Accelerated Recombination Reaction through Interfacial Fe^IV=O Accumulation on Photoanode Surfaces

Area of Science:

• Materials Science
• Electrochemistry
• Photocatalysis

Background:

• Understanding water oxidation kinetics is crucial for renewable energy technologies.
• The role of iron-oxo species (FeIV=O) accumulation in recombination kinetics at semiconductor interfaces remains underexplored.

Purpose of the Study:

• To investigate the impact of FeIV=O accumulation on recombination reaction kinetics at the hematite-electrolyte interface.
• To identify strategies for mitigating accumulation-accelerated recombination (AAR).

Main Methods:

• Kinetic analysis of FeIV=O accumulation and recombination at a model hematite-electrolyte interface.
• Investigating the effects of surface deprotonation, electron evacuation, and Co-substitution on recombination rates.

Main Results:

• Observed fast second-order recombination kinetics for accumulated FeIV=O, termed "accumulation-accelerated recombination" (AAR).
• Demonstrated that AAR can be slowed to first-order kinetics via surface deprotonation, electron evacuation, or Co-substitution.

Conclusions:

• FeIV=O accumulation adversely affects interfacial recombination kinetics, leading to efficiency losses.
• Insights into AAR are vital for optimizing semiconductor-based energy systems like photocatalysts and photovoltaic devices.