Synergetic effect of PdNP and MWCNT as cocatalysts for enhanced electrocatalytic hydrogen evolution activity of MoS2

To achieve an optimal performance, efficient electrocatalysts for HER are critical. At present, the most efficient and typical electrocatalysts for HER are Pt based compounds, which can realize excessive catalytic activity with almost no overpotential [1]. But the high cost and low abundance of Pt hinders the large-scale hydrogen production through acidic electrolyzers like polymer electrolyte membrane (PEM) electrolyzers [2]. Here, the hybrid material of MoS2-coated Pd nanoparticles loaded on the multiwalled carbon nanotubes (Pd-MoS2/MWCNT) was synthesized using chemical process and hydrothermal method. The nanohybrid was characterized by X-ray diffraction (XRD) patterns, Raman scattering, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Pd- MoS2/MWCNT showed the high activity for hydrogen evolution reaction with a small onset overpotential of 70 mV, a high exchange current density of 7.1 × 10−2 mA cm−1 and Tafel slope of 54 mV decade−1 as well as an excellent stability in acid media. It was found that these catalyst exhibited excellent HER activity compared to MoS2 nanoflower, Pd-MoS2 and MoS2/MWCNT due to the synergistic effect of the high catalytic activity of MoS2 nanoflowers and the excellent conductivity and large surface area of MWCNT and providing more free sites for the adsorption of H using Pd nanoparticles, exposing much more active sites and reducing intrinsic resistance. The turnover frequency per active site is also calculated. This work demonstrates the feasibility of increasing HER activity of MoS2-based catalysts by combining MoS2with MWCNT and Pd noble metal nanoparticles.