Utilization of Water-Insoluble Carbon Nitride-Phosphotungstic Acid Hybrids in Composite Proton Exchange Membranes.

Phosphotungstic acid (HPW) can retain water in proton exchange membranes to increase proton conductivity; however, its water-soluble nature limits further application. In this work, we combined HPW and graphitic carbon nitride (g-CN) via sintering to prepare water-insoluble hybrids (HWN), where HPW was chemically linked to g-CN to fix HPW. Then, HWN fillers were added to a sulfonated polyether ether ketone (SPEEK) matrix to prepare composite membranes.