Bipolar Membrane Electrolyzer

Electrolyzers can be used to produce chemicals in a sustainable manner. One important product is hydrogen, which can serve as an energy carrier and a potential carbon-free fuel. Typical water electrolyzers consist of two electrodes: the cathode, where hydrogen production occurs, and the anode, where oxygen production occurs. To ensure low overpotentials and efficient operation, the electrodes comprise catalysts selected based on the local pH environment in each electrode. To enable the use of economically viable catalysts and ensure efficient operation, acidic conditions should be preferred in the cathode and alkaline conditions in the anode. To maintain such conditions, bipolar membranes can be used. These membranes consist of two oppositely charged ion exchange membranes, resulting in effective block of all salt ions. Therefore, under high (reverse bias) applied voltage, water dissociation takes place in the membrane junction, producing hydronium and hydroxide ions that can maintain the desired conditions.

Although bipolar membrane water electrolyzers are promising, their adoption is limited due to the development of a second limiting current, restricting the currents that can be used in such a system. This limiting current is attributed to the limitation of water transport toward the membrane junction. In our lab, we study this phenomenon to better understand the underlying mechanisms, which may lead to higher currents being carried by this system.