All Printed Photoanode/Photovoltaic Mini-Module for Water Splitting

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Photoelectrochemical (PEC) water splitting using bismuth vanadate (BiVO4) photoanodes is a promising route for cost-effective hydrogen production.
• Challenges include the trade-off between light absorption and charge transfer, and poor long-term stability, limiting PEC efficiency.
• Printing large-area BiVO4 photoanodes is desirable for scalability but requires optimized fabrication methods.

Purpose of the Study:

• To develop an advanced solution-processed recipe for printing BiVO4 photoanodes with enhanced PEC performance and stability.
• To investigate the effect of BiI3 doping on crystal growth, charge transfer, and photocurrent generation in printed BiVO4 films.
• To analyze the degradation mechanisms affecting the long-term stability of BiVO4 photoanodes.

Main Methods:

• Solution-processed deposition of BiVO4 films with BiI3 dopant, controlling crystal growth and orientation.
• Characterization of film morphology, crystal structure (preferential (001) orientation), and surface properties.
• Fabrication of tandem devices with perovskite solar modules and evaluation of PEC water splitting performance under AM 1.5 G illumination.

Main Results:

• The BiVO4 films exhibited a preferential (001) orientation and nanorod morphology, facilitating faster charge transfer.
• The optimized photoanode achieved a photocurrent density of 5.88 mA cm-2 at zero bias in a tandem configuration.
• A solar-to-hydrogen efficiency of 7.02% was obtained for unbiased water splitting, with stability analysis revealing degradation pathways.

Conclusions:

• The BiI3-doped, solution-processed BiVO4 photoanode demonstrates significant potential for efficient and cost-effective PEC water splitting.
• Controllable crystal growth and nanorod morphology are key to improving photocurrent and charge transfer.
• Understanding degradation mechanisms, such as vanadium loss and Bi2O3 enrichment, is crucial for enhancing long-term device stability.