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308 results on '"Bang, Jin Ho"'

9. Unveiling the critical role of crystallinity in photogenerated hole transfer behavior of TiO2 with an aminoxyl radical mediator.

Author

Jeon, Minwook, Kim, Hayoung, Yoo, Sunghoon, Park, Seongsu, Leem, Gyu, Lee, Seunghyun, and Bang, Jin Ho

Subjects
TITANIUM dioxide surfaces, SOLAR energy conversion, TITANIUM dioxide, SURFACE charges, CHEMICAL amplification
Abstract

[Display omitted] • TiO 2 is an excellent photoelectrode for light-energy conversion. • The effect of crystallinity on photoelectrochemical behavior is investigated. • The surface defects in polycrystalline TiO 2 act as recombination centers. • The surface trap states lead to an anomalous hole transfer mechanism in TiO 2. Integrating aminoxyl radical mediators (ARMs) with titanium dioxide (TiO 2) based photoelectrochemical (PEC) processes presents a promising approach for achieving mild and sustainable chemical transformations. However, a comprehensive understanding of the interaction between ARMs and PEC processes remains elusive. This study investigates the PEC behavior of photoelectrodes fabricated from single- and polycrystalline TiO 2 in the presence of a representative ARM, 4-acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl radical, in acetonitrile. Interestingly, we observe contrasting PEC behavior: photocurrent enhancement for single-crystalline TiO 2 and photocurrent suppression for polycrystalline TiO 2. We attribute this difference to subtle variations in surface properties arising from the material's crystallinity. Photoelectrochemical impedance spectroscopy (PEIS) is employed to gain deeper insights into the influence of surface defects on charge transfer and recombination mechanisms. The PEIS results suggest that an anomalous hole transfer mechanism mediated by surface trap states governs the PEC performance of polycrystalline TiO 2. [ABSTRACT FROM AUTHOR]

Published
2024
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22. Recent progress in Co‐free, Ni‐rich cathode materials for lithium‐ion batteries.

Author

Hussain, Sk. Khaja and Bang, Jin Ho

Subjects
*LITHIUM-ion batteries, *CATHODES, *ELECTROCHEMICAL electrodes, *ENERGY density, *METAL ions, *GRAPHITIZATION
Abstract

Cobalt (Co) has played an important role in nickel (Ni)‐rich cathode materials in terms of improving electrochemical performance, boosting energy density, and improving cycling life for lithium‐ion batteries (LIBs). While Co resources are becoming more cost‐effective, they pose environmental challenges that can lead to limitations in production and indicate the need for alternative Co‐free, Ni‐rich cathodes. This review aims to compile some of the concepts established in recent years to overcome the electrochemical disadvantages of Ni‐rich cathodes without Co. With the development of strategies involving single‐crystals, core‐shell structures, and substitution of Co by other metal ions, problems associated with capacity reduction and the underlying structure degradation mechanism have been resolved. Therefore, structural transformation strategies focusing on potential cathodes with improved energy density and lifetime have been pursued for safe LIBs. We also address possible issues and some new insights to improve the performance of Co‐free, Ni‐rich cathodes for practical applications. [ABSTRACT FROM AUTHOR]

Published
2024
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38. Modulation of the photoelectrochemical behavior of Au nanocluster–TiO2 electrode by doping† †Electronic supplementary information (ESI) available: Supplemental computational and experimental methods, more characterization results and electrochemical analysis, and coordinates for the structures of Au18(SCH3)14. See DOI: 10.1039/d0sc01220c

Author

Naveen, Malenahalli H., Khan, Rizwan, Abbas, Muhammad A., Cho, Eunbyol, Lee, Geun Jun, Kim, Hahkjoon, Sim, Eunji, and Bang, Jin Ho

Subjects
Chemistry
Abstract

Optoelectronic properties of Au18(SR)14 are modulated by Ag doping, and its influence on photoelectrochemical performance is investigated. The best compromise for light conversion efficiency is made when a single Ag atom is incorporated., Despite the successful debut of gold nanoclusters (Au NCs) in solar cell applications, Au NCs, compared to dyes and quantum dots, have several drawbacks, such as lower extinction coefficients. Any modulation of the physical properties of NCs can have a significant influence on the delicate control of absorbance, energy levels, and charge separation, which are essential to ensure high power conversion efficiency. To this end, we systematically alter the optoelectronic structure of Au18(SR)14 by Ag doping and explain its influence on solar cell performance. Our in-depth spectroscopic and electrochemical characterization combined with computational study reveals that the performance-dictating factors respond in different manners to the Ag doping level, and we determine that the best compromise is the incorporation of a single Ag atom into an Au NC. This new insight highlights the unique aspect of NCs—susceptibility to atomic level doping—and helps establish a new design principle for efficient NC-based solar cells.

Published
2020

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