The oxidative exfoliation of graphite is a promising approach to the large-scale production of graphene. Conventional oxidation of graphite essentially facilitates the exfoliation process; however, the oxidation procedure releases toxic gases and requires extensive, time-consuming steps of washing and reduction to convert exfoliated graphene oxide (GO) into reduced graphene oxide (rGO). Although toxic gases can be controlled by modifying chemical reactions, filtration, dialysis, and extensive sonication are unfavorable for large-scale production. Here, we report a complete, scalable, and green synthesis of GO, without NaNO₃, followed by reduction with citric acid (CA). This approach eliminates the generation of toxic gases, simplifies the washing steps, and reduces the time required to prepare rGO. To validate the proposed method, we present spectroscopical and morphological studies, using energy-dispersive X-ray spectroscopy (EDS), UV-visible spectroscopy, infrared spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Thermal gravimetric analysis (TGA) is used to analyze the thermal properties of GO and rGO. This eco-friendly method proposes a complete guideline protocol toward large-scale production of oxidized graphene, with potential applications in supercapacitors, fuel cells, composites, batteries, and biosensors.

The use of graphene oxide (GO) in combination with mesoporous materials has gained interest in the development of adsorbents. In this study, GO was impregnated into zeolite at three concentrations (ZGO2.5, ZGO5, and ZGO10) through a simple thermal process to enhance the adsorption of methylene blue (MB). Characterization of the resulting materials was performed using spectroscopic techniques such as UV-Vis and FT-IR spectroscopy, SEM, and EDS, confirming the presence of GO on zeolite. Batch experiments were conducted to evaluate their performance, analyzing contact time, pH effect, and adsorption kinetics. Pseudo-first-order, pseudo-second-order, and Elovich kinetic models were applied, and the adsorption mechanism was studied using Langmuir, Freundlich, Temkin II, and Dubinin–Radushkevich (D-R) isotherms at different temperatures. Optimal adsorption was achieved at 273 K, 100 mg L⁻¹ of MB, adsorbent mass of 100 mg, 250 rpm, and pH 5–9, with 90% removal efficiency after 70 min. The pseudo-second-order, Freundlich, and D-R models best described the process (R² > 0.98), suggesting a mixed physisorption–chemisorption mechanism. The maximum adsorption capacity from the D-R isotherm reached 119 mg g⁻¹ at 333 K. Thermodynamic studies showed that adsorption was a spontaneous and endothermic process. These findings highlight the potential of GO-impregnated zeolite as an effective adsorbent for MB.

A novel method is presented to prepare few-layer graphene (FLG) in N-methyl-2-pyrrolidinone (NMP) by using a simple, low-cost and energy-effective shear exfoliation assisted by zeolite and using a cappuccino mixer to produce shear. We propose that the exfoliation of natural graphite flakes can be achieved using inelastic collisions between graphite flakes and zeolite particles in a dynamic colloidal fluid. To confirm the exfoliation of FLG, spectroscopy and morphological studies are carried out using Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Additionally, the obtained graphene shows a linear flow of current and low resistance. The proposed method shows great promise for the industrial-scale synthesis of high-quality graphene with potential applications in future graphene-based devices, and furthermore, this method can be extended to exfoliate inorganic layered materials such as BN and MoS₂.

Herein, we introduce a simple precipitation method for preparing graphene oxide–silver nanoparticle (GO/AgNP) composites, utilizing Calendula officinalis (C. officinalis) seed extract as both a reducing and stabilizing agent. Our research combines the sustainable preparation of graphene oxide (GO) with the green synthesis of silver nanoparticles (AgNPs), aiming to explore the potential of the obtained composite as a novel antibacterial material. To establish a benchmark, the synthesis was also performed using sodium citrate, a conventional reducing agent. The resultant GO/AgNP composites were characterized through several analytical techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, X-ray diffraction (XRD), infrared (IR) spectroscopy, and ultraviolet–visible (UV-vis) spectroscopy, confirming the successful functionalization of GO with AgNPs. The antibacterial effectiveness of the composites was systematically assessed against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with nanoparticle concentrations spanning from 0 to 250 µg/mL, utilizing mostly disk diffusion and colony-forming unit (CFU) count assays. The AgNPs were characterized by a size range of 15–50 nm. Notably, the GO/AgNP composite prepared using C. officinalis seed extract demonstrated superior antibacterial activity at all tested concentrations, outperforming both pure GO and the GO/AgNP composite prepared with sodium citrate. The most pronounced antibacterial effect was observed at a concentration of 32.0 µg/mL. Therefore, this innovative synthesis approach may offer a valuable contribution to the development of new therapeutic agents to combat bacterial infections, suggesting further exploration into antibacterial coatings or potential drug development.

Building on our earlier work on graphene oxide (GO)-impregnated clinoptilolite for methylene blue (MB) removal, this study directly compares GO-modified zeolite (GOZ) with an ascorbic-acid-reduced analogue (rGOZ) prepared on the same clinoptilolite matrix by liquid-phase impregnation and evaluated under identical batch conditions. Spectroscopic/microscopic, elemental (CHNS) and textural analyses (UV–Vis, FT-IR, SEM/EDS, N ₂ sorptiometry and thermogravimetry) confirm successful attachment of the carbon phases (~ 9% graphene loading) and reveal distinct surface chemistries: GOZ retains abundant oxygenated groups, whereas rGOZ is more graphitic and both composites exhibit partial pore blocking. Relative to pristine clinoptilolite (q ~ 35 mg g ⁻¹ at 298 K), the maximum MB uptake (Langmuir) increases to ~ 157 mg g ⁻¹ for GOZ and ~ 123 mg g ⁻¹ for rGOZ, demonstrating a substantial enhancement upon carbon-phase incorporation. Adsorption is favored near neutral pH, follows pseudo-second-order kinetics for both composites, and shows endothermic, entropy-driven, spontaneous behavior over 298–333 K. Equilibrium data indicate more heterogeneous/pore-filling contributions for GOZ and a more monolayer-like, π–π-assisted uptake for rGOZ, consistent with their different functional-group densities. Regeneration by 0.1 N HCl washing over five cycles shows higher durability of GOZ, with MB removal decreasing from ~ 98% (cycle 1) to ~ 84% (cycle 5), compared with rGOZ decreasing from ~ 93 to ~ 71%. Overall, these results quantify how the oxidation state of the graphene phase governs MB uptake and reuse performance in clinoptilolite-based hybrid adsorbents. Graphical abstract

Here, we highlight the research presented in this Special Issue, focusing on the innovative use of graphene and other two-dimensional (2D) materials to develop advanced coating technologies. The contributions herein address critical challenges such as the scalable fabrication and stable dispersion of such materials and their compatibility with conventional coating systems, offering solutions that enhance their mechanical strength, chemical stability, and multifunctionality. The featured studies demonstrate the diverse applications of these materials, from protective anticorrosive barriers to high-performance optoelectronic devices and environmental remediation. Moving forward, future research is encouraged to explore novel 2D materials, hybrid coating strategies, and advanced computational modeling to overcome existing limitations and unlock new possibilities.