Poly(arylene ether ketone)-based bipolar membranes for acid–alkaline water electrolysis applications

Abstract

Bipolar membranes are one of the attractive candidates for water electrolysis applications, because they enable hydrogen and oxygen evolution reactions to take place under their optimal pH conditions, thereby minimizing the overall cell voltage for water splitting. This study demonstrates the preparation of bipolar membranes using dual-sulfonated poly(arylene ether ketone) as a cation exchange layer and butyl-N₃-substituted imidazolium-functionalized poly(arylene ether ketone) as an anion exchange layer. The synthesized bipolar membrane (BPM) was employed in an acid–alkaline dual-electrolyte water electrolysis system as a separator to restrain bulk neutralization. Results indicate that this BPM promoted water spitting reactions between the membranes at an applied voltage of 2.31 V and a current density of 160 mA cm⁻² in 1 M H₂SO₄ and 2 M KOH without any deposition of water dissociation catalysts at room temperature. The BPM synthesized in this work also exhibited excellent chemical stability by experiencing a weight loss less than 3.4% in both strong acids and bases after 28 days. These results indicate that this BPM is feasible to be applied in the novel type acid–alkaline water electrolysis system to produce hydrogen energy.