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Modulating Carrier Kinetics in BiVO4 Photoanodes through Molecular Co4O4 Cubane Layers


Chen, Hang; Li, Jingguo; Meng, Lingshen; Bae, Sanghyun; Erni, Rolf; Abbott, Daniel F; Li, Shangkun; Triana, Carlos A; Mougel, Victor; Patzke, Greta R (2023). Modulating Carrier Kinetics in BiVO4 Photoanodes through Molecular Co4O4 Cubane Layers. Advanced Functional Materials, 33(48):2307862.

Abstract

Understanding the role and immobilization of molecular catalysts on photoelectrodes is essential to use their full potential for efficient solar fuel generation. Here, a CoII4O4 cubane with proven catalytic performance and an active H2O─Co2(OR)2─OH2 edge-site moiety is immobilized on BiVO4 photoanodes through a versatile layer-by-layer assembly strategy. This delivers a photocurrent of 3.3 mA cm−2 at 1.23 VRHE and prolonged stability. Tuning the thickness of the Co4O4 layer has remarkable effects on photocurrents, dynamic open circuit potentials, and charge carrier behavior. Comprehensive-time and frequency-dependent perturbation techniques are employed to investigate carrier kinetics in transient and pseudo-steady-state operando conditions. It is revealed that the Co4O4 layer can prolong carrier lifetime, unblock kinetic limitations at the interface by suppressing recombination, and enhance charge transfer. Additionally, its flexible roles are identified as passivation/hole trapping/catalytic layer at respective lower/moderate/higher potentials. These competing functions are under dynamic equilibrium, which fundamentally defines the observed photocurrent trends.

Abstract

Understanding the role and immobilization of molecular catalysts on photoelectrodes is essential to use their full potential for efficient solar fuel generation. Here, a CoII4O4 cubane with proven catalytic performance and an active H2O─Co2(OR)2─OH2 edge-site moiety is immobilized on BiVO4 photoanodes through a versatile layer-by-layer assembly strategy. This delivers a photocurrent of 3.3 mA cm−2 at 1.23 VRHE and prolonged stability. Tuning the thickness of the Co4O4 layer has remarkable effects on photocurrents, dynamic open circuit potentials, and charge carrier behavior. Comprehensive-time and frequency-dependent perturbation techniques are employed to investigate carrier kinetics in transient and pseudo-steady-state operando conditions. It is revealed that the Co4O4 layer can prolong carrier lifetime, unblock kinetic limitations at the interface by suppressing recombination, and enhance charge transfer. Additionally, its flexible roles are identified as passivation/hole trapping/catalytic layer at respective lower/moderate/higher potentials. These competing functions are under dynamic equilibrium, which fundamentally defines the observed photocurrent trends.

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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
Scopus Subject Areas:Physical Sciences > Electronic, Optical and Magnetic Materials
Physical Sciences > General Chemistry
Physical Sciences > Biomaterials
Physical Sciences > General Materials Science
Physical Sciences > Condensed Matter Physics
Physical Sciences > Electrochemistry
Uncontrolled Keywords:Electrochemistry, Condensed Matter Physics, Biomaterials, Electronic, Optical and Magnetic Materials
Language:English
Date:3 September 2023
Deposited On:21 Feb 2024 08:14
Last Modified:29 Jun 2024 01:40
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:1616-301X
OA Status:Hybrid
Publisher DOI:https://doi.org/10.1002/adfm.202307862
  • Content: Published Version
  • Language: English
  • Licence: Creative Commons: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)