Layered transition metal dichalcogenides (TMDs) are at the forefront of materials research. One of the most important applications of these materials is their electrocatalytic activity towards hydrogen evolution, and these materials are suggested to replace scarce platinum. Whilst there are significant efforts towards this goal, there are various reports of electrocatalysis of MoS2 (which is the most commonly tested TMD) with large variations of the reported electrocatalytic effect of the material, with overpotential varying by several hundreds of millivolts. Here, we analyzed surface properties of various bulk as well as single layer MoS2 samples using inverse gas chromatography. All samples displayed significant variations in surface energies and their heterogeneities. The surface energy ranged from 50 to 120 mJ m-2 depending on the sample and surface coverage. We correlated the surface properties and previously reported structural features of MoS2 with their electrochemical activities. We concluded that the observed differences in electrochemistry are caused by the surface properties. This is an important finding with an enormous impact on the whole field of electrocatalysis of layered materials.
Bibliographical noteFunding Information:
Financial support from the Ministry of Education, Youth and Sports of the Czech Republic via projects LO1305 and CZ.1.05/ 2.1.00/19.0377, and the Grant agency of the Czech Republic via project P208/12/G016 is gratefully acknowledged. Z. S. and J. L. were supported by the Czech Science Foundation (GACR No. 17-11456S) and by specific university research (MSMT No. 20-SVV/2017). M. P. thanks Tier 1 grant (99/13) for funding. This work was created with the financial support of the Neuron Foundation for science support. M. O. thanks the ERC Consolidator grant 683024 from the European Union’s Horizon 2020. We thank Martin Pykal for the design of TOC.
© 2017 The Royal Society of Chemistry.
All Science Journal Classification (ASJC) codes
- Materials Science(all)