Highly Stable Engineered Homogeneous Bipolar Membranes for Efficacious Water Electrolysis for Hydrogen Generation

Bipolar membrane (BPM)-based water electrolysis presents a viable strategy for high-efficiency hydrogen production by facilitating independent pH regulation at the anode and cathode, thereby overcoming the limitations of conventional proton exchange membrane (PEM) and anion exchange membrane (AEM) electrolyzers. In BPMs, proton transport (H⁺) typically outpaces hydroxide (OH^-) migration, necessitating an ultra-thin AEM layer to minimize OH^- transport resistance and enhance membrane electrode assembly (MEA) efficiency. This study investigates the impact of AEM thickness variation (10, 20, and 30 µm) on BPM performance. The BPM-A10/C30 MEA, comprising a 10 µm AEM and 30 µm CEM, exhibited superior electrochemical performance among their prepared colleagues. To assess the influence of electrolyte conditions, three distinct electrolyte combinations are employed for the hydrogen generation using best optimized BPM-A10/C30 membrane by varying the catholyte as 0.5 m H₂SO₄, deionized (DI) water and sea water while 1 m KOH is used as anolyte for all sets of experiments. First combination (Cathode: 0.5 m H2SO4/Anode: 1 m KOH) shows the best results to achieve a maximum current density of 1000 mA cm^{- 2} at 1.9 V and demonstrates the lowest overall cell resistance of 0.09 Ω cm². Optimizing AEM thickness significantly improves ion transport dynamics and operational stability of MEA at high current density, thereby advancing cost-effective and scalable hydrogen production technologies.