Facet-engineered BiVO4 photocatalysts for water oxidation: lifetime gain versus energetic loss
Author(s)
Type
Journal Article
Abstract
A limiting factor to the efficiency of water Oxygen Evolution Reaction (OER) in metal oxide nanoparticle photocatalysts is the rapid recombination of holes and electrons. Facet-engineering can effectively improve charge separation and, consequently, OER efficiency. However, the kinetics behind this improvement remain poorly understood. This study utilizes photoinduced absorption spectroscopy to investigate the charge yield and kinetics in facet-engineered BiVO4 (F-BiVO4) compared to a non-faceted sample (NF-BiVO4) under operando conditions. A significant influence of preillumination on hole accumulation is observed, linked to the saturation and, thus, passivation of deep and inactive hole traps on the BiVO4 surface. In DI-water, F-BiVO4 shows a 10-fold increase in charge accumulation (∼5 mΔOD) compared to NF-BiVO4 (∼0.5 mΔOD), indicating improved charge separation and stabilization. With the addition of Fe(NO3)3, an efficient electron acceptor, F-BiVO4 demonstrates a 30-fold increase in the accumulation of long-lived holes (∼45 mΔOD), compared to NF-BiVO4 (∼1.5 mΔOD) and an increased half-time, from 2 to 10 s. Based on a simple kinetic model, this increase in hole accumulation suggests that facet-engineering causes at least a 50–100 meV increase in band bending in BiVO4 particles, thereby stabilizing surface holes. This energetic stabilization/loss results in a retardation of OER relative to NF-BiVO4. This slower catalysis is, however, offset by the observed increase in density and lifetime of photoaccumulated holes. Overall, this work quantifies how surface faceting can impact the kinetics of long-lived charge accumulation on metal oxide photocatalysts, highlighting the trade-off between lifetime gain and energetic loss critical to optimizing photocatalytic efficiency.
Date Issued
2024-10-02
Date Acceptance
2024-09-13
Citation
Journal of the American Chemical Society, 2024, 146 (39), pp.27080-27089
ISSN
0002-7863
Publisher
American Chemical Society (ACS)
Start Page
27080
End Page
27089
Journal / Book Title
Journal of the American Chemical Society
Volume
146
Issue
39
Copyright Statement
© 2024 The Authors. Published by American Chemical Society. This publication is licensed under
CC-BY 4.0 .
CC-BY 4.0 .
License URL
Identifier
http://dx.doi.org/10.1021/jacs.4c09219
Publication Status
Published
Date Publish Online
2024-09-21