Nanostructured cobalt-modified molybdenum carbides electrocatalysts for hydrogen evolution reaction

• Published in: International journal of hydrogen energy Vol. 41; no. 48; pp. 22899 - 22912
• Main Authors: Bukola, Saheed, Merzougui, Belabbes, Creager, Stephen E., Qamar, Mohammad, Pederson, Larry R., Noui-Mehidi, Mohamed N.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 28.12.2016
• Subjects: Brine water; Electrocatalyst; Hydrogen evolution reaction; Molybdenum carbide; Sustainable fuel; Hydrogen evolution reaction; Electrocatalyst; Molybdenum carbide; Sustainable fuel; Brine water
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2016.10.017

A series of nanostructured catalysts based on cobalt-modified molybdenum carbides, intended as alternative replacement for platinum has been developed for the hydrogen evolution reaction (HER) from brine. The catalysts were synthesized by simple impregnation of the metal salts on carbon support and followed by pyrolysis in CH4 atmosphere. The obtained catalysts show impressive HER activities in both brine and alkaline media. At current density of −7.0 mA cm−2, the overpotential for Co modified Mo/C catalysts was greater than that obtained with a commercial Pt/C catalyst by 63–89 mV and 15–148 mV for brine and alkaline solution, respectively. Our findings for HER in both media are consistent with electrochemical desorption of hydrogen gas following the Volmer-Heyrovsky mechanism as the rate-determining step. The HER activities of the catalysts were correlated to their high mesopore surface areas with active pores, nanocrystallites, and low charge transfer resistances as confirmed by electrochemical impedance spectroscopy. [Display omitted] •Synthesis of a series of cobalt-modified molybdenum carbides of size 12–44 nm.•Cobalt encapsulation imparts more stability to Mo2C matrix.•Hydrogen evolution reaction was studied in both synthetic brine water and 0.1 M KOH.