Floating membraneless PV-electrolyzer based on buoyancy-driven product separation

Citation data:

International Journal of Hydrogen Energy, ISSN: 0360-3199, Vol: 43, Issue: 3, Page: 1224-1238

Publication Year:
2018
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DOI:
10.1016/j.ijhydene.2017.11.086
Author(s):
Jonathan T. Davis; Ji Qi; Xinran Fan; Justin C. Bui; Daniel V. Esposito
Publisher(s):
Elsevier BV
Tags:
Energy; Physics and Astronomy
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article description
This paper describes the design and performance of a scalable, stand-alone photovoltaic (PV) electrolysis device used for hydrogen (H 2 ) production by solar-driven water electrolysis. The electrolyzer component of this device is based on a simple, membraneless design that enables efficient operation with high product purity and without active pumping of the electrolyte. Key to the operation of this PV-electrolyzer is a novel electrode configuration comprised of mesh flow-through electrodes that are coated with catalyst on only one side. These asymmetric electrodes promote the evolution of gaseous H 2 and O 2 products on the outer surfaces of the electrodes, followed by buoyancy-driven separation of the detached bubbles into separate overhead collection chambers. The successful demonstration of this concept was verified with high-speed video and analysis of product gas composition with gas chromatography. While the device based on asymmetric electrodes achieved product cross-over rates as low as 1%, a control device based on mesh electrodes that were coated on both sides with catalyst had cross-over rates typically exceeding 7%. The asymmetric electrode configuration was then incorporated into a standalone, floating PV-electrolyzer and shown to achieve a solar-to-hydrogen efficiency of 5.3% for 1 sun illumination intensity. The simplicity of this membraneless prototype, as characterized by the lack of a membrane, scaffolding, or actively pumped electrolyte, makes it attractive for low-cost production of hydrogen.