Field Effect Modulation of Electrocatalytic Hydrogen Evolution at Back-Gated Two-Dimensional MoS2 Electrodes

Yan Wang, Sagar Udyavara, Matthew Neurock, Daniel Frisbie

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

Electrocatalytic activity for hydrogen evolution at monolayer MoS2 electrodes can be enhanced by the application of an electric field normal to the electrode plane. The electric field is produced by a gate electrode lying underneath the MoS2 and separated from it by a dielectric. Application of a voltage to the back-side gate electrode while sweeping the MoS2 electrochemical potential in a conventional manner in 0.5 M H2SO4 results in up to a 140 mV reduction in overpotential for hydrogen evolution at current densities of 50 mA/cm2. Tafel analysis indicates that the exchange current density is correspondingly improved by a factor of four to 0.1 mA/cm2 as gate voltage is increased. Density functional theory calculations support a mechanism in which the higher hydrogen evolution activity is caused by gate-induced increase in the electronic charge on Mo metal centers adjacent to the S vacancies (the active sites), leading to enhanced Mo-H bond strengths. Overall, our findings indicate that the back-gated working electrode architecture is a convenient and versatile platform for investigating the connection between tunable electronic charge at active sites and overpotential for electrocatalytic processes on ultrathin electrode materials.

Original languageEnglish (US)
Pages (from-to)6118-6123
Number of pages6
JournalNano letters
Volume19
Issue number9
DOIs
StatePublished - Sep 11 2019

Bibliographical note

Funding Information:
The authors thank Dr. Chang-Hyun Kim for valuable discussions, Tony Whipple, Dr. Sushil Kumar Pandey, and Dr. Youngdong Yoo for their help in the CVD synthesis, and Dr. Tao He, Dr. Zhuoran Zhang, and Rui Ma for collecting AFM images. Y.W. acknowledges support through the Doctoral Dissertation Fellowship from the University of Minnesota. Parts of this work were carried out in the College of Science and Engineering Characterization Facility, University of Minnesota, which has received capital equipment funding from the NSF through the UMN MRSEC program under Award Number DMR-1420013, and in the Minnesota Nano Center which is supported by NSF through the National Nano Coordinated Infrastructure Network, Award Number NNCI - 1542202. We would also like to thank the National Science Foundation CCI program (award 1740656) for partial support and the MSI Supercomputing Institute at the University of Minnesota for computing resources.

Publisher Copyright:
© 2019 American Chemical Society.

Keywords

  • Electrocatalysis
  • MoS
  • density functional theory
  • field effect
  • gating
  • hydrogen evolution reaction

MRSEC Support

  • Shared

PubMed: MeSH publication types

  • Journal Article

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