Enhanced Photoelectrochemical Water Oxidation on Bismuth Vanadate by Electrodeposition of Amorphous Titanium Dioxide

David Eisenberg, University of Texas at Austin, Austin, United States
Hyun S. Ahn, University of Texas at Austin, Austin, United States
Allen J. Bard, University of Texas at Austin, Austin, United States

Bismuth vanadate (BiVO₄) is a promising semiconductor material for photoelectrochemical water oxidation. Even though most thin film syntheses yield discontinuous bismuth vanadate layers, energy loss through back reduction of photo-oxidized products on the conductive substrate has never been considered for this material.

We report that a 15-seconds electrodeposition of amorphous titanium dioxide (a-TiO₂) on W:BiVO₄/F:SnO₂ blocks this undesired back reduction, and dramatically improves the photoelectrochemical performance of the electrode.

As a result of the treatment, water oxidation photocurrent increases by up to 5.5 times, and its onset potential shifts negatively by ~500 mV. In addition to blocking solution-mediated recombination at the substrate, the a-TiO₂ film – which is found to lack any photocatalytic activity in itself – is hypothesized to react with surface defects and deactivate them towards surface recombination. The proposed treatment is simple, effective, and may be extended to a wide variety of thin film photoelectrodes.


Enhanced Photoelectrochemical Water Oxidation on Bismuth Vanadate by Electrodeposition of Amorphous Titanium Dioxide David Eisenberg, University of Texas at Austin, Austin, United States Hyun S. Ahn, University of Texas at Austin, Austin, United States Allen J. Bard, University of Texas at Austin, Austin, United States Bismuth vanadate (BiVO₄) is a promising semiconductor material for photoelectrochemical water oxidation. Even though most thin film syntheses yield discontinuous bismuth vanadate layers, energy loss through back reduction of photo-oxidized products on the conductive substrate has never been considered for this material. We report that a 15-seconds electrodeposition of amorphous titanium dioxide (a-TiO₂) on W:BiVO₄/F:SnO₂ blocks this undesired back reduction, and dramatically improves the photoelectrochemical performance of the electrode. As a result of the treatment, water oxidation photocurrent increases by up to 5.5 times, and its onset potential shifts negatively by ~500 mV. In addition to blocking solution-mediated recombination at the substrate, the a-TiO₂ film – which is found to lack any photocatalytic activity in itself – is hypothesized to react with surface defects and deactivate them towards surface recombination. The proposed treatment is simple, effective, and may be extended to a wide variety of thin film photoelectrodes.

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