Superacid sulfated SnO2 doped with CeO2: A novel inorganic filler to simultaneously enhance conductivity and stabilities of proton exchange membrane

Towards the breaking of the “trade-off” between proton conductivity and stabilities of sulfonated poly(aryl ether sulfone) (SPAES)-based proton exchange membranes, a strategy of compositing with the superacids of sulfated SnO 2 (ST) and SnO 2 -xCeO 2 (CSTx) is designed and carried out. The superacids of ST and CSTx have been synthesized by sulfonation of SnO 2 with sulfuric acid and subsequently doped with CeO 2 . By the solution casting approach, the composite membranes are obtained in a homogenous state and show excellent mechanical strength , thermal, dimensional and chemical stability. ST or CSTx in the composite membranes provides excess active sites and forms additional proton-conducting channels by a network of hydrogen bonds . Although with low IEC levels, all the composite membranes show larger water absorption and proton conductivity than the control SPAES membrane. As a result, the SPAES-2CST3 membrane achieves a power output of 673.6 mW/cm 2 at 80 °C, which is higher than the control membrane (481.8 mW/cm 2 ). The durability of the SPAES-2CST3 membrane under accelerated stress test conditions is significantly enhanced compared to the control SPAES membrane, and the aged SPAES-2CST3 membrane exhibits lower hydrogen crossover and better cell performance than the aged control SPAES membrane.