Work Function Engineering of MXene-Based Cocatalyst Through Transition-Metal-Ion Intercalation for Enhanced...

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Photoelectrochemical (PEC) water splitting offers a pathway for solar energy conversion.
• Efficiency is often limited by slow oxygen evolution reactions (OER) at photoanodes.
• Oxygen evolution cocatalysts (OECs) improve OER but are hindered by insufficient carrier separation.

Purpose of the Study:

• To enhance carrier separation in PEC systems by engineering the work function of OECs.
• To investigate the effect of transition-metal-ion intercalation on the work function of Ti3C2 (MXene-based OEC).
• To improve the performance of BiVO4-based photoanodes for PEC water splitting.

Main Methods:

• Work function engineering of Ti3C2 via transition-metal-ion intercalation.
• Fabrication of composite photoanodes integrating modified Ti3C2 with BiVO4.
• Electrochemical and photoelectrochemical characterization, including photocurrent density and applied bias photon-to-current efficiency (ABPE) measurements.
• Theoretical calculations to understand electronic properties and interfacial behavior.

Main Results:

• Transition-metal-ion intercalation successfully regulated the work function of Ti3C2.
• The composite photoanode (BiVO4/intercalated Ti3C2) achieved a photocurrent density of 3.43 mA cm-2 at 1.23 V vs RHE, approximately double that of BiVO4/Ti3C2.
• Peak ABPE increased to 1.47%, also roughly doubling the control sample.
• Intercalation strengthened the interfacial built-in electric field, promoting carrier separation and suppressing recombination.

Conclusions:

• Work function engineering of OECs is an effective strategy to enhance carrier separation in PEC water splitting.
• Transition-metal-ion intercalation in Ti3C2 provides a tunable route to modulate electronic properties and improve OEC performance.
• This work establishes work function modulation as a key design principle for developing high-performance OECs in PEC systems.