Optical response of green synthesized thin Cr2O3 films prepared via drop and spin coatings

This study investigated the impact of optical bandgap energy on the optical constants of Cr2O3 thin films, which were prepared via green synthesis method and deposited using drop and spin-coatings at 600, 800, 1000, and 1200 rpm onto Cu substrates. The deposited Cr2O3 thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and UV–VIS-NIR spectroscopy. XRD revealed that the prepared nanocoating surfaces are pure eskolaite Cr2O3 phase. The grain size of the prepared Cr2O3 films decreased from 15 nm to 12 nm for the drop and spin coatings, respectively. The morphology of the drop and spin coated samples showed nanorods, mesospherical, and quasi-spherical shaped nanoparticles, respectively, along with the presence of O and Cr. The bandgap energy increased from 2.35 eV to 2.50 eV, with increasing Spin Coater rotational speeds (RS) from drop to 1200 rpm, respectively. As bandgap energy increase, the carriers' spatial dimension shrinks, resulting in grains smaller than or equal to the exciton's Bohr radius. Thicker film materials tend to have lower bandgap energies due to strain effects, whereas smaller grain sizes tend to have higher bandgap energies. The determined refractive index and extinction coefficient values vary as the bandgap energy varies for all prepared samples. These findings confirmed that differences in bandgap energy affect the refractive index (n) and extinction coefficient (k) of Cr2O3 thin films. These are attributed to quantum confinement, internal scattering, and interference effects of Cr2O3 thin film surfaces

Room Temperature Surface Bio-Sulfurisation via Natural Sativum Annilin and Bioengineering of Nanostructured CuS/Cu2S

In this contribution, we report, for the first time, on the surface bio-sulfurisation of metallic surfaces at room temperature via natural sativum annilin. More precisely, this bio-sulfurisation is validated on bioengineered nanostructured Cu2-XS surfaces using natural organosulfur compounds emitted from Sativum allium L. as efficient sulfurisation chemical agents. It is validated that virgin copper surfaces can be sulfurised at room temperature without adding any extra chemical or physical processes. In addition to the validation of the green sulfurisation process of the copper surface, the bioengineered Cu2-XS exhibited a multiscale 1-D tubular morphology with Cu2-XS nanotubules and nanocones. Such a nanostructured Cu2-XS surface exhibited an excessive optical selectivity, a superhydrophobicity response in addition to a remarkable site selective mercury adsorption