Electronic Structure and Performance Bottlenecks of CuFeO 2 Photocathodes

Chang Ming Jiang, Sebastian E. Reyes-Lillo, Yufeng Liang, Yi Sheng Liu, Guiji Liu, Francesca M. Toma, David Prendergast, Ian D. Sharp, Jason K. Cooper

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The path to realizing low-cost, stable, and earth-abundant photoelectrodes can be enabled through a detailed understanding of the optoelectronic properties of these materials by combining theory and experimental techniques. Of the limited set of oxide photocathode materials currently available, CuFeO 2 has emerged as a promising candidate warranting detailed attention. In this work, highly compact thin films of rhombohedral (3R) CuFeO 2 were prepared via reactive co-sputtering. Despite its 1.43 eV indirect band gap, a cathodic photocurrent of 0.85 mA/cm 2 was obtained at 0.4 V versus reversible hydrogen electrode in the presence of a sacrificial electron acceptor. This unexpected performance was related to inefficient bulk charge separation because of the ultrafast (<1 ps) self-trapping of photogenerated free carriers. The electronic structure of 3R-CuFeO 2 was elucidated through a combination of optical and X-ray spectroscopic techniques and further complemented by first-principles computational methods including a many-body approach for computing the O K-edge X-ray absorption spectrum. Through resonant inelastic X-ray scattering spectroscopy, the visible absorption edges of CuFeO 2 were found to correspond to Cu ↠Fe metal-to-metal charge transfer, which exhibits a high propensity toward self-trapping. Findings of the present work enable us to understand the performance bottlenecks of CuFeO 2 photocathodes and suggest feasible strategies for improving material limitations.

Original languageEnglish
Pages (from-to)2524-2534
Number of pages11
JournalChemistry of Materials
Volume31
Issue number7
DOIs
Publication statusPublished - 9 Apr 2019

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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    Jiang, C. M., Reyes-Lillo, S. E., Liang, Y., Liu, Y. S., Liu, G., Toma, F. M., Prendergast, D., Sharp, I. D., & Cooper, J. K. (2019). Electronic Structure and Performance Bottlenecks of CuFeO 2 Photocathodes. Chemistry of Materials, 31(7), 2524-2534. https://doi.org/10.1021/acs.chemmater.9b00009