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Balancing charge recombination and hole transfer rates in hematite photoanodes by modulating the Co2+/Fe3+ sites in the OER cocatalyst.
- Source :
-
Journal of Colloid & Interface Science . Jan2024:Part B, Vol. 654, p915-924. 10p. - Publication Year :
- 2024
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Abstract
- [Display omitted] This work investigates the roles of Co and Fe sites in a composite cocatalyst on the performance of hematite photoanodes for photoelectrochemical (PEC) water splitting. The cobalt/iron-based composite (Co-Fe-O) cocatalyst, consisting of adjustable Co2+/Fe3+ratios, was synthesized using a one-step hydrothermal method. It reveals that Co2+ sites with a robust capacity for low-bias hole capture, which is insignificantly affected by partial substitution by Fe3+, decelerate the charge recombination process. However, it also leads to a slower charge transfer, with slower oxygen-evolution kinetics on Co sites than on Fe sites. Consequently, the modulation of the Co2+/Fe3+ ratio facilitates the redistribution of surface strap states, striking a delicate balance between charge recombination and charge transfer rates. This optimization led to the highest low-bias photocurrent density of 1.6 mA cm−2 at 1.0 V vs. RHE (a 2.4-fold increase) for the cocatalyst with a Co2+/Fe3+ ratio of 1:2 (CoFe 2 O 4 nanoparticles). Additionally, the cocatalyst with a Co2+/Fe3+ ratio of 1:4 (mixture of CoFe 2 O 4 and Fe 2 O 3 nanoparticles, demonstrated an impressive high-bias photocurrent density of 3.8 mA cm−2 at 1.6 V vs. RHE (a 2.3-fold increase). This study emphasizes the promising potential of modulating active sites within a cocatalyst to achieve efficient PEC water splitting on a hematite-based photoanode. [ABSTRACT FROM AUTHOR]
- Subjects :
- *PHOTOELECTROCHEMISTRY
*IRON oxide nanoparticles
*HEMATITE
*CHARGE transfer
Subjects
Details
- Language :
- English
- ISSN :
- 00219797
- Volume :
- 654
- Database :
- Academic Search Index
- Journal :
- Journal of Colloid & Interface Science
- Publication Type :
- Academic Journal
- Accession number :
- 173523239
- Full Text :
- https://doi.org/10.1016/j.jcis.2023.10.086