Heterostructured Co0.5Mn0.5Fe2O4-polyaniline nanofibers: highly efficient photocatalysis for photodegradation of methyl orange

Fabrication of a reusable carbon quantum dots (CQDs) modified nanocomposite with enhanced visible light photocatalytic activity

In awareness of industrial dye wastewater, carbon quantum dots (CQDs) and cobalt zinc ferrite (CZF) nanocomposites were synthesised for the making of carbon quantum dots coated cobalt zinc ferrite (CZF@CQDs) nanophotocatalyst using oxidative polymerization reaction. The results of TEM, zeta potential value, and FTIR confirm highly dispersed 1-4 nm particles with the - 45.7 mV carboxylic functionalized surface of CQDs. The results of the synthesised CZF@CQDs photocatalyst showed an average particle size of ~ 15 nm according to TEM, SEM, and XRD. The photocatalyst showed a 1.20 eV band gap, which followed the perfect visible light irradiation. TGA and DTA revealed the good thermal stability of the nanophotocatalyst. VSM was carried out, and the saturation magnetisations for CZF and CZF@CQDs were 42.44 and 36.14 emu/g, respectively. A multipoint study determined the BET-specific surface area of the CZF@CQDs photocatalyst to be 149.87 m2/g. Under visible light irradiation, the final CZF@CQDs nanophotocatalyst demonstrated remarkable efficiency (~ 95% within 25 min) in the photocatalytic destruction of Reactive Blue 222 (RB 222) and Reactive Yellow 145 (RY 145) dyes, as well as mechanical stability and recyclability. Even after the recycling of the degradation study, the nanophotocatalyst efficiency (~ 82%, 7th cycles) was predominantly maintained. The effects of several parameters were also investigated, including initial dye concentration, nanophotocatalyst concentration, CQD content, initial pH of the dye solution, and reaction kinetics. Degradation study data follow the first-order reaction rate (R2 > 0.93). Finally, a simple and low-cost synthesis approach, rapid degradation, and outstanding stability of the CQD-coated CZF nanophotocatalyst should make it a potential photocatalyst for dye wastewater treatment.

Hydrothermal synthesis of cobalt substitute zinc-ferrite (Co1-xZnxFe2O4) nanodot, functionalised by polyaniline with enhanced photocatalytic activity under visible light irradiation

Fabrication and development of effective visible-light-responsive photocatalysts are required to tackle critical environmental issues. The aim of this study was to develop a nanocomposite material with improved photocatalytic activity for the degradation of industrial dyes such as Reactive Orange-16 (RO-16), Reactive Blue (RB-222), Reactive Yellow-145 (RY-145), and Disperse Red-1 (DR-1) without the need for a post-separation process after use. Here we report the hydrothermal synthesis of nanodots of Co_1-xZn_xFe₂O₄ (x = 0.3, 0.5 and 0.7), coated with polyaniline, by in situ polymerization. The Co_1-xZn_xFe₂O₄ nanodots, coated with polyaniline (PANI) nanograins, facilitated optical properties by easily capturing visible light. X-ray Diffraction (XRD) patterns and Scanning Electron Microscopy (SEM) images have confirmed the single-phase spinel structure of Co_1-xZn_xFe₂O₄ nanodot and nano-pore size of the Co_1-xZn_xFe₂O₄/PANI nanophotocatalyst. The specific surface area of the Brunauer-Emmett-Teller (BET) of the Co_1-xZn_xFe₂O₄/PANI photocatalyst was determined to be 24.50 m²/g by multipoint analysis. The final Co_1-xZn_xFe₂O₄/PANI (x = 0.5) nanophotocatalyst showed high efficiency in the catalytic degradation of toxic dyes (∼98% within 5 min), with good mechanical stability and recyclability under visible light irradiation. The nanophotocatalyst was re-used and its efficiency was largely maintained, even after seven cycles (∼82%) of degradation. The effects of various parameters, such as initial dye concentration, nanophotocatalyst concentration, initial pH of dye solution, and reaction kinetics were studied. According to the Pseudo-first-order kinetic model, photodegradation data followed the first-order reaction rate (R² > 0.95) of degradation of dyes. In conclusion, a simple and low-cost synthesis process, speedy degradation and excellent stability of polyaniline-coated Co_1-xZn_xFe₂O₄ nanophotocatalyst could be used as a promising photocatalyst for dye-wastewater treatment.

Effect of Thioacetamide Concentration on the Preparation of Single-Phase SnS and SnS2 Thin Films for Optoelectronic Applications

Eco-friendly tin sulfide (SnS) thin films were deposited by chemical solution process using varying concentrations of a sulfur precursor (thioacetamide, 0.50–0.75 M). Optimized thioacetamide concentrations of 0.6 and 0.7 M were obtained for the preparation of single-phase SnS and SnS2 films for photovoltaic absorbers and buffers, respectively. The as-deposited SnS and SnS2 thin films were uniform and pinhole-free without any major cracks and satisfactorily adhered to the substrate; they appeared in dark-brown and orange colors, respectively. Thin-film studies (compositional, structural, optical, and electrical) revealed that the as-prepared SnS and SnS2 films were polycrystalline in nature; exhibited orthorhombic and hexagonal crystal structures with (111) and (001) peaks as the preferred orientation; had optimal band gaps of 1.28 and 2.92 eV; and exhibited p- and n-type electrical conductivity, respectively. This study presents a step towards the growth of SnS and SnS2 binary compounds for a clean and economical power source.