A new class of bubble-free water electrolyzer that is intrinsically highly efficient. (3rd September 2019)

• Record Type: Journal Article
• Authors: Tiwari, Prerna; Tsekouras, George; Wagner, Klaudia; Swiegers, Gerhard F.; Wallace, Gordon G.
• Is Part Of: International journal of hydrogen energy. Volume 44:Number 42(2019)
• Page Start: 23568
• Page End: 23579
• Publication Date: 2019-09-03
• Subjects: Electrolysis -- Gortex -- Overpotential -- Water-splitting -- Hydrogen; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2019.07.100
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: A new class of ' bubble-free ' alkaline electrolyzer with electrodes comprising of PTFE-based Gortex gas diffusion layers coated with catalysts, is described (PTFE = poly(tetrafluoroethylene)). At ≥80 °C (E o cell 1.18 V), the electrolyzers displayed the lowest cell onset potentials (≥1.28 V) yet reported, indicating that they exhibit the highest-known intrinsic efficiency when the influence of impedance is stripped out. The overpotentials at each electrode, particularly the oxygen-generating anode, were significantly diminished by the presence of the porous Gortex substrate, which exhibited a powerful ' gas-philic' capillary action (6.3 bar capillary pressure). The bubble-free process arose from preferential coalescence of newly-formed gases on the PTFE surfaces, where the capillary action of the Gortex continuously extracted them before they could nucleate bubbles. In so doing, observable bubble formation was avoided, along with the energy penalties associated with the formation and release of gas bubbles. Highlights: A new class of "bubble-free" alkaline electrolyzer is described. The electrolyzers have the lowest cell onset potentials (≥1.28 V; 80 °C) yet reported. Ignoring impedance, they exhibit the highest reported intrinsic efficiency. A capillary action by the Gortex drastically decreased electrode overpotentials.