Electrochemical synthesis of flake-like Fe/MWCNTs nanocomposite for hydrogen evolution reaction: Effect of the CNTs on dendrite growth of iron and its electrocatalytic activity

Fe/multi-walled carbon nanotubes (Fe/MWCNTs) nanocomposite was produced using electrochemical techniques onto platinum substrate. Linear sweep voltammetry (LSV) analysis revealed that deposition rate of the nanocomposite is higher than of the pure Fe deposition. X-ray diffraction (XRD) was used to confirm nanocomposite formation. Scanning electron microscopy (SEM) images showed dendrite growth of the pure Fe onto a flake-like (thickness of about 90 nm) structure with a filamentous carbon network. The morphology of the nanocomposite consisted of only uniform nanoflakes with thickness of about 50 nm. Adsorption of the MWCNTs on the flakes led to decrease the nucleation energy and avoided formation of the prisms that are essential for dendrite growth. The nanocomposite showed superior catalytic activities for hydrogen evolution reaction (HER), twice of the pure Fe when the overpotential of −1.3 V was applied. The overpotential–time results indicated that HER activity of thin films decreased during the long-term working. But, nanocomposite was more stable than the pure Fe.