High-temperature proton exchange membranes from H₃PO₄ incorporated polyacrylamide-graft-sodium alginate hydrogels

Proton exchange membrane fuel cells (PEMFCs) have attracted growing interests because of their merits in cost-effectiveness, low experimental impact, and scalable materials. In the current work, a new class of high-temperature proton exchange membranes (PEMs) from H3PO4 incorporated polyacrylamide-graft-sodium alginate (PAAm-g-SA) hydrogels having three-dimensional (3D) frameworks have been successfully realised. After being dried, the incorporated H3PO4 can be reserved in the 3D frameworks of hydrogel matrices, leading to formation of interconnected conducting channels. The dependences of proton conductivity on synthesis conditions such as SA dosage and H3PO4 concentration have been carefully demonstrated. The results show an anhydrous proton conductivity as high as 0.0852 S cm− 1 at 180°C can be obtained by optimising synthesis strategies. Moreover, the resultant H3PO4 incorporated PAAm-g-SA membranes display reasonable long-term stability, which demonstrates them to be potential candidates for high-temperature PEMFC applications.