Synthesis of semiconducting SWNTs by arc discharge and their enhancement of water splitting performance with TiO2 photocatalyst

A feasible and scalable CO2-assisted arc discharge method was developed to directly synthesize single-walled carbon nanotubes (SWCNTs) with largely semiconducting species. Not only was electronic-type selectivity achieved on a large scale, with a semiconducting SWCNT (s-SWCNT) content of >90%, but also diameter selectivity was obtained, with a majority having diameters of >1.5 nm. The photo-catalytic water splitting performance of these SWCNTs with different ratios of s-SWCNTs to metallic single-walled carbon nanotubes (m-SWCNTs) was examined. The results show that, compared with m-SWCNTs, s-SWCNTs demonstrate a much better photocatalytic effect when used together with the common photo-catalyst TiO2.