Structural chemistry-driven MXene selection for engineering MXene/polyoxometalate interfaces for photocatalytic...

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Efficient photocatalysts are crucial for solar-driven hydrogen production.
• Understanding cocatalyst structure's role in interfacial charge transfer is key for rational catalyst design.
• MXenes and polyoxometalates are promising materials for photocatalysis.

Purpose of the Study:

• To systematically compare Keggin-type phosphotungstic acid (PW) modified Ti3C2 and Ti2C MXenes.
• To elucidate the role of MXene structural chemistry in photocatalytic hydrogen evolution.
• To establish structure-activity relationships in MXene/polyoxometalate systems for efficient photocatalytic interfaces.

Main Methods:

• Synthesis and characterization of PW-modified Ti3C2 and Ti2C MXenes.
• Comprehensive structural, spectroscopic, optical, and electrochemical analyses.
• Response surface methodology for process optimization.

Main Results:

• PW incorporation suppressed charge-carrier recombination and enhanced surface area in MXenes.
• PW coupling increased oxygen-vacancy density, more pronounced in Ti3C2-based systems, promoting interfacial charge transfer.
• Ti2C/PW achieved higher peak hydrogen evolution rates (up to 4773 μmol/gcat.h), while optimized Ti3C2/PW reached 2718 μmol/gcat.h, showing stable performance.

Conclusions:

• Superior performance of MXene/PW arises from stronger interfacial electronic coupling, higher oxygen-vacancy concentration, and Schottky-type junction formation.
• Ti3C2/PW demonstrated more stable and predictable structure-activity behavior, highlighting the importance of MXene selection.
• This work provides clear structure-activity relationships for MXene/polyoxometalate systems in photocatalytic hydrogen production.