Lead-free 0.9Bi 0.5 Na 0.5 TiO 3 –0.1BaTiO 3 (BNBT) ceramics modified with Bi 0.95 Sr 0.05 FeO 3 (BSF = 0–5 wt.%) were synthesized by high-energy ball milling followed by thermal treatment. X-ray diffraction confirmed a single tetragonal P4bm perovskite phase with no detectable secondary phases, and Rietveld refinement revealed composition-dependent variations in lattice parameters and microstrain consistent with solid-solution formation, supported by EDS maps showing a homogeneous elemental distribution at x = 5. The x = 4 composition exhibited the highest room-temperature dielectric permittivity (εᵣ = 2333 at 50 Hz, tanδ = 0.05–0.09) and a broad, thermally stable permittivity plateau (∼9000 between 200 and 300 °C). Ferroelectric characterization showed a progressive reduction in coercive field and the development of pinched P–E loops, attributed to defect-dipole formation and polar nanoregion growth, in line with the more heterogeneous domain configuration observed by Piezoresponse Force Microscopy (PFM). This composition achieved d 33 = 297 pC/N and g 33 = 17.9 × 10 −3 V m/N (where d 33 is the piezoelectric charge coefficient and g 33 is the piezoelectric voltage coefficient), an ∼80% enhancement over unmodified BNBT, although with a lower depolarization temperature (T d ≈ 90 °C vs. ≈ 120 °C for BNBT, from in situ d 33 (T) measurements), establishing BSF addition as a viable compositional design strategy for high-performance lead-free piezoelectrics.
In this study, MoS 2 /rGO nanocomposites were successfully synthesized via a simple hydrothermal method using graphene oxide (GO), sodium molybdate (Na 2 MoO 4 .2H 2 O), and thiourea (CH 4 N 2 S) as precursors. The effects of hydrothermal reaction time on the structural evolution, phase composition, and electrochemical performance of MoS 2 /rGO nanocomposites were systematically investigated. Structural and chemical analyses revealed the formation of flower-like MoS 2 nanosheets on rGO, with nanoflower size increasing as hydrothermal reaction time increased. XRD and Raman analyses indicated improved crystallinity of hexagonal 2H-MoS 2 with increasing hydrothermal reaction time, while HRTEM confirmed its layered structure with an interplanar spacing of approximately 0.63 nm corresponding to the (002) planes. Interestingly, XPS analysis revealed the coexistence of 1T and 2H MoS 2 phases, with the relative 1T-phase fraction decreasing as hydrothermal reaction time increased. Electrochemical measurements demonstrated that the capacitive performance of the MoS 2 /rGO nanocomposites improved with increasing hydrothermal time, achieving a maximum specific capacitance of 175.01 F g −1 at 10 mV s −1 for the MoS 2 /rGO-24 h electrode. The enhanced electrochemical performance may be attributed to the combined contributions of improved GO reduction and increased MoS 2 crystallinity. Moreover, the MoS 2 /rGO-24 h electrode exhibited excellent cycling stability, retaining 87.95% of its initial capacitance after 10,000 charge–discharge cycles. These results suggest that the MoS 2 /rGO nanocomposites are promising electrode materials for high-performance supercapacitor applications.
In this study, MoS2/rGO nanocomposites were successfully synthesized via a simple hydrothermal method using graphene oxide (GO), sodium molybdate (Na2MoO4.2H2O), and thiourea (CH4N2S) as precursors. The effects of hydrothermal reaction time on the structural evolution, phase composition, and electrochemical performance of MoS2/rGO nanocomposites were systematically investigated. Structural and chemical analyses revealed the formation of flower-like MoS2 nanosheets on rGO, with nanoflower size increasing as hydrothermal reaction time increased. XRD and Raman analyses indicated improved crystallinity of hexagonal 2H-MoS2 with increasing hydrothermal reaction time, while HRTEM confirmed its layered structure with an interplanar spacing of approximately 0.63 nm corresponding to the (002) planes. Interestingly, XPS analysis revealed the coexistence of 1T and 2H MoS2 phases, with the relative 1T-phase fraction decreasing as hydrothermal reaction time increased. Electrochemical measurements demonstrated that the capacitive performance of the MoS2/rGO nanocomposites improved with increasing hydrothermal time, achieving a maximum specific capacitance of 175.01 F g−1 at 10 mV s−1 for the MoS2/rGO-24 h electrode. The enhanced electrochemical performance may be attributed to the combined contributions of improved GO reduction and increased MoS2 crystallinity. Moreover, the MoS2/rGO-24 h electrode exhibited excellent cycling stability, retaining 87.95% of its initial capacitance after 10,000 charge–discharge cycles. These results suggest that the MoS2/rGO nanocomposites are promising electrode materials for high-performance supercapacitor applications.
Perfluorinated and polyfluorinated compounds (PFASs), especially Perfluorooctanesulfonate (PFOS), have become emerging and challenging pollutants in water resources due to their high chemical stability, bioaccumulation, and toxicity. In this study, a CuO/ZnO nanocomposite was prepared by a green synthesis method, and its structural and morphological properties were characterized using XRD, FTIR, SEM, TEM, and PSD analyses. The photocatalytic performance of the nanocomposite for PFOS removal under UV irradiation was evaluated. RSM based on CCD was applied to investigate and optimize the effects of initial PFOS concentration, solution pH, photocatalyst dosage, and irradiation time. The ANOVA results indicated that the developed quadratic model was highly significant (p < 0.0001) and showed excellent predictive ability with R2 = 0.9927. Irradiation time was identified as the most influential factor affecting PFOS removal, while the interaction between photocatalyst dosage and irradiation time was the only significant interaction (p = 0.0183). The optimum conditions were determined as an initial PFOS concentration of 20.33 mg L−1, pH of 6.0, photocatalyst dosage of 1.27 g L−1, and irradiation time of 208.5 min, resulting in a predicted removal efficiency of 95.69%. Confirmation experiments showed good agreement with the predicted value, achieving an average removal efficiency of 95.11 ± 0.64%. Overall, the green-synthesized CuO/ZnO nanocomposite demonstrated high efficiency for PFOS removal, and the RSM model proved to be an effective tool for optimizing the photocatalytic process. This study provides valuable insights into the application of CuO/ZnO nanocomposites for PFOS degradation and the development of sustainable PFAS treatment technologies.
Food packaging is susceptible to mechanical damage during transportation, handling, storage, and distribution. Thus, healing-capable biopolymer films have attracted interest for potential application in food packaging. This study explores the properties, mechanical recovery efficiency, and healing behavior of biopolymer films, specifically chitosan and pectin, under different temperatures (5, 23, and 30 °C) and relative humidities (RH: 33 and 75%). Films were evaluated following a standardized incision and direct application of distilled water to the damaged region, followed by six days of conditioning under the selected temperature and RH conditions. It was found that chitosan films exhibited higher water vapor permeability and thermal degradation temperatures than pectin films. However, under the condition producing the highest measured recovery (30 °C and 75% RH), pectin films exhibited higher mechanical recovery efficiencies (tensile strength (TS): 95.26%, elongation at break (EAB): 92.41%) than chitosan films (TS: 92.71%, EAB: 88.25%). The mechanical recovery of both films increased with the increment in temperature and RH, which was consistent with enhanced biopolymer chain mobility and moisture-induced plasticization. Pectin films achieved a smooth and homogeneous surface after healing, while chitosan films retained faint fibrous ridges along the former cut lines. These observations are consistent with moisture-assisted chain rearrangement and reversible interactions, including hydrogen bonding in both films and possible calcium ion (Ca2+)-carboxylate group (COO−) ionic association in the calcium chloride (CaCl2)-crosslinked pectin network. The findings provide a comparative assessment of the temperature- and RH- dependent mechanical recovery of chitosan and pectin films following water-assisted healing for potential healing-capable food packaging applications.
