Optimization of CCVD synthesis conditions for single-wall carbon nanotubes by statistical design of experiments (DoE)

Abstract

We report the successful optimization of single-wall carbon nanotube (SWCNT) synthesis by catalytic chemical vapor deposition (CCVD) on FeMo/MgO catalyst using acetylene as carbon source. Taking a starting parameter set from the literature we optimized seven (catalyst composition, catalyst amount, reaction temperature, reaction time, preheating time, C 2H 2 volumetric flow rate, inert gas volumetric flow rate) factors to our local experimental system by relying on statistical design of experiments (DoE). Performance was assessed using two quantitative descriptors: mass of carbonaceous material formed and SWCNT content as calculated from FT-Raman spectra. The parameter space was first screened for important factors using a 2 III 7 - 4 fractional factorial design, then the response surface defined by the three most significant parameters was obtained from Box–Behnken design and the optimal parameter set was found. The superiority of the DoE method over the conventional COST (change one separate factor at a time) approach is shown by the fact that we were able to optimize seven individual factors with only 21 + 2 runs. The described method can readily be used to swiftly adapt a literature-based CCVD process to the local instrumentation of any laboratory.