway for translating nanoscale CNT assemblies into continuous macroscopic sheets. Scaling this process to larger reactor diameters is essential for improving throughput and enabling industrial-level production; however, such scale-up introduces complex transport, catalytic, and process-control challenges that must be systematically understood and optimised. In this study, we investigate the synthesis of CNT sheets in a large-diameter (100 mm) FCCVD reactor, with a focus on resolving key limitations associated with scalability and continuous sheet formation. The influence of precursor delivery rates, carrier and fuel gas composition, catalyst formulation, residence time, and operating pressure on CNT sheet growth has been comprehensively examined. Extensive characterisation, including Raman spectroscopy, SEM, TEM, XPS, TGA, and computational fluid dynamics (CFD) analyses, provides detailed insight into the structural, chemical, and thermal features of the resulting CNT networks and the underlying mechanisms governing aerogel formation in an enlarged reaction volume. Through systematic optimisation of process parameters, we demonstrate the successful production of macroscale CNT sheets with a yield of 4.0% and a carbon conversion rate of 7.5 mg min⁻¹, representing a significant improvement over conventional reactor geometry. These results establish critical guidelines for process intensification and highlight the practical viability of large-diameter FCCVD reactors for high-efficiency, high-productivity CNT sheet manufacturing.