• Oliviero, Laetitia
• Martin, Vincent
• Kumar, Kavita
• Santos, Keyla Teixeira
• Zavala, Luz A.
• Maillard, Frédéric
• Dubau, Laetitia

Abstract

The development of clean and renewable energy is one of the most tackled challenge nowadays. Among the strategies to replace fossil fuel, hydrogen obtained via water electrolysis has attracted considerable attention. Noble metal-based catalysts such as carbon-supported platinum nanoparticles (Pt/C) are the benchmark material for hydrogen evolution reaction (HER) in proton-exchange membrane water electrolyzers (PEMWEs). However, the scarcity and consequent high price of this metal limit its worldwide application. Molybdenum (Mo)-based electrocatalysts are the most promising candidates to replace Pt/C catalysts at the PEMWE cathode [1]. Several synthetic approaches, including modulation of their structure and morphology, have gained momentum to enhance their electrocatalytic performance [2]. Another approach to enhance the intrinsic HER activity consists in using promoter single atoms (doping with Co, Ni or Pt) [3]. Here we report on the catalytic performance and durability of MoS2, Co-MoS2 and Pt1wt%-CoMoS2 nanoclusters supported on high surface area carbon. Physico-chemical analyses provide evidence that (i) all catalytic materials feature similar morphology, size and dispersion, (ii) 2H structure of MoS2 has been synthesized and (iii) the promoting atoms are mostly located at the edges. At a current density of 10 mA cm-2 , an overpotential of 188 mV was obtained for MoS2/C, 140 mV and 118 mV for CoMoS2/C andPt1%-CoMoS2/C respectively [4]. Since the density of active sites was identical for the three catalysts, the promoting Co/Pt atoms located at the edges of the MoS2 slabs seem to positively modify the nature of the active sites, and the neighboring atoms (electronic effect) [3]. The durability of the materials was assessed by monitoring the dissolution of Mo, Co and Pt elements in situ using a flow cell connected to an inductively coupled plasma mass spectrometry (ICP-MS) and ex situ after a durability test in potentiostatic conditions allowing to access and compare the stability number (S-number) of each catalyst. In summary, the present study suggests that doping/promoting MoS2 catalysts with Co or Co-Pt is a promising alternative to replace Pt/C electrocatalysts in acid water electrolyzers.[1] Hua, W., Sun, HH., Xu, F. et al. A review and perspective on molybdenum-based electrocatalysts for hydrogen evolution reaction. Rare Met. 39, 335–351 (2020). [2] Chen, J.; Maugé, F.; Fallah, J. El; Oliviero, L. IR Spectroscopy evidence of MoS2 morphology change by citric acid addition on MoS2/Al2O3 catalysts – A step forward to differentiate the reactivity of M-edge and S-edge. J. Catal. 320, 170–179 (2014). [3] Zavala-Sanchez, L., Portier, X., Maugé, F., Oliviero, L. Formation and stability of CoMoS nanoclusters by the addition of citric acid: A study by high resolution STEM-HAADF microscopy, Catalysis Today, 377, 127-134 (2021). [4] Zavala, L.A, Kumar, K., Martin, V., Maillard, F., Maugé, F., Portier, X., Oliviero, L., Dubau L. Direct evidence of the role of Co or Pt, Co single-atom promoters on the performance of MoS2 nanoclusters for the hydrogen evolution reaction. ACS Catal. 13, 1221-1229 (2023).

Topics

• nanoparticle
• density
• impedance spectroscopy
• dispersion
• surface
• molybdenum
• Carbon
• Platinum
• Hydrogen
• current density
• durability
• spectrometry
• infrared spectroscopy
• microscopy
• inductively coupled plasma mass spectrometry