Photoelectrochemical water splitting using visible-light-responsive BiVO4 fine particles prepared in an aqueous acetic acid solution

Fine BiVO4 particles with a tetragonal scheelite structure (s-t) were synthesized from Bi2O3 and V2O5 in an aqueous acetic acid solution. The crystal phase of BiVO4 changed from s-t to monoclinic scheelite structure (s-m) by calcination at 673 K. The fine BiVO4 photocatalysts showed O-2 evolution from an aqueous silver nitrate solution and methylene blue decoloration under visible light irradiation. BiVO4(s-m) electrodes were readily prepared by pasting the obtained fine BiVO4(s-t) particles on FTO plates and subsequently calcining at 673 K. The BiVO4 electrode gave an excellent anodic photocurrent with 12% of an IPCE at 440 nm at 1.5 V vs. Ag/AgCl. A wet photovoltaic cell consisting of the BiVO4 photoelectrode and a Pt counter electrode was constructed for water splitting. H-2 and O-2 evolved from water with an externally applied bias smaller than 1.23 V vs. the Pt counter electrode under visible light and simulated sunlight irradiation.