Core-shell nanomaterials based on La₂FeCrO₆ coated with metal oxides for optical applications

Abstract

In this research work, the preparation of core/shell nanoparticles comprising La2FeCrO6 (LFCO) as the core was accompanied by the choice of ZnO and CuO as different shells. Structural and optical characteristics were investigated for the LFCO (core) relative to La2FeCrO6/ZnO and La2FeCrO6/CuO core/shell NPs. X-ray diffraction reveals the conformation of core/shell structures within average crystallite sizes of 22.46 nm and 25.03 nm. Raman spectroscopy and Fourier-transform infrared spectroscopy (FTIR) were performed to provide fundamental information about the vibrational modes and functional groups of core/shell NPs, respectively. X-ray photoelectron spectroscopy (XPS) detects the electronic states of the constituent elements of the core/shell nanostructures, including lanthanum, iron, chromium, oxygen, zinc, and copper. Optical characteristics have been extensively analyzed using UV spectroscopy. The energy gap (Eg) was determined by utilizing both Tauc and Derivation of Absorbance Spectrum Fitting (DASF) methods. LFCO/ZnO and LFCO/CuO core/shell NPs exhibit a direct optical transition, similar to that of the core LFCO NPs, with a decrease in band gap value from 3.4 eV for the core to 3.3 eV and 3.18 eV for LFCO/ZnO and LFCO/CuO core/shell NPs respectively. The enhanced transparency of core/shell NPs, particularly at longer wavelengths, is evident from the decrease in refractive index (n) compared to that of the core (LFCO) NPs. This decrease is attributed to the encapsulation of LFCO with either ZnO or CuO NPs. The samples exhibit a decline in both linear and non-linear optical susceptibilities with respect to the square of photon energy. The LFCO/CuO sample shows excellent results in the photocatalytic degradation of aqueous organic dyes, considering it a promising candidate for wastewater treatment and the removal of organic pollutants.