Comparative hydrogen uptake study on titanium–MWCNTs composite prepared by two different methods

Abstract

Hydrogen uptake of a multi-walled carbon nanotubes (MWCNTs) is increased 5- and 25-fold at 298 K and an equilibrium pressure of ∼16 atm, upon addition of a hydrogen spillover catalyst titanium, from 0.43 to 2.0 wt.%. Two important preparation methods; high-energy ball milling and sputtering method is utilized to synthesize Ti–MWCNTs composite. Thermogravimetric analysis suggests decoration of Ti on MWCNTs is ∼3.5 wt.% and TEM demonstrates nanostructural characterization of both pristine and Ti–MWCNTs. Enhancement of hydrogen uptake of sputtered sample is attributed to the efficient spillover mechanism due to well-arranged decoration of titanium nanoparticles on the outer surface of MWCNTs compared to milled sample. Adsorption and re-adsorption of sputtered composite indicate inconsistent hydrogen storage capacity between 1.56 and 2.0 wt.%.