Nanocarbon boosts energy-efficient hydrogen production in carbon-assisted water electrolysis

• Published in: International journal of hydrogen energy 2009-08, Vol.34 (15), p.6078-6084
• Main Authors: Seehra, M.S., Bollineni, S.
• Format: Article
• Language: English
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Carbon; Carbon-assisted water electrolysis; Catalysis; Catalysts; Electric potential; Electrolysis; Energy; Energy efficiency; Exact sciences and technology; Fuels; Hydrogen; Nanocarbon; Nanomaterials; Nanostructure; Voltage
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2009.06.023

To improve upon our previously reported slow hydrogen evolution rate R H at the energy-efficient lower voltages in CAWE (carbon-assisted water electrolysis) at room temperature, new results using different carbons and catalysts to improve R H are reported here. Compared to earlier results with carbon GX203, about a ten-fold increase in R H is reported using high surface area carbon BP2000 at the operating voltage E o = 1.12 V. With added FeSO 4 catalyst, E o is lowered to 0.72 V without lowering R H, representing about 30% decrease in the energy barrier of the process. For comparison, in water electrolysis without carbon, measurable R H is observed only for E o ≥ 2 V. This large improvement in R H at the energy efficient E o = 0.72 V is suggested to result from nanoscale particle size of carbon BP2000 as well as from electrons provided by the catalyst through the reaction Fe 2+ ⇌ Fe 3+ + e −. By measuring the amounts of H 2 evolved at the cathode and CO 2 evolved at the anode using gas chromatography, the mechanism for CAWE is established to be the reaction: C (s) + 2H 2O (ℓ) → CO 2 (g) + 2H 2 (g). The reaction slows down with time as carbon is depleted by oxidation.