Work

Spatially Engineered WO 3 Nanofibers on BiVO 4 : A Route to High-Efficiency Photoelectrochemical Water Splitting

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide This study employs aerosol-assisted chemical vapor deposition (AACVD) to fabricate WO 3 /BiVO 4 heterojunction photoanodes with an inverted architecture (WO 3 atop BiVO 4 ). The unique permeable nanofiber morphology of WO 3 provides a solution to enhance water oxidation performance. By correlating precursor volume (10–40 mL) and spatial position within the deposition chamber (inlet/mid/outlet) with film properties, we demonstrate that a midreactor position yields “grass-like” WO 3 nanofibers (diameter: 100–230 nm, length: 3.5–3.98 μm), enabling dual functionality: (i) > 50% light transmittance to the underlying BiVO 4 absorber, and (ii) electrolyte penetration into the heterointerface between WO 3 and BiVO 4 . In contrast, rod-like WO 3 produced near the inlet causes severe light scattering, reducing the incident photon-to-current efficiency (IPCE) by six times above wavelengths of 350 nm. Optimized samples, produced with a deposition volume of 30 mL to deposit WO 3 atop of BiVO 4 positioned in the middle of the deposition chamber (i.e., WO 3 -30/BiVO 4 -mid), achieve a photocurrent density of 0.82 mA·cm –2 at 1.23 V RHE under 1 sun irradiance, which is 121% higher than single-layer BiVO 4 (0.37 mA·cm –2 ) and exceeds some conventional WO 3 -under/BiVO 4 heterojunctions in which WO 3 is underneath BiVO 4 . Transient absorption spectroscopy confirms prolonged carrier lifetimes in our unique heterostructure through improved charge-carrier separation. This work challenges current traditional heterojunction design rules for the WO 3 /BiVO 4 system by showcasing how permeable WO 3 nanostructures atop BiVO 4 photoanodes can improve light harvesting and facilitate charge-carrier separation to significantly improve activity.

Source: ACS Applied Energy Materials

DOI: 10.1021/acsaem.5c02686