Journal article

Publication year: 2023

Pages: 12237-12248

Journal: ACS Applied Energy Materials

Volume number: 6

Issue number: 24

ISSN: 2574-0962

Open access status: Hybrid

DOI Link: https://doi.org/10.1021/acsaem.3c01926

Publisher: American Chemical Society

Abstract: 
BiFeO3 (BFO) has recently been identified as a promising photocathode material for photoelectrochemical (PEC) water splitting due to its light absorption and photoelectrochemical properties. The performance-limiting factors, in particular the impact of stoichiometry on the performance, still need to be understood. The effect of the ratio of Bi/Fe in the precursor solution for sol-gel synthesis on the properties and performance of BFO thin films is investigated in this study. Thin films with a stoichiometric Bi/Fe ratio and with a 10% excess of Bi are prepared on fluorine-doped tin-oxide substrates. While bulk characterization techniques show the formation of phase-pure BFO, surface characterization techniques indicate Bi enrichment on the surface. Light absorption and band gap do not change with excess Bi, whereas the current density is two times higher for Bi excess films compared to stoichiometric films at 0.6 V vs RHE. Electrochemical impedance spectroscopy attributes this improved performance of excess Bi thin films to a lower recombination rate and a lower charge transfer resistance. The lower recombination rate is attributed to fewer Bi and O vacancies, which can act as recombination centers. Therefore, adjusting the Bi/Fe ratio is an effective strategy to enhance the PEC performance of BFO photocathodes.

Harvard Citation style: Prasad, N., Rohnke, M., Verheijen, M., Sturm, J., Hofmann, J., Hensen, E., et al. (2023) Role of Excess Bi on the Properties and Performance of BiFeO₃ Thin-Film Photocathodes, ACS Applied Energy Materials, 6(24), pp. 12237-12248. https://doi.org/10.1021/acsaem.3c01926

APA Citation style: Prasad, N., Rohnke, M., Verheijen, M., Sturm, J., Hofmann, J., Hensen, E., & Bieberle-Hu''tter, A. (2023). Role of Excess Bi on the Properties and Performance of BiFeO₃ Thin-Film Photocathodes. ACS Applied Energy Materials. 6(24), 12237-12248. https://doi.org/10.1021/acsaem.3c01926