Breaking through water-splitting bottlenecks over carbon nitride with fluorination

Area of Science:

• Materials Science
• Photocatalysis
• Green Chemistry

Background:

• Graphitic carbon nitride (g-C3N4) possesses suitable band structure for photocatalytic water splitting but is limited by inefficient oxygen evolution.
• Previous efforts required organic co-catalysts, hindering practical applications for hydrogen and oxygen production.

Purpose of the Study:

• To identify and overcome the bottleneck in visible-light-driven overall water splitting using single-phased g-C3N4.
• To enhance the photocatalytic activity of g-C3N4 for efficient hydrogen and oxygen evolution.

Main Methods:

• In-situ observation of surface bonding changes during photocatalysis.
• Surface modification of g-C3N4 via fluorination.
• Density Functional Theory (DFT) calculations to elucidate reaction mechanisms.

Main Results:

• Fluorination significantly minimizes intermediate C=O bonding on the g-C3N4 surface.
• Achieved an order-of-magnitude increase in H2 evolution rate compared to pristine g-C3N4.
• Demonstrated continuous O2 evolution, indicating successful overall water splitting.

Conclusions:

• Surface C-F interaction optimizes the oxygen evolution pathway on neighboring N atoms.
• Fluorination effectively mitigates detrimental C-O and N-O interactions, enhancing catalyst performance.
• This strategy presents a promising route for efficient photocatalytic water splitting using g-C3N4.