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Abstract: In the past few years, research on Pt substitutes has focused on the electrocatalytic properties of layered transition metal dichalcogenides (LTMDs). The decoration of LTMDs with platinum-group metal (PGM) demonstrates a synergetic effect with PGM deposited on the LTMD basal plane. We report on the hydrogen evolution reaction (HER) electrocatalysis by PGM grown on vertically aligned (VA) MoS2. The VA-MoS2 films were processed by chemical vapor deposition (CVD) and the PGM (Pt and Pd) were electrodeposited specifically on the edges of the MoS2 flakes from a simple metallic foil. Electron microscopy shows the formation of nm-scale metallic clusters binding through the dangling bonds of the unsaturated sulfides. The VA-MoS2 remains intact through the electrodeposition process, as demonstrated by Raman spectroscopy and high-resolution transmission electron microscopy. In acidic media, both electrocatalysts VA-MoS2@Pt and VA-MoS2@Pd show a very low overpotential (91 and 106 mV respectively at 10 mAcm2) with high current density at 300 mV overpotential (318 and 174 mAcm2 respectively). Interestingly, the Tafel slope of VA-MoS2@Pt is even lower than that of platinum foil (24 vs 33 mVdec1 respectively).
Keywords: Hydrogen evolution reaction, Layered transition metal dichalcogenides, Nanoparticles, Electrodeposition, MoS2