Rationally embedded zinc oxide nanospheres serving as electron transport channels in bismuth vanadate/zinc oxide heterostructures for improved photoelectrochemical efficiency.

In this work, we demonstrate the fabrication of Mo, W co-doped BiVO4/ZnO nanosphere (Mo, W: BVO/ZnO NS) heterostructures using a simple solution dry-out method that uniformly embeds ZnO NSs in Mo, W: BVO nanocrystals. Photoelectrochemical (PEC) examination confirmed that Mo, W: BVO/ZnO NSs exhibit higher PEC performance than pure Mo, W: BVO, and this improved performance of Mo, W: BVO/ZnO NSs also depends on decreased ZnO NS size. Moreover, a layered ZnO/Mo, W: BVO (ZnO film coated with Mo, W: BVO layer) heterostructure was prepared using a simple physical piled method that exhibited far lower PEC performances than those of Mo, W: BVO/ZnO NS heterostructures. These results clearly revealed that the formation of the Mo, W: BVO/ZnO NS heterostructure could increase the charge carrier density and it possessed a much larger contact area. These improvements were favorable for the transfer and transport of photoexcited charge carriers. This work offers an effective strategy to fabricate heterostructures with effective charge separation by a simple solution dry-out method that is suitable for other heterostructure-engineered photoanodes in solar water-splitting applications.