Graphene oxide (GO) and reduced graphene oxide (rGO) are well known for their exceptional characteristics in a variety of applications. Reduced graphene oxide differs from graphene oxide in terms of morphological aspects, quality, functionalized groups, and crystallinities. Several attempts to synthesize GO and rGO have been documented in studies. The paper discussed the numerous ways to synthesize GO and rGO, and a literature review revealed that Hummers’ technique stands out as the most commonly used. Graphite is mixed with potassium permanganate, sodium nitrate, and strong sulfuric acid to make GO. Notably, Hummers’ technique has the advantage of faster synthesis and higher GO quality. The paper discusses several investigations, including the morphological and structural characteristics, chemical bonding information, and mechanical properties of GO and rGO. Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and the Vickers Hardness Tester are generally used to study these characteristics. The FTIR analysis revealed that the most common peaks in both GO and rGO were found to be associated with the O-H, C=O, C-OH, and C-O functional groups. XRD examination, on the other hand, revealed a diffraction peak at 2θ = 10.2°, indicating oxidized graphite in the case of GO, as well as a graphitic peak at 2θ = 26.3°, indicating graphitic graphite. Furthermore, the addition of GO and rGO into ceramics or polymers was discovered to cause significant changes in their mechanical characteristics, such as tensile strength, Young’s modulus, and others. This demonstrates the revolutionary potential of graphene in improving the performance of composite materials.

Eggshells are a potentially polluting industrial waste that are disposed of as landfill which has proven to be hazardous to the environment. The usage of chicken eggshells as a biofiller for polymer matrix composites instead of its disposal as landfill has proven advantageous in various studies. On the other hand, using eggshells as a filler material to replace inorganic calcium carbonate usage would be another environment friendly act. The present study is focused on studying the effects of eggshell filler addition and post-curing on polymer composites which could be utilised for domestic applications. Herein, uncarbonised and carbonised eggshell filler material were processed from waste eggshells. Hybridisation of the carbonised and uncarbonised eggshell filler was carried out. All three variants of eggshell fillers (10 wt.%) were used in the fabrication of composites. A hand lay-up technique was employed in the fabrication of unfilled composites along with three variants of filled composites, namely, uncarbonised, carbonised, and hybrid eggshell filled composites. The fabricated and cured composites were further subjected to post-curing at a temperature of 60 °C for a period of 2 h. All four variants of post-cured composites were then subjected to mechanical testing according to American Society for Testing and Materials (ASTM) standards. The tests revealed that all three variants of filled composites possess better mechanical properties in comparison with unfilled composites. Further, in comparison with unfilled composites, the carbonised eggshell filled composites showcased 42% and 49% improvement in flexural and tensile properties, respectively. The modes of failure of the specimens were observed and tabulated. SEM imaging revealed that the eggshell filler contributed to the strengths of the composites by means of arresting and deviating cracks. It was also observed that the post-cured specimens displayed improved properties when compared with our previous studies on non-post-cured specimens. In summary, the study showcased the benefits of eggshell filler addition and the post-curing of polymer composites.

The mesoporous titanium oxide has attracted significant attention as a photoanode material for Dye-Sensitized Solar Cells (DSSCs). In the present work, we coated a planar NiO layer on the TiO₂ film to minimize charge recombination with the dye and/or electrolyte molecules. The structural, morphological, elemental, optical, and electrical properties of the TiO₂ and bi-layered TiO₂/NiO films were studied using various characterization techniques. DSSCs based on N3 dye-sensitized TiO₂ and bi-layered TiO₂/NiO films were fabricated using PI as the redox electrolyte. The photocurrent density–voltage (J–V) characteristics of the DSSCs were studied using a solar simulator. Various parameters, such as open-circuit voltage (V_oc), short-circuit photocurrent density (J_sc), and fill factor (FF), were calculated from the J–V characteristics. DSSCs based on bi-layered TiO₂/NiO films showed superior performance compared to bare TiO₂ films. The J–V characteristics of bilayer film shows enhanced open-circuit voltage (Voc) ~ 0.56 V, short-circuit current density (Jsc) ~ 2.14 mA/cm², fill factor (FF) ~ 75%, and efficiency (ƞ) ~ 0.91%. The TiO₂/NiO solar cell showed a ~ 28% increase in efficiency compared to TiO₂-based DSSC. Hence, the bi-layered TiO₂/NiO films have potential applications in optoelectronic and photovoltaic devices.

Resin transfer molding (RTM) is a key process for manufacturing high-performance fiber-reinforced composites, in which resin infiltration dynamics play a critical role in process efficiency and defect minimization. This study presents a numerical and experimental analysis of resin flow in biaxial noncrimp carbon fiber reinforcement using FormuLITE 2500A/2401B epoxy. A model based on Darcy’s law and resin sorption effects was developed to investigate the influence of injection pressure (15–25 kPa), permeability (350 × 10⁻¹² m² to 0.035 × 10⁻¹² m²), porosity (0.78–0.58), viscosity (0.28–0.48 Pa·s), and injection radius (0.001–0.003 m) on flow-front progression. The results show that a higher injection pressure increased the infiltration depth by 30% at 250 s, while a 100× reduction in permeability reduced infiltration by 75%. The increased viscosity slowed the resin flow by ~18%, and the lower porosity reduced the flow-front progression by 15%. The experimental validation demonstrated a relative error of <5% between the numerical predictions and the measured data. This study provides critical insights into RTM process optimization for uniform fiber impregnation and defect minimization.