CeO2 stabilized by tourmaline as a novel inorganic filler to simultaneously increase the conductivity and durability of proton exchange membranes

Abstract

An effective new bifunctional inorganic filler, a tourmaline (TM)-loaded CeO₂ core–shell micronanostructure (TM-CeO₂), was designed and implemented to simultaneously increase the stability and proton conductivity of perfluorosulfonic acid (PFSA)-based proton exchange membranes. Composite membranes exhibited excellent mechanical strength, chemical stability, and proton conductivity upon the introduction of TM-CeO₂ into the PFSA matrix. The presence of TM provided excellent proton conductivity and mechanical strength to composite membranes, while the addition of CeO₂ alleviated the chemical deterioration of composite membranes by scavenging hydroxyl radicals. The maximum power density of the PFSA/TM-CeO₂ (1 wt%) composite membrane at 80 °C and 100% RH was 1006 mW cm⁻¹, whereas that of the pristine PFSA membrane under identical conditions was only 906 mW cm⁻¹. Additionally, proton exchange membrane fuel cells (PEMFCs) containing PFSA/TM-CeO₂ membranes show a decay of only 0.29 mV h⁻¹ in 168 h while operating at 80 °C and 50% RH. Compared to PFSA/TM-CeO₂, PEMFCs with a pristine PFSA membrane showed a decay of 2.18 mV h⁻¹ under the same conditions. These results clearly indicate that PFSA/TM-CeO₂ composite membranes may be promising candidates for PEM fuel cells.