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Sb2S3/TiO2 Heterojunction Photocathodes: Band Alignment and Water Splitting Properties


Prabhakar, Rajiv Ramanujam; Moehl, Thomas; Siol, Sebastian; Suh, Jihye; Tilley, David (2020). Sb2S3/TiO2 Heterojunction Photocathodes: Band Alignment and Water Splitting Properties. Chemistry of Materials, 32(17):7247-7253.

Abstract

Antimony sulfide (Sb2S3) is a promising light-absorbing semiconductor for photovoltaic applications, though it remains vastly unexplored for photoelectrochemical water splitting. Sb2S3 was synthesized by a simple sulfurization of electrodeposited antimony metal at relatively low temperatures (240–300 °C) with elemental sulfur. Using a TiO2 buffer layer and a platinum co-catalyst, photocurrent densities up to ∼9 mA cm–2 were achieved at −0.4 V vs RHE in 1 M H2SO4 under one sun illumination. Using X-ray photoelectron spectroscopy band alignment studies and potential-dependent incident photon-to-current efficiency measurements, a conduction band offset of 0.7 eV was obtained for the Sb2S3/TiO2 junction as well as an unfavorable band bending at the heterointerface, which explains the low photovoltage that was observed (∼0.1 V). Upon inserting an In2S3 buffer layer, which offers a better band alignment, a 0.15 V increase in photovoltage was obtained. The excellent photoelectrochemical water splitting performance and the identification of the origin of the low photovoltage of the Sb2S3 photocathodes in this work pave the way for the further development of this promising earth-abundant light-absorbing semiconductor for solar fuel generation.

Abstract

Antimony sulfide (Sb2S3) is a promising light-absorbing semiconductor for photovoltaic applications, though it remains vastly unexplored for photoelectrochemical water splitting. Sb2S3 was synthesized by a simple sulfurization of electrodeposited antimony metal at relatively low temperatures (240–300 °C) with elemental sulfur. Using a TiO2 buffer layer and a platinum co-catalyst, photocurrent densities up to ∼9 mA cm–2 were achieved at −0.4 V vs RHE in 1 M H2SO4 under one sun illumination. Using X-ray photoelectron spectroscopy band alignment studies and potential-dependent incident photon-to-current efficiency measurements, a conduction band offset of 0.7 eV was obtained for the Sb2S3/TiO2 junction as well as an unfavorable band bending at the heterointerface, which explains the low photovoltage that was observed (∼0.1 V). Upon inserting an In2S3 buffer layer, which offers a better band alignment, a 0.15 V increase in photovoltage was obtained. The excellent photoelectrochemical water splitting performance and the identification of the origin of the low photovoltage of the Sb2S3 photocathodes in this work pave the way for the further development of this promising earth-abundant light-absorbing semiconductor for solar fuel generation.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
08 Research Priority Programs > Solar Light to Chemical Energy Conversion
Dewey Decimal Classification:540 Chemistry
Uncontrolled Keywords:Materials Chemistry, General Chemistry, General Chemical Engineering
Language:English
Date:8 September 2020
Deposited On:21 Sep 2020 10:29
Last Modified:21 Sep 2020 10:29
Publisher:American Chemical Society (ACS)
ISSN:0897-4756
OA Status:Closed
Publisher DOI:https://doi.org/10.1021/acs.chemmater.0c01581
Project Information:
  • : FunderSNF
  • : Grant IDPYAPP2 160586
  • : Project Title

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Embargo till: 2021-08-19