Interlayer Atomic Voids by Partial Cesium Defect in Layered Titanate Activate Photo(electro)catalytic H₂ and O₂...

Area of Science:

• Materials Science
• Photocatalysis
• Semiconductor Chemistry

Background:

• Layered oxide semiconductors often show limited photocatalytic activity despite suitable band gaps.
• Bulk layered cesium titanate is an example of an inactive semiconductor.
• Cesium vacancies are introduced to enhance photocatalytic properties.

Purpose of the Study:

• To investigate the effect of cesium vacancies on the photocatalytic (PC) and photoelectrocatalytic (PEC) activity of layered titanate.
• To enhance hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) efficiency.
• To understand the mechanism behind the enhanced activity using computational modeling.

Main Methods:

• Synthesis of Cs-vacant layered titanate via thermal treatment.
• Testing PC activity for HER using H2O/MeOH (80:20).
• Testing PEC activity for OER.
• Computational modeling using hybrid density functional theory (DFT).

Main Results:

• Cs-vacant layered titanate treated at 700 °C showed significantly improved PC activity for HER and PEC activity for OER.
• Bulk cesium titanate exhibited minimal PC and PEC activity.
• Computational modeling revealed increased surface area, interlayer voids, and midgap states due to Cs vacancies.
• These defects enhance charge carrier separation and stabilization.

Conclusions:

• Introducing cesium vacancies is a promising strategy to activate and enhance the photocatalytic and photoelectrocatalytic performance of layered titanates.
• The developed material is a cocatalyst-free semiconductor light absorber with high efficiency for hydrogen production.
• The findings provide insights into defect engineering for improved semiconductor photocatalysis.