Modulating Dion-Jacobson-type lanthanum tantalates with TiO₂ via molten salt route for optimizing photocatalytic performance

Developing innovative nanostructures with tailored properties for environmental applications through sustainable, energy-efficient, and time-saving methodologies remains an important challenge in advanced materials. Molten salts serve as an effective ionic transport medium, enabling improved control over nucleation and crystal growth, leading to highly crystalline nanostructures. Although chlorides and carbonates are commonly used as flux agents, molten potassium bisulfate acts as a superior fluxing and intercalating agent, promoting the pillaring of titanium species within the perovskite layers.

Herein, we report a molten-salt-assisted strategy to modify the RbLaTa₂O₇ Dion-Jacobson-type layered perovskite with TiO₂, using KHSO₄ as a flux. This approach enables the preparation of TiO₂-modified lanthanum tantalate at a lower temperature compared with conventional solid-state reactions. X-ray diffraction (XRD) results demonstrated the successful preparation of TiO₂-modified perovskite without destroying the pristine lamellar framework. The titanium species induces a red shift in the absorption edge of the pristine layered perovskite, thereby narrowing its bandgap from 3.84 eV to 3.22 eV. Additionally, the DRIFT spectra confirm the formation of a TiO₆ octahedral network within the layered perovskite after the molten salt treatment through the appearance of new low-frequency bands at 430 – 480 cm^-1. The photocatalytic degradation of phenol by pristine and TiO₂-modified catalysts was assessed under a xenon lamp and simulated solar irradiation. The optimized band structure of the lamellar perovskites significantly boosts photocatalytic activity, demonstrating the TiO₂-modified-based material`s potential as a green, solar-powered catalyst for wastewater purification. Current studies focus on optimizing photocatalytic parameters to achieve the mineralization of phenol as a model organic pollutant.