Nanomaterials最新文献

Tandem solar cells have the potential to be more efficient than the Shockley-Queisser limit imposed on single junction cells. In this study, optical and electrical modeling based on experimental data were used to investigate the possibility of boosting the performance of kesterite/c-Si tandem solar cells by inserting an alternative nontoxic TiO₂ buffer layer into the kesterite top subcell. First, with SCAPS-1D simulation, we determined the data reported for the best kesterite (CZTS (Eg = 1.5 eV)) device in the experiments to be used as a simulation baseline. After obtaining metric parameters close to those reported, the influence on the optoelectronic characteristics of replacing CdS with a TiO₂ buffer layer was studied and analyzed. Different top subcell absorbers (CZTS0.8Se0.2 (Eg = 1.4 eV), CZTS (Eg = 1.5 eV), CZTS (Eg = 1.6 eV), and CZT0.6Ge0.4S (Eg = 1.7 eV)) with different thicknesses were investigated under AM1.5 illumination. Then, to achieve current matching conditions, the c-Si bottom subcell, with an efficiency at the level of commercially available subcells (19%), was simulated using various top subcells transmitting light calculated using the transfer matrix method (TMM) for optical modeling. Adding TiO₂ significantly enhanced the electrical and optical performance of the kesterite top subcell due to the decrease in parasitic light absorption and heterojunction interface recombination. The best tandem device with a TiO₂ buffer layer for the top subcell with an optimum bandgap equal to 1.7 eV (CZT0.6Ge0.4S4) and a thickness of 0.8 µm achieved an efficiency of approximately 20%. These findings revealed that using a TiO₂ buffer layer is a promising way to improve the performance of kesterite/Si tandem solar cells in the future. However, important optical and electrical breakthroughs are needed to make kesterite materials viable for tandem applications.

Amidst the swift expansion of the electric vehicle industry, the imperative for alternative battery technologies that balance economic feasibility with sustainability has reached unprecedented importance. Herein, we utilized Perovskite-based oxide compounds barium titanate (BaTiO₃) and strontium titanate (SrTiO₃) nanoparticles as anode materials for lithium-ion batteries from straightforward and standard carbonate-based electrolyte with 10% fluoroethylene carbonate (FEC) additive [1M LiPF₆ (1:1 EC: DEC) + 10% FEC]. SrTiO₃ and BaTiO₃ electrodes can deliver a high specific capacity of 80 mA h g^-1 at a safe and low average working potential of ≈0.6 V vs. Li/Li⁺ with excellent high-rate performance with specific capacity of ~90 mA h g^-1 at low current density of 20 mA g^-1 and specific capacity of ~80 mA h g^-1 for over 500 cycles at high current density of 100 mA g^-1. Our findings pave the way for the direct utilization of perovskite-type materials as anode materials in Li-ion batteries due to their promising potential for Li⁺ ion storage. This investigation addresses the escalating market demands in a sustainable manner and opens avenues for the investigation of diverse perovskite oxides as advanced anodes for next-generation metal-ion batteries.

Water-in-oil microemulsions, as stable colloidal dispersions from quasi-ternary mixtures, have been used in diverse applications, including nanoreactors for confined chemical processes. Their use as soft templates not only includes nanomaterial synthesis but also the interfacial assembly of nanoparticles in hybrid nanostructures. Especially the hierarchical arrangement of different types of nanoparticles over a surface in filament networks constitutes an interesting bottom-up strategy for facile and tunable film coating. Herein, we demonstrate the versatility of this surface assembly from microemulsion dispersions. Transmission and Scanning Electron Microscopy, in addition to UV-Vis Transmittance Spectroscopy, proved the assembly tunability after solvent evaporation under different conditions: the nanostructured films can be formed over different surfaces, using different compositions of liquid phases, as well as with the incorporation of different nanoparticle materials while keeping equivalent surface functionalization. This offers the possibility of adapting different components and conditions for coating tuning on a larger scale with simple procedures.

This study focused on searching for more effective nanomaterials for environmental remediation and health protection; thus, coliform bacteria, yeast and the organic food dye sunset yellow were selected as target pollutants to be eliminated under solar light by Ag/Cr-TiO₂ and Pd/Cr-TiO₂. Firstly, Cr³⁺ was in situ incorporated into the anatase crystalline lattice by the sol-gel method; then, Ag or Pd nanoparticles were deposited on Cr-TiO₂ by chemical photoreduction. The scientific challenge addressed by the development of these composites was to analyse the recovery of Cr, to be employed in photocatalyst formulation and the enhancement of the TiO₂ photocatalytic activity by addition of other noble metals. By extensive characterization, it was found that after TiO₂ doping with chromium, the parameters of the crystal lattice slightly increased, due to the incorporation of Cr ions into the lattice. The TiO₂ band gap decreased after Cr addition, but an increase in the optical absorptions towards the visible region after noble metals deposition was also observed, which was dependent of the Ag or Pd loading. Generally, it was observed that the noble metals type is a factor that strongly influenced the effectiveness of the photocatalysts concerning each substrate studied. Thus, by using Ag(0.1%)/Cr-TiO₂, the complete elimination of E. coli from samples of water coming from a highly polluted river was achieved. Pd(0.5%)/Cr-TiO₂ showed the highest efficiency in the elimination of S. cerevisiae from a lab prepared strain. On the other hand, the Pd(0.1%)/Cr-TiO₂ sample shows the highest dye degradation rate, achieving 92% of TOC removal after 180 min.

Transparent heaters are gaining significant attention for applications such as antifog glass, smart windows, and smart farm greenhouses. A transparent heater basically consists of transparent conducting materials that serve as a heating area and contact pad electrode to apply power. To fabricate a transparent heater, materials with excellent light transmittance and low sheet resistance are required. Among various transparent conducting materials, such as Indium Tin Oxide (ITO), carbon nanotube (CNT), graphene, and silver nanowires (AgNWs), AgNWs are particularly favored due to their good electrical, optical, and mechanical properties. However, in order to improve the heating characteristics of transparent heaters, research is essential not only on improving the properties of transparent conducting materials but also on the design of contact pad electrodes that can uniformly improve current distribution. Here, we explore various shapes of contact pad electrodes for AgNW-based transparent heaters to improve current distribution. Shapes such as line, spot, twisted, and parallel-type contact pad electrodes are designed and investigated to optimize overall heating characteristics. We analyze the heating properties of these transparent heaters with various contact pad electrodes, demonstrating how their specific shape and size affect heating characteristics and uniformity. We also investigate the optimal shape of the contact pad electrode to minimize transmission loss through UV-VIS spectroscopy. As a result, we confirm that the shape of the contact pad electrode was important for simultaneously achieving high heating characteristics of 120 °C, good heating uniformity, and over 80% transparency in an AgNW-based transparent heater.

A series of red-emitting phosphors, Na_3.6Y_1.8-x(PO₄)₃:xEu³⁺, have been synthesized by a high-temperature solid-phase method. The impact of the partial Li⁺/K⁺ ion substitution on the crystal structure and photoluminescence (PL) performance of Na_3.6Y_1.05(PO₄)₃:0.75Eu³⁺ phosphor have been investigated. Various techniques have been used for characterization of the as-obtained materials. X-ray diffraction (XRD) analysis was utilized to confirm the composites of these samples, and the morphology and element distribution were examined by scanning electron microscope (SEM) and transmission electron microscope (TEM). This study found that the developed Na_3.6Y_1.8-x(PO₄)₃:xEu³⁺ phosphors exhibited a prominent emission peak at ~620 nm when excited at 393 nm, which corresponded to ⁵D₀ → ⁷F₂ transitions of Eu³⁺ ions. Furthermore, the robust emission peak at ~705 nm (⁵D₀ → ⁷F₄) of these phosphors enables a better match with plant pigment absorption. Beyond that, the partial substitution of Li⁺/K⁺ ions probably changed the crystal structure, and reduces the symmetry around Eu³⁺, leading to significantly enhanced luminous intensities by 23.24% and 18.29%, with the highest quantum yields (QYs) reaching 99.85% and 96.29%, respectively. Additionally, the prepared phosphors show non-thermal quenching and superior thermal stability at elevated temperatures from 298 to 473 K. These findings and results suggest that Li⁺/K⁺-substituted Na_3.6Y_1.05(PO₄)₃:0.75Eu³⁺ phosphors can serve as promising red-emitting phosphors for plant lighting applications.

The use of surface-enhanced Raman spectroscopy (SERS) in liquid solutions has always been challenging due to signal fluctuations, inconsistent data, and difficulties in obtaining reliable results, especially at very low analyte concentrations. In our study, we introduce a new method using a three-dimensional (3D) SERS substrate made of silica microparticles (SMPs) with attached plasmonic nanoparticles (NPs). These SMPs were placed in low-concentration analyte solutions for SERS analysis. In the first approach to perform SERS in a 3D environment, glycerin was used to immobilize the particles, which enabled high-resolution SERS imaging. Additionally, we conducted time-dependent SERS measurements in an aqueous solution, where freely suspended SMPs passed through the laser focus. In both scenarios, EFs larger than 200 were achieved, which enabled the detection of low-abundance analytes. Our study demonstrates a reliable and reproducible method for performing SERS in liquid environments, offering significant advantages for the real-time analysis of dynamic processes, sensitive detection of low-concentration molecules, and potential applications in biomolecular interaction studies, environmental monitoring, and biomedical diagnostics.

Hydrogen sulfide (H₂S) is a highly toxic and corrosive gas commonly found in industrial emissions and natural gas processing, posing serious risks to human health and environmental safety even at low concentrations. The early detection of H₂S is therefore critical for preventing accidents and ensuring compliance with safety regulations. This study presents the development of porous ZnO/SnO₂-nanocomposite gas sensors tailored for the ultrasensitive detection of H₂S at sub-ppb levels. Utilizing a screen-printing method, we fabricated five different sensor compositions-ranging from pure SnO₂ to pure ZnO-and characterized their structural and morphological properties through X-ray diffraction (XRD) and scanning electron microscopy (SEM). Among these, the SnO₂/ZnO sensor with a composition-weight ratio of 3:4 demonstrated the highest response at 325 °C, achieving a low detection limit of 0.14 ppb. The sensor was evaluated for detecting H₂S concentrations ranging from 5 ppb to 500 ppb under dry, humid air and N₂ conditions. The relative concentration error was carefully calculated based on analytical sensitivity, confirming the sensor's precision in measuring gas concentrations. Our findings underscore the significant advantages of mixture nanocomposites in enhancing gas sensitivity, offering promising applications in environmental monitoring and industrial safety. This research paves the way for the advancement of highly effective gas sensors capable of operating under diverse conditions with high accuracy.

Nowadays, the development of devices based on organic materials is an interesting research challenge. The performance of such devices is strongly influenced by material selection, material properties, design, and the manufacturing process. Usually, buckminsterfullerene (C60) is employed as electron transport material in organic photovoltaic (OPV) devices due to its high mobility. However, considering its low solubility, there have been many attempts to replace it with more soluble non-fullerene compounds. In this study, bulk heterojunction thin films with various compositions of zinc phthalocyanine (ZnPc), a perylene diimide derivative, or C60 were prepared by matrix-assisted pulsed laser evaporation (MAPLE) technique to assess the influence of C60 replacement on fabricated heterostructure properties. The investigations revealed that the optical features and the electrical parameters of the organic heterostructures based on this perylene diimide derivative used as an organic acceptor were improved. An increase in the J_SC value (4.3 × 10^-4 A/cm²) was obtained for the structures where the perylene diimide derivative acceptor entirely replaced C60 compared to the J_SC value (7.5 × 10^-8 A/cm²) for the heterostructure fabricated only with fullerene. These results are encouraging, demonstrating the potential of non-fullerene compounds as electron transport material in OPV devices.

The deprived electrochemical kinetics of the oxygen evolution reaction (OER) catalyst is the prime bottleneck and remains the major obstacle in the water electrolysis processes. Herein, a facile hydrothermal technique was implemented to form a freestanding polyhedron-like Co₃O₄ on the microporous architecture of Ni foam, its reaction kinetics enhanced through sulfide counterpart transformation in the presence of Na₂S, and their catalytic OER performances comparatively investigated in 1 M KOH medium. The formed Co₃S₄ catalyst shows outstanding catalytic OER activity at a current density of 100 mA cm^-2 by achieving a relatively low overpotential of 292 mV compared to the pure Co₃O₄ catalyst and the commercial IrO₂ catalyst. This enhancement results from the improved active centers and conductivity, which boost the intrinsic reaction kinetics. Further, the optimized Co₃S₄ catalyst exhibits admirable prolonged durability up to 72 h at varied current rates with insignificant selectivity decay. The energy dispersive X-ray spectroscopy (EDX) and Raman spectra measured after the prolonged OER stability test reveal a partial transformation of the active catalyst into an oxyhydroxide phase (i.e., CoOOH@Co₃S₄), which acts as an active catalyst phase during the electrolysis process.