Core-Shell-Structured LaTaON₂ Transformed from LaKNaTaO₅ Plates for Enhanced Photocatalytic H₂ Evolution

Area of Science:

• Materials Science
• Photocatalysis
• Inorganic Chemistry

Background:

• Lanthanum oxynitride (LaTaON2) shows promise as a photocatalyst due to its visible light absorption.
• However, its practical application is limited by uncontrolled facets and high defect densities, leading to low H2 evolution activity.

Purpose of the Study:

• To synthesize high-quality LaTaON2 with well-defined facets and low defect densities.
• To improve the photocatalytic H2 evolution activity of LaTaON2.
• To explore a novel strategy for fabricating oxynitrides using lattice-matched oxide precursors.

Main Methods:

• Synthesis of core-shell structured LaKNaTaO5/LaTaON2 via nitridation of layered perovskite-type LaKNaTaO5.
• Utilizing the volatilization of K and Na species to promote controlled transformation of LaKNaTaO5 into LaTaON2 along the [010] direction.
• Loading the synthesized material with a Rh co-catalyst.

Main Results:

• The nitridation process resulted in plate-like LaTaON2 shells with exposed (010) facets on lattice-matched LaKNaTaO5 cores.
• The Rh-loaded LaKNaTaO5/LaTaON2 exhibited a four-fold increase in photocatalytic H2 evolution activity compared to conventional LaTaON2.
• The material effectively utilized visible light up to 620 nm.

Conclusions:

• A novel strategy for producing oxynitrides with controlled facets and low defect densities has been demonstrated.
• The core-shell LaKNaTaO5/LaTaON2 structure significantly enhances photocatalytic H2 evolution.
• This approach offers a promising route for developing advanced photocatalysts for solar fuel production.