Highly exfoliated graphitic carbon nitride for efficient removal of wastewater pollutants: Insights from DFT and statistical modelling.

The present work entails the synthesis of thermally modified graphitic carbon nitride (GCN) using a two-step thermal treatment procedure and its subsequent use in the photocatalytic reduction of toxic pollutants such as rhodamine B dye (RhB) and chromium (VI) (Cr(VI)) from aquatic environments. The as-synthesised exfoliated GCN (GCNX) is characterised by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller analysis (BET), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). These characterisations helped to elucidate the phase formation, chemical structure, composition, surface area, optical properties, and morphology of the sample. With assistance from a visible light source, GCNX can degrade RhB dye within 30 min in the presence of hydrogen peroxide (H2O2) and reduce Cr(VI) to Cr(III) in under 2 h in the presence of formic acid (FA/HCOOH). Variations in different catalytic parameters, including catalyst amount, pH of the solution, initial RhB or Cr(VI) concentration, and variation in H2O2 or FA concentration, are performed to inspect their effects on the photodegradation activity of GCNX. Moreover, the GCNX catalyst exhibits impressive stability and reusability. A thorough statistical evaluation follows the response surface methodology to understand the complex interaction between the factors contributing to the catalytic activity. The band alignment of differently functionalised GCN blocks in their pristine form and their H2O2/FA-adsorbed states is investigated using first-principles calculations to provide a further understanding of the RhB and Cr(VI) reduction mechanisms. The modified GCN can thus be effectively employed as a low-cost material for removing contamination from aquatic environments.

Size-modulation of functionalized Fe3O4: nanoscopic customization to devise resolute piezoelectric nanocomposites.

Magnetite (Fe3O4), a representative relaxor multiferroic material, possesses fundamentally appealing multifaceted size-dependent properties. Herein, to evaluate a prototype spinel transition metal oxide (STMO), monodispersed and highly water-dispersible spherical magnetite nanoparticles (MNPs) with an enormous size range (3.7-242.8 nm) were synthesized via a facile microwave-assisted and polyol-mediated solvothermal approach at a controlled temperature and pressure using unique crystallite growth inhibitors. The excellent long-term colloidal stability of the MNPs in a polar environment and increase in their zeta potential confirmed the coordinative effect of the carboxylate groups derived from the covalent surface functionalization, which was also validated by FTIR spectroscopy, TGA and XPS analysis. The optical bandgap (Eg) between the crystal field split-off bands, which was calculated using the absorption spectra, increased gradually with a decrease in size of the MNPs within a broad UV-Vis range (1.59-4.92 eV). The red-shifting of the asymmetric Raman peaks with a smaller size and short-range electron-phonon coupling could be explained by the modified phonon confinement model (MPCM), whereas ferrimagnetic nature rejigged by superparamagnetism was verified from Mössbauer analysis. These stoichiometric, non-toxic, polar and magnetic nanocrystals are not only ideal for biomedical applications, but also suitable as electroactive porous host networks. Finally, the size-modulated MNPs were incorporated in poly(vinylidene fluoride) [PVDF]-based polytype nanogenerators as an electret filler to demonstrate their piezoelectric performance (VOC∼115.95 V and ISC∼1.04 µA), exhibiting substantial electromagnetic interference shielding.

CsPbBrCl2/g-C3N4 type II heterojunction as efficient visible range photocatalyst.

Photocatalytic activity of low band gap semiconductor largely restrained by high recombination rate of photogenerated charge carriers. To enhance the catalytic performance numerous protocols were adopted amongst which designing of novel hybrid via coupling of semiconductors are very intriguing from modest application point of view. Here, we report facile realization of type II heterojunctions embracing polymeric graphitic carbon nitride (g-C3N4/GCN) and all-inorganic cesium lead halide perovskite (CsPbBrCl2) for degradation complex organic effluents under visible-light illumination. Synthesized hybrid presented much improved performance in toxic cationic and anionic dyes degradation as compared to individual building units. Signature of favorable staggered gap junction's formation at interface was confirmed via Mott-Schottky analysis. Such kind of junctions delay the recombination of photogenerated electron holes and facilitates active radical generation at catalyst surface thereby ensures improved photocatalytic performance. Charge transfer process in heterojunction further illustrated via Density functional theory (DFT) based calculations. Several scavenger tests have been performed to examine the impact of different active radicals in the photocatalysis which suggests manifold performance improvement in the presence of very small concentrations of EDTA. A plausible photocatalytic mechanism in accordance with the type II junction has been proposed.