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Omosebi, A.

Publications and source records attributed to Omosebi, A..

6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Ultra‐low Mass Sputtered and Conventional Catalyst Layers on Plasma‐etched Nafion for PEMFC Applications

Abstract This paper presents performance results for the use of plasma‐etched Nafion membranes to suppress polarization losses in proton exchange membrane fuel cells (PEMFCs) configured from 0.1 mg cm −2 conventional Pt/C dispersion and 0.02 mg cm −2 ultra‐thin sputter‐deposited Pt catalyst layers. Four MEA configurations, namely, etched membrane‐conventional electrode, pristine membrane‐conventional electrode, etched membrane‐sputter electrode, and pristine membrane‐sputter electrode cells were explored, and their respective maximum power densities were ∼514.6, 417.9, 170.1 and 138.3 mW cm −2 . The results demonstrated that independent of MEA fabrication approach, cells with O 2 plasma treated membranes had reduced ohmic resistances and delivered superior performance over their pristine counterparts, validating the utility of membrane etching for achieving improved PEMFC performance.

Omosebi, A.↗
DOE OSTI2017

Capacitive Deionization Using Alternating Polarization: Effect of Surface Charge on Salt Removal

Alternating polarization (AP) at ±1.2/0 V is performed on a capacitive deionization stack assembled with carbon xerogel (CX) electrodes. Long-term testing shows enhanced cycling stability without the formation of inversion peaks. AP also leads to an arch-shaped plot of salt adsorption capacity (SAC) versus cycling time, with the highest SAC of approximately 3 mg (NaCl) g −1 (CX) during this long-term test. Characterization of both the freshly prepared and cycled electrodes depict that AP results in surface charge of all the electrodes being modified from positive to negative character. Here by leveraging balances of electronic, surface, and ionic charges in carbon micropores, it is found that a portion of the electronic charge contributes to the ionic charge for salt adsorption, and another portion is parasitically consumed to balance the surface charge during the charge reconciliation process. When the consumption of electronic charge for charge reconciliation becomes minimal, both the positive and negative surface charges are nearly equivalent on the CX electrode. Under such a condition, the highest SAC values can be achieved for AP testing.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗