Search Results (1,334)

The widespread adoption of sodium-ion batteries (SIBs) remains constrained by the inherent limitations of conventional anode materials, particularly their inadequate electronic conductivity, limited active sites, and pronounced structural degradation during cycling. To overcome these limitations, we propose a novel redox engineering approach to fabricate oxygen-vacancy-rich SnO₂ dots anchored on reduced graphene oxide (rGO), which are encapsulated within N-doped carbon nanofibers (denoted as ov-SnO₂/rGO@N-CNFs) through electrospinning and subsequent carbonization. The introduction of rich oxygen vacancies establishes additional sodium intercalation sites and enhances Na⁺ diffusion kinetics, while the conductive N-doped carbon network effectively facilitates charge transport and mitigates SnO₂ aggregation. Benefiting from the well-designed architecture, the hierarchical ov-SnO₂/rGO@N-CNFs electrode achieves remarkable reversible specific capacities of 351 mAh g⁻¹ after 100 cycles at 0.1 A g⁻¹ and 257.3 mAh g⁻¹ after 2000 cycles at 1.0 A g⁻¹ and maintains 177 mAh g⁻¹ even after 8000 cycles at 5.0 A g⁻¹, demonstrating exceptional long-term cycling stability and rate capability. This work offers a versatile design strategy for developing high-performance anode materials through synergistic interface engineering for SIBs. Full article

This review article compiled previous reports in the fabrication of hydroquinone (HQ) electrochemical sensors using differently modified electrodes. The electrode materials, which are also called electrocatalysts, play a crucial role in electrochemical detection of biomolecules and toxic substances. Metal oxides, MXenes, carbon-based materials such as reduced graphene oxide (rGO), carbon nanotubes (CNTs), layered double hydroxides (LDH), metal sulfides, and hybrid composites were extensively utilized in the fabrication of HQ sensors. The electrochemical performance, including limit of detection, linearity, sensitivity, selectivity, stability, reproducibility, repeatability, and recovery for real-time sensing of the HQ sensors have been discussed. The limitations, challenges, and future directions are also discussed in the conclusion section. It is believed that the present review article may benefit researchers who are involved in the development of HQ sensors and catalyst preparation for electrochemical sensing of other toxic substances. Full article

Membrane separation technology has shown significant potential in the treatment of mixed dye wastewater. In this study, a reduced graphene oxide (AH-rGO) membrane was prepared using an amino-hydrothermal method and applied for the first time in mixed dye separation. These membranes can selectively recover high-value dyes while addressing the technical challenges of balancing permeability and selectivity in traditional membrane materials, which are often at odds with each other in the treatment of mixed dye wastewater. We simulated actual dye wastewater using four dyes: methyl orange (MO), methyl blue (MB), rhodamine B (RB), and Victoria Blue B (VBB). The four combinations of mixed dyes were MO/VBB, RB/VBB, MO/MB, and RB/MB, all of which demonstrated high water permeability and separation efficiency. Notably, the MO/VBB combination achieved a maximum water permeability rate of 118.79 L m⁻² h⁻¹ bar⁻¹ and a separation factor of 24.2. The AH-rGO membrane is currently the highest-permeability membrane available, achieving excellent separation results with typical mixed dye wastewater. Additionally, it demonstrates good stability. The experimental results indicate that the overall performance of the AH-rGO membrane is superior to that ofother graphene oxide (GO) membranes, which reveals the significant application potential of this membrane in the field of mixed dye wastewater treatment. Full article

To investigate the impermeability of foam concrete in various challenging environments, this study evaluates its water resistance by measuring the water contact angle and water absorption. Polyurethane (PU) was used to fabricate polyurethane foam concrete (PFC), enabling a monolithic hydrophobic modification to improve the permeation performance of foam concrete. The study also examines the effects of carbonation and freeze–thaw environments on the permeation resistance of PFC. Graphene oxide (GO), KH-550, and a composite hydrophobic coating (G/S) consisting of GO and KH-550 were employed to enhance the permeation resistance of PFC through surface hydrophobic modification. The functionality of the G/S composite hydrophobic coating was confirmed using energy dispersive X-ray spectrometry (EDS) and Fourier transform infrared spectroscopy (FTIR). The results showed the following: (1) The water contact angle of PFC increased by 20.2° compared to that of ordinary foam concrete, indicating that PU-based hydrophobic modification can significantly improve its impermeability. (2) After carbonation, a micro–nano composite structure resembling the surface of a lotus leaf developed on the surface of PFC, further enhancing its impermeability. However, freeze–thaw cycles led to the formation and widening of microcracks in the PFC, which compromised its hydrophobic properties. (3) Surface hydrophobic modifications using GO, KH-550, and the G/S composite coating improved the anti-permeability properties of PFC, with the G/S composite showing the most significant enhancement. (4) GO filled the tiny voids and pores on the surface of the PFC, thereby improving its anti-permeability properties. KH-550 replaced water on the surface of PFC and encapsulated surface particles, orienting its R-groups outward to enhance hydrophobicity. The G/S composite emulsion coating formed a hydrophobic silane layer inside the concrete, which enhanced water resistance by blocking water penetration, reducing microscopic pores in the hydrophobic layer, and improving impermeability characteristics. Full article

The increasing incidence of oil contamination in many aquatic ecosystems, particularly in oil-rich regions such as Qatar, poses significant threats to marine life and human activities. Our study addresses the critical need for effective and eco-friendly oil-water separation techniques, focusing on developing graphene and chitosan-based three-dimensional (3D) polymeric sponges. These materials have demonstrated potential due to their high porosity and surface area, which can be enhanced through surface treatment to improve hydrophobicity and oleophilicity. This study introduces a new technique dependent on the optimization of the graphene oxide (GO) concentration within the composite sponge to achieve a superior oil uptake capacity (51.4 g oil/g sponge at 3% GO), and the detailed characterization of the material’s performance in separating heavy oil-water emulsions. Our study seeks to answer key questions regarding the performance of these modified sponges and their scalability for industrial applications. This research directly aligns with Qatar’s environmental goals and develops sustainable oil-water separation technologies. It addresses the pressing challenges of oil spills, ultimately contributing to improved marine ecosystem protection and efficient resource recovery. Full article

This study reports the impact of a silver nanoparticles/reduced graphene oxide@titanium dioxide nanocomposite (Ag/rGO@TiO₂) on the mechanical and biocompatibility properties of poly(styrene-co-methylmethacrylate)/poly methyl methacrylate (PS-PMMA/PMMA)-based bone cement. The chemical, structural, mechanical, and thermal characteristics of Ag/rGO@TiO₂ nanocomposite-reinforced PS-PMMA bone cement ((Ag/rGO@TiO₂)/(PS-PMMA)/PMMA) were evaluated using Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction (XRD), nano-indentation, and electron microscopy. FT-IR, XRD, and transmission electron microscopy results confirmed the successful synthesis of the nanocomposite and the nanocomposite-incorporated bone cement. The elastic modulus (E) and hardness (H) of the ((Ag/rGO@TiO₂)/(PS-PMMA)/PMMA) bone cement were measured to be 5.09 GPa and 0.202 GPa, respectively, compared to the commercial counterparts, which exhibited E and H values of 1.7 GPa to 3.7 GPa and 0.174 GPa, respectively. Incorporating Ag/rGO@TiO₂ nanocomposites significantly enhanced the thermal properties of the bone cement. Additionally, in vitro studies demonstrated that the bone cement was non-toxic to the MG63 cell line. Full article

White-light-emitting diodes (wLEDs) are central to next-generation lighting technologies, yet their reliance on critical raw materials (CRMs), such as rare-earth elements, raises concerns regarding sustainability and supply security. In this work, we present a simple, low-cost method to produce photoluminescent carbon-based nanostructures—known as oxidative debris (OD)—via alkaline treatment of graphene oxide (GO) using KOH solutions ranging from 0.04 M to 1.78 M. The resulting OD, isolated from the supernatant after acid precipitation, exhibits strong and tunable photoluminescence (PL) across the visible spectrum. Emission peaks shift from blue (~440 nm) to green (~500 nm) and yellow (~565 nm) as a function of treatment conditions, with excitation wavelengths between 300 and 390 nm. Optical, morphological. and compositional analyses were performed using UV-Vis, AFM, FTIR, and Raman spectroscopy, confirming the presence of highly oxidized aromatic domains. The blue-emitting (S2) and green/yellow-emitting (R2) fractions were successfully separated and characterized, demonstrating potential color tuning by adjusting KOH concentration and treatment time. This study highlights the feasibility of reusing GO-derived byproducts as sustainable phosphor alternatives in wLEDs, reducing reliance on CRMs and aligning with green chemistry principles. Full article

In this work, a glassy carbon electrode (GCE) modified with reduced graphene oxide and β-cyclodextrin (rGO/β-CD) nanocomposite was developed for the electrochemical detection of nitrofurantoin (NFT). The structural and morphological characteristics of the synthesized nanocomposite were determined using scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Moreover, the electrochemical behavior of the modified electrodes was thoroughly examined using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), with the rGO/β-CD-modified glassy carbon electrode (GCE) demonstrating superior electron transfer capability. Key experimental parameters, including scan rate, material loading, and solution pH, were systematically optimized. After optimizing the experimental conditions, the modified sensor showed excellent electrocatalytic performance and selectivity toward NFT, achieving a broad linear detection range from 0.5 to 120 μM, a low limit of detection (LOD) of 0.048 μM, and a high sensitivity of 12.1 µA µM^–1 cm^–2 using differential pulse voltammetry (DPV). Furthermore, the fabricated electrode exhibited good anti-interference ability, stability, precision, and real-time applicability for NFT detection in a wastewater sample. These results highlight the potential of the rGO/β-CD nanocomposite as a high-performance platform for electrochemical sensing applications. Full article

Background/Objectives: Autopolymerizing poly (methyl methacrylate) (PMMA) resin is widely used in provisional restorations; however, its inadequate mechanical properties represent a significant limitation. This study aimed to develop electrospun fibers with chemically reduced graphene oxide (rGO) and to evaluate the effect of fiber reinforcement on the mechanical and physical properties of a commercially available PMMA resin. Methods: Electrospinning was employed to produce nanofibers containing 0.02 wt% and 0.05 wt% rGO within a PMMA matrix. Fiber characterization was performed using SEM-EDS, XRD, TGA/DTG, and FTIR. Following characterization, the fibers were blended into PMMA resin at 1%, 2.5%, and 5% (by weight). The resulting fiber-reinforced composites were tested for flexural strength, elastic modulus, surface roughness, and Vickers microhardness. Results: The addition of 1% and 2.5% PMMA/rGO-0.02 fibers and 1% PMMA/rGO-0.05 fibers significantly improved the flexural strength of PMMA compared with the control group (p < 0.05). A statistically significant increase in elastic modulus was observed only in the group containing 1% PMMA/rGO-0.02 fibers (p < 0.05). However, there were no significant differences in surface roughness or microhardness between the control and experimental groups (p > 0.05). Conclusions: Incorporating electrospun PMMA-rGO fibers into PMMA resin enhances flexural properties at low concentrations without altering surface characteristics. These findings suggest that such fiber-reinforced systems hold promises for improving the mechanical performance and functional longevity of provisional dental restorations under clinical conditions. Full article

In this study, we synthesized anode materials based on iron oxide (Fe₂O₃), titanium dioxide (TiO₂), and reduced graphene oxide (rGO) via the electrophoretic deposition technique. The structural and morphological characteristics of electrodes were examined through various methods including SEM, XRD, Raman, and XPS. Among the investigated compositions, the three-component Fe₂O₃/TiO₂/rGO electrode displayed superior electrochemical characteristics in comparison to the binary Fe₂O₃/rGO and TiO₂/rGO electrodes. Specific capacities of 571, 683, and 729 mAh/g were achieved at 0.5 mA for the respective Fe₂O₃:TiO₂ molar ratios of 1:1, 2:1, and 3:1. The 2:1 ratio configuration offered the most promising balance between cycling stability and capacity, highlighting its potential as a high-performance anode in lithium-ion batteries. This work contributes valuable insights into the synergistic behavior of dual-transition metal oxides in composite electrode design using a low-cost and scalable method. Full article

Fibrous structure is a promising building block for developing high-performance wearable piezoresistive sensors. However, the inherent non-conductivity of the fibrous polymer remains a bottleneck for highly sensitive and fast-responsive piezoresistive sensors. Herein, we reported a polyaniline/reduced graphene oxide @ polydopamine/poly (vinylidene fluoride) (PANI/rGO@PDA/PVDF) nanofiber piezoresistive sensor (PNPS) capable of versatile wearable biomonitoring. The PNPS was fabricated by integrating rGO sheets and PANI particles into a PDA-modified PVDF nanofiber network, where PDA was implemented to boost the interaction between the nanofiber networks and functional materials, PANI particles were deposited on a nanofiber substrate to construct electroactive nanofibers, and rGO sheets were utilized to interconnect nanofibers to strengthen in-plane charge carrier transport. Benefitting from the synergistic effect of multi-dimensional electroactive materials in piezoresistive membranes, the as-fabricated PNPS exhibits a high sensitivity of 13.43 kPa⁻¹ and a fast response time of 9 ms, which are significantly superior to those without an rGO sheet. Additionally, a wide pressure detection range from 0 to 30 kPa and great mechanical reliability over 12,000 cycles were attained. Furthermore, the as-prepared PNPS demonstrated the capability to detect radial arterial pulses, subtle limb motions, and diverse respiratory patterns, highlighting its potential for wearable biomonitoring and healthcare assessment. Full article

Graphene, a two-dimensional carbon material, possesses exceptional properties such as high electron mobility, exceptional strength that surpasses that of steel, chemical resistance, environmental friendliness, and a large specific surface area. In this study, we used the modified Hummer process to produce graphene oxide, which was applied to an aluminum alloy substrate as a corrosion-resistant coating. The aluminum alloy used in our study is AA2024, which is widely applied in industry and aircraft. The coating layer was characterized by micro-Raman spectroscopy and atomic force microscopy (AFM) before and after the reduction process. Micro-Raman spectroscopy provided information on the degree of reduction and the presence of functional groups in the coating layer. AFM images enabled the study of surface morphology and topography. After the reduction process, achieved by annealing in an argon atmosphere at 140 °C, micro-Raman spectroscopy and AFM were again used to assess structural and morphological changes. The reduction resulted in the formation of reduced graphene oxide (RGO), which exhibited improved conductivity and stability. The combination of micro-Raman spectroscopy and AFM characterization techniques provided detailed information on the properties and effectiveness of the coating layer. This research contributes to developing anti-corrosion methods using advanced materials and surface engineering techniques. Full article

OoC systems employing human cells mirror the functionality of human organs and faithfully simulate their physiological microfluidic environment. Despite the potential of OoC technology in emulating tissue complexity, a significant gap persists in the continuous real-time monitoring of cellular behaviors and their responses to external stimuli, arising from the lack of biosensors integrated onto OoC microfluidic platforms. Addressing this limitation constitutes the primary objective of this study. By developing and incorporating biosensors onto a modular integrated OoC platform, we aim to enable the monitoring of changes taking place in the cellular environment under various stimuli in real time. An in-series modular integration of a biosensor array into an OoC platform is demonstrated herein, along with its potential to sustain human cell proliferation and accommodate the detection of IL-6, as an example of a mediator protein secreted as part of the immune response to inflammation. The implementation of commercially fabricated PCB components also addresses the issue of cost efficiency and manufacturing scaling-up of sensor-integrated OoCs. This advancement will not only enhance the accuracy and reliability of preclinical studies, but also pave the way for improved drug development and disease treatment. Full article

The poor thermal and physical properties of conventional engine oils limit vehicle performance and durability. This research aims to investigate the effect of nanoparticles such as fullerene C₆₀, titanium dioxide (TiO₂), iron oxide (Fe₂O₃), and reduced graphene oxide (rGO) nanoparticles on 10W30 Mobil engine oil. In this study, the effect of nanoparticle concentrations at different mass fractions (0.01, 0.05, and 0.1) was examined within the temperature range 30–120 °C. The nanofluids were prepared using a two-step direct mixing method and thermal properties were measured using a LAMBDA thermal conductivity meter, which uses the transient hot wire method according to the ISO standards. Due to the low concentrations of the nanofluids, surfactants were not required at all, and the stability of the nanofluids was visually monitored over a period of four weeks. Accordingly, the largest improvement in thermal conductivity occurred with TiO₂/10W30 at a mass fraction of 0.1 wt.% at 80 °C, and the specific heat capacity improved due to Fe₂O₃/10W30 addition at a mass fraction of 0.1 at 70 °C; these were 5.8% and 14.4%, respectively, for the base oil. Thermal diffusivity remained largely unaffected by the addition of the nanoparticles, and fullerene C₆₀ showed no significant effect on any thermal property. It was concluded that the thermal properties of the engine oil were considerably enhanced by the added nanoparticles at different weight fractions and temperature values. Full article

In this study, a simple and efficient hydrothermal strategy was developed to modify reduced graphene oxide (rGO) with copper (II) oxide (CuO) nanoparticles by varying the weight ratio of rGO relative to CuO (rGO@CuO_1:1, rGO@CuO_1:2, and rGO@CuO_2:1). The obtained materials were further characterized using analytical tools. Photocatalytic performance was assessed using adsorption–photocatalysis experiments under a household LED light source (10 W, λ > 400 nm), and the degree of degradation of doxycycline (DOX) was evaluated using UV-Vis spectrophotometer. The highest efficiency of 100% was achieved with a DOX concentration of 70 ppm, rGO@CuO_1:1 dosage of 1 mg/mL, and pH 7 within 30 min of irradiation. The degradation kinetics followed the pseudo-first-order model (R² ~0.99) and the Langmuir adsorption isotherm, indicating that DOX on the surface is governed by a dynamic equilibrium between adsorption and degradation rates. Furthermore, efficacy was tested using real water samples, and the recyclability of the catalyst was evaluated in up to five cycles. Full article