MWCNT coatings obtained by thermal CVD using ethanol decomposition

A low-cost and reliable method to produce MWCNT coatings on large surfaces, with possibility to scale up to larger output, aiming at gas sensor applications is reported. The process was based on ethanol decomposition in the temperature range 700–900 °C. Different qualities of carbon were produced depending on the experimental parameters. For the samples deposited on sapphire and using Ni as catalyst a high diversity of carbon products (amorphous carbon, graphite plates, MWCNTs, onion-like graphene, etc.) were registered, while for the samples deposited on quartz MWCNTs with better crystallinity were observed. Carbon nanofibres (about 50–60 nm diameter) were observed only for the samples with Fe catalyst. Depending on temperature, nanotubes with different thickness of amorphous carbon coating occurred. According to our findings, the deposition of amorphous carbon phase can be minimized depending on the oxygen content in the process.