Electrosprayed heterojunction WO_3/BiVO_4 films with nanotextured pillar structure for enhanced photoelectrochemical water splitting

摘要

We demonstrate that the addition of a tungsten oxide (WO_3) layer beneath a bismuth vanadate (BiVO_4) photocatalyst layer with a nanotextured pillar morphology significantly increases the photocurrent density in photoelectrochemical water splitting. The WO_3-BiVO_4 bilayer films produced a photocurrent of up to 3.3 mA/cm~2 under illumination at 100 mW/cm~2 (AM1.5 spectrum). The bilayer film was characterized by scanning electron microscopy, X-ray diffraction, and photoelectrochemical methods, which confirmed the superiority of the bilayer film in terms of its morphology and charge separation and transport ability. Both WO_3 and BiVO_4 were deposited by electrostatic spraying under open-air conditions, which resulted in nanotextured pillars of BiVO_4 atop a smooth WO_3 film. The optimal coating conditions are also reported.