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Exploration of electrochemical hydrogen pumping with ultralow feed concentration down to 1 ppm
Shakil, Mostafijur Rahman
Shakil, Mostafijur Rahman
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t25045_Shakil.pdf
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2025-12-01
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A systematic study of noble-metal electrodes showed that the output current increases proportionally with low hydrogen concentrations, rising from 0.42 to 3.1 μA over 1–10 ppm H₂. The strongest sensitivity was achieved with an applied cell voltage of 0.050–0.100 V, highlighting this range as optimal for low-level H2 detection.
Under identical anode potentials (0.800–1.100 V vs. RHE), the current response (ΔI) for H2-in-N2 feed was 20–100 times higher equivalent to 1.3–2.0 orders of magnitude than that for H₂-in-air feed at the same H₂ concentration (5 ppm) and flow rate (5,000 sccm). A strong correlation between current response and hydrogen concentration was established (average regressed value = 0.915 with $R^2$ = 0.995) across 1–25 ppm H₂ and 5,000–20,000 sccm flow rates, while the current–flow rate relationship followed a fractional power law (average fractional power = 0.453 with $R^2$ = 0.979).
Under air-dominant conditions, similar current responses (3.8 μA and 1.6 μA) were recorded at 1.130 V vs. RHE and 0 V vs. air electrode, with negligible background currents. The formation of surface oxides (Pt–O) under high potentials led to diminished catalytic activity, with HOR activity on Pt–O being 20–40 times lower than on metallic Pt, indicating a ~1.5-order reduction in reactivity.
At 10 ppm H₂ and 0.100–0.600 V vs RHE, a limiting current of 3,532 μA (54% of the 6,572 μA theoretical maximum) was achieved. The results follow Pourbaix predictions, with surface oxides forming on Pt, Pd, and PtRu near 0.9, 0.8, and 0.75 V vs SHE. This clarifies how potential, gas composition, and oxidation affect low-level H₂ sensing. Durability remained high, with only a 5% drop after 50 cycles.
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Thesis (M.S.)-- Wichita State University, College of Engineering, Dept. of Mechanical Engineering
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Wichita State University
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© Copyright 2025 by Mostafijur Rahman Shakil
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