The effect of surface states accumulation on photo-electrochemical performances of Bi24Fe2O39 grown by supersonic beams

Holes accumulation on the surface of bismuth ferrite oxides (BFO) photoanodes for photoelectrochemical (PEC) water splitting (WS) is one of the major issues limiting the overall cell efficiency. However, among the various BFO crystal structures, no evidence of this mechanism has been reported for Bi24Fe2O39, a scarcely investigated phase. Herein we characterize the morphological, structural and PEC properties of 100 nm thick nanogranular films of a Bi24Fe2O39 single phase synthesized by supersonic cluster beam deposition. The films were tested as photoanodes for the WS reaction in KOH and Na2SO4 + Na2SO3 electrolytes. The PEC data provide direct evidence of holes accumulation on the surface of the material with increasing applied biases. The interesting performances of this material at low biases suggest a possible use as photocatalyst under visible light irradiation.