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37 results on '"Cha, Hyeonjin"'

2. Effects of the Anode Diffusion Layer on the Performance of a Nonenzymatic Electrochemical Glucose Fuel Cell with a Proton Exchange Membrane.

Author

Kim, Jaeyeon, Choi, Heesoo, Yoo, Hongnyoung, Kim, Hyeok, Park, Taehyun, Cha, Hyeonjin, and Kwon, Obeen

Abstract

It is necessary to apply a nonenzymatic glucose fuel cell using a proton exchange membrane for an implantable biomedical device that operates at low power. The permeability of glucose with high viscosity and a large molecular weight in the porous medium of the diffusion layer was investigated for use in fuel cells. Carbon paper was prepared as an anode diffusion layer, and it was analyzed with a diffusion layer treated with polytetrafluoroethylene (PTFE) and a microporous layer (MPL). When untreated carbon paper was applied, the peak power density (PPD) and open-circuit voltage (OCV) increased as the glucose concentration and flow rate increased. On this occasion, the highest PPD of 17.81 μW cm-2 was achieved at 3 mM and a 2.0 mL min-1 glucose aqueous solution (at atmospheric pressure and 36.5 °C). The diffusion layer, which became more hydrophobic through PTFE treatment, adversely affected glucose permeability. In addition, the addition of an MPL decreased OCV and PPD with increasing glucose concentrations and flow rates. Compared with untreated carbon paper, the PPD was six times lower approximately. Consequently, it was confirmed that the properties of carbon paper, such as low hydrophobicity, high porosity, and thin thickness, would be advantageous for nonenzymatic glucose fuel cells.

Published
2021

33. Non‐destructive platinum catalyst‐replenishment method for deteriorated polymer electrolyte membrane fuel cells.

Author

Kim, Jaeyeon, Yoo, Hongnyung, Kim, Hyeok, Kim, Dasol, Kim, Geon Hwi, Kwon, Obeen, Choi, Heesoo, Cha, Hyeonjin, and Park, Taehyun

Subjects
PROTON exchange membrane fuel cells, CATALYSTS, PLATINUM catalysts, X-ray photoelectron spectroscopy, FUEL cells
Abstract

A novel method for replenishing platinum catalysts on an electrolyte membrane of polymer electrolyte membrane fuel cell (PEMFC) is studied. The method injects electrocatalyst‐supplementing ink into a pre‐assembled fuel cell in a simple and non‐destructive manner. For replenishing, straightforward catalyst‐replenishment equipment and corresponding protocol are proposed. The protocol consists of injection, penetration, and purge processes. As a feasibility study, the method is performed on fuel cells with pristine membranes. Target fuel cells for this study include a membrane‐assembled cell without catalyst layers (CLs) (Cell 1) and a cell assembled with a membrane‐coated cathodic CL (Cell 2). An open‐circuit voltage of 0.804 V in Cell 1 and a current of 77 mA in Cell 2 are measured, as supported through electrochemical impedance spectroscopy. Results of energy‐dispersive X‐ray spectroscopy and X‐ray photoelectron spectroscopy also support the presence of platinum catalysts. [ABSTRACT FROM AUTHOR]

Published
2022
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