Abstract
Although the artificial Z-scheme system, mimicking natural photosynthesis, has shown promising applications in photocatalytic water splitting, it often suffers from the side reaction of redox mediator, which considerably undermines the efficacy of photocarrier utilizations. Herein, we propose to suppress the side reaction by using ferroelectric polarization, which not only provides a strong driving force to spatially separate photocarriers to the oppositely poled surface but also induces spatially selective adsorption of redox ions. Single-domain ferroelectric PbTiO3 nanoplates have been adopted as a model ferroelectric to construct the Z-scheme system with BiVO4 particles and a cationic redox mediator. In contrast to the inactive multi-domain ferroelectric PbTiO3-based system, the so-formed Z-scheme system delivers stable high activity for photocatalytic overall water splitting under both visible light and simulated solar insolation. This work offers a proof of concept to realize efficient solar photocatalytic water splitting based on single-domain ferroelectric Z-scheme system.
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•Ferroelectric polarization induced the spatial separation of carriers and redox mediators•Single-domain ferroelectric PbTiO3-based Z-scheme system for overall water splitting•Greatly suppressed side reaction
The Z-scheme system involving two isolated photocatalysts and a redox mediator has been actively used for photocatalytic water splitting. However, this system always suffers from the redox mediators’ side reaction largely due to random distributions of both the redox mediators and photogenerated electrons/holes on the photocatalyst surfaces. The side reaction could be suppressed by making use of ferroelectric polarization to enable the selective adsorption of the cationic redox mediator on the negatively poled surface of ferroelectric photocatalyst, which simultaneously has the ability to induce the spatial separation of photogenerated electrons and holes on the positively and negatively poled surfaces. This strategy was validated by constructing a Z-scheme system with single-domain ferroelectric PbTiO3 as water reduction photocatalyst, faceted BiVO4 as water oxidation photocatalyst, and cationic redox mediator for enhanced photocatalytic overall water splitting.
The single-domain PbTiO3 has a built-in electric field to enable the spatial separation of the photocarriers and the selective adsorption of redox mediators on oppositely poled surfaces, i.e., electrons on the positively poled surface and cationic redox mediators on the negatively poled surface. This feature endows PbTiO3 as a promising water reduction photocatalyst in the Z-scheme system due to the suppression of mediator side reactions. This strategy could be applicable for designing much more efficient Z-scheme systems.