Self-powered dual-electrode hydrogen production using a composite ion exchange membrane.

The electro-oxidation of formaldehyde at low potential with anodic hydrogen evolution offers an energy-saving way for hydrogen production. Coupling this reaction in an acidic catholyte with an alkaline anolyte within an acid-alkali hybrid electrochemical system enables self-powered hydrogen production with electricity generation. However, the performance of such systems is constrained by the membrane: conventional forward-bias bipolar membranes suffer from high ohmic resistance due to the delamination, while monopolar ion exchange membranes lead to undesirable acid-alkali neutralization. To address these limitations, we design a composite ion exchange membrane, composed of a through-pore anion exchange membrane and a cation exchange membrane. Employing this membrane, the resulting system achieves a Faradaic efficiency for hydrogen of 198 ± 3 % and outputs a peak power density of 142 mW cm-2. A numerical model demonstrates that the through-pore anion exchange membrane effectively regulates charge carrier transport, yielding low resistance and improved acid-alkali utilization efficiency. Here, we provide a promising pathway for sustainable hydrogen production by enabling the efficient conversion of acid-alkali chemical energy into electricity.