Two-photon absorption induced optical limiting action of Ag-doped lanthanum molybdate decorated reduced graphene oxide nanocomposites

Abstract

In this research, we aimed to investigate the linear and non-linear optical properties of Ag-La₂(MoO₄)₃@RGO nanocomposites. For this purpose, Graphene Oxide (GO) was synthesized by Modified Hummer’s method after which GO was chemically reduced to Reduced graphene oxide (RGO). The nanocomposite Ag-doped La₂(MoO₄)₃ is prepared by a simple and facile co-precipitation method. The prepared nanocomposite was characterized by Fourier transform infrared (FTIR), Ultraviolet-Visible (UV-Vis) absorption, X-ray diffraction (XRD), Scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDX). XRD and EDX analysis indicated the reduction of GO and successful synthesis of Ag-doped La₂(MoO₄)₃ nanocomposite. FESEM images portray the presence of thin layers of graphene sheets and Ag-doped La₂(MoO₄)₃ on the sheets of reduced graphene oxide. Ground state absorption studies show that the reduction of graphene oxide causes a hypsochromic shift in the absorption maxima of the graphene layers. The photoluminescence of Ag- La₂(MoO₄)₃@RGO demonstrates the utmost emission in the UV range caused by the valence band and conduction band's direct transitions in the band gap region. Z-scan method using Nd: YAG laser exposes that both nanocomposite and specific counterparts hold reverse saturable absorption behaviour. The source of optical limiting action is attributed to the excited state absorption process, emerging from the influence of the plasmon resonance state of Ag nanoparticles. Strong nonlinear absorption and lower onset limiting threshold make the Ag-La₂(MoO₄)₃@RGO nanocomposite desirable material for laser safety devices.