Loading-Controlled Photoactivity in TiO₂@BiVO₄ Heterostructures

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Titanium dioxide (TiO2) is a widely studied semiconductor for photoanodes.
• Bismuth vanadate (BiVO4) is a promising material for visible light absorption.
• Heterostructures of TiO2/BiVO4 offer potential for improved photoelectrochemical performance.

Purpose of the Study:

• To investigate the effect of BiVO4 nanoparticle amount and form on TiO2 photoanodes.
• To understand the influence of annealing temperature on BiVO4 phase and optical properties.
• To correlate photoanode morphology with photocurrent response under UV and visible light.

Main Methods:

• Preparation and annealing of BiVO4 nanopowders at various temperatures (200–500 °C).
• Deposition of BiVO4 on nanostructured TiO2 via drop-casting and successive ionic layer adsorption and reaction (SILAR).
• Structural, optical, and photoelectrochemical characterization of TiO2/BiVO4 heterostructures.

Main Results:

• Annealing temperature influences BiVO4 phase transition and visible light absorption.
• Morphology of BiVO4 on TiO2 affects photocurrent response under UV and visible light.
• TiO2@d photoanode showed high relative visible light activity but suffered from transport losses.

Conclusions:

• BiVO4 nanoparticle presence on TiO2 significantly influences charge separation and photon utilization.
• Optimizing BiVO4 morphology is crucial for efficient charge transfer and reduced recombination.
• Understanding band alignment and charge transfer mechanisms in TiO2/BiVO4 heterostructures is key for device performance.