Perovskite-Type Oxynitride Nanofibers Performing Photocatalytic Oxygen And Hydrogen Generation

Ba5Nb4O15 nanofibers with tailored nanofiber diameters are prepared via electrospinning, and treated in ammonia gas to synthesize niobate oxynitride nanofibers. Most importantly, the nanofibers retain their fiber morphology during ammonolysis, and the nanofiber diameter of the converted fibers can be adjusted. Only a thorough characterization, including detailed Rietveld refinements, can reveal that the ammonolysis of Ba5Nb4O15 results not only in BaNbO2N, but also generates Ba2NbO3N as additional oxynitride phase. Such BaNbO2N-Ba2NbO3N composite nanofibers with adjusted nanofiber diameters are applied in photocatalytic water oxidation and hydrogen generation. After decoration with CoNbO4 or Pt cocatalyst, the materials show a diameter-dependent photocatalytic activity, respectively, with an optimum nanofiber diameter. The presented synthesis demonstrates a novel sol-gel-derived possibility for nanostructuring of oxynitrides, which can pave the way for new synthesis strategies of nanostructured complex oxynitrides.