Sustainable synthesis of diamond-like carbon and carbon fibres from hyperbaric ethanol–water mixtures through the critical point

Freestanding carbon fibres with diamond-like carbon content were grown from ethanol-water mixtures using hyperbaric-pressure laser chemical vapour deposition. Pressures of up to 103 bar were investigated, through the critical point of the precursor fluid. Rapid fibre axial growth rates of up to 100 μ m/s were observed. Process-structure relationships and a Raman spectral P-T phase diagram were developed, providing a potential route to optimising sp 3 -bonding. Most fibre growth was mass transport limited, but near the critical point, a kinetically-limited regime emerged. Due to divergent thermophysical properties of the precursor fluid, and the thermal diffusion effect, growth rates were suppressed at/near the critical point.