Cobalt ferrite (CoFe2O4) spinel thin films were prepared on FTO substrates by electrodeposition using deposition times ranging from 30 to 120 s, followed by thermal annealing. The influence of deposition time on the structural, morphological, optical, and electrochemical responses of the films was investigated. XRD and FTIR analyses supported the formation of the cubic spinel CoFe2O4 phase, while SEM observations revealed changes in surface coverage, compactness, and morphology with deposition time. Optical measurements showed an overall decrease in transmittance and a shift of the absorption edge. Absorbance-based Tauc analysis yielded estimated optical band-gap values of approximately 2.50, 2.12, 2.25, and 2.00 eV for the films deposited for 30, 60, 90, and 120 s, respectively. The positive tendency of the Mott–Schottky plots was consistent with n-type semiconductor behavior. The transient photocurrent measurements exhibited light-dependent responses, with the highest magnitude observed for the 120 s sample. The Bode and Nyquist plots also showed deposition-time-dependent differences in the measured impedance response. These results indicate that deposition time influences the measured morphological, optical, and electrochemical characteristics of electrodeposited CoFe2O4 thin films.
Monoclinic BiVO4 photocatalysts were prepared using a surfactant-free hydrothermal method at 160 °C with different holding times ranging from 0 to 24 h. The influence of hydrothermal duration on the morphological evolution and photocatalytic performance was systematically investigated. X-ray diffraction (XRD) confirmed that all synthesized samples possessed a pure monoclinic phase. According to SEM and BET analyses, a short holding time (2 h) led to a three-dimensionally interconnected structure with the highest specific surface area (12.01 m2·g−1), whereas longer durations caused particle sintering and a reduction in surface area. The sample obtained at 2 h showed the lowest steady-state photoluminescence (PL) intensity and a bandgap of approximately 2.46 eV, indicating improved charge separation. Short hydrothermal times favored abundant surface active sites, while extended holding times promoted grain growth and diminished surface reactivity, thereby lowering the photocatalytic efficiency. As a result, the 2 h sample achieved an 88% degradation rate for 15 mg · L−1 methylene blue within 180 min, and exhibited superior visible-light activity together with excellent structural and photochemical stability over three consecutive cycles. These findings demonstrate that the hydrothermal holding time is a simple yet effective parameter for tailoring the morphology of BiVO4 and optimizing its visible-light-driven degradation of pollutants.
Perovskite solar cell (PSC) is an evolving technology with great potential to drive the solar photovoltaic industry forward, but instability arising from ingress of environmental stressors has limited the technology uptake making imminent commercialization unattractive. This study reviews the barrier, thermal, mechanical, optical and chemical properties of several encapsulation and edge seal materials and polymer composites to advise on their suitability in packaging PSC. It proposes nanofiller composite with enhanced barriers and thermal properties for effective packaging of PSC. Implementing a systematic review process achieved by deploying the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) algorithm, 11 encapsulation, 7 edge seal and 13 filler materials sourced from 110 relevant peer reviewed papers are reviewed. Graphical plot and Venn Diagram techniques are used to analyse the materials properties. The review reveals that UV cured epoxy demonstrates the potential of being the most suitable material but its relatively high-water vapour transmission rate (WVTR) of 0.16 gm−2day−1 and low thermal conductivity of circa 0.25 W/mK limit its application. It is found that addition of boron nitride nano platelets (BNNP) to matrix of epoxy reduces the WVTR by 50%, increases the thermal conductivity significantly and is indifferent to the electrical conductivity, but addition of graphene reduces the WVTR of epoxy by 80%, increases both the thermal conductivity and electrical conductivity. Optimal weight percent of BNNP in epoxy matrix has produced composite which demonstrates suitability in packaging PSC, effectively. This review provides an insight which guides researchers on development of suitable nano-composite materials toward packaging of PSC.
Single-crystal silicon is a critical substrate material in silicon-based semiconductor manufacturing, and its nanoscale surface integrity directly affects subsequent device fabrication accuracy and reliability. In this study, a molecular dynamics (MD) model was developed to clarify the atomistic interaction mechanism between an Al2O3 abrasive and single-crystal silicon during nanoscale polishing. Polishing depths from 1 to 3 nm at intervals of 0.5 nm were used to represent different abrasive-workpiece contact states, and their effects on surface formation, material flow, thermo-mechanical response, microstructural evolution, subsurface damage, and residual stress were analyzed. The results show that the average normal force, average temperature in the chip zone, subsurface damage layer thickness, and maximum von Mises residual stress do not increase proportionally with polishing depth. With increasing depth, they increase by 132.4%, 95.6%, 94.7%, and 15.6%, respectively. Meanwhile, the maximum chip width increases by 68.5%, while the maximum chip height increases by 358.0%, and the relative increase in normal force also exhibits different growth rates. In summary, as the polishing depth increases, the material response is mainly characterized by intensified material pile-up in front of and above the abrasive, as well as the expansion of subsurface lattice distortion and structural disorder; in contrast, the lateral affected range and peak residual stress do not increase synchronously. The findings provide atomistic guidance for understanding Al2O3-Si interfacial interactions and balancing material removal with damage control in nanoscale polishing of single-crystal silicon.
In this work, the structural, optical, and electrochemical properties of strontium (Sr) and calcium (Ca) co-doped Zinc Sulfide (ZnS) nanoparticles specifically comprising a fixed 2% Ca loading with varying Sr fractions (0%, 2%, and 4%) are investigated to assess their feasibility as advanced electrode materials for energy storage applications. It is hypothesized that the sequential incorporation of oversized alkaline-earth dopants induces controlled lattice strain and dense non-radiative defect states, which act as active pathways to suppress charge carrier recombination and lower interfacial electronic resistance. A controlled chemical procedure was used to create the Sr-modified nanoparticles, which produced pure crystalline phases and a homogeneous surface morphology with decreased particle aggregation at higher Sr doping concentration. Optical absorption spectra showed maximum absorption in the UV region and variation in the bandgap values. Photoluminescence spectra showed a drop in the emission intensity, indicating better charge carrier separation and a reduced rate of photogenerated electron-hole pair recombination. The electrochemical investigations revealed improved charge transport profiles, demonstrating a peak specific capacitance of approximately 83 F/g for the optimized 4% Sr sample. The enhanced conductivity and decreased charge transfer resistance validated the beneficial effect of Sr inclusion in promoting interfacial electron transfer. These results show that the structural, optical, and electrochemical characteristics of Ca-ZnS nanoparticles may be effectively tailored by Sr inclusion, making them suitable materials for possible energy storage applications.
