The investigation of Mo3Sb7 and Mo3Sb7-xTex as electrocatalysts for the hydrogen evolution reaction

Abstract

Proton exchange membrane electrolysers are considered one of the most promising devices for storing the excess, intermittent energy generated by renewable sources through water electrolysis. Hydrogen production by electrolysis is currently facilitated by expensive noble metals that act as electrocatalysts. Therefore, the future development of the hydrogen evolution reaction (HER) relies on sourcing relatively inexpensive materials that can act as alternative catalysts to noble metals. Herein, we explore the catalytic activity of Mo3Sb7 towards the HER and the effect that tellurium doping has on the system. Mo3Sb7 showed a large overpotential of 570 mV at a current density of 10 mA cm−2. However, the replacement of Sb with Te increased the stability of the catalyst and in the case of Mo3Sb5.4Te1.6 reduced the overpotential required to achieve 10 mA cm−2 to 511 mV. This improvement in performance is also mirrored in the Tafel slopes of the materials with Mo3Sb5.4Te1.6 having a Tafel slope of 136.2 ± 0.5 mV dec-1 compared to 167.5 ± 0.6 mV dec-1 exhibited by Mo3Sb7. Although the three compounds tested are suboptimal HER catalysts, compared to state-of-the-art materials, they nevertheless provide an interesting system to observe the effects of tellurium doping on the catalytic performance.

Keywords

• Hydrogen
• Water electrolysis
• Electrocatalytic materials
• Electrochemical measurements