Photocatalytic behaviors of epitaxial BiVO₄ (010) thin films

Photocatalytic studies performed on well-defined epitaxial thin films and heterostructures allow the direct investigation of crystallographic-dependent reactivity, and can provide fundamental insights into the reaction mechanisms. In this work, we show that phase-pure, monoclinic BiVO₄ nanoislands with a truncated pyramid shape with the (010) top surface and {110} sidewalls can be grown on (001)-oriented yttria-stabilized zirconia (YSZ) substrates with an epitaxial relationship of BiVO₄(010)[001] // YSZ(001)[100]. The resulting nanostructures show a strong size-dependent mass-normalized photocatalytic activity, with highly dispersed nanoislands at low coverage being the most active. Pb(NO₃)₂ photooxidation or photoreduction reactions can be controlled in aqueous solution with and without adding NaIO₃ as a electron scavenger, leading to the selective deposition of PbO₂ or Pb on {110} or (010) surfaces of BiVO₄, respectively.