Microfluidic Electrolyzers for Production and Separation of Hydrogen from Sea Water using Naturally Abundant Solar Energy

Abstract We report the design and development of a microfluidic electrolyzer for the continuous production and in situ separation of hydrogen fuel. A series of photovoltaic cells was integrated with a microchannel to produce a high‐intensity electric field under direct solar illumination, which electrolyzed the sea water in the microchannel. The rate of hydrogen production could be varied by tuning the electric field intensity or the flow rate of the sea water. The addition of an outlet near the cathode led to the in situ separation of hydrogen in the straight‐channel electrolyzer. Hydrogen was also separated from oxygen by using a Y‐shaped electrolyzer in which the electrodes were placed on the Y‐arms. The power required for the proposed process was much lower than that of macroscopic analogues because the smaller gap between the electrodes ensured a lower electrical resistance and high‐intensity field inside the microchannel. The large‐scale integration of an array of such electrolyzers could lead to an economic, portable, continuous, and clean pathway to produce hydrogen under ambient conditions.