Understanding graphene oxide’s stability (or lack thereof) in liquid solvents is critical for fine-tuning the material’s characteristics and its potential involvement in future applications. In this work, through the use of structural and surface investigations, the alteration of the structural and edge-surface properties of 2D graphene oxide nanosheets was monitored over a period of eight weeks by involving DLS, zeta potential, XRD, XPS, Raman and FT-IR spectroscopy techniques. The samples were synthesized as an aqueous suspension by an original modified Marcano-Tour method centred on the sono-chemical exfoliation of graphite. Based on the acquired experimental results and the available literature, a phenomenological explanation of the two underlying mechanisms responsible for the meta-stability of graphene oxide aqueous dispersions is proposed. It is based on the cleavage of the carbon bonds in the first 3–4 weeks, while the bonding of oxygen functional groups on the carbon lattice occurs, and the transformation of epoxide and hydroxyl groups into adsorbed water molecules in a process driven by the availability of hydrogen in graphene oxide nanosheets.

Advances in energy storage and energy conversion play an essential role nowadays because the energy demands are becoming greater than ever. To overcome the actual performances of the materials used to build supercapacitors, a combination of transition metal dichalcogenides (TMDCs) and graphene oxide (GO) or reduced graphene oxide (rGO) as graphene-based structures are often studied for their excellent properties, such as high specific area and good electrical conductivity. Nevertheless, synthesis pathways and parameters play key roles in obtaining better materials as components for supercapacitors with higher technical performances. Driven by the desire to understand the influence of the structural and morphological particularities on the performances of supercapacitors based on MoS₂/graphene oxide (GO) composites, a survey of the literature was performed by pointing out the alterations induced by different synthesis pathways and key parameters to the above-mentioned particularities.

Stone cultural heritage faces significant deterioration from environmental factors, necessitating protective treatments that preserve both functionality and appearance. In this study, graphene oxide (GO) was evaluated as a protective coating for both natural and artificially aged Euganean trachyte and Vicenza stone samples. GO was applied as a low-concentration aqueous dispersion (0.5 mg/mL) by brush, and samples were subsequently exposed to UV light for 7 h to simulate weathering. Performance was assessed in accordance with European standards through measurements of water capillary absorption, water vapor permeability, contact angle, and color variation; further characterization was conducted using FT–IR, Raman spectroscopy, SEM, and XRD. Results indicate that GO coatings reduce the water capillary absorption coefficient by up to 49% for Euganean trachyte and 22% for Vicenza stone, while maintaining vapor permeability close to that of untreated samples. Although UV exposure permanently darkens the coating, it slightly enhances hydrophobicity, likely due to differential photoreduction of thin surface layers versus thicker pore-associated GO domains. These findings suggest that, while GO, particularly after UV weathering, shows promise for stone protection, further research is crucial to optimize coating uniformity and assess long-term durability under realistic environmental conditions.

Seafood-derived carbonate waste, primarily calcium carbonate (CaCO₃), has attracted growing interest for sustainable reuse, yet the unique potential of aged biogenic sources remains underexplored. Blue crab (Callinectes sapidus) shells are particularly distinctive: they consist of Mg-calcite with an intrinsic 3D-porous structure and naturally embedded astaxanthin, a potent antioxidant not found in other calcite- or aragonite-based residues. While organic degradation over time is often assumed to compromise functionality, this study demonstrates that five-years-aged crustacean shell waste retains both its crystallinity and bioactive carotenoids after calibrated ball milling. Across four powder batches produced under distinct milling conditions by varying frequencies and durations, dynamic light scattering confirmed only subtle particle size variation, while Raman spectroscopy, XRD, FT-IR, and SEM-EDX confirmed structural and chemical integrity and highlighted the subtle amorphization induced by slightly different milling parameters, which, in turn, driven to slightly different conversion efficiency into phosphate mineral. Strikingly, all powders underwent rapid transformation into dicalcium phosphate dihydrate (brushite) enriched with carotenoids upon reaction with phosphoric acid. This work reveals, for the first time, that years-aged biogenic Mg-calcite waste not only preserves its naturally embedded carotenoids but also offers a direct route to functional phosphate composites, establishing its untapped value in environmental and biomedical applications.

Biogenic carbonate waste from seafood exploitation, primarily composed of calcium carbonate (CaCO₃), occurs in various polymorphic forms, making it valuable for envi-ronmental and biomedical applications. Mg-calcite from blue crab (Callinectes sapidus) shells is especially promising due to its 3D-ordered porosity and naturally embedded astaxanthin antioxidant, offering advantages over other calcite- or aragonite-based waste. These properties enable its use in pharmaceutical formulations and biostimulants for ac-tive compound loading and controlled release. However, long-term aged biogenic waste may experience organic degradation, potentially altering its physical, chemical, and functional performance. In this study, calibrated ball milling conditions were applied to years-aged biogenic waste to assess structural integrity, crystallinity, and functionality of the resulting powders. Notably, the antioxidant carotenoid remained preserved across all fine powders. Dynamic light scattering revealed that particle size distribution varied subtly between two milling durations (12 and 15 min) and frequencies (25 and 27 Hz). Pigmentation, crystallinity, and repurposing potential of the powders were investigated using Raman spectroscopy, X-ray diffraction (XRD), FT-IR, and SEM-EDX. Ultimately, all four powder batches showed successful conversion into phosphate minerals enriched with antioxidants when treated with phosphoric acid, highlighting the potential of aged shell waste in high-value applications under optimized mechanical and chemical condi-tions.