Cu(In,Ga)(S,Se)2 Photocathodes with a Grown-In CuxS Catalyst for Solar Water Splitting

Byungwoo Kim, Gi Soon Park, Yun Jeong Hwang, Da Hye Won, Woong Kim, Dong Ki Lee, Byoung Koun Min

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


As CuInGa-based chalcopyrite photocathodes suffer from poor hydrogen evolution activity, n-type overlayers and hydrogen evolution catalysts (HECs) need to be deposited on the film surface to drive surface band bending and reduce the overpotential for the hydrogen evolution reaction (HER). Here, we present a Cu(In,Ga)(S,Se)2 (CIGSSe) photocathode with grown-in CuxS HECs enabling solar water splitting without the deposition of additional n-type overlayers and HECs. The controlled two-step chalcogenization using a Cu-rich CuInGa precursor film resulted in the natural formation of the CuxS phase at the CIGSSe film surface and an increase in S content by substituting Se. Electrochemical water reduction tests elucidated that the naturally formed CuxS alters the surface state of CIGSSe and reduces the overpotential for HER. Also, the S incorporation allows fine-tuning to make the CIGSSe band gap favorable for solar water splitting. Consequently, the CIGSSe photocathode showed -25.7 mA·cm-2 photocurrent density and 3 h photostability for photoelectrochemical hydrogen evolution.

Original languageEnglish
Pages (from-to)2937-2944
Number of pages8
JournalACS Energy Letters
Issue number12
Publication statusPublished - 2019 Dec 13

Bibliographical note

Funding Information:
This work was supported by the Energy Technology Development Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant (No. 20163010012570) funded by the Korean Government. This work was also partially supported by the program of the Korea Institute of Science and Technology (KIST). We thank Dr. Chaehwan Jeong of the Applied Optics & Energy R&D group at the Korea Institute of Industrial Technology (KITECH) for helping with the TRPL measurement.

Publisher Copyright:
© 2019 American Chemical Society.

ASJC Scopus subject areas

  • Chemistry (miscellaneous)
  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Materials Chemistry


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