Design, fabrication, and characterization of a proposed microchannel water electrolyzer

• Published in: Journal of power sources 2016-03, Vol.307 (C), p.122-128
• Main Authors: Oruc, Muhammed E., Desai, Amit V., Nuzzo, Ralph G., Kenis, Paul J.A.
• Format: Article
• Language: English
• Subjects: Mass/heat/ion/charge transport limitation; PDMS electrolyzer; Photovoltaic thermal systems; Platinum black on gold electrodes; Pulsed operation for electrolyte transport
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2015.12.062

Solar energy-powered water electrolysis is a cost-effective and scalable method to produce hydrogen, an environment-friendly and potentially sustainable energy carrier. To this end, we report a microchannel water electrolyzer with a planar design that can be integrated with a photovoltaic cell, where the electrolyzer utilizes the waste heat generated during the photoelectric process to enhance the production of hydrogen (and oxygen) via the electrochemical splitting of water. We performed a systematic parametric investigation to study the effect of the channel dimensions, electrolyte temperature and flow rate, and the mode of operation (pulsed vs. continuous) on the electrolyzer's performance. The balance between mass, heat and ion/charge transport limitations acts to determine an optimal geometry and specific operating conditions for the device. The highest hydrogen production rate was observed for pulsed operation (15 s pulses) at a temperature of 60 °C, and a potential of 2.0 V, for a 400-μm tall electrolyzer chamber. We also show that tuning of the geometry and operating conditions can yield an almost 7-fold increase in the hydrogen production rate. This study not only reports a new and improved approach over existing photovoltaic thermal systems but also presents design and operational considerations for microfluidic-based electrochemical energy devices. [Display omitted] •A planar design for a water electrolyzer that can be integrated with PVT systems.•Higher chamber thicknesses minimize mass transport limitations caused by bubbles.•Higher operating temperatures and applied potential lead to more H2 production.•Pulsed flow operation is preferred to continuous flow.•Lower pulse duration is preferred for higher rates of hydrogen evolution.