Investigations on structural and optical properties of PVP capped CdS Co Eu Ce Sm DOPED CdS and mesoporous CdS nanoparticles

Abstract

Semiconductor nanoparticles are very important topic in the ongoing research activity across the world. As the semiconductor particles exhibit size-dependant properties like scaling of the energy gap and corresponding change in the optical properties, they are considered as the front runners among the technologically important materials. Cadmium sulfide (CdS) with its direct band gap of 2.42 eV at room temperature is a potential candidate for optoelectronic applications in the visible wavelength range. Nanocrystals (NCs) synthesized by chemical route provides the chance to control their size distribution and to improve the crystallinity by altering the concentration of the reagents and their mixing rate at different temperatures. Morphology and elemental mapping of the synthesised nanoparticles were studied by SEM and EDX analyses. From the photoluminescence studies, enhanced near band edge (NBE) emission and reduced defect related emission were observed. Longitudinal optical (LO) phonon modes, correspond to pure CdS were observed in Raman spectrum. Europium (2 mol. %), Cerium (1, 2 and 3 mol. %) and Samarium (2 and 5 mol. %) doped CdS nanoparticles were synthesised by chemical co-precipitation method. Mesoporous cadmium sulfide has been prepared using mesoporous silica (SBA-15) as a template with tunable pore diameter. Structural, optical and textural parameters of the synthesised mesoporous CdS were investigated. Low angle XRD indicates the presence of mesoporosity and was also confirmed by HRTEM analysis. Cubic zinc blende phase of mesoscopic CdS and its crystallinity was evident by higher angle XRD and SAED pattern respectively. Raman spectra confirm the presence of fundamental and overtone bands of cadmium sulfide. Photocatalytic activity of the mesoporous CdS for the degradation of methylene violet (MV) demonstrates that photodegradation rate increases with increasing time under visible light irradiations. newline