Boosting the photocatalytic hydrogen evolution performance via an atomically thin 2D heterojunction visualized by scanning photoelectrochemical microscopy

Jae Yoon Lee, Sungwoo Kang, Donghun Lee, Seokhoon Choi, Seunghoon Yang, Kangwon Kim, Yoon Seok Kim, Ki Chang Kwon, Soo ho Choi, Soo Min Kim, Jihoon Kim, Jungwon Park, Haeli Park, Woong Huh, Hee Seong Kang, Seong Won Lee, Hong Gyu Park, Min Jae Ko, Hyeonsik Cheng, Seungwu HanHo Won Jang, Chul Ho Lee

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


Heterojunction catalyst can facilitate efficient photoelectrochemical (PEC) hydrogen evolution by reducing a potential barrier for charge transfer at the semiconductor/electrolyte interface. Such a heterojunction effect at the atomic thickness limit has not yet been explored although it can be strengthened because of strong built-in field and ultrafast charge transfer across the junction. Here, we first investigate a novel strategy to boost the hydrogen evolution performance of the p-type WSe2 photocathode via reducing the overpotential with an atomically thin heterojunction catalyst comprising MoS2 and WS2 monolayers. To unveil an effective role of the heterojunction by isolating its kinetic contribution from other collective catalytic effects, we develop and utilize an in situ scanning PEC microscopy, which enables the spatially-resolved visualization of the enhanced photocatalytic hydrogen evolution performance of the heterojunction. Notably, significant reduction in overpotential, from +0.28 ± 0.03 to −0.04 ± 0.05 V versus (vs.) the reversible hydrogen electrode (RHE), is achieved when the MoS2/WS2 heterojunction is introduced as a catalyst even without intentional generation of catalytic sites. As a result, the photocurrent of ~4.0 mA cm−2 occurs even at 0 V vs. RHE. Furthermore, the beneficial effect of the atomically scaled vertical heterojunction is explained by the built-in potential resulted from efficient charge transfer in type-II heterojunctions with the support of first-principles calculations. Our demonstration not only offers an unprecedented approach to investigating the fundamental PEC characteristics in relation to the tailored properties of a catalyst but also proposes a new catalytic architecture, thereby enabling the design of highly efficient PEC systems.

Original languageEnglish
Article number104053
JournalNano Energy
Publication statusPublished - 2019 Nov

Bibliographical note

Publisher Copyright:
© 2019 Elsevier Ltd


  • Catalyst
  • Heterojunction
  • Photoelectrochemical hydrogen evolution
  • Spatially resolved PEC characterization
  • Transition metal dichalcogenides

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • General Materials Science
  • Electrical and Electronic Engineering


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