Search Results (3,505)

Flexible gel sensors can lose mechanical compliance and electrical stability at low temperature or during solvent loss. A poly(vinyl alcohol) (PVA)/sodium alginate (SA)/graphene oxide (GO) composite gel was prepared by freeze–thaw cycling and post-treated in either aqueous NaCl or a NaCl-containing water/glycerol mixture (1:2, v/v). The water/glycerol–NaCl-treated gel (F-G/S/P/G) exhibited a maximum tensile stress of 428 ± 27 kPa and an elongation at break of 432 ± 27% at room temperature (n = 3), and remained visibly deformable after 24 h at −20 °C. During ambient storage, it retained approximately 89% of its initial mass after 35 days. The cycle-averaged peak ΔR/R₀ increased from 0.135 at 20% strain to 1.142 at 250% strain, and the 20–60% linear region gave a gauge factor of 1.01 (R² = 0.9988). Three independently prepared sensing elements gave a peak ΔR/R₀ of 0.710 ± 0.019 at 100% strain, with response and recovery times of 1.22 ± 0.07 and 1.04 ± 0.06 s, respectively. After 500 cycles at 100% strain, the normalized peak response retained 95.1% of its initial value. Overall, F-G/S/P/G combined low-temperature deformability, ambient-storage mass retention, and repeatable resistance sensing. Full article

Distal-less homeobox 1 (DLX1) has emerged as a promising urinary biomarker for prostate cancer. This study developed a label-free piezoelectric acoustic biosensor for selective DLX1 detection using a quartz crystal microbalance (QCM). The QCM gold electrode was sequentially functionalized with L-cysteine, graphene oxide (GO), and an amine-terminated DLX1 capture probe covalently immobilized through EDC–NHS-mediated amide bond formation. Stepwise surface functionalization was characterized by X-ray photoelectron spectroscopy (XPS), supported by contact angle measurements, X-ray diffraction, and field-emission scanning electron microscopy. XPS provided multi-element evidence for Au–S thiolate formation, GO deposition, amide coupling, probe immobilization, and Watson–Crick hybridization with the synthetic DLX1 target. Under optimized conditions, the biosensor exhibited a linear response to DLX1 concentrations and achieved a limit of detection of 81.19 nM. Non-complementary sequences, including PCA3 and SARS-CoV-2, produced frequency shifts below 9 Hz, confirming high selectivity. Comparative experiments showed that GO-mediated covalent immobilization was essential for reliable detection, whereas direct DNA attachment to bare Au generated anomalous positive frequency shifts, which were attributed to weak physisorption. The proposed platform offers a sensitive and selective strategy for quantitative DLX1 detection and may support future point-of-care nucleic acid diagnostics. Full article

The demand for lightweight, flexible, and lead-free radiation shielding for next-generation extravehicular activity suits and aerospace habitat liners is rapidly intensifying. This study investigates the structural organization and X-ray attenuation performance (10–60 keV) of polyethylenimine/graphene oxide (PEI/GO) composites with GO loadings up to 50 wt%. Microstructural evolution was systematically tracked via optical image quantification (dispersion, connectivity, and local mixing indices) correlated with micro-Raman spectral mapping. Raman analysis confirmed a structural transition at 40 wt% GO, driven by a dynamic competition between covalent amine–epoxide/carboxyl functionalization and localized π–π stacking of sp² domains. X-ray transmission and linear attenuation coefficients were evaluated using a dual approach, coupling experimental X-ray exposures with deterministic NIST XCOM calculations and stochastic Monte Carlo simulations. The results demonstrate that GO significantly amplifies low-energy photoelectric absorption due to its oxygen-rich functionalities. An anomalous thickness-dependent attenuation paradox, which can be explained by accounting for forward-scattered Compton buildup in thick blocks and spatial edge refraction along non-percolating cluster interfaces in thin films, was observed experimentally. These findings provide critical material design rules for advanced, flexible, and wearable photon shields operating without mass penalties. Full article

Porous three-dimensional reduced graphene oxide (3DrGO) combines a hierarchical pore network with tunable surface chemistry, making it an attractive material for applications involving mass transport and interfacial phenomena. In this work, the pore structure and surface properties of 3DrGO were investigated using conventional and low-field nuclear magnetic resonance (NMR) techniques. Scanning electron microscopy (SEM), N₂ adsorption–desorption isotherms, X-ray photoelectron spectroscopy (XPS), Carr-Purcell-Meiboom-Gill (CPMG) NMR relaxometry, and Fast Field Cycling (FFC) NMR relaxometry were employed to characterize the material over multiple length scales and probe confined liquid dynamics. While SEM and gas adsorption resolved the macro- and mesoporous structure, CPMG relaxometry revealed several confined liquid populations. Comparison of the NMR relaxation and XPS data suggested that the abundance of oxygen-containing surface groups contributes to differences between polar and nonpolar molecule-surface interactions, with stronger apparent interactions for polar liquids. The desorption behavior was consistent with nonuniform liquid coverage under partially saturated conditions. Analysis of NMR dispersion profiles further indicated a rough, chemically heterogeneous surface, highlighting the potential of low-field NMR techniques as powerful tools for correlating pore architecture, surface chemistry, and molecular dynamics in porous 3DrGO. Full article

Constructing heterointerfaces between semiconductor photocatalysts and carbonaceous materials is an effective strategy for enhancing photocatalytic performance. However, the role of graphene oxide (GO) in modulating the interfacial electronic properties of Aurivillius-layered perovskites has remained unexplored, until now. In this work, GO/Na_0.5Bi_2.5Nb₂O₉ (ABNO) composites, denoted as GABNO, with different GO loadings were successfully synthesized using a hydrothermal method. Structural, chemical and surface characterizations confirmed the formation of intimate GO/ABNO heterointerfaces without altering the crystal structure of ABNO. GO incorporation established electronically coupled heterointerfaces and modified the interfacial electronic environment, as evidenced by XPS and flat-band potential analyses. Among all samples, GABNO 0.1 (0.1 mg GO loading) exhibited the highest photocatalytic activity, achieving nearly 100% Rhodamine B removal within 120 min and significantly enhancing methyl orange removal under UV–visible light irradiation. Radical trapping experiments further revealed that GO altered the dominant photocatalytic reaction pathway from hole-dominated oxidation to superoxide-radical-mediated degradation. The superior photocatalytic performance is attributed to GO-induced interfacial electronic interactions, which facilitate efficient interfacial electron utilization and alter the dominant photocatalytic reaction pathway. This work provides new insight into the design of GO/Aurivillius-layered perovskite and highlights interfacial electronic regulation as an effective strategy for developing high-performance photocatalysts for environmental remediation. Full article

Polyethylene terephthalate (PET) and polystyrene (PS) nanoplastics are major aquatic contaminants due to their high persistence, mobility, and potential ecological impacts. In this study, PET–NPs and PS–NPs were prepared by nanoprecipitation, and the adsorption of both types of nanoplastics by graphene oxide–chitosan (GO–CS), graphene oxide–microcrystalline cellulose 50µm (GO–MCC50µm), and graphene oxide–microcrystalline cellulose 90µm (GO–MCC90µm) composites was systematically investigated. The structural and physical properties of the materials were characterized using transmission electron microscopy (TEM), pH_pzc analysis, Dynamic Light Scattering (DLS), zeta potential, and X-ray photoelectron spectroscopy (XPS). Batch adsorption experiments evaluated the effects of pH, contact time, initial concentration, and temperature on adsorption efficiency, while the adsorption mechanism was analyzed through kinetic, isotherm, and thermodynamic studies. The maximum Langmuir adsorption capacities for PS–NPs were 13.60, 12.59, and 11.19 mg·g⁻¹ for GO–CS, GO–MCC50µm, and GO–MCC90µm composites, respectively. The maximum adsorption capacities for PET–NPs were 56.17, 33.33, and 23.20 mg·g⁻¹ for GO–CS, GO–MCC50µm, and GO–MCC90µm composites, respectively. This study provides new insights into the effects of adsorbent surface chemistry, particle size, and nanoplastic morphology on adsorption processes, highlighting graphene oxide–polysaccharide composites as promising eco-friendly materials for nanoplastic removal from aqueous media. Full article

Alkaline water electrolysis (AWE) is a promising technology for sustainable hydrogen production, although its performance is limited by electrode overpotential, interfacial charge-transfer resistance, and limited electrochemically accessible surface area. In this study, a monolayer ternary carbon nanomaterial (CNM) composite comprising reduced graphene oxide (rGO), carbon nanotubes (CNTs), and Vulcan XC-72 was fabricated on stainless steel (SS) using a hybrid polyvinyl alcohol–polytetrafluoroethylene (PVA–PTFE) binder. Thermal treatment generated a porous conductive network that enhanced electrolyte accessibility and electron transport. Electrochemical characterization in 0.12 M NaOH showed that the CNM-modified electrode exhibited substantially higher current response and CV-derived double-layer capacitance (C_dl) of 62.61–78.51 mF/cm², compared with 3.43–3.74 mF/cm² for bare SS. Electrochemical fitting further showed markedly higher exchange-current density (i₀) parameters for the modified electrode, along with a reduced solution resistance (Rs) of ~2.1–2.2 Ω·cm² and a lower Rct. The oxyhydrogen (HHO) production rate reached 0.304 mL/min at 3.8 V, compared with 0.262 mL/min for bare SS at 4.0 V. Repeated HHO measurements showed ~2% variation (n = 3), indicating good reproducibility of the gas-production response. These results demonstrate that the rGO/CNT/XC-72 composite provides an effective and reproducible surface-engineering approach for enhancing electrochemical performance and HHO production in alkaline electrolysis systems. Full article

Graphene and graphene oxide (GO) are promising nanofillers for improving thermal transport in cementitious materials, but their performance is strongly affected by interactions with calcium silicate hydrate (C-S-H). Understanding how these fillers retain or lose their heat-transport capability after incorporation into the cement hydrate matrix is therefore important for rational nanocomposite design. Reverse non-equilibrium molecular dynamics simulations were conducted to compare isolated graphene/GO sheets with the corresponding sheets embedded in C-S-H. The extrapolated thermal conductivity of pristine graphene decreased from 1854.6 to 1264.2 W/(m·K) after embedding, giving a retention ratio of 0.68. Increasing the oxidation degree reduced the intrinsic conductivity of GO through defect-induced phonon scattering, while the additional reduction caused by C-S-H progressively weakened. At an oxidation degree of 20%, GO retained more than 90% of its isolated-sheet conductivity. Atomic heat-flux analysis showed that C-S-H markedly broadened the transport-direction distribution of graphene but produced only limited additional disturbance in GO. Interfacial binding energy increased with oxidation degree, and radial distribution function analysis identified short-range Ca-O coordination and hydrogen bonding at the GO/C-S-H interface. Phonon density of states analysis further revealed pronounced substrate-induced phonon softening in graphene, whereas the vibrational spectrum of GO remained comparatively stable. These results clarify the trade-off between intrinsic conductivity and matrix-induced thermal stability in graphene-based cementitious nanocomposites. Full article

Graphene oxide (GO) offers a high-surface-area platform for the noncovalent association of hydrophobic bioactive compounds, but its biological response depends strongly on surface chemistry. Here, GO was carboxylated with sodium chloroacetate and physically associated with curcumin (CUR) to obtain a graphene oxide–curcumin nanoadduct (GO-COOH-CUR). Ultraviolet-visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to assess chemical and morphological changes. XPS showed a lower C/O ratio and a higher fitted O-C=O contribution after carboxylation, although residual Na and Cl were detected. UV-vis, FTIR and XPS features were consistent with the presence of curcumin in the formulation with 83.35% of encapsulation efficiency (EE). In 24 h MTT assays, CO-COOH-CUR maintained BHK-21 metabolic activity above 70% across 3.125 µg mL⁻¹ and reduced MCF-7 metabolic activity at the higher tested concentrations. Because formulation concentrations were expressed as a total mass and curcumin concentration is not reported here, direct potency or selectivity comparisons with free curcumin were not made. Qualitative histological evaluation performed 30 days after subdermal implantation in three male Wistar rats showed preserved adjacent tissue architecture, with no evident necrosis, prominent inflammatory infiltrate, organized fibrous capsule, or foreign-body giant cell response in the sections evaluated. These findings support further evaluation of GO-COOH-CUR within the limits of MTT-based and qualitative assessment. Full article

This work reports the synthesis and characterization of sustainable, multifunctional chitosan/graphene oxide hybrid nanoparticles (GOCS_NPs) prepared via a low-temperature ionotropic gelation method utilizing sodium tripolyphosphate as a green crosslinker. Combined DLS and TEM analyses confirmed the successful formation of submicron spherical nanoparticles with a mean diameter of 295 ± 15 nm (PDI 0.26), and GOCS_NPs were evaluated as a dual-action platform for the adsorption of a model cationic dye, Methylene Blue (MB), and for antimicrobial remediation against Staphylococcus aureus and Escherichia coli. Equilibrium adsorption studies revealed that incorporating GO dramatically increased the maximum monolayer adsorption capacity from 2.78 mg g⁻¹ (for CS_NPs) to 37.16 mg g⁻¹ (for GOCS_NPs), closely following the Langmuir and Sips models through a pseudo-second order sorption mechanism. Furthermore, desorption investigations demonstrated that the GOCS_NPs maintained substantial adsorption performance over multiple adsorption–desorption cycles under controlled conditions. Concurrently, GOCS_NPs exhibited a dose-dependent enhancement in antibacterial efficacy, showing greater activity against Gram-negative E. coli (MIC of 1.25 mg mL⁻¹) than against Gram-positive S. Aureus (MIC of 2.50 mg mL⁻¹). Overall, these findings elucidate the structure–property–performance relationships of these carbon–biopolymer hybrid nanocomposites, validating their suitability as an advanced, eco-friendly, and reusable platform for comprehensive and sustainable wastewater remediation. Full article

Aluminum and its alloys feature low weight and high strength. They are widely applied in aerospace, automobile manufacturing, and marine engineering. However, they are highly susceptible to localized corrosion. Such defects can severely restrict the service life of the substrate materials. Pristine graphene exhibits atomic-level compact impermeability, stable chemical inertness, and excellent mechanical properties. It is a promising candidate material for the protection of aluminum substrates. Nevertheless, an electrically insulating interlayer is generally required between pristine graphene and aluminum to achieve reliable protection. This measure avoids the risk of galvanic corrosion. This paper systematically reviews the latest research progress of graphene-based coatings on aluminum, focusing on pristine graphene, graphene oxide (GO), reduced graphene oxide (rGO), and graphene-polymer composite coatings. It focuses on the preparation methods and corrosion protection performance of the materials. This study compares various mainstream preparation technologies in detail. The technologies include chemical vapor deposition, electrochemical deposition, mechanical exfoliation, solution coating, laser induction, and thermal spraying. The corrosion protection mechanism is discussed from three dimensions. The dimensions include physical barrier effect, tortuous path mechanism, and electrochemical protection. Key influencing factors, such as coating defects and environmental conditions, are also investigated. This paper summarizes the application potential of graphene-based coated aluminum in high-end manufacturing fields. It points out the major existing challenges of the material. The challenges involve coating uniformity, adhesion strength, long-term stability, and industrial production. Finally, future research directions are proposed in this work. These directions include the development of innovative coating technologies, the construction of composite protection systems, the design of intelligent self-healing functions, and the exploration of environmentally friendly preparation processes. Full article

This study evaluated the effect of modifying pine and birch wood veneers with graphene oxide (GO) and the duration of UV irradiation on roughness parameters (Ra, Rz, Rq). Surface roughness was evaluated in directions both perpendicular and parallel to the grain after 0, 16, 32, and 48 h of photoageing exposure. The study showed that the measurement direction was the main factor determining the values of the roughness parameters. The interaction between impregnation and UV exposure time was significant, indicating that the effect of UV radiation depended on the impregnation used. The roughness parameters for birch were relatively stable. In contrast, for non-impregnated pine, UV radiation caused an increase in roughness, particularly in the direction perpendicular to the grain. Graphene oxide impregnation altered the ageing course of the pine surface, resulting in reduced roughness parameters at longer exposure times. Full article

Flexible electronic textiles hold potential applications across various fields, yet current functionalization methods frequently suffer from poor coating uniformity and severe aesthetic alteration. This study addresses these challenges by establishing a multi-analytical approach, based on Raman spectroscopy together with DLS, Zeta potential and XPS measurements, to optimize graphene oxide (GO) precursor selection prior to electrostatic deposition onto cotton fabrics using a polyethyleneimine linker. This coating strategy was inspired by layer-by-layer deposition technique and centrifugation was used to partition a heterogeneous commercial GO precursor into three distinct homogeneous fractions. Raman spectroscopy revealed that centrifugation acts not merely separating GO based on its size but effectively sorts GO sheets based on their chemical functionalization degree. Consequently, this approach allows for the identification of the optimal precursor fraction, balancing sheet dimensions with defect density, to ensure strong functionalization. Overall, this work established a foundational spectroscopic methodology for precursor selection, deposition monitoring and process optimization, which can also be extended to the characterizing and comparison of different commercial GO batches from different industrial suppliers. Finally, micro-Raman mapping and XPS were preliminary applied to verify the textile fiber functionalization. Full article

To address cathode passivation, performance deterioration, and toxic stress during the removal of hexavalent chromium [Cr(VI)] in biocathode microbial fuel cells (MFCs), this study constructed nanomaterial-hybridized biocathodes to improve electricity generation and Cr(VI) removal in MFCs. Reduced graphene oxide (rGO), nano-iron sulfide (nano-FeS), and rGO/nano-FeS were separately hybridized with biocathodes to systematically investigate the effects of different hybridized biocathodes on the performance of MFCs for Cr(VI)-containing wastewater treatment. The results showed that the FeS group exhibited the best Cr(VI) removal capability, with a maximum removal kinetic constant of 0.184 h⁻¹, which was 3.60 times that of the Control group, and showed the smallest performance decline after three consecutive cycles. Mechanistic analysis indicated that nano-FeS promoted the transformation of Cr(VI) into Cr(III) and Cr(0) through its strong adsorption and reducing capacities; it also enhanced biofilm cell activity and the protein/polysaccharide ratio in extracellular polymeric substances; furthermore, it shaped a multi-taxon-dominated microbial community capable of Cr(VI) tolerance and reduction and enhanced the associated metabolic functions, thereby improving resistance to Cr(VI) stress and effectively alleviating cathode passivation. In contrast, rGO tended to enhance biocathode conductivity and electricity generation in MFCs, with the rGO + FeS group achieving the highest power density output of 51.54 ± 3.62 mW/m², which was 1.22 times that of the Control group, as well as the smallest decline in power density after three consecutive cycles. Overall, nanomaterial hybridization reshaped interfacial electron transfer and microbial stress resistance in biocathodes, enabling efficient Cr(VI) removal and stable electricity generation, and providing a new strategy to construct long-term stable bioelectrochemical systems for heavy metal-containing wastewater treatment. Full article

This study reports the synthesis and comprehensive characterization of a novel 5% cadmium-doped cerium oxide/reduced graphene oxide (5% Cd-CeO₂/rGO) nanocomposite for the enhanced visible-light-driven photocatalytic degradation of methyl orange (MO). The nanocomposite was prepared using a simple co-precipitation method followed by thermal reduction, which integrates the excellent electron-transport properties of reduced graphene oxide (rGO) with the oxygen-vacancy-rich characteristics of Cd-doped CeO₂, resulting in improved photocatalytic performance. The successful synthesis of the nanocomposite and the direct interaction between the rGO sheets and ultrafine CeO₂ nanoparticles were verified through structural and morphological analyses using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM). XPS results indicated an increase in the Ce³⁺ concentration and oxygen vacancy density after Cd doping and rGO incorporation, both of which play a crucial role in enhancing photocatalytic activity. Under visible-light irradiation, the 5% Cd-CeO₂/rGO nanocomposite exhibited substantially higher photocatalytic activity and methyl orange (MO) degradation efficiency than pristine CeO₂ and reduced graphene oxide (rGO). The improved photocatalytic performance demonstrates the beneficial role of combining metal-ion doping with conductive carbon supports to facilitate charge separation and electron transport in semiconductor photocatalysts. The developed nanocomposite also shows promising potential for the design of next-generation semiconductor-based materials for photocatalytic, energy conversion, and optoelectronic applications. Full article