Sub-particle reaction and photocurrent mapping to optimize catalyst-modified photoanodes

Area of Science:

• Photoelectrochemistry
• Solar energy conversion
• Catalysis

Background:

• Photoelectrochemical water splitting is key for solar fuel production.
• Optimizing photoanodes with oxygen evolution catalysts (OECs) is crucial but challenging.
• Surface heterogeneity and catalyst deposition control impact performance.

Purpose of the Study:

• To map photoelectrocatalytic activity on single nanorods.
• To understand the relationship between water oxidation sites and charge-carrier recombination.
• To guide rational design of OEC deposition for improved photoelectrode performance.

Main Methods:

• Utilized super-resolution imaging with charge-carrier-selective and spatiotemporal resolution.
• Mapped electron- and hole-driven photoelectrocatalytic activities on single titanium oxide nanorods.
• Quantified photocurrent associated with water oxidation at sub-particle resolution.

Main Results:

• Identified that highly active water oxidation sites are also primary sites for charge-carrier recombination.
• Demonstrated that site-selective OEC deposition improves overall nanorod performance.
• Discovered optimal OEC deposition sites for photocurrent enhancement (lower-activity sites) and onset potential reduction (more positive onset potential sites) differ from typical conditions.

Conclusions:

• Established an activity-based strategy for rationally engineering catalyst-improved photoelectrodes.
• Findings are applicable to various semiconductor and catalyst materials.
• Precise control over OEC deposition is essential for maximizing solar fuel production efficiency.