Fabrication of a Robust PEM Water Electrolyzer Based on Non‐Noble Metal Cathode Catalyst: [Mo3S13]2− Clusters Anchored to N‐Doped Carbon Nanotubes

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 16; no. 37; pp. e2003161 - n/a
• Main Authors: Holzapfel, Peter K. R., Bühler, Melanie, Escalera‐López, Daniel, Bierling, Markus, Speck, Florian D., Mayrhofer, Karl J. J., Cherevko, Serhiy, Pham, Chuyen V., Thiele, Simon
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01-09-2020
• Subjects: Activation; Carbon nanotubes; Catalysts; Chemical energy; Clean energy; Clusters; Current density; Dissolution; Electrochemical activation; Electrode polarization; Electrodissolution; hydrogen evolution reaction; Hydrogen evolution reactions; Molecular structure; molybdenum sulfide; Nanotechnology; Nitrogen; Noble metals; non‐noble metal catalysts; Photoelectrons; porous transport electrodes; proton exchange membrane water electrolysis; Stability analysis; Stability tests; Water splitting
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202003161

High investment costs and a dependence on noble metal catalysts currently obstruct the large‐scale implementation of proton exchange membrane water electrolyzers (PEMWEs) for converting fluctuating green electricity into chemical energy via water splitting. In this context, this work presents a high‐performing and stable non‐noble metal catalyst for the hydrogen evolution reaction (HER), consisting of [Mo3S13]2− clusters supported on nitrogen doped carbon nanotubes (NCNTs). Strikingly, a significant electrochemically induced activation of the Mo3S13‐NCNT catalyst at high current densities is observed in full cell configuration, enabling a remarkable current density of 4 A cm−2 at a cell voltage of 2.36 V. To the authors’ knowledge, this is the highest reported value to date for a PEMWE full cell using a non‐noble metal HER catalyst. Furthermore, only a minor degradation of 83 µV h−1 is observed during a stability test of 100 h constant current at 1 A cm−2, with a nearly unchanged polarization behavior after the current hold. Catalyst stability and activity are additionally analyzed via online dissolution measurements. X‐ray photoelectron spectroscopy examination of the catalyst before and after electrochemical application reveals a correlation between the electrochemical activation occurring via electrodissolution with changes in the molecular structure of the Mo3S13‐NCNT catalyst.
A remarkable current density of 4 A cm−2 at 2.36 V and minor degradation during 100 h current hold at 1 A cm−2 are demonstrated for a proton exchange membrane water electrolyzer using [Mo3S13]2− clusters supported on nitrogen doped carbon nanotubes as a hydrogen evolution reaction catalyst. This work also reveals insights into the activation behavior of this catalyst group.