Search Results (84)

High-performance thermal protection materials are urgently required in harsh thermal environments, such as hypersonic vehicles, the thermal runaway of energy batteries and high-temperature equipment. Conventional aerogels only exhibit passive thermal insulation and fail to resist instantaneous high-temperature attack. Herein, a cooling material of ammonium oxalate (AO) was introduced to achieve efficient, active endothermic protection. A cellular isolation effect induced by graphene nanosheets combined with anti-solvent crystallization was adopted to significantly decrease the size of AO crystals by over 93%. Based on superfine morphology and the constructed conduction network, the decomposition rate and heat absorption capacity of obtained graphene-doped AO powders (GdAPs) are improved by 41.2% and 30.4%, respectively. The mechanisms of morphology regulation and enhanced heat absorption are explored specifically in this study. Furthermore, GdAPs are embedded in phenolic resin to prepare thermal protection composite materials. Benefiting from their nearly complete thermal decomposition, GdAPs serve as a sacrificial template to generate discrete micropores in pyrolyzed resin. So, the as-prepared carbon aerogels (CAs) with a regulable microstructure exhibit an extremely low thermal conductivity of 0.056 W/(m·K), which is lower than those of reported CAs with the same density. Based on the above advantages, a synergistic endothermic-insulating thermal protection material is reported for the first time, and its heating rate is only 28.6% of that of commercial silica aerogel under identical high-temperature shock. Therefore, a new accessible strategy is demonstrated to provide high-efficiency thermal protection for resisting both abrupt and prolonged high temperature. Full article

Silica aerogels are ideal candidates for gas adsorption due to their exceptional porosity and high specific surface area; however, the inherent mechanical fragility of their skeletal framework significantly compromises their operational stability in engineering applications. While the incorporation of carbon nanomaterials effectively enhances the mechanical robustness of aerogels, the specific microscopic mechanisms by which filler microstructure and surface chemistry dictate gas adsorption behavior remain insufficiently understood. In this study, we employed all-atom molecular dynamics (MD) simulations to develop a model of silicon-based porous composites synergistically doped with carbon nanotubes (CNTs) and graphene. The adsorption and diffusion characteristics of nitrogen (N₂) were systematically investigated across a CNT doping concentration range of 5% to 20%, and the influence of surface hydrophilicity/hydrophobicity on adsorption performance was quantitatively analyzed by modulating potential energy parameters. Our results demonstrate that the introduction of CNTs reconfigures the porous architecture, leading to an approximately 18.25% increase in the normalized specific surface area, which subsequently drives a 15% enhancement in the overall adsorption capacity of the composite. Nevertheless, analysis reveals that the weight-specific adsorption efficiency of the CNT component itself exhibits a declining trend as the doping concentration increases. This phenomenon is primarily attributed to the convex curvature of the CNTs, which restricts the effective contact area and weakens the adsorption potential, alongside the steric hindrance effects arising from local filler agglomeration at higher concentrations. Furthermore, surface chemical properties exert a significant regulatory influence on adsorption; a strongly hydrophilic modified surface (λ = 1.5) achieved an adsorption capacity approximately 98% higher than the baseline condition—an improvement that exceeds the gains provided by purely physical volume expansion. This research elucidates the synergistic mechanism between physical architecture and surface chemical modification in the adsorption process, suggesting that while the physical architecture determines the abundance of potential adsorption sites, the surface chemistry governs the actual efficiency of site utilization. These findings provide critical theoretical insights for the future design of composite aerogel materials that balance structural stability with superior adsorption performance. Full article

Lithium–sulfur (Li-S) battery technology has attracted significant research interest owing to sulfur’s remarkable theoretical capacity and exceptional energy density potential. Nevertheless, the low conductivity of sulfur and the “shuttle effect” pose challenges to its practical applications. To enhance electrochemical performance, this work developed nitrogen-doped graphene (NG) nanosheets as a separator coating for Li-S battery. As a modification layer for separators, NG acts as a physical barrier that prevents polysulfides from migrating across the separator to reach the anode, thereby mitigating the shuttle effect. Additionally, NG improves the conductivity of the separator and enhances wettability between the separator and electrolyte, facilitating uniform transmission of lithium ions. Notably, NG functionalized separators demonstrate excellent mechanical flexibility, contributing to improved cycle stability for batteries. Furthermore, theoretical calculations indicate a strong interaction between NG and lithium polysulfides (LiPSs), effectively inhibiting polysulfide migration. The Li-S battery utilizing the NG modified separator maintains a capacity retention rate of 51.5% after 100 cycles at 0.1 C with a sulfur loading of 1.47 mg/cm² and exhibits a capacity decay rate of only 0.092% after 500 cycles at a discharge rate of 1 C. This work highlights the potential advantages of employing NG as a separator coating layer in enhancing the electrochemical performance of the Li-S battery. Full article

Forward osmosis (FO) membranes face challenges in balancing high water permeability, low reverse salt flux (RSF), and mechanical durability. Although nanopores in graphene have great theoretical potential, the existing methods make it difficult to independently optimize the nanopores of the graphene layer and the microstructure of the substrate without damaging each other. Here, we propose a defect engineering strategy based on oxygen plasma etching to address this collaborative optimization challenge. Monolayer porous graphene (PG) was integrated with polysulfone (Psf) substrates, followed by oxygen plasma etching to introduce nanopores and oxygen-containing functional groups (e.g., carboxyl, hydroxyl). By controlling the etching time to 10 s, the resulting membrane (S-PG10) exhibited a water flux of 0.24 LMH in 0.5 M NaCl, representing an order-of-magnitude increase compared to the pristine graphene membrane (S-G). Remarkably, S-PG10 maintained a high salt rejection (>96%) and a low J_s/J_w (<0.35 g·L⁻¹). Substrate modification via short-term plasma etching (5 min) further doubled the water flux of S*5-PG10 (0.47 LMH in 0.5 M NaCl) by increasing porosity (81.8%→85.6%) and hydrophilicity. However, prolonged etching (>15 min) degraded mechanical strength and increased RSF due to pore structure disruption. To enhance robustness, Poly(D,L-lactic acid) (PDLLA)-doped substrates (S^#-PG) were engineered, with 0.1 wt.% PDLLA optimizing mechanical properties while maintaining low RSF and high flux. Excessive PDLLA (10 wt.%) induced hydrophobicity and crystalline structures, reducing permeability. The study demonstrates that synergistic optimization of plasma etching duration on the graphene selective layer (5~10 s) and substrates (5 min) as well as PDLLA doping (0.1 wt.%) balances pore architecture, surface chemistry, and substrate integrity, achieving FO membranes with superior water-salt selectivity and mechanical stability. These findings provide critical insights into designing high-performance graphene-based membranes for sustainable desalination and water purification. Full article

Poly (3,4-ethylenedioxythiophene polystyrene sulfonate) (PEDOT:PSS) is a solution-processable hole transport layer known for its high work function and excellent hole mobility. The incorporation of graphene serves as an effective strategy to augment the hole-transport properties of PEDOT:PSS. In this study, the electronic structure of graphene-doped PEDOT:PSS (G-PEDOT:PSS) was investigated using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). It was found that the work function of PEDOT:PSS increases with graphene doping concentration, rising from 4.86 eV for undoped PEDOT:PSS to 5.03 eV for PEDOT:PSS incorporating 10 wt% graphene. The impact of this modification on the energy-level alignment with zinc phthalocyanine (ZnPc), which is a prototypical p-type organic semiconductor, was examined through in situ XPS and UPS analyses. Despite the increased work function, the hole injection barriers for both PEDOT:PSS and G-PEDOT:PSS to ZnPc were determined to be identical at 0.26 eV. This lack of change in the barrier is explicitly attributed to Fermi-level pinning, where the integer charge transfer level of ZnPc is pinned to the Fermi level of the substrate, preventing a further reduction in the energy offset. That said, for other p-type organic semiconductors with higher ionization energies, the use of G-PEDOT:PSS could potentially enable more efficient hole injection. Full article

Rechargeable aqueous Zn-MnO₂ batteries are positioned as a highly promising candidate for next-generation energy storage, owing to their compelling combination of economic viability, inherent safety, exceptional capacity (with a theoretical value of ≈308 mAh·g⁻¹), and eco-sustainability. However, this system still faces multiple critical challenges that hinder its practical application, primarily including the ambiguous energy storage reaction mechanism (e.g., unresolved debates on core issues such as ion transport pathways and phase transition kinetics), dendrite growth and side reactions (e.g., the hydrogen evolution reaction and corrosion reaction) on the metallic Zn anode, inadequate intrinsic electrical conductivity of MnO₂ cathodes (≈10⁻⁵ S·cm⁻¹), active material dissolution, and structural collapse. This review begins by systematically summarizing the prevailing theoretical models that describe the energy storage reactions in Zn-Mn batteries, categorizing them into the Zn²⁺ insertion/extraction model, the conversion reaction involving MnO_x dissolution–deposition, and the hybrid mechanism of H⁺/Zn²⁺ co-intercalation. Subsequently, we present a comprehensive discussion on Zn anode protection strategies, such as surface protective layer construction, 3D structure design, and electrolyte additive regulation. Furthermore, we focus on analyzing the performance optimization strategies for MnO₂ cathodes, covering key pathways including metal ion doping (e.g., introduction of heteroions such as Al³⁺ and Ni²⁺), defect engineering (oxygen vacancy/cation vacancy regulation), structural topology optimization (layered/tunnel-type structure design), and composite modification with high-conductivity substrates (e.g., carbon nanotubes and graphene). Therefore, this review aims to establish a theoretical foundation and offer practical guidance for advancing both fundamental research and practical engineering of Zn-manganese oxide secondary batteries. Full article

The presence of secondary electromagnetic waves (EMWs) results in EMW pollution and a large need for EMW-shielding materials. Therefore, new, lightweight, flexible, chemically resistant, and durable EMW shielding materials are demanded, while graphene and its derivatives meet the above-mentioned requirements. Among graphene derivatives, N-doped graphene exhibits promising electrical properties for shielding applications, although achieving sufficient N-incorporation in the graphene sheets remains a challenge. Herein, we produced graphene oxide using the modified Hummers’ method (GO) and the electrochemical exfoliation of highly ordered pyrolytic graphite. These two GO samples were thermally treated at 500 °C and 800 °C under a pure NH₃ gas for 1 h. UV-Vis, infrared, and Raman spectroscopies and X-ray diffraction, elemental, and thermogravimetric analyses were used to investigate the structural properties of modified GO. One of the highest levels of N-doping of GO was measured (11.25 ± 0.08 at%). The modification under a NH₃ atmosphere leads to simultaneous N-doping and reduction of graphene, resulting in the formation of electrically conductive and EMW shielding materials. Density functional theory (DFT) revealed the effect of heteroatoms on the energy band gap of GO. The cluster corresponding to N-doped rGO had a reduced bandgap of 0.77 eV. Full article

Due to its persistence and potential negative effects on ecosystems and human health, microplastic pollution in aquatic environments has become a major worldwide concern. Photocatalytic degradation is a sustainable manner to degrade microplastics to non-toxic by-products. In this review, comprehensive discussion focuses on the synergistic effects of various photocatalytic materials including TiO₂, ZnO, WO₃, graphene oxide, and metal–organic frameworks for producing heterojunctions and involving multidimensional nanostructures. Such mechanisms can include the generation of reactive oxygen species and polymer chain scission, which can lead to microplastic breakdown and mineralization. The advancements of material modifications in the (nano)structure of photocatalysts, doping, and heterojunction formation methods to promote UV and visible light-driven photocatalytic activity is discussed in this paper. Reactor designs, operational parameters, and scalability for practical applications are also reviewed. Photocatalytic systems have shown a lot of development but are hampered by shortcomings which include a lack of complete mineralization and production of intermediary secondary products; variability in performance due to the fluctuation in the intensity of solar light, limited UV light, and environmental conditions such as weather and the diurnal cycle. Future research involving multifunctional, environmentally benign photocatalytic techniques—e.g., doped composites or composite-based catalysts that involve adsorption, photocatalysis, and magnetic retrieval—are proposed to focus on the mechanism of utilizing light effectively and the environmental safety, which are necessary for successful operational and industrial-scale remediation. Full article

With the continuous progress of global renewable energy, the reliability of the performance of heat storage materials is becoming increasingly important. In this study, graphene oxide (GO) was used as an additive to investigate its influence on the heat storage performance of quaternary nitrate molten salt. Quaternary nitrate molten salts doped in different proportions of 0.5, 1.0, 1.5, and 2.0 wt.% were prepared by the high-temperature hot melting method, and their properties were characterized in detail. The results show that the optimal concentration value of graphene oxide nanosheets is 1.0 wt.%, at which point the thermal parameters such as the specific heat capacity and thermal conductivity of the molten salt are optimal. Meanwhile, differential scanning calorimetry and thermogravimetric analysis tests verified the enhanced effect of the thermal performance. Furthermore, transmission electron microscopy and scanning electron microscopy analyses indicated that the insertion and encapsulation of nanosheets in the channel structure between nitrate crystals were effective. The modification methods used in this paper can enhance the thermophysical properties of nitrates. Meanwhile, the methods proposed in this paper can provide new ideas for the practice of heat-requiring systems. Full article

Photoelectrochromic devices, which combine light-induced color change with energy-efficient optical modulation, have attracted significant attention for applications such as smart windows, displays, and optical sensors. However, achieving high optical modulation, fast switching speeds, and long-term stability remains a major challenge. In this study, we explore the structural and photoelectrochromic enhancements in tungsten oxide (WO₃) films achieved by doping with molybdenum disulfide quantum dots (MoS₂ QDs) and grapheneoxide–molybdenum disulfide quantum dots (GO–MoS₂ QDs) for advanced photoelectrochromic devices. X-ray diffraction (XRD) analysis revealed that doping with MoS₂ QDs and GO–MoS₂ QDs leads to a reduction in the crystallite size of WO₃, as evidenced by the broadening and decrease in peak intensity. Transmission Electron Microscopy (TEM) confirmed the presence of characteristic lattice fringes with interplanar spacings of 0.36 nm, 0.43 nm, and 0.34 nm, corresponding to the planes of WO₃, MoS₂, and graphene. Energy-Dispersive X-ray Spectroscopy (EDS) mapping indicated a uniform distribution of tungsten, oxygen, molybdenum, and sulfur, suggesting homogeneous doping throughout the WO₃ matrix. Scanning Electron Microscopy (SEM) analysis showed a significant decrease in film thickness from 724.3 nm for pure WO₃ to 578.8 nm for MoS₂ QD-doped WO₃ and 588.7 nm for GO–MoS₂ QD-doped WO₃, attributed to enhanced packing density and structural reorganization. These structural modifications are expected to enhance photoelectrochromic performance by improving charge transport and mechanical stability. Photoelectrochromic performance analysis showed a significant improvement in optical modulation upon incorporating MoS₂ QDs and GO–MoS₂ QDs into the WO₃ matrix, achieving a coloration depth of 56.69% and 70.28% at 630 nm, respectively, within 10 min of 1.5 AM sun illumination, with more than 90% recovery of the initial transmittance within 7 h in dark conditions. Additionally, device stability was improved by the incorporation of GO–MoS₂ QDs into the WO₃ layer. The findings demonstrate that incorporating MoS₂ QDs and GO–MoS₂ QDs effectively modifies the structural properties of WO₃, making it a promising material for high-performance photoelectrochromic applications. Full article

Doping undermines fairness in sports and threatens athlete health, while conventional detection methods like LC-MS and GC-MS face challenges such as complex procedures, matrix interferences, and lengthy processing times, limiting on-site applications. Two-dimensional (2D) materials, including graphene, MoS₂, and metal–organic frameworks (MOFs), offer promising solutions due to their large surface areas, tunable electronic structures, and special interactions with doping agents, such as hydrogen bonding, π-π stacking, and electrostatic forces. These materials enable signal transduction through changes in conductivity or fluorescence quenching. This review highlights the use of 2D materials in doping detection. For example, reduced graphene oxide–MOF composites show high sensitivity for detecting anabolic steroids like testosterone, while NiO/NGO nanocomposites exhibit strong selectivity for stimulants like ephedrine. However, challenges such as environmental instability and high production costs hinder their widespread application. Future efforts should focus on improving material stability through chemical modifications, reducing production costs, and integrating these materials into advanced systems like machine learning. Such advancements could revolutionize doping detection, ensuring fairness in sports and protecting athlete health. Full article

The symmetry of the valence and conduction bands in graphene and carbon nanotubes allows for easy modification of the electronic structure, which is correlated with their electrocatalytic activity. Modifying the electronic structure of the sp²-bonded nanocarbons by substituting carbon atoms with electron donors/acceptors and through covalent functionalization can facilitate heterogeneous electron transfer (HET), which is beneficial for designing carbon-based, high-performance electrocatalysts. Based on the Gerischer–Marcus model, we discuss how we can match the density of π-electron states (DOS) of a nanocarbon electrode to the redox potential of redox species using electron and hole doping. Along with the results, this article provides guidance on how to match the properties of nanocarbons to specific electroactive analytes, oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and oxygen evolution reaction (OER). Full article

Background/Objectives: Graphene and its derivatives have garnered attention for their unique properties that could enhance dental biomaterials. Understanding their interactions with biological systems is crucial for optimizing their application in dentistry. This study aimed to comprehensively evaluate the biocompatibility, molecular interactions, and toxicity profiles of graphene and its derivatives for potential dental applications using in silico approaches. Methods: The study employed molecular-docking simulations, 100 ns molecular dynamics (MD) simulations, pharmacophore modeling, and in silico toxicity assessments. Key bone-related proteins and receptors were selected to assess the potential of graphene-based materials in dental restorative and regenerative therapies. Results: Molecular-docking simulations revealed strong interactions of Graphene Quantum Dots (GQDs) and sulfur-doped graphene with critical bone-related receptors, suggesting their potential for reinforcing dentin and promoting bone regeneration. MD simulations demonstrated stable complex formations, with occasional fluctuations indicating areas for material optimization. In silico toxicity assessments indicated favorable profiles for high-purity graphene and selected doped graphenes (nitrogen-, fluorine-, and sulfur-doped), while graphene oxide (GO) exhibited concerning toxicity levels, highlighting the importance of mitigating strategies. Conclusions: Graphene and its derivatives exhibit promising biocompatibility and molecular interaction profiles relevant to dental applications. Challenges such as GO’s toxicity and occasional instability in simulations suggest the need for further research into surface modifications and material refinement. These findings pave the way for advancing graphene-based dental materials toward clinical implementation, potentially revolutionizing dental prosthetics and treatments. Full article

The synergistic effect of CNT and three-dimensional N-doped graphene foam (3DNG) on improving corrosion resistance of zinc-reinforced epoxy (ZRE) composite coatings was studied in this work. Although CNT itself was demonstrated to be effective to promote the anti-corrosion performance of the ZRE coating, the incorporation of additional 3DNG leads to further enhancement of its corrosion resistance under the synergistic effect of the hybrid carbon nanofillers with different dimensions. Both the content of the carbonaceous fillers and the ratio between them affected the performance of the coating. The optimal content of hybrid filler in the coating was determined to be only 0.1% with 3DNG:CNT = 1:3. With the modification of hybrid fillers, the corrosion current of the coating could be reduced by more than six orders of magnitude. Additionally, the immersion test of the pre-scratched coating directly demonstrated the evident contribution of the hybrid fillers to the sacrificial anode-based surface protection mechanism of the coating. These results confirmed the synergistic effect of the hybrid 1D and 3D carbonaceous fillers on promoting the corrosion inhibition of their coating, which could be promising for application in other functional composites. Full article

Changes in the work function provide a fingerprint to characterize analyte binding in charge transfer-based sensor devices. Hence, a rational sensor design requires a fundamental understanding of the microscopic factors controlling the modification of the work function. In the current investigation, we address the mechanisms behind the work function change (WFC) for the adsorption of four common volatile organic compounds (toluene, ethanol, 2-Furfurylthiol, and guaiacol) on different nitrogen-doped graphene-based 2D materials using density functional theory. We show that competition between the surface dipole moment change induced by spatial charge redistribution, the one induced by the pure adsorbate, and the one caused by the surface deformation can quantitatively predict the work function change. Furthermore, we also show this competition can explain the non-growing work function change behavior in the increasing concentrations of nitrogen-doped graphenes. Finally, we propose possible design principles for WFC of VOCs interacting with N-doped graphene materials. Full article