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ZnO spheres were synthesized by solid state oxidation of ZnS microspheres at different oxidation temperatures of 600 and 700 °C in an ambient atmosphere. The high temperature transformation of ZnS microspheres into hexagonal structured and highly crystalline ZnO microspheres comprising interconnected nanoparticles facilitating efficiently electron transport as well as charge collection through an intended path in the solar cell. The comparative physico-chemical and photovoltaic studies were done for synthesized ZnO microspheres. The structural study by x-ray diffraction of ZnO confirmed the hexagonal ZnO; the UV–Visible spectroscopy study showed λmax varying from 410 to 413 nm and 397 to 407 nm for ZnO microspheres synthesized by heating at 600 and at 700 °C, respectively. Additionally, crystalline and electronic structures were validated by density functional theory studies. The computational studies also revealed growth of hexagonal ZnO, where the bandgap varied with the oxidation temperature. The photovoltaic properties of ZnO microspheres synthesized at 600 °C exhibited better performance than the ones synthesized at 700 °C due to high surface roughness leading to enhanced dye loading and favorable charge collection. Dye-sensitized solar cells fabricated from ZnO microspheres synthesized at 600 and 700 °C exhibited the maximum power conversion efficiency of 3.38% and 3.06% correspondingly.

Abstract Herein, we report the synthesis of metallic molybdenum microspheres and hierarchical MoS2 nanostructures by facile template-free solvothermal and hydrothermal approach, respectively. The morphological transition of the Mo microspheres to hierarchical MoS2 nanoflower architectures is observed to be accomplished with change in solvent from ethylenediamine to water. The resultant marigold flower-like MoS2 nanostructures are few layers thick with poor crystallinity while spherical ball-like molybdenum microspheres exhibit better crystalline nature. This is the first report pertaining to the synthesis of Mo microspheres and MoS2 nanoflowers without using any surfactant, template or substrate in hydro/solvothermal regime. It is opined that such nanoarchitectures of MoS2 are useful candidates for energy related applications such as hydrogen evolution reaction, Li ion battery and pseudocapacitors. Inquisitively, metallic Mo can potentially act as catalyst as well as fairly economical Surface Enhanced Raman Spectroscopy (SERS) substrate in biosensor applications.

A novel approach for the in-situ fabrication of combined cobalt oxide / sulphide nanoparticles in sulphur containing polymer polyphenylenesulphide (PPS) by polymer inorganic solid-solid reaction technique is reported here. At present, there is considerable interest in polymer-metal chalcogenides / oxides based nano-composites on account of their optical, magnetic, electronic and catalytic properties. We have demonstrated the suitability of solid-solid reaction methodology by reacting commonly available cobalt precursors with engineering thermoplastic PPS. The cobalt precursor was reacted with PPS in 1:1, 1:5, 1:10, and 1:15 molar ratios, respectively, by heating the mixture at the melting temperature of the polymer (285 ºC) for six hours. The resultant products were characterized by X-ray diffractometry (XRD), Field-emission scanning electron microscopy (FESEM), Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), Diffuse reflectance spectroscopy (DRS) techniques and High resolution transmission electron microscope (HRTEM). The shift in melting temperature of PPS was observed. Increase in absorption peak is observed in the range of 320 to 370 nm with the increase in PPS concentration. Resultant nanoparticles of cobalt sulphide and cobalt oxide embedded in the PPS matrix showed spherical and distorted rod like morphology.

In this communication, we report facile and economical in-situ preparation of lead sulphide (PbS) nanorods and nanocubes within the Polyphenylene sulphide (PPS) matrix. PPS plays a dual role in the synthesis of the resultant nanostructures as - (i) a chalcogen source and (ii) a stabilizing matrix. We studied the effect of change of lead precursor from lead nitrate to acetate on the morphological properties of the resultant nanostructures. The effect of molar ratios of the reactants (1:1, 1:5, 1:10, 1:15 and 1:20) on the morphology of the products was also studied. The resultant nanocomposites were characterized by various physico-chemical techniques like X-ray Diffractometry (XRD), SEM equipped with EDAX, TEM and UV-Visible spectroscopy. The prima-facie observations suggest effective formation and subsequent entrapment of lead sulphide nanorods and nanocubes, respectively, when lead acetate and lead nitrate precursors were used. Additionally, simultaneous occurrence of nanocrystalline cubic lead as an impurity phase is noticed in case of heated admixtures for both the precursors.