Directional Change of Interfacial Electric Field by Carbon Insertion in Heterojunction System TiO₂/WO₃

Area of Science:

• Materials Science
• Photocatalysis
• Surface Chemistry

Background:

• Z-scheme photocatalytic systems offer superior redox capabilities but their construction remains challenging.
• Understanding charge transfer mechanisms in heterojunctions is crucial for optimizing photocatalyst performance.

Purpose of the Study:

• To investigate the role of work function and band bending in establishing Z-scheme charge transfer in TiO2/WO3 heterojunctions.
• To demonstrate how modifying these parameters can enhance photocatalytic activity.

Main Methods:

• Fabrication of TiO2/WO3 heterojunctions with controlled work function and band bending via carbon insertion.
• Characterization using ultraviolet photoelectron spectroscopy (UPS).
• Photocatalytic activity assessment via hydroxyl radical (•OH) formation rate measurement.
• First-principles calculations to elucidate charge transfer mechanisms.

Main Results:

• Carbon insertion effectively controlled work function and band bending in TiO2/WO3 through orbital hybridization and electron density redistribution.
• The modified TiO2/WO3 heterojunction exhibited a 2-fold increase in •OH radical formation rate compared to the unmodified system.
• First-principles calculations confirmed the formation of an interfacial electric field, facilitating the shift from Type II to Z-scheme charge transfer.

Conclusions:

• Work function and band bending are key determinants for constructing efficient Z-scheme photocatalytic systems.
• Tailoring these electronic properties via interfacial engineering, such as carbon insertion, can reconstruct charge transfer pathways.
• This approach enables the design of advanced heterojunction photocatalysts with enhanced performance.