Diaqua oxalato strontium(II) complex as a precursor for facile fabrication of Ag-NPs@SrCO3, characterization, optical properties, morphological studies and adsorption efficiency

Abstract

Diaqua oxalato strontium(II) complex [Sr(C2O4)(H2O)2] was prepared via a precipitation reaction. Thermal treatment of the as-synthesized precursor at 550 °C resulted in formation of strontium carbonate (SrCO3) nanocrystals. A new composite of silver nanoparticles decorated with strontium carbonate (Ag-NPs@SrCO3) was fabricated by heating a mixture of silver oxalate and strontium carbonate in air at 150 °C for 2 h. The spectral, morphological and thermal properties of the materials have been studied using different physicochemical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HR-TEM), Fourier infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), diffrential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). From the Debye–Scherrer equation the calculated particle size of Sr(C2O4)(H2O)2], SrCO3 and Ag-NPs@SrCO3 are 62.1, 58.7, and 58.5 nm, respectively. The SEM and TEM images indicate tetragonal structure of [Sr(C2O4)(H2O)2] while SrCO3 and Ag-NPs@SrCO3 appeared as cubic structures. The calculated energy band gap of SrCO3 and Ag-NPs@SrCO3 using the Tauc equation are estimated at 5.9 and 4.7 eV, respectively. The adsorption capacity of the materials is tested for the adsorption of Congo red anionic dye and exhibited promising results. The adsorption capacity followed the order Ag-NPs@SrCO3>SrCO3> [Sr(C2O4)(H2O)2] with efficiencies of 73.90, 67.55, and 60.50%, respectively.