Organic phosphonic acid modified SBA-15 assisted enhanced high-temperature proton exchange membrane fuel cell performance of polybenzimidazole membranes

To tackle the challenges of phosphoric acid (PA) leakage and suboptimal proton transfer efficiency in PA-polybenzimidazole (PBI) high-temperature proton exchange membranes (HTPEMs), this research has pioneered the development of a novel porous silicon material, DP/S15, which has been tailored through organic phosphonic acid modification. S15 or DP/S15 was utilized to fabricate PBI composite membranes and subjected these membranes to a thorough examination of their properties. The integration of DP/S15 into the membrane matrix notably enhanced acid uptake and facilitated the formation of a robust and extensive proton transportation network. This was largely attributable to the synergistic interaction between the organic phosphonic acid groups in DP/S15 and PA. As a result, the membranes incorporating DP/S15 exhibited a host of commendable properties, most notably their substantial mechanical strength, which registered at 89.80 MPa with undoped PA and 13.10 MPa with doped PA. Furthermore, theoretical analyses lent credence to the efficient adsorption between DP/S15 and phosphoric acid. Consequently, the composite membranes delivered superior performance metrics, evident in their high conductivity (reaching 57.7 mS cm-1 at 160 °C) and excellent PA retention capabilities (up to 89.5%). Of paramount significance was the performance of the single fuel cell equipped with the PA-DP/S15-PBI composite membrane, which achieved a peak power density of 672.29 mW cm-2. This figure impressively surpassed that of the pure PBI membrane by 262.23 mW cm-2. In light of these promising outcomes, the PA-DP/S15-PBI composite membrane harbors significant potential for deployment in HT-PEMFCs.