Photoelectrochemical properties of SrNbO2N photoanodes for water oxidation fabricated by the particle transfer method

Abstract

SrNbO₂N photoanodes, which have a band gap energy of 1.8 eV, were tested for photoelectrochemical water oxidation in water splitting. The photoanodes were fabricated either by a particle transfer method or an electrophoretic deposition method. The effects of the precursors, fabrication method, and CoO_x catalyst loading were studied in order to identify the shortcomings of the photoanodes and improve their photoelectrochemical properties for water oxidation. SrNbO₂N photoanodes fabricated by particle transfer generated a photocurrent that was one order of magnitude higher than that of photoanodes prepared via electrophoretic deposition. The stoichiometric oxide precursor (Sr₂Nb₂O₇) was found to be preferable to the Sr-rich oxide precursor (Sr₅Nb₄O₁₅). CoO_x increased the photoanodic current on SrNbO₂N photoelectrodes. Nevertheless, the incident photon-to-current efficiency was still limited to 10% at most. Potential problems with SrNbO₂N photoanodes were discussed.