Efficient hydrogen evolution catalysis triggered by electrochemically anchored platinum nano-islands on functionalized-MWCNT

Abstract

We report the electrochemical deposition (ECD) of platinum nano-islands (Pt NIs) on functionalized multi-walled carbon nanotubes (ECD Pt NIs@f-MWCNT) as an efficient electrocatalyst for the hydrogen evolution reaction (HER). Pristine MWCNT was acid treated to induce the number of oxygen functional groups on the surface and enhances the wettability. Thereafter, Pt nanoparticles (Pt Nps) were deposited by a simple electrodeposition technique on the oxygen enriched MWCNT surface. The Pt NIs@f-MWCNT has been physicochemically characterized using X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and X-ray photoelectron Spectroscopy (XPS). The TEM analysis showed the presence of Pt NIs on MWCNT wherein, the NIs were made up of small Pt nanoclusters of ∼4 nm in dimension. The electrochemical HER studies were carried out using linear sweep voltammetry (LSV), Tafel polarization and electrochemical impedance spectroscopy (EIS). An overpotential (ɳ) of −84 mV was obtained at a current density (j) of −10 mA/cm2. The amount of Pt loading has been optimized through electrodeposition. Enhanced HER activity was observed with a Pt loading of 3.8 μg/cm2. In order to ascertain the durability of the catalyst, accelerated degradation test (ADT) was carried out for 10,000 cycles at a scan rate (ʋ) of 100 mV/s. The turnover frequency (TOF) was estimated to be 6.3 s−1 at ɳ = −70 mV.