Electrospun SrNb2O6 photoanodes from single-source precursors for photoelectrochemical water splitting

Electrospinning of SrNb2O6 nanofibers from a single bimetallic alkoxide precursor [SrNb2((OPr)-Pr-i)(12)((HOPr)-Pr-i)] and the application of resulting oxide nanofiber meshes as potential photoanode material for solar water splitting is reported. Direct formation of single phase SrNb2O6 nanofibers from the precursor gel was favored by the tailored Sr:Nb ratio (1:2) and preordering of cations through Sr-O(R)-Nb units present in the molecular precursor. X-ray diffraction and photoelectron spectroscopy confirmed the chemical composition and formation of SrNb2O6 phase. A minor amount of orthorhombic SrNb6O16 phase was observed, when small excess of alkali metal was present during the precursor synthesis. The optical bandgap of photoelectrodes, produced by doctor blading and spin coating of the nanofibers, revealed bandgap energies between 3.25 and 3.43 eV, owing to different microstructure of the photoelectrodes. The measurement of photoelectrochemical properties in basic conditions showed photocurrent density values at 1.23 eV ranging from 0.06 mA/cm(2) to 0.16 mA/cm(2). A maximum value of 0.6 mA/cm(2) was obtained for spin-coated nanofiber photoelectrodes.