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Photoacoustic (PA) sensor was designed and developed to evaluate thermal effusivity of Fe3O4 nanofluid. The PA sensor is based on open cell mode (OPC) to measure acoustic signals from low concentration of nanoparticulate suspensions in ethylene glycol (EG). Spherical Fe3O4 nanoparticles (NPs) were obtained by chemical precipitation method in powder form. The obtained NPs were stabilized by acetylacetone (acac) in EG. Thermal conductivity estimation was carried out with the help of transient hot wire method. The developed PA sensor was calibrated by measuring thermal effusivity of standard samples. The acoustic signals of the PA experiments have been analyzed with a simple Rosencwaig-Gersho theoretical model.

In this paper, we report the electrorheological (ER) properties of low concentration Fe2O3 nanofluids prepared in ethylene glycol (EG). Spherical Fe2O3 nanoparticles (NPs) were obtained by emulsion method in powder form. The obtained NPs were stabilized in time by acetylacetone in EG. The prepared Fe2O3 NPs were characterized using X-ray diffraction and transmission electron microscopy. Fe2O3 nanofluids were tested for ER behavior at low dc electric fields. Giant ER (GER) effect was observed in Fe2O3 nanofluid of higher concentration at electric field of 10 V/mm. The current passing through suspensions and electrohydrodynamic (EHD) convection was reflected in ring like structure formation of Fe2O3 NPs. Relation between suspension viscosity and Mason number revealed that the analysis has to be revised for GER fluids.

The visible light induced photocatalytic H2 evolution from water with the help of photogenerated electrons in the TiN/red phosphorous (RP) nanocomposite is studied. The porous TiN nanotubes are obtained by nitridation (heat treatment under NH3 flow) process on hydrothermal synthesized TiO2 fibers. The RP is incorporated into the porous TiN nanotubes by heat treatment in the sealed ampules. The porous TiN nanotube provide an effective conducting channel for the photogenerated electrons, which is reflected in the enhanced photocatalytic H2 evolution compared to the pristine RP.