RESUMEN
A novel sulfated tin oxide solid superacid granular stacked one-dimensional (1D) hollow nanofiber (SO42-/FSnO2) is proposed as a nanofiller in sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) to manipulate a highly conductive proton nanochannel. It has unique microstructures with an open-end hollow nanofibric morphology and grain-stacked single-layer mesoporous fiber wall, which greatly enlarge the specific surface area and aspect ratio. The diverse acid sites, that is, SO42-, Sn-OH Brönsted, and Sn4+ Lewis superacids, provide a high concentration of strong acidic proton carriers on the nanofiber surface and dynamically abundant hydrogen bonds for rapid proton transfer and interfacial interactions with -SO3H groups in the SPPESK along the 1D hollow nanofiber. As a result, long-range orientated ionic clusters are observed in the SO42-/FSnO2 incorporated membrane, leading to simultaneous enhancement of proton conductivity (226.7 mS/cm at 80 °C), mechanical stability (31.4 MPa for the hydrated membrane), fuel permeation resistance, and single-cell performance (936.5 and 147.3 mW/cm2 for H2/O2 and direct methanol fuel cells, respectively). The superior performance, as compared with that of the zero-dimensional nanoparticle-incorporated membrane, Nafion 115, and previously reported SPPESK-based membranes, suggests a great potential of elaborating superstructural 1D hollow nanofillers for highly conductive proton-exchange membranes.
RESUMEN
Rechargeable metal-air batteries and water splitting are highly competitive options for a sustainable energy future, but their commercialization is hindered by the absence of cost-effective, highly efficient and stable catalysts for the oxygen evolution reaction. Here we report the rational design and synthesis of a double perovskite PrBa0.5Sr0.5Co1.5Fe0.5O5+δ nanofiber as a highly efficient and robust catalyst for the oxygen evolution reaction. Co-doping of strontium and iron into PrBaCo2O5+δ is found to be very effective in enhancing intrinsic activity (normalized by the geometrical surface area, â¼4.7 times), as validated by electrochemical measurements and first-principles calculations. Further, the nanofiber morphology enhances its mass activity remarkably (by â¼20 times) as the diameter is reduced to â¼20 nm, attributed to the increased surface area and an unexpected intrinsic activity enhancement due possibly to a favourable eg electron filling associated with partial surface reduction, as unravelled from chemical titration and electron energy-loss spectroscopy.