Synergistic Rh/La Codoping Enables Trap-Mediated Charge Separation in Layered Perovskite Photocatalysts

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Two-dimensional layered perovskite oxides are promising for solar-driven hydrogen evolution.
• Doping is used to enhance photocatalyst performance, but its effects on electronic structure and local chemistry are not fully understood.

Purpose of the Study:

• Investigate the codoping of Rh and La into KCa2Nb3O10 nanosheets.
• Enhance photocatalytic hydrogen evolution reaction (HER) activity.

Main Methods:

• Exfoliation of Dion-Jacobson perovskite KCa2Nb3O10.
• Codoping with Rh and La.
• Synchrotron techniques and high-resolution microscopy for structural and spectroscopic analysis.

Main Results:

• Optimal doping (0.2 wt% Rh, 1.3 wt% La) increased H2 evolution rate from 12.3 to 69.0 μmol h-1.
• Rh3+ substitution at Nb5+ sites introduced shallow acceptor states for charge separation.
• La3+ substitution at Ca2+ sites compensated charge imbalance and modulated lattice distortions and oxygen vacancies.
• Codoping enhanced charge carrier lifetime and separation efficiency via a trap-mediated mechanism.

Conclusions:

• Codoping strategy provides a mechanistic foundation for defect engineering in layered perovskites.
• Achieved volcano-shaped activity trend indicates an optimal compositional window.
• Offers a pathway for rational design of efficient photocatalysts for hydrogen evolution.