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A new ZnO@SBA-15 nanocomposite material has been fabricated by an “in situ” generation of ZnO NPs on SBA-15 support. The as-synthesized nanocomposite material was fully characterized with various spectroscopic techniques and their catalytic activity was tested for the synthesis of a diverse range of dihydropyrimidinones (DHPMs) and thione derivatives via Biginelli condensation reaction. The catalytic efficiency of ZnO@SBA-15 nanocomposite was far superior with a remarkably lower catalyst loading and shorter reaction time compared to unsupported ZnO nanoparticles. The catalyst was recycled for minimum of four times without significant loss in its catalytic activity. Moreover, a tentative catalytic cycle for the reaction is also proposed.

Keggin-type phosphotungstic acid (H 3 PW 12 O 40 , PTA) encapsulated in the mesocages of chromium-based terephthalate metal–organic framework (MIL-101) was established to be an active heterogeneous catalyst for three component Biginelli condensation reaction with excellent yields (75–90%) and selectivity under solvent free condition. Here phosphotungstic acid can be effectively incorporated into the matrix of MIL-101 by an impregnation method. The synthesized PTA@MIL-101 was characterized by employing various spectroscopic techniques as well as different analytical methods. Moreover, the catalyst could easily be recovered and recycled without any significant loss of its catalytic activity.

We have synthesized Fe 3 O 4 nanoparticles on mesoporous SBA-15 by an “in situ” approach. The synthesized nanocomposite material was well characterized using wide and low angle XRD, N 2 adsorption–desorption isotherm, TEM, FTIR, XPS, and VSM analysis. The Fe 3 O 4 @SBA-15 nanocomposite material was used as a magnetically recoverable catalyst (MRC) for three component coupling reaction of aldehyde, amine and alkyne. The reported catalyst was recycled up to five times without significant loss in its catalytic activity.

ZnO nanomaterials of different morphologies are synthesized by different methodologies. These semiconductor photocatalysts are potentially explored for self-sensitized photodegradation of malachite green (MG) dye in water in a batch reactor. The effects of various parameters like initial dye concentration, catalyst loading, solution pH, light source on degradation efficiency was also investigated. The experimental results showed substantial reduction of COD, besides removal of colour. The photodegradation of MG dye followed the pseudo first order kinetics of Langmuir–Hinshelwood model. The hydrothermally synthesized flower shaped homocentric pencil like ZnO nanorod bundles exhibit excellent photocatalytic activity under solar light. A comparative study of photodegradation efficiency among ZnO nanoparticles, ZnO nanoparticles (hydrothermal) and flower shaped homocentric pencil like ZnO nanorod bundles were also performed. Semiconductor photocatalysis often leads to partial or complete mineralization of organic pollutants. The CO 2 gas evolved due to mineralization of MG was determined using Warburg manometric method under solar light. The possible mechanism of photodegradation under both solar and UV light were also proposed.