title: Investigation of the Electric Structures of Heterointerfaces in Pt- and In₂S₃-Modified CuInS₂ Photocathodes Used for Sunlight-Induced Hydrogen Evolution.
abstract: Copper indium disulfide (CuInS2) modified with an In2S3 layer and a Pt catalyst showed a more efficient photoelectrochemical (PEC) property for hydrogen evolution from a nearly neutral (pH 6) 0.2 M NaH2PO4 solution under simulated sunlight illumination (AM 1.5G) than that of a CuInS2 electrode modified with a CdS layer and a Pt catalyst. Analysis of the PEC properties of In2S3-modified CuInS2 (In2S3/CuInS2) and CdS-modified CuInS2 (CdS/CuInS2) in solutions containing an electron scavenger (Eu(3+)) showed identical enhancement of the PEC properties of In2S3/CuInS2 when compared to those of CdS/CuInS2, indicating the formation of a favorable heterointerface in In2S3/CuInS2 for efficient charge separation. Spectroscopic evaluation of conduction band offsets revealed that In2S3/CuInS2 had a notch-type conduction band offset, whereas a cliff-type offset was formed in CdS/CuInS2: these results also revealed a better interface electric structure of In2S3/CuInS2 than that of CdS/CuInS2.
authors.affiliation: †Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.|‡Chemistry Department, Faculty of Science and Mathematics, Diponegoro University, Semarang, Indonesia.
authors.lastname: Gunawan
authors.affiliation: †Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Wilman
authors.initials: W
authors.lastname: Septina
authors.affiliation: †Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Harada
authors.affiliation: §Department of Materials Science and Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, 606-8501 Kyoto, Japan.
authors.forename: Yoshitaro
authors.initials: Y
authors.lastname: Nose
authors.affiliation: †Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Ikeda
keywords: X-ray photoelectron spectroscopy; copper indium disulfide; heterointerface; indium disulfide; photocathodes