Single-crystalline porous hematite nanorods and spindle-like nanostructures were successfully synthesized by a low temperature reflux condensation method. Two different iron sources, namely, FeCl3·6H2O and Fe(NO3)3·9H2O, were hydrolyzed in the presence of urea to selectively prepare nanorods and spindle-like nanostructures. Initially, the akagenite phase was obtained by refluxing the precursor for 12 h and then the as-prepared akagenite nanostructures were transformed to porous hematite nanostructures upon calcination at 300 °C for 1 h. The shape and the aspect ratio of the 12 h refluxed sample was retained even after calcination and this shows the topotactic transformation of the nanostructure. TEM and HRTEM investigations have shown the porous nature of the prepared sample. Brunauer–Emmett–Teller and Barret–Joyner–Halenda measurements have shown a large surface area and distribution of mesopores in the nanorods sample. The photocatalytic activity of the prepared nanostructures towards RhB has reflected this variation in the pore size distribution and specific surface area, by showing a higher activity for the nanorods sample. Magnetic studies by VSM have shown a weak ferromagnetic behaviour in both the samples due to shape anisotropy.

A new organic stilbazolium derivative crystal 2-[2-(3-hydroxy-4-methoxy-phenyl)-vinyl]-1-methyl-pyridinium naphthalene-2-sulfonate dehydrate (C25H23NO5S·2H2O) (VSNS) was synthesized successfully.

Tin-based perovskite materials have the drawbacks of high density of Sn vacancies, structural deformations of SnI 6 − octahedra, and oxidation of unstable Sn 2+ states, resulting in poor chemical stability processed at inert and open atmosphere. In this work, we demonstrate the temperature effects on reduction of Sn vacancies (V sn ) in polymorphic CsSnI 3 perovskite solar cells. Evidence of light-induced I − ion diffusion and an interplay between iodide and Sn vacancies were briefly presented. We have observed by X-ray photoelectron spectroscopy that the formation of iodide vacancies (V I ) are highly activated at 60 °C, contributing to the reduction of acceptor defects, mainly Sn vacancies (V sn ). The formation of SnO − and SnO 2 − at high temperature mitigates the Sn−I interaction and eventually increases the trap density at Au/CsSnI 3 interfaces. We have observed by time-of-flight secondary ion mass spectrometry that the delocalized I − ions are accumulated near the metal contacts and form AuI − ions which diffuse through the material, inhibiting the exciton transport.

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