Interfacial Electrostatic Interaction Overcomes Backward Electron Transfer without CrO_x-Based Core-Shell Cocatalyst...

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Z-scheme water splitting utilizes redox mediators to couple H2-evolving and O2-evolving photocatalysts for efficient overall water splitting.
• Backward electron transfer from the redox mediator is a major limitation, hindering H2 and O2 evolution.
• Current strategies often employ chromium oxide (CrOx) shells, raising concerns about chromium toxicity and elution.

Purpose of the Study:

• To develop a chromium-free strategy to suppress backward electron transfer in Z-scheme water splitting.
• To design a charge-switchable cobalt complex mediator that enhances photocatalytic efficiency.
• To demonstrate an alternative to CrOx shells for improved safety and performance.

Main Methods:

• Fabrication of a Z-scheme system using a positively charged H2-evolving photocatalyst.
• Design and synthesis of a charge-switchable cobalt complex as a redox mediator.
• Investigation of electrostatic interactions at the photocatalyst-mediator interface to control electron transfer.

Main Results:

• The designed cobalt complex mediator effectively suppressed backward electron transfer without CrOx.
• The charge-switchable mediator selectively interacted with the photocatalyst, optimizing electron transport.
• Achieved an apparent quantum yield of 7.2% for Z-scheme water splitting, demonstrating high efficiency.

Conclusions:

• A novel chromium-free approach using electrostatic interactions effectively mitigates backward electron transfer in Z-scheme water splitting.
• The charge-switchable cobalt complex offers a safer and efficient alternative to CrOx-based mediators.
• This work paves the way for developing advanced photocatalytic systems for sustainable hydrogen production.