Iron doped titania/multiwalled carbon nanotube nanocomposite: A robust electrocatalyst for hydrogen evolution reaction in aqueous acidic medium

Abstract

Development of Pt free catalyst for hydrogen evolution reaction (HER) is a key area in the field of alternate fuel production. The present work describes the electrocatalytic activity of Fe doped TiO2/MWCNT nanocomposite towards hydrogen evolution electrocatalyst. The catalyst is prepared using a surfactant wrapping in situ sol gel method. This method generates a well-defined nanocomposite with individual MWCNTs decorated with active Fe doped titania particles. The nanocomposite catalyses the evolution of H2 at potentials between -0.55 V and -0.10 V vs RHE in acidic aqueous medium. A comparative study of different catalysts (Fe doped TiO2/MWCNT, platinized Fe doped TiO2, Fe doped TiO2 and bare TiO2) towards HER shows better catalytic activity by Fe doped TiO2/MWCNT than the rest, with a small overpotential of 221 mV and a tafel slope value of 0.152 V dec−1 at current density 10 mA cm−2. The catalyst maintains stability for 63,809 s. The performance enhancement of Fe doped TiO2/MWCNT can be attributed specifically to the increased electric conductivity by MWCNTs. The catalytic activity increases with increasing MWCNT content (from wt% 0.35 to 0.50). MWCNTs also lower the band gap in the synthesized catalyst, thereby promoting charge separation by shortening the charge transfer distance from the generation site to the surface, making spatial charge separation and overall increasing the number of active sites in the final composite.