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449 results on '"Kang, Soon-Hyung"'

30. Effective Corrosion‐Resistant Single‐Atom Alloy Catalyst on HfO2‐Passivated BiVO4 Photoanode for Durable (≈800 h) Solar Water Oxidation.

Author

Arunachalam, Maheswari, Lee, Kug‐Seung, Zhu, Kai, and Kang, Soon Hyung

Subjects
GREEN fuels, SURFACE passivation, CHEMICAL reactions, OXIDATION of water, STANDARD hydrogen electrode, BARIUM
Abstract

Green hydrogen (H2) production from solar water splitting necessitates photoelectrodes with superior photoelectrochemical (PEC) activity and durability. However, surface defects and photocorrosion instability—especially at high potentials—limit PEC performance and stability. Herein, the prototypical bismuth vanadate (BiVO4) photoanode is used to demonstrate a holistic approach to improve photocurrent density and long‐term stability. In this approach, high surface‐area nanostructuring of BiVO4 is combined with barium (Ba) doping with semi‐crystalline hafnium oxide (HfO2) surface passivation and single‐atom nickel platinum (NiPt) catalysts. The introduction of Ba2+ ions into BiVO4 increases the concentration of conductive V4+ ions or the ratio of V4+ ions to oxygen vacancies, avoiding V5+ dissolution during water oxidation. The semi‐crystalline HfO2, which serves as a passivation layer, prevents BiVO4 photocorrosion by suppressing harmful chemical reactions when holes are transferred to the electrolyte. The synergistic use of isolated single‐atom and Ni‐Pt coordination improves charge transfer at the photoanode/electrolyte interface, leading to enhanced PEC kinetics and stability. As a result, a photoelectrode is demonstrated with ≈6.5 mA cm−2 at 1.23 V versus a reversible hydrogen electrode (RHE) and continuous operation for 800 h with a negligible degradation rate. This work provides a promising approach to improve photoanodes for PEC H2 production. [ABSTRACT FROM AUTHOR]

Published
2024
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32. Electrochromic Performances of rGO-WO3 Thin Film and Its Application as an Integrated Device Powered with Quantum Dot-Sensitized Solar Cells.

Author

Prasad, Aryal Krishna, Park, Jong-Young, Kang, Soon-Hyung, and Ahn, Kwang-Soon

Abstract

Reduced graphene oxide (rGO)-embedded WO3 composite thin film (rGO-WO3) is synthesized and investigated for its electrochromic performances. Furthermore, a novel application of quantum dot-sensitized solar cells (QDSSCs), to operate the rGO-WO3 electrochromic devices (ECDs), is demonstrated with development of an integrated device. The co-existence of both WO3 nanostructure and rGO sheet ameliorates the EC performances of composite thin film, compared to WO3 thin film. The rGO-WO3, possessing 0.1 g of rGO, nanocomposite shows an optimum optical contrast (%ΔT) of 66.3% and excellent optical stability displaying 1.7% degradation in %ΔT, while the WO3 film only exhibits a %ΔT of 52.2% and, 4.2% of optical degradation. Incorporation of rGO sheet into the WO3 nanostructure introduces de-agglomerated morphology, enhances electrochemically active surface area, and which facilitates the ion-transfer kinetics. The series-connected QDSSCs results an optimum open circuit voltage (Voc) of 1.03 V upon 1 sun illumination, which is found to be adequate for the study of switching performances of ECDs. QDSSCs assisted rGO-WO3 EC film exhibits a significant %ΔT of 43% and coloration time of 7 s. Additionally, QDSSCs device is illuminated with various light intensities to study the intensity and Voc dependent EC performances of rGO-WO3. [ABSTRACT FROM AUTHOR]

Published
2024
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