Valence and oxide impurities in MoS2 and WS2 dramatically change their electrocatalytic activity towards proton reduction

Naziah Mohamad Latiff; Lu Wang; Carmen C Mayorga-Martinez; Zdeněk Sofer; Adrian C Fisher; Martin Pumera

doi:10.1039/c6nr03086f

Valence and oxide impurities in MoS₂ and WS₂ dramatically change their electrocatalytic activity towards proton reduction

Nanoscale. 2016 Sep 22;8(37):16752-16760. doi: 10.1039/c6nr03086f.

Authors

Naziah Mohamad Latiff¹, Lu Wang¹, Carmen C Mayorga-Martinez¹, Zdeněk Sofer², Adrian C Fisher³, Martin Pumera¹

Affiliations

¹ Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore. pumera.research@gmail.com.
² Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, 166 28, Prague 6, Czech Republic.
³ Department of Chemical Engineering and Biotechnology, University of Cambridge, UK.

PMID: 27714024
DOI: 10.1039/c6nr03086f

Abstract

Layered molybdenum disulfide (MoS₂) and tungsten disulfide (WS₂) have received renewed interest in recent years as they are catalytic towards the hydrogen evolution reaction (HER) and they are touted as future replacements of platinum in electrolyzers. There is a significant discrepancy in the found onset potentials of MoS₂ and WS₂ towards the hydrogen evolution reaction. Here we show that the presence of valence sulfide impurities, such as MoS₃ and WS₃, and their oxide counterparts, such as MoO₂, MoO₃ and WO₂, WO₃ can contribute to the catalytic activity towards hydronium reduction to hydrogen of MoS₂ and WS₂. Therefore, it is highly possible that the differences in the reported onset potentials and thus catalytic activities of the MoS₂ and WS₂ are due to the presence of catalytic impurities.