1. Reaction kinetics on facet-engineered bismuth tungstate photoanodes for water oxidation.
- Author
-
Cao, Guangming, Hu, Jundie, Wang, Yuanxing, Qu, Jiafu, Ma, Dekun, Jin, Jiaqi, Sun, Wei, Yang, Xiaogang, and Li, Chang Ming
- Subjects
- *
OXIDATION of water , *PHOTOELECTROCHEMISTRY , *CHEMICAL kinetics , *PHOTOELECTROCHEMICAL cells , *CHARGE transfer kinetics , *BISMUTH , *SURFACE charges - Abstract
[Display omitted] • Enhanced photoelectrochemical water oxidation on Bi 2 WO 6 photoanodes by heterojunction and facet-engineering. • The heterojunction of WO 3 /Bi 2 WO 6 improved charge separation and transfer. • Crystalline {2 0 0} and {1 3 1} orientations on WO 3 /Bi 2 WO 6 and Bi 2 WO 6 films, respectively. • A 1st-order and a 2nd-order charge reaction kinetics were discovered on {2 0 0} and {1 3 1} facets, respectively. Charge separation and transfer kinetics play a significant role in photocatalytic water oxidation, which is sensitive to the crystal facets. Herein, the bismuth tungstate (Bi 2 WO 6) films were used as a model photoanode to investigate how the photogenerated charges react on {1 3 1} and {2 0 0} facets under constantly applied bias in a photoelectrochemical (PEC) cell. On the WO 3 electron transport layer, the Bi 2 WO 6 films have a {2 0 0} orientation while possessing a {1 3 1} orientation on the fluorine-doped tin oxide substrate. It is discovered that {2 0 0} facets on the WO 3 /Bi 2 WO 6 heterojunction display a low overpotential of PEC water oxidation, showing a 1st-order reaction behavior and faster charge transfer rate constant. Differently, water oxidation on the {1 3 1} facet on Bi 2 WO 6 displays a 2nd-order reaction behavior. Further, density functional theory calculations were applied to demonstrate how the rate-determining step and the major formed intermediate correlate with the charge accumulation and reaction orders. The findings of this work shed fundamental light on how to rationally design and precisely modulate surface charge density and reaction kinetics for efficient (photo)electrocatalysts. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF