Intermediate-temperature polymer electrolyte membrane fuel cells (IT-PEMFCs), operating with phosphoric acid (H3PO4) doped polybenzimidazole (PBI), are severely limited by H3PO4 evaporation at high temperatures and poor resiliency in the presence of water. Polycations (PCs), on the other hand, provide good acid retention due to strong ion-pair interactions but have low conductivity due to lower ion-exchange capacity when compared to PBI. In this work, a class of H3PO4 doped PC–PBI membrane blends was prepared, and the optimal blend (50:50 ratio) exhibited remarkably high in-plane proton conductivity, near 0.3 S cm–1 at 240 °C, while also displaying excellent thermal stability and resiliency to water vapor. Microwave dielectric spectroscopy demonstrated that incorporating PBI into the PCs raised the dielectric constant by 50–70% when compared to the PC by itself. This observation explains, in part, the high proton conductivity of the optimal membrane blend. Finally, an all-polymeric membrane electrode assembly with the new materials gave a competitive IT-PEMFC performance of 680 mW cm–2 at 220 °C under dry H2/O2. Importantly, the cell was stable for up to 30 h at 220 °C and over 84 h at 180 °C. The IT-PEMFC had reasonable performance (450 mW cm–2) with 25% carbon monoxide in the hydrogen fuel.

Left image is the relationship for the overpotential for water dissociation as a function of bipolar junction electric field whereas the right image presents micrographs and the procedure to make bipolar membranes with micropatterned interfaces.

Conventional hydrogen separations from reformed hydrocarbons often deploy a water gas shift (WGS) reactor to convert CO to CO2, followed by adsorption processes to achieve pure hydrogen. The purified hydrogen is then fed to a compressor to deliver hydrogen at high pressures. Electrochemical hydrogen pumps (EHPs) featuring proton-selective polymer electrolyte membranes (PEMs) represent an alternative separation platform with fewer unit operations because they can simultaneously separate and compress hydrogen continuously. In this work, a high-temperature PEM (HT-PEM) EHP purified hydrogen to 99.3%, with greater than 85% hydrogen recovery for feed mixtures containing 25–40% CO. The ion-pair HT-PEM and phosphonic acid ionomer binder enabled the EHP to be operated in the temperature range from 160 to 220 °C. The ability to operate the EHP at an elevated temperature allowed the EHP to purify hydrogen from gas feeds with large CO contents at 1 A cm–2. Finally, the EHP with the said materials displayed a small performance loss of 12 μV h–1 for purifying hydrogen from syngas for 100 h at 200 °C.