Peculiarities on methyl orange adsorption by porous ZnIn2S4 prepared in different conditions

Abstract

Introduction Synthesis of nanostructured materials with well-controlled morphology and large specific surface area is essential in adsorption and catalysis for environmental depollution applications. Methods and objectives In the present work, several varieties of high porous zinc indium sulfde (ZnIn2S4) were prepared using microwave-assisted and oil bath precipitation. The role of synthesis temperature and zinc concentration on the morpho-structure, porosity, and optical properties of ZnIn2S4 was investigated. Results Hexagonal ZnIn2S4 phase was formed at 180°C while disordered cubic ZnS-In2S3 phase was identified at 160°C. Based on ICP-OES measurements, it was found that all samples contain lower amounts of zinc than theoretically expected leading to non-stoichiometric compounds. The specific surface area increases from 88.4 to 425.6 m2 /g with temperature and zinc amount, values that are higher than those reported in literature. The morphology of ZnIn2S4 is changing from agglomerated rounded nanoparticles to micro-fewer, nano-petals, or hollow microspheres depending on the synthesis conditions. A growth mechanism was also proposed for all the nanostructures with different morphologies. The band gap of ZnIn2S4 decreases from 3.61 to 2.81 eV due to morpho-structural and porosity changes. The blue-green luminescence was attributed to different defect sites in ZnIn2S4 structures. Adsorption investigations of the methyl orange were carried out and discussed. Conclusion Oil - bath samples present a higher adsorption ability than micro-wave samples due to structural and morphology differences.