Natural Biowaste-Cocoon-Derived Granular Activated Carbon-Coated ZnO Nanorods: A Simple Route To Synthesizing a Core–Shell Structure and Its Highly Enhanced UV and Hydrogen Sensing Properties

Granular activated carbon (GAC) materials were prepared via simple gas activation of silkworm cocoons and were coated on ZnO nanorods (ZNRs) by the facile hydrothermal method. The present combination of GAC and ZNRs shows a core–shell structure (where the GAC is coated on the surface of ZNRs) and is exposed by systematic material analysis. The as-prepared samples were then fabricated as dual-functional sensors and, most fascinatingly, the as-fabricated core–shell structure exhibits better UV and H₂ sensing properties than those of as-fabricated ZNRs and GAC. Thus, the present core–shell structure-based H₂ sensor exhibits fast responses of 11% (10 ppm) and 23.2% (200 ppm) with ultrafast response and recovery. However, the UV sensor offers an ultrahigh photoresponsivity of 57.9 A W^–1, which is superior to that of as-grown ZNRs (0.6 A W^–1). Besides this, switching photoresponse of GAC/ZNR core–shell structures exhibits a higher switching ratio (between dark and photocurrent) of 1585, with ultrafast response and recovery, than that of as-grown ZNRs (40). Because of the fast adsorption ability of GAC, it was observed that the finest distribution of GAC on ZNRs results in rapid electron transportation between the conduction bands of GAC and ZNRs while sensing H₂ and UV. Furthermore, the present core–shell structure-based UV and H₂ sensors also well-retained excellent sensitivity, repeatability, and long-term stability. Thus, the salient feature of this combination is that it provides a dual-functional sensor with biowaste cocoon and ZnO, which is ecological and inexpensive

Utilization of Sulfonated Waste Polystyrene-Based Cobalt Ferrite Magnetic Nanocomposites for Efficient Degradation of Calcon Dye

We presented a simple and efficient method for making a polymer–metal nanocomposite using various amounts of cobalt ferrite magnetic nanoparticles (CoFe2O4 MNp) with sulfonated waste polystyrene (SWPS) and utilized for Calcon dye degradation. The MNp was encapsulated with SWPS to avoid agglomeration and maintain its smaller size. ATR-FTIR, Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), dynamic light scattering (DLS), field emission scanning electron microscopy (FESEM), high-resolution transmittance electron microscopy (HR-TEM), atomic force microscopy (AFM) and solid UV were used to analyze the produced polymeric magnetic nanoparticles (SWPS/MNp). As the MNp loading increases, the average particle size decreases. For Calcon dye degradation, SWPS/MNp (20 wt%) was utilized with a smaller average particle size, and the structural changes were detected using a UV-Vis spectrophotometer. As a result, the Calcon dye’s characteristic absorbance peak at 515 nm was red-shifted to 536 and 565 nm after 5 min, resulting in a color shift from dark brown to light blue that could be seen with the naked eye. A strong linear correlation was found between the red-shifted absorbance and the concentration of dye solution over the range of 10–100 ppm under optimal conditions. The proposed dye degradation process is simple, efficient, and environmentally friendly and has been successfully used to purify organic azo-dye-containing water

High Selectivity Fuel from Efficient CO₂ Conversion by Zn-Modified rGO and Amine-Functionalized CuO as a Photocatalyst

Reduced graphene oxide (rGO) has been used in copper (II) oxide (CuO)-based photocatalysts as an additive material. An application of this CuO-based photocatalyst is in the CO2 reduction process. The preparation of rGO by a Zn-modified Hummers’ method has resulted in a high quality of rGO in terms of excellent crystallinity and morphology. However, implementing Zn-modified rGO in CuO-based photocatalysts for the CO2 reduction process has yet to be studied. Therefore, this study explores the potential of combining Zn-modified rGO with CuO photocatalysts and performing these rGO/CuO composite photocatalysts to convert CO2 into valuable chemical products. The rGO was synthesized by using a Zn-modified Hummers’ method and covalently grafted with CuO by amine functionalization with three different compositions (1:10, 1:20, and 1:30) of rGO/CuO photocatalyst. XRD, FTIR, and SEM were used to investigate the crystallinity, chemical bonds, and morphology of the prepared rGO and rGO/CuO composites. The performance of rGO/CuO photocatalysts for the CO2 reduction process was quantitively measured by GC–MS. We found that the rGO showed successful reduction using a Zn reducing agent. The rGO sheet could be grafted with CuO particles and resulted in a good morphology of rGO/CuO, as shown from the XRD, FTIR, and SEM results. The rGO/CuO material showed photocatalytic performance due to the advantages of synergistic components and resulted in methanol, ethanolamine, and aldehyde as fuel with amounts of 37.12, 8730, and 17.1 mmol/g catalyst, respectively. Meanwhile, adding CO2 flow time increases the resulting quantity of the product. In conclusion, the rGO/CuO composite could have potential for large-scale CO2 conversion and storage applications