Hydrogen storage of nanostructured TiO 2-impregnated carbon nanotubes

Abstract

Hydrogen uptake study of carbon nanotubes (CNTs) impregnated with TiO 2-nanorods and nanotubes has been performed at room temperature and moderate hydrogen pressures of 8–18 atm. Under hydrothermal synthesis conditions, nanorods (NRs) and nanoparticles (NPs) are found to form either of the two polymorphic phases, i.e., nanorods are formed of predominantly anatase phase while nanoparticles are formed of rutile phase. NRs and NPs are introduced into the CNT matrix via the wetness-impregnation method. These composites store up to 0.40 wt.% of hydrogen at 298 K and 18 atm, which is nearly five times higher the hydrogen uptake of pristine CNTs. The excess amount of hydrogen stored in TiO 2-impregnated CNTs is determined from the amount of TiO 2 in the sample and the measured hydrogen uptake of TiO 2 nanoparticles. Higher hydrogen uptake of NP-impregnated CNTs when compared pristine CNTs is accounted for by considering initial binding of hydrogen on TiO 2 and subsequent spillover in CNT–TiO 2-NPs.