Design, Operation and Simulation of a Passive Osmosis-Integrated Electrolyzer for Seawater Electrolysis

Utilizing abundant seawater for green hydrogen production through electrolysis is a promising pathway to produce a sustainable energy carrier. However, modern seawater electrolyzers have shown insufficient durability due to electrode corrosion and/or competitive production of chlorinated products that result from the presence of Cl − . In this work, a new cell, driven by osmotic separation, was designed and operated that can passively draw fresh water from seawater into compartments with high acid and/or alkaline concentration for electrolysis, thereby eliminating the need for an external energy source for desalination. The work focuses first on demonstrating the passive transport of water through membranes over a wide range of acid and base concentrations. Then, electrodes are integrated, and the cells are operated under multiple configurations and current densities. It is observed that some co-ion diffusion occurs, which is quantified through pH measurements and quantitative Cl − titration. Water transport and ion crossover experiments are supported by comprehensive continuum-level modeling. Finally, strategies for improving future performance are discussed. The findings in this work, a first step in the development of an osmosis-driven electrolyzer cell (ODEC), showcase the promise of this novel electrolyzer design for future direct seawater electrolysis.