Novel one-step synthesis of wool-ball-like Ni-carbon nanotubes composite cathodes with favorable electrocatalytic activity for hydrogen evolution reaction in alkaline solution

In this work, supergravity fields are performed to prepare Ni-CNTs composite cathodes with wool-ball like morphology from the Watts bath containing well-distributed functionalized CNTs. The prepared Ni-CNTs composite cathodes are used as noble metal-free electrocatalyst with favorable electrocatalytic activity for hydrogen evolution reaction (HER) in alkaline solutions. The crystal structure and morphology of the composite cathodes are characterized by XRD and SEM measurements. The electrochemical activities of the cathodes are characterized through Tafel polarization measurement, electrochemical impedance spectroscopy and cyclic voltammetric study in 1.0 M NaOH solution. The results indicate that catalytic activities of the Ni-CNTs cathodes prepared under supergravity fields are enhanced significantly, and the sample prepared at rotating speed 3000 rpm from the bath containing 1 g dm(-3) CNTs exhibits the highest HER activity with smallest Tafel slope and largest exchange current density of 823.9 mu A cm(-2). Furthermore, the effects of both the CNTs concentrations and the intensities of super gravity fields on the properties of the Ni-CNTs cathodes are investigated. (C) 2016 Published by Elsevier B.V.