Due to their unique physicochemical properties, iron oxide nanoparticles have become an interesting class of materials that can be used in various technological processes. This study highlights the production of hematite nanoparticles (Fe2O3) by the simple co-precipitation method using primary reactants that are iron(III) chloride hexahydrate (FeCl3 6H2O) and ammonia solution. These nanomaterials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The XRD analysis showed that the formation of crystalline Fe2O3 phase was successful and it had crystallite dimensions calculated as about 40 nm. FTIR analysis showed typical Fe-O bands vibrationally, which justified the creation of pure iron oxide structures. SEM micrographs exhibited the morphology of spherical particles and were made to behave as clusters at high temperatures of calcination. Also, the synthesized Fe2O3 nanoparticles possessed significant antimicrobial and antifungal efficacy against specific pathogenic strains, and this should suggest their future use in biomedical and environmental remediation processes.
ZnO–CuO heterojunction thick films were developed via a screen-printing approach and systematically evaluated for low-temperature methane sensing. The formation of a p–n heterojunction between n-type ZnO and p-type CuO significantly modulates charge transport and surface reactivity. Structural analysis confirmed the coexistence of hexagonal ZnO and monoclinic CuO phases, while microstructural studies revealed a porous and well-connected morphology favorable for gas adsorption. Among all compositions, the 5 wt.% CuO–ZnO film exhibited the smallest crystallite size (~44 nm), higher defect density, and enhanced surface activity, leading to improved electronic properties with optimized resistivity and reduced activation energy. Gas sensing results demonstrated a maximum sensitivity of 94.98% toward CH₄ at a low operating temperature of 60 °C (500 ppm), along with fast response and recovery times (8 s/37 s), excellent selectivity, and long-term stability. The superior performance is attributed to the synergistic effects of increased oxygen vacancies, efficient charge transfer across the ZnO–CuO interface, and enhanced modulation of the depletion layer. These findings establish ZnO–CuO heterojunction thick films as promising candidates for energy-efficient methane sensing applications.
Electrical and thermal conducting flexible composite materials are in demand for next-generation electronics. Devices like biomedical instruments, conducting textiles, low-power sources, electronic skin, and flexible displays require stretchable conductors possessing high electrical conductivity under excessive strain and deformation. In this respect, renewable, sustainable materials and/or their biomimicry could help to generate a three-dimensional, highly dense structure. We in this study have hence used the naturally occurring, densified non-conducting feather skeleton to develop three-dimensional conducting films. Herein, the natural feathers were treated with polydopamine solution to create a coating layer with dual action, as a linker for conductive filler as well as for self-adherence of feathers. The optimized amount of feathers and polydopamine is adsorbed with modified carbon nanotubes. Two simple laboratory methods of dip coating and freeze-drying process for the adsorption of conducting material, were optimized. The feathers themselves and polydopamine-coated feathers showed nil electrical conductivity, while different concentrations of filler-containing films showed electrical resistance from 5 to 1 kilo ohm. The film showed similar resistance after bending (50%), stretching (50%), compressing, and even breaking the film and reforming it 10 times exhibited similar trends. The high conductivity, electromechanical stability, and easy production methods make such nano-bio composites as renewable substrates for next-generation electronic devices.
Water hyacinth (Pontederia crassipes), an invasive aquatic weed with severe negative ecological impacts, represents an abundant and low-cost biomass resource due to its high cellulose content. In this study, cellulose was extracted from water hyacinth through degreasing, alkaline treatment, and bleaching, followed by chemical conversion into carboxymethyl cellulose (CMC) via mercerization and etherification. Structural modification was confirmed by FTIR spectroscopy which indicated successful etherification without degradation of the cellulose backbone. X-ray diffraction analysis and morphological examination by SEM of cellulose and CMC showed a clear transformation from well-aligned fibrillar structures in cellulose to a more fragmented, rough, and flaky surface in CMC. Both SEM and X-ray diffraction analysis revealed a pronounced reduction in crystalline order after carboxymethylation, reflecting disruption of the hydrogen-bonded cellulose lattice and increased amorphous character. EDX analysis also revealed a systematic increase in oxygen content consistent with incorporation of oxygen-bearing carboxymethyl groups. Thermogravimetric analysis demonstrated major CMC degradation onset at approximately 250°C suggesting its robust thermal degradation capabilities suited for industrial applications. The synthesized CMC achieved a degree of substitution of 0.69 ± 0.03 (n = 3) indicating a moderate degree of carboxymethyl substitution. From Atomic Absorption Spectroscopy (AAS), a significant decrease in total residual chromium is observed after CMC was introduced and found that CMC can remove 98.69% of total chromium within 30 minutes from water when used at a concentration of 0.75 g/L. Previous works mainly focus on either cellulose or CMC-modified cellulose derived from water hyacinth for water treatment. But here we report the use of CMC extracted from water hyacinth in its nascent form without further chemical modification or composite formation for chromium removal from wastewater for the very first time.
