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 mA cm−2) with high current density at 300 mV overpotential (318 and 174 mA cm−2 respectively). Interestingly, the Tafel slope of VA-MoS2@Pt is even lower than that of platinum foil (24 vs 33 mV dec−1 respectively).
Bibliographical noteFunding Information:
The authors are deeply grateful to Dr Doron Naveh for fruitful discussions and access to his facilities, Chen Stern for her assistance with the MoS 2 growth and Noam Gotlib for the Raman spectroscopy. The authors thank Dr Vladimir Ezersky and Dr Ilana Perelshtein for the HRTEM, Prof. Arlene Gordon and Yuval Elias for proofreading. The authors thank Dr Yuval Elias and Yulia Kostikov for proofreading the article. D.Z. acknowledges partial financial support from the Israel Council for Higher Education through the Israel National Research center for Electrochemical Propulsion (INREP) and the Israel Ministry of Science and Technology .
© 2017 Elsevier Ltd
- Hydrogen evolution reaction
- Layered transition metal dichalcogenides