We report growth of quaternary Cu2 ZnSnS4 (CZTS) thin films prepared by the electrochemical deposition from salt precursors containing Cu (II), Zn (II) and Sn (IV) metals. The influence of different sulfurization times t (t = 75, 90, 105, and 120 min) on the structural, compositional, morphological, and optical properties, as well as on the electrical properties is studied. The films sulfurized 2 hours showed a prominent kesterite phase with a nearly stoichiometric composition. Samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and Raman and UV-VIS-NIR spectrometer at different stages of work. X-ray diffraction and Raman spectroscopy analyses confirmed the formation of phase-pure CZTS films. (FESEM) shows that compact and dense morphology and enhanced photo-sensitivity. STEM - EDS elemental map of CZTS cross-section confirms homogeneous distribution. From optical study, energy gap was enlarged with a changed sulfurization times in the range of 1.37-1.47 eV.
This work reports the use of a ternary composite that integrates p-Toluene sulfonic acid doped polyaniline (PANI), chitosan, and reduced graphene oxide (RGO) as the active sensing layer of a surface plasmon resonance (SPR) sensor. The SPR sensor is intended for application in the non-invasive monitoring and screening of diabetes through the detection of low concentrations of acetone vapour of less than or equal to 5 ppm, which falls within the range of breath acetone concentration in diabetic patients. The ternary composite film was spin-coated on a 50-nm-thick gold layer at 6000 rpm for 30 s. The structure, morphology and chemical composition of the ternary composite samples were characterized by FTIR, UV-VIS, FESEM, EDX, AFM, XPS, and TGA and the response to acetone vapour at different concentrations in the range of 0.5 ppm to 5 ppm was measured at room temperature using SPR technique. The ternary composite-based SPR sensor showed good sensitivity and linearity towards acetone vapour in the range considered. It was determined that the sensor could detect acetone vapour down to 0.88 ppb with a sensitivity of 0.69 degree/ppm with a linearity correlation coefficient of 0.997 in the average SPR angular shift as a function of the acetone vapour concentration in air. The selectivity, repeatability, reversibility, and stability of the sensor were also studied. The acetone response was 87%, 94%, and 99% higher compared to common interfering volatile organic compounds such as propanol, methanol, and ethanol, respectively. The attained lowest detection limit (LOD) of 0.88 ppb confirms the potential for the utilisation of the sensor in the non-invasive monitoring and screening of diabetes.
To non-invasively monitor and screen for diabetes in patients, there is need to detect low concentration of acetone vapor in the range from 1.8 ppm to 5 ppm, which is the concentration range of acetone vapor in diabetic patients. This work presents an investigation for the utilization of chitosan-polyethylene glycol (PEG)-based surface plasmon resonance (SPR) sensor in the detection of trace concentration acetone vapor in the range of breath acetone in diabetic subjects. The structure, morphology, and elemental composition of the chitosan-PEG sensing layer were characterized using FTIR, UV-VIS, FESEM, EDX, AFM, and XPS methods. Response testing was conducted using low concentration of acetone vapor in the range of 0.5 ppm to 5 ppm using SPR technique. All the measurements were conducted at room temperature and 50 mL/min gas flow rate. The sensor showed good sensitivity, linearity, repeatability, reversibility, stability, and high affinity toward acetone vapor. The sensor also showed better selectivity to acetone compared to methanol, ethanol, and propanol vapors. More importantly, the lowest detection limit (LOD) of about 0.96 ppb confirmed the applicability of the sensor for the non-invasive monitoring and screening of diabetes.
Supercapacitors are energy storage devices with high power density, rapid charge/discharge rate, and excellent cycle stability. Carbon-based supercapacitors are increasingly attracting attention because of their large surface area and high porosity. Carbon-based materials research has been recently centered on biomass-based materials due to the rising need to maintain a sustainable environment. Cellulose and lignin constitute the major components of lignocellulose biomass. Since they are renewable, sustainable, and readily accessible, lignin and cellulose-based supercapacitors are economically viable and environmentally friendly. This review aims to systematically analyze published research findings on electrospun lignin, cellulose, and lignin/cellulose nanofibers for use as supercapacitor electrode materials. A rigorous scientific approach was employed to screen the eligibility of relevant articles to be included in this study. The research questions and the inclusion criteria were clearly defined. The included articles were used to draw up the research framework and develop coherent taxonomy of literature. Taxonomy of research literature generated from the included articles was classified into review papers, electrospun lignin, cellulose, and lignin/cellulose nanofibers for use as supercapacitor electrode materials. Furthermore, challenges, recommendations, and research directions for future studies were equally discussed extensively. Before this study, no review on electrospun lignin/cellulose nanofiber-based supercapacitors has been reported. Thus, this systematic review will provide a reference for other researchers interested in developing biomass-based supercapacitors as an alternative to conventional supercapacitors based on petroleum products.
Methylammonium lead iodide (MAPbI3) is a benchmark absorber for low-cost, high-efficiency perovskite solar cells (PSCs), but its practical deployment is constrained by small grain sizes, high defect densities, and moisture-sensitive surfaces that limit both efficiency and stability. Here, we demonstrate that covalent organic frameworks (COFs) built from commercially available building blocks provide a powerful, multifunctional route to overcome these limitations by simultaneously regulating crystallization, passivating defects, and tuning surface properties in MAPbI3 thin films. Three hydrazone-linked and β-ketoenamine frameworks, denoted DMTH-COF, Boc-PDA-COF and Tp-COF, were prepared by condensing 2,5-dimethoxyterephthalohydrazide (DMTH), Boc-PDA-phenylenediamine (Boc-PDA), and 1,3,5-triformylphloroglucinol (Tp), respectively, and were incorporated at low loading into the MAPbI3 precursor solution. X-ray diffraction and FE-SEM reveal that all three additives preserve the tetragonal perovskite phase while enlarging the grain size from a few hundred nanometers in pristine films to about 1 μm for DMTH-modified layers, accompanied by narrowed diffraction peaks and reduced microstrain. Raman and FTIR spectroscopy show COF-induced modifications of Pb-I and CH3NH3+ vibrational modes, indicating specific coordination and hydrogen-bonding interactions that stabilize the lattice and reduce trap density. UV-Vis spectra confirm strong visible-light absorption at an unchanged optical bandgap of 1.56 eV across all films, while steady-state PL and EQE measurements evidence enhanced radiative efficiency and improved photon-to-current conversion, particularly at longer wavelengths. X-ray photoelectron spectroscopy confirms that the framework is retained within the film after annealing, the modified absorber showing a N 1s component at 399.7 eV that is absent from the pristine reference, while the Pb 4f and I 3d core levels shift in parallel with their spin-orbit splittings preserved and no metallic lead detected. These material-level improvements translate into substantial device gains in n-i-p PSCs (FTO/c-TiO2/m-TiO2/COF:MAPbI3/Spiro-OMeTAD/Au). Relative to pristine MAPbI3 cells (PCE ≈ 14.7%), COF-modified devices exhibit higher Voc, Jsc, and FF, with DMTH-COF-modified cells achieving Voc = 1.183 V, Jsc = 22.98 mA cm-2, FF = 76.46%, and PCE = 20.78%, alongside reduced series resistance, increased shunt resistance, and improved device-to-device reproducibility. Water-contact-angle and EDX analyses confirm that COF addition increases surface hydrophobicity and preserves near-ideal Pb:I stoichiometry, supporting enhanced environmental stability. This study introduces bulk COF doping as a simple, scalable strategy to engineer MAPbI3 microstructure, energetics, and surface chemistry in a single processing step, and identifies DMTH-COF as the most effective of the three frameworks. More broadly, it positions COF-perovskite hybrids as a tunable platform for high-efficiency, durable perovskite optoelectronics.