Simple preparation of highly active water splitting FTO/BiVO4 photoanode modified with tri-layer water oxidation catalysts

Abstract

A colloidal BiVO₄ solution, prepared from equimolar mixing of Bi(NO₃)₃·5H₂O and NH₄VO₃ in MeOH containing 15% (v/v) 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMI triflate) ionic liquid, was coated on a fluorine-doped tin oxide conducting glass (FTO) with a doctor blade technique; it was sintered at 450 °C for 2 h to produce a super highly mechanically stable film of nanocrystalline scheelite-monoclinic, s-m BiVO₄ photoanode. This technique endowed an excellent solar-driven water splitting activity for both the bare photoanode and that modified with tri-layers of non-precious water oxidation catalysts. The presence of EMI triflate in the precursor solution is essential for the mechanical stability of the film. Moreover, carbon, nitrogen, and oxygen of the EMI triflate were left over in the resulting film, and they did not affect its crystalline phase.