Unravelling the charge transfer and kinetics of BiVO4 by Co dopant and NiFeOx co-catalyst for efficient photoelectrochemical water splitting

Abstract

Understanding the kinetic mechanism for charge transfer and reaction involved in the photoelectrochemical (PEC) process of BiVO4-based photoanodes is key to designing better photoelectrodes in solar water splitting. Herein, we demonstrate cobalt-doping-induced CoOx quantum dots and NiFeOx co-catalyst on BiVO4 (Co–BiVO4/NiFeOx), which was uniformly constructed on a FTO substrate with a nanoporous topological network structure composed of nanoworm-like particles. The Co–BiVO4/NiFeOx photoanode achieved a remarkable photocurrent density of 6.42 mA cm−2 at 1.23 VRHE. Multiform online PEC and operando electrochemical investigation are employed to comprehensively elucidate the kinetic processes of the BiVO4-based photoanodes. The surface-derived CoOx quantum dots and BiVO4 were favourable for promoting charge separation and transfer to NiFeOx by an enhanced built-in electric field. Theoretical calculations were employed to clarify the basic mechanism in that Co doping substitutes the Bi sites, Fe sites acted as the active sites, and the OH → OH* step was the rate-determining step in the elemental oxygen evolution reaction for Co–BiVO4/NiFeOx. The NiFeOx co-catalyst, with water oxidation active sites, is beneficial for hole capture and transfer through the self-adjustable valence of Fe, thereby promoting OH–h+ interactions. Finally, we present a synergetic mechanism that elucidates how the charge transfer dynamics and surface oxygen evolution reaction kinetics are enhanced by quantum dot binding and the catalytically active states.

Graphical abstract: Unravelling the charge transfer and kinetics of BiVO4 by Co dopant and NiFeOx co-catalyst for efficient photoelectrochemical water splitting

Supplementary files

Article information

Article type
Paper
Submitted
23 Jan 2025
Accepted
26 Mar 2025
First published
08 Apr 2025

J. Mater. Chem. A, 2025, Advance Article

Unravelling the charge transfer and kinetics of BiVO4 by Co dopant and NiFeOx co-catalyst for efficient photoelectrochemical water splitting

L. Fu, Z. Li, X. Shang and Y. Zheng, J. Mater. Chem. A, 2025, Advance Article , DOI: 10.1039/D5TA00638D

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