In situ XAFS study of the chemical state of a Co catalyst during single-walled carbon nanotube growth under conventional growth conditions using alcohol catalytic chemical vapor deposition

[Display omitted] •In situ XAFS analysis for single-walled carbon nanotube growth from Co catalysts.•Composition of Co catalysts was varied during temperature rise and nanotube growth.•Single-walled carbon nanotubes were grown from Co carbide catalysts. In situ X-ray absorption fine structure spectroscopy (XAFS) analysis was performed on cobalt (Co) catalysts during single-walled carbon nanotube (SWCNT) growth by alcohol catalytic chemical vapor deposition. Co K-edge XAFS analysis showed that Co catalysts prepared from Co acetates were composed of both Co oxides and carbides, which were reduced as the temperature increased to 800 °C. Upon addition of ethanol, the Co catalysts gradually changed to carbides. Our results show that Co catalysts are mainly composed of carbides formed during SWCNT growth under conventional growth conditions in alcohol catalytic chemical vapor deposition (ACCVD).