We report here a systematic study of growth of aligned WO 3 (002)-oriented nanowires (NWs) on (111)-oriented Platinised silicon substrate using a pulsed laser deposition (PLD) method. Transmission electron microscopy (TEM) analysis has shown that the wires are single-crystalline and grow along [001] t or [100] t directions. X-ray diffraction (XRD) measurements confirm phase and structural analysis. We investigated the effect of ablated particle flux on nanowire growth, in particular, the role of the nucleating centre at the interface as it get modified by the ablated particle flux. We observe a critical value of the laser energy (that determines a critical flux and energy of ablated moieties) at which a compact nanograin film gets converted to aligned nanowire film. We attribute the existence of such a threshold to the desorption process from the catalyst droplet. By cross-sectional TEM and compositional mapping accompanied by simulation, we confirm that the interfacial layer between the substrate and NW is modified by the ablated particle flux and energy.Aligned NWs above threshold energy can be attributed to formation of favorable nucleation sites for a preferred orientation.

We report, the photoresponse behaviour of Tungsten trioxide (WO3) films of different surface morphology, grown by using pulsed laser deposition (PLD). The Growth parameters for PLD were changed for two substrates SiO2/Si (SO) and SrTiO3 (STO), such a way which, result nanocrystalline film on SO and needle like structured film on STO. The photoresponse is greatly modified in these two films because of two different surface morphologies. The nanocrystalline film (film on SO) shows distinct photocurrent (PC) ON/OFF states when light was turned on/off, the enhancement of PC is ∼27%. Whereas, the film with needle like structure (film on STO) exhibits significantly enhanced persistent photocurrent even in light off condition, in this case, the enhancement of PC ∼ 50% at room temperature at lowest wavelength (λ = 360 nm) at a nominal bias voltage of 0.1 V.

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We report the isotope selective diffusion of carbon dioxide (CO2) gas through large aspect ratio (length/diameter = 20:1) and porous one-dimensional nanostructure of tungsten oxide (WO3). This novel effect was demonstrated in an ensemble of binary oxide, WO3 nanostructures with large surface area. When atmospheric CO2, which has two major stable isotopes (12CO2 and 13CO2), flows through such an ensemble of nanotubes, it allows only the 12CO2 isotopes to diffuse through it and hinders diffusion of the 13CO2 isotopes. The selective diffusion leads to different isotopic fractionations of ambient CO2 (12C:13C), in other words, generating different isotope-enriched CO2 gases as established through high-precision cavity-enhanced absorption spectroscopy technique. The phenomena are strongly dependent on the surface morphology of nanostructures of binary oxide, and the surface-induced diffusion process is most likely to be the effects of physical processes enabling the Knudsen diffusion, but is not related to any chemical activities.