Bilayer TiO₂/Mo-BiVO₄ Photoelectrocatalysts for Ibuprofen Degradation

Heterojunction formation between BiVO₄ nanomaterials and benchmark semiconductor photocatalysts has been keenly pursued as a promising approach to improve charge transport and charge separation via interfacial electron transfer for the photoelectrocatalytic degradation of recalcitrant pharmaceutical pollutants. In this work, a heterostructured TiO₂/Mo-BiVO₄ bilayer photoanode was fabricated by the deposition of a mesoporous TiO₂ overlayer using the benchmark P25 titania catalyst on top of Mo-doped BiVO₄ inverse opal films as the supporting layer, which intrinsically absorbs visible light below 490 nm, while offering improved charge transport. A porous P25/Mo-BiVO₄ bilayer structure was produced from the densification of the inverse opal underlayer after post-thermal annealing, which was evaluated on photocurrent generation in aqueous electrolyte and the photoelectrocatalytic degradation of the refractory anti-inflammatory drug ibuprofen under back-side illumination by visible and UV-Vis light. Significantly enhanced photoelectrochemical performance on both photocurrent density and pharmaceutical degradation was achieved for the bilayer structure with respect to the additive effect of the constituent layers, which was related to the improved light harvesting arising from the backscattering by the mesoporous TiO₂ layer in combination with the favorable charge transfer at the TiO₂/Mo-BiVO₄ interface.