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The flower-like Cr2O3−Cr(OH)3/poly-2-chloroaniline (P2CA) nanocomposite is synthesized through oxidative polymerization of 2CA using K2Cr2O7, with the preparation process performed on a polypyrrole (Ppy) seeding film. SEM images show that the P2CA material has a tissue-like structure, with fibers exhibiting a great degree of behavior. The Cr2O3−Cr(OH)3/P2CA composite displays a large porous structure with flower-shaped properties and a slotted behavior, featuring circular empty holes, with nanoparticles having a pore structure ranging from 5 to 100 nm. The calculated bandgap values for P2CA and Cr2O3−Cr(OH)3/P2CA are 2.02 and 1.87 eV, respectively. The Cr2O3−Cr(OH)3/P2CA composite photoelectrode is utilized for hydrogen gas production from sewage water, with the produced current density (Jph) reflecting the hydrogen generation rate. The Jph value in on/off light conditions demonstrates a significant enhancement under light of 0.002 and 0.018 mA.cm−2, correspondingly. Furthermore, the Jph increases from − 0.005 to − 0.006 mA.cm−2 at 340 and 730 nm, respectively, indicating the responsivity of this composite in the infrared region. So, the results demonstrate the potential of the Cr2O3−Cr(OH)3/P2CA nanocomposite photoelectrode as a cost-effective and efficient alternative for the production of hydrogen gas, without the limitations associated with previous materials and techniques. [ABSTRACT FROM AUTHOR]

The porous-spherical MnO2-Mn(OH)2/Ppy (polypyrrole) nanocomposite is synthesized through a one-pot, cost-effective oxidative polymerization method using KMnO4. This synthesis technique demonstrates great promise in terms of its ability to achieve mass production of the nanocomposite. The nanocomposite has a great optical property related to its wide optical absorbance from UV to near IR region (250 till 730 nm). The electrical properties of the MnO2-Mn(OH)2/Ppy nanocomposite photodetector were systematically tested under various optical conditions. Through these measurements, the performance of the photodetector was evaluated and characterized. The current density (Jph) is used to estimate the sensitivity of the generated electrons under the photon's irradiation. Under off/on light, the produced Jph are 4.2 and 9.5 mA cm−2, correspondingly. While, as the wavelengths increase from 340 to 730 nm, the Jph values exhibit a decrease, declining from 0.34 to 0.28 mA/cm². This trend illustrates the nanocomposite excellent responsiveness to photons across a wide range of optical regions. The promising sensitivity related to the photoresponsivity (R) of of 3.42 mA W−1. These values are estimated through detectivity (D) calculation, in which the D value is 6.42*108 Jones. With its exceptional reproducibility, the developed photodetector demonstrates strong suitability for industrial applications. Additionally, its synthesis process incurs low costs, further enhancing its attractiveness for practical implementation in various industries. [ABSTRACT FROM AUTHOR]

Great efforts are constantly being made by industry-specific coffee agencies to standardize the certification of coffee quality. In consequence, international trade requires quick and reliable analyses because of their high cost, the risk of misclassification, the difficulty of large-scale analysis, and, most importantly, the subjectivity generated by tasters. A powerful analytical method that can be used to accurately evaluate and identify coffee varieties is Laser-Induced Breakdown Spectroscopy (LIBS). In this study, it provided a quick, cost-effective, and residue-free method commonly used in laboratories for direct analysis, determining multi-elemental composition, and exploring the organic composition of roasted coffee. The mineral composition of eight varieties of pure roasted coffee was determined using a pulsed nanosecond laser produced from a Nd:YAG laser at 1064 nm. The most important spectral variables for coffee variety identification were sequestered using LIBS coupled with a chemometric-tool-based principal component analysis (PCA). The nine main wavelengths chosen corresponded to the elements of C(I), Mg(II, I), Ca(II), Fe(I), K(I), H(I), and O(I), in addition to the CN group. The overall findings indicated that using LIBS to identify coffee varieties is feasible based on a simple, quick, and eco-friendly strategy without the requirement for complex preparation or wasting time in preparation. Such studies can help to protect the coffee market and businesses by certifying product quality. Using LIBS and full statistical illustrations with PCA, the prevention of unfair competition, protection of consumers, and determination of coffee quality can be achieved. [ABSTRACT FROM AUTHOR]

A highly uniform spherical MoO2-MoO3/polypyrrole core-shell nanocomposite has been successfully synthesized as an optoelectronic photon sensing material, capable of detecting light in the UV, Vis, and IR domains. The nanocomposite is prepared through the oxidation of pyrrole using Na2MoO4, resulting in a uniform spherical morphology that has been confirmed by TEM, theoretical modeling, and SEM analyses. This morphology contributes to its promising optical behavior, characterized by a small bandgap of 1.36 eV. The optoelectronic photosensing capability of the nanocomposite has been evaluated across the UV, Vis, and IR spectra, demonstrating high efficiency. The photoresponsivity R values indicate the ability of the nanocomposite to generate hot electrons in response to incident photons. With an R value of 4.15 mA·W−1 at 440 nm, this optoelectronic device exhibits considerable promise for integration into an advanced technological apparatus. The detection (D) value of 9.30 × 108 Jones at 440 nm further confirms the high sensitivity in the Vis region. The excellent stability of the device can be attributed to the inherent MoO2-MoO3 oxide and Ppy polymer materials. This stability has been demonstrated through reproducibility studies and current-voltage measurements under various optical conditions. The combination of stability, efficiency, and sensitivity makes this optoelectronic device well suited for light sensing applications in both industrial and commercial settings. Its promising performance opens up opportunities for advancements in various fields requiring accurate and reliable light detection. [ABSTRACT FROM AUTHOR]

Undoped and codoped (Eu/Na) ZnO nanocrystals (NCs) were successfully manufactured through an economical sol-gel method. X-ray diffraction (XRD) analysis demonstrated pure hexagonal wurtzite structure without secondary phases for all the samples. The size of the NCs was found to decrease with codoping by Eu3+/Na+ which is related to the existence of strain and stress in the lattice. The dominance of the E2(high) mode in Raman spectra indicates the good crystallinity of the samples. The study from the X-ray photoelectron spectroscopy (XPS) shows the successful insertion of both Eu3+ and Na+ ions into the ZnO lattice and the generation of the zinc and oxygen vacancies (Vo) defects. The band gap energy was reduced and the Urbach energy increased with Na+ content, proving the distortion of the lattice. From the photoluminescence (PL) study, the activation of the Eu3+ ions by Na+ ones was evidenced. Longer PL lifetimes were obtained from Eu3+ ions when they were sensitized by Na+, which may be beneficial to several applications. A process of excitation transfer from both the ZnO host and Na+ sensitizers to the Eu3+ ions was evidenced and discussed. As an application, we tested the performances of the prepared NCs as photocatalysts for Rhodamine B photodegradation under sunlight irradiation. The ZnO NCs codoped with 1% Eu/4% Na displayed the best photodegradation rate with a good stability and a high kinetic rate constant k of 0.021 min−1. The photocatalytic mechanism is discussed in terms of longer radiative recombination from Eu3+ and the generated oxygen vacancies. [ABSTRACT FROM AUTHOR]

This study utilized the exceptional optical and electrical properties of polypyrrole (Ppy) to fabricate high-performance optoelectronic devices. The synthesis of the porous-spherical Cr2O3-Cr(OH)3-Ppy/Ppy nanocomposite thin film was achieved by preparing a second thin film of Cr2O3-Cr(OH)3-Ppy on the initial Ppy film using K2Cr2O7 as an oxidant. The nanocomposite's properties were thoroughly characterized, including XRD and optical absorbance analyses. The XRD analysis showed that the crystalline size of the nanocomposite was 20 nm, while optical absorbance analysis demonstrated that the nanocomposite had a higher absorbance in a wide optical range compared to Ppy nanomaterials, as evidenced by the enhancement in bandgap (Eg) value from 3.33 eV for Ppy to 1.89 eV for Cr2O3-Cr(OH)3-Ppy. The fabricated nanocomposite thin film exhibited excellent light-sensing behavior, as evidenced by the evaluation of Jph values under different light conditions and various monochromatic lights with a detectivity (D) of 3.6 × 106 Jones (at 340 nm). The device demonstrated its potential as a solar cell, with a short circuit current (JSC) of 13 µA and an open circuit voltage (VOC) of 1.91 V. Given the nanocomposite's low cost, high technical production, and superior optoelectronic properties, it has significant potential for use in commercially available high-tech devices. [ABSTRACT FROM AUTHOR]

Hydrogel nanocomposites are attracting increasing attention in field of biology owing to their unique properties. The present work focuses on the fabrication and characterization of novel hydrogel nanocomposite systems in which silver nanoparticles (AgNPs) are embedded in a carrageenan (κ-CGN)-sodium alginate (SA) hydrogel. The performance of the prepared κ-CGN-SA hydrogel and κ-CGN-SA/AgNPs hydrogel nanocomposite was determined by UV-visible spectroscopy, FTIR, XRD, SEM, EDX spectrum, EDX mapping, and TEM analysis. Surface plasmon resonance at 428 nm confirmed the presence of AgNPs in the κ-CGN-SA hydrogel. The results indicate that AgNPs with an average diameter of 30 nm were uniformly dispersed in the κ-CGN-SA hydrogel matrix. The amount of Ag+ ion release kinetic from the κ-CGN-SA hydrogel matrix is very low, showing that AgNPs were well trapped within the κ-CGN-SA/AgNPs hydrogel nanocomposite. The high antibacterial activity of the κ-CGN-SA/AgNPs hydrogel nanocomposite was found to be 89.6 ± 1.4% and 91.4 ± 2.3% against the gram-positive S. aureus and the gram-negative E. coli, respectively. Moreover, the κ-CGN-SA/AgNPs hydrogel nanocomposite showed good biocompatibility by the MTT test. The novel κ-CGN-SA/AgNPs hydrogel nanocomposite low cytotoxicity and antibacterial efficacy is proposed as a potential candidate for biomedical applications. [ABSTRACT FROM AUTHOR]