Accelerating water oxidation on BiVO4 photoanodes via surface modification with Co dopants

Barzgar Vishlaghi, Mahsa and Kahraman, Abdullah and Österbacka, Nicklas and Usman, Emre and Erdem, Emre and Sennaroğlu, Alphan and Wiktor, Julia and Kaya, Sarp (2023) Accelerating water oxidation on BiVO4 photoanodes via surface modification with Co dopants. Journal of Materials Chemistry A . ISSN 2050-7488 (Print) 2050-7496 (Online) Published Online First

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Despite the vast investigations on improving the photoelectrochemical performance of BiVO4 for water splitting, charge recombination in the near-surface region remains a challenge. In this study, we showed that the diffusion of Co2+ ions into the BiVO4 subsurface boosted the water oxidation activity and charge injection efficiency remarkably. The increase in the concentration of oxygen vacancies upon the incorporation of cobalt ions was shown by electron paramagnetic resonance (EPR) spectroscopy and confirmed by density functional theory (DFT) calculations. DFT calculations revealed that vanadium sites in the subsurface region were the most favorable sites for substitution with cobalt ions. Charge localization at surface oxygen vacancies was found less favorable in the presence of cobalt in the subsurface layer, eliminating surface recombination. This resulted in 4.25 times larger charge injection efficiency and 6.2 times higher photocurrent density at the potential of ∼0.6 V, as compared to pristine BiVO4. This enhancement was significantly larger as compared to CoOx-loaded BiVO4, indicating that the suppressed recombination at the surface and improved charge transfer kinetics obtained solely by CoOx deposition are not sufficient for enhanced activity of BiVO4. A longer charge carrier lifetime obtained upon cobalt incorporation was observed by transient absorption spectroscopy and verified the reduced rate of recombination.
Item Type: Article
Divisions: Faculty of Engineering and Natural Sciences > Academic programs > Materials Science & Eng.
Faculty of Engineering and Natural Sciences
Depositing User: Emre Erdem
Date Deposited: 07 Aug 2023 16:51
Last Modified: 07 Aug 2023 16:51

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