Observation of H2 Evolution and Electrolyte Diffusion on MoS2 Monolayer by In Situ Liquid-Phase Transmission Electron Microscopy

Jihoon Kim, Anseong Park, Joodeok Kim, Seung Jae Kwak, Jae Yoon Lee, Donghoon Lee, Sebin Kim, Back Kyu Choi, Sungin Kim, Jimin Kwag, Younhwa Kim, Sungho Jeon, Won Chul Lee, Taeghwan Hyeon, Chul Ho Lee, Won Bo Lee, Jungwon Park

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Unit-cell-thick MoS2 is a promising electrocatalyst for the hydrogen evolution reaction (HER) owing to its tunable catalytic activity, which is determined based on the energetics and molecular interactions of different types of HER active sites. Kinetic responses of MoS2 active sites, including the reaction onset, diffusion of the electrolyte and H2 bubbles, and continuation of these processes, are important factors affecting the catalytic activity of MoS2. Investigating these factors requires a direct real-time analysis of the HER occurring on spatially independent active sites. Herein, the H2 evolution and electrolyte diffusion on the surface of MoS2 are observed in real time by in situ electrochemical liquid-phase transmission electron microscopy (LPTEM). Time-dependent LPTEM observations reveal that different types of active sites are sequentially activated under the same conditions. Furthermore, the electrolyte flow to these sites is influenced by the reduction potential and site geometry, which affects the bubble detachment and overall HER activity of MoS2.

Original languageEnglish
Article number2206066
JournalAdvanced Materials
Issue number45
Publication statusPublished - 2022 Nov 10

Bibliographical note

Funding Information:
J.K. and A.P. contributed equally to this work. J.K., J.K., B.K.C., S.K., J.K., T.H., and J.P. acknowledge the Institutes for Basic Science (Grant No. IBS‐R006‐D1). J.P. acknowledges the National Research Foundation of Korea (NRF) grant, funded by the Korea government (MSIT) (Grant No. NRF‐2021M3H4A1A02049904).

Publisher Copyright:
© 2022 Wiley-VCH GmbH.


  • 2D materials
  • H  bubble formation
  • electrolyte insertion
  • hydrogen evolution reaction (HER)
  • molybdenum sulfide (MoS )

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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