Search Results (3,152)

Biochar has traditionally been investigated as a soil amendment for improving fertility, carbon sequestration, and nutrient retention. However, recent advances in fine milling, colloidal stabilization, and nanotechnology have enabled the development of biochar-derived materials for foliar application. Unlike conventional soil application, foliar delivery enables direct interaction with leaf tissues, potentially providing faster physiological responses, improved resource-use efficiency, and complementary functions to existing plant biostimulants. This review critically evaluates the scientific basis, agronomic performance, and regulatory implications of foliar biochar applications across diverse crop systems. We synthesize and compare major formulation types, including finely milled suspensions, aqueous extracts, nano-biochar dispersions, and biochar-based composite carriers, based on their formulation characteristics, application methods, and reported biological effects. Across multiple crops, foliar biochar has been associated with enhanced chlorophyll content, improved gas exchange, strengthened antioxidant systems, better osmotic adjustment, and increased nutrient uptake, particularly under abiotic stresses such as salinity, drought, and heat. Mechanistically, these responses are linked to surface deposition effects, redox-active functional groups, modulation of leaf microclimate, and delivery of soluble bioactive compounds. Nevertheless, outcomes remain highly context-dependent, influenced by feedstock origin, pyrolysis conditions, particle size, formulation chemistry, dose, and crop species. Potential risks including phytotoxicity, nanoparticle exposure, environmental fate, and regulatory ambiguity especially for nano-scale formulations pose additional challenges for large-scale adoption. By integrating physiological, agronomic, environmental, and legislative perspectives, this review also highlights key barriers to commercialization, including formulation stability, limited field-scale validation, environmental safety, and regulatory uncertainty, while identifying research priorities needed to determine whether foliar biochar can become a scalable and scientifically validated biostimulant for sustainable agriculture. Full article

Nanomaterials are increasingly used in manufacturing, medicine, consumer products, and environmental technologies due to their unique physicochemical properties. Although these materials offer substantial technological and societal benefits, their widespread use has raised concerns about potential health risks. Of particular importance is exposure during pregnancy, as certain nanoparticles can cross the placental barrier and reach the developing embryo. Fetal tissues are highly sensitive to environmental insults, so maternal exposure to nanoparticles may disrupt normal development and increase the risk of abnormal pregnancy outcomes. This review examines the current understanding of nanoparticle-induced developmental toxicity, with a focus on the vulnerability of the maternal–fetal unit. We discuss the structure and function of the placental barrier and the mechanisms that enable nanoparticle transfer from mother to fetus. Particular attention is given to how nanoparticle characteristics, including size, shape, composition, and surface chemistry, influence biodistribution, placental transport, tissue accumulation, and toxicity. We summarize the major molecular and cellular mechanisms implicated in fetotoxicity, highlighting oxidative stress, apoptosis, autophagy, and DNA damage as recurring pathways identified across experimental studies. These interconnected processes contribute to placental dysfunction, impaired fetal growth, developmental abnormalities, and adverse pregnancy outcomes. We also compare findings across different classes of nanoparticles, including metal, metal oxide, carbon-based, and polymeric nanomaterials, identifying both shared toxicological mechanisms and material-specific effects. Evidence from animal models demonstrates that susceptibility varies according to nanoparticle properties, exposure conditions, and species, underscoring the complexity of nanoparticle–biological interactions and the limitations of extrapolating experimental findings directly to humans. Overall, the available evidence indicates that nanoparticle exposure during pregnancy represents a potential risk to fetal health, although important knowledge gaps remain regarding human exposure and long-term developmental outcomes. A better understanding of the mechanisms underlying nanoparticle-induced fetotoxicity is essential for improving human health risk assessment, refining experimental models, informing regulatory policies, and supporting the safe-by-design development of nanomaterials. Such knowledge will help ensure the responsible application of nanotechnology while minimizing potential risks during pregnancy. Finally, this review is distinguished by its integrated analysis of how the chemical characteristics of nanoparticles govern placental transfer and the mechanistic pathways of fetotoxicity across multiple nanomaterial classes, providing a unified framework that connects material properties with their potential for abnormal fetal development and adverse pregnancy outcomes. Full article

Molecularly imprinted polymers combined with carbon nanomaterials have proven effective in constructing electrochemical sensors with high selectivity, sensitivity, and robustness. Herein, a polypyrrole-based molecularly imprinted electrochemical sensor was developed on a multi-walled carbon nanotube-modified glassy carbon electrode for homocysteine detection in human serum. The sensor was fabricated via drop-coating of sodium dodecyl sulfate-dispersed multi-walled carbon nanotubes, followed by in situ electropolymerization of pyrrole using homocysteine as the template. The morphology, interfacial properties, and electrochemical behavior of the electrode were systematically characterized by scanning electron microscopy and electrochemical techniques. Under optimized conditions, the sensor showed a linear response to homocysteine in the range of 1.0 × 10⁻¹⁰ mol/L to 1.0 × 10⁻⁵ mol/L, with a detection limit of 7.12 × 10⁻¹¹ mol/L (S/N = 3). The sensor also exhibited good selectivity against common interferents, as well as acceptable reproducibility and stability. Recovery tests in human serum yielded recoveries of 91.00~110.50% (average: 100.73%), demonstrating its potential for practical homocysteine analysis in complex biological matrices. Full article

Supercapacitors offer high power density, fast charging/discharging capability, and long cycle life, yet their relatively low energy density limits broader deployment in electric vehicles, portable electronics, and grid storage systems. MXenes, a family of two-dimensional transition metal carbides, nitrides, and carbonitrides, have emerged as promising electrode materials due to their high electrical conductivity, tunable surface chemistry, hydrophilicity and intrinsic pseudocapacitive behavior. However, restacking of MXene layers reduces accessible surface area and ion transport efficiency, constraining electrochemical performance. To address this limitation, MXene-based nanocomposites incorporating carbon nanomaterials, conducting polymers, and metal oxides have been extensively developed. This review systematically evaluates recent advances in MXene-based nanocomposites for high-energy-density supercapacitors, highlighting electrochemical performance. A quantitative benchmarking comparison with commonly used electrode materials, including graphene, carbon nanotubes, and activated carbon, is provided. Key challenges in synthesis, performance standardization, and stability are discussed, along with future prospects for developing safer and scalable production methods of MXene-based electrodes. Full article

As critical infrastructure for carbon capture, utilization, and storage (CCUS) and large-scale energy storage, subsurface salt caverns are seriously challenged by fluid-induced sediment mobilization during the supplementary debrining. Conventional bulk resin consolidation often causes severe viscous fingering, uneven consolidation, and pore clogging under hypersaline conditions. Here, we develop a foam-templated hybrid polymer gel co-stabilized by silica nanoparticles, polyvinyl alcohol, and the zwitterionic surfactant. The key novelty is the use of foam as a transient transport template that redistributes the resin phase and promotes selective cementation at grain-contact points instead of indiscriminate pore filling. This nano-reinforced gel system remained stable under hypersaline conditions (24% NaCl), and temperatures ranging from 20–80 °C. Micro-CT analysis showed that this selective templating preserved an interconnected pore network with a porosity above 45% and a CT-derived permeability of approximately 1.18 D, while reducing binder consumption by 55.6% relative to bulk resin injection. Crucially, a 1:200 geometrically scaled, velocity-matched pilot model demonstrated that this gel strategy limited sediment entrainment below 0.5% and reduced fluid discharge by 45.9%. These results establish a material-efficient consolidation strategy that combines sediment stabilization with permeability preservation, providing a promising solution for safer supplementary debrining in salt-cavern CCUS and energy-storage operations. Full article

The valorization of agricultural waste into high-value carbon nanomaterials offers dual benefits: it reduces pollution and provides low-cost materials for sustainable technologies. This work synthesizes graphene-like carbon from Ghars date waste via mild KOH-assisted pyrolysis at 1000 °C. The material (G-GhW1000) exhibits a sharp (002) XRD peak at 26.16° (d-spacing = 3.40 Å), a characteristic π → π* transition at 253 nm, and a high C/O ratio of 27.37. Dispersed in tap water (0.5 g/L) by simple hand shaking (without ultrasonication), it serves as a photothermal nanofluid in a modified single-slope solar still (MSS). Under outdoor conditions, the MSS produces 4.69 L·m⁻²·day⁻¹, which is 18.7% higher than a conventional still, with thermal efficiency rising from 27.2% to 30.8% (with a reproducible 19.0% enhancement in summer). Samples prepared at 800 °C and 900 °C give 4.0% and 6.4% lower yields, while the 1100 °C sample gives only 6.0% improvement, confirming 1000 °C as the optimal temperature. The superior performance at 1000 °C is attributed to the optimal balance between graphitization, deoxygenation, and structural integrity, as evidenced by XRD, FTIR, EDX and UV-Vis analyses. The enhanced performance is linked to higher water temperature (68 °C) and larger ΔT. The distilled water meets WHO standards (TDS 9.35 mg/L, >99.4% reduction) with no detectable graphene-like carbon carryover. This work demonstrates the potential of waste-derived graphene-like carbon as a low-cost additive for solar desalination, addressing water scarcity and waste management within a circular economy framework. To our knowledge, this is the first study to use Ghars date waste-derived graphene-like carbon in a solar still. Full article

Chitosan has emerged as a multifunctional biopolymer widely exploited in electrochemical sensing due to its unique physicochemical properties, including biocompatibility, film-forming capacity, protonated amino groups, and strong affinity for metal ions and biomolecules. These intrinsic characteristics enable efficient electrode modification, enhanced analyte adsorption, and immobilization of enzymes, nanoparticles, and 2D materials. In recent years, integrating chitosan with conductive nanostructures, such as carbon nanomaterials, metal oxides, metallic nanoparticles, and layered 2D materials, has significantly enhanced sensor performance, providing high sensitivity, selectivity, stability, and low detection limits across a broad range of analytes. This review presents an updated overview of chitosan’s roles in electrochemical sensing, including its functionalization techniques, electron transfer mechanism, and analyte identification. Key applications, such as biomolecule detection, heavy-metal monitoring, environmental pollutant analysis, pharmaceuticals, and emerging wearable sensing platforms, are discussed. Finally, current challenges and future research directions are highlighted to support the development of next-generation chitosan-based electrochemical sensors. Full article

Nitrites and nitrates are admitted into the body through the consumption of various foods, primarily cured meat products. These nitrites and nitrates are precursors of reactive nitrogen species NO and NO₂, which, in excess, promote nitrosative stress. Attempts have been made to combat oxidative and nitrosative stress through C₆₀ fullerenols in animal models. Furthermore, experimental and theoretical studies have shown that the use of carbon nanomaterials such as defective or doped graphene and C₆₀ metallofullerenes facilitates the capture of NO_x pollutants contained in the air. This leads us to propose that the inclusion of metals in C₆₀ fullerenols may have the potential to capture these reactive nitrogen species and be considered in nitrosative stress tests in animal models. Alternatively, viewed from another perspective, a certain grade of hydroxylation of metallofullerenes could enhance the capture of atmospheric nitrogen pollutants. Therefore, Li, Ca and Y metals were included in C₆₀ fullerenols at different coating grades. Using density functional theory (DFT), we analyzed the antiradical character of these metallofullerenols, and the adsorption energies of the free radicals (NO_x) were calculated to evaluate the ability of these metallofullerenols to adsorb these nitrogen species. Although both fullerenols and endohedral metallofullerenes have individually shown promise as radical scavengers, a systematic understanding of how the encapsulated metal and the grade of hydroxylation jointly govern the capture of nitrogen species is still lacking. In particular, it remains unclear whether increasing the number of hydroxyl groups monotonically enhances the capture capacity or whether optimal combinations of metal identity and surface functionalization exist. Addressing this gap is crucial, since excessive hydroxylation may alter the electronic structure, stability, and mechanism of interaction with NO_x radicals, potentially compromising capture capacity. Therefore, a rational evaluation that simultaneously considers electronic donor–acceptor properties, local reactivity, and adsorption thermodynamics is required to identify metallofullerenols with possible potential to sense or scavenge NO_x. Full article

Biochar has attracted increasing attention in soil remediation due to its porous structure, abundant surface functional groups, and environmental compatibility. Beyond its conventional roles as an adsorbent and soil amendment, biochar has increasingly been recognized as an electron shuttle that mediates electron transfer between electron donors and acceptors, thereby promoting redox reactions involved in pollutant transformation, immobilization, and toxicity mitigation. However, the structural basis, influencing factors, and underlying electron-transfer mechanisms of biochar-mediated processes remain insufficiently integrated. This review summarizes biochar-mediated electron transfer in soil remediation. Three pathways are discussed: direct electron transfer through conductive carbon matrices, indirect electron transfer mediated by redox-active surface functional groups, and composite interfacial electron transfer involving microorganisms, metal oxides, and nanomaterials. By introducing the synergistic effects between biochar and microorganisms, metal oxides, and nanomaterials, the functions of biochar in immobilizing heavy metals and degrading organic pollutants are emphasized. Biochar’s electron-shuttling ability is closely related to aromatic carbon structures, redox-active functional groups, and persistent free radicals, while key factors affecting electron-shuttling performance, including feedstock properties, pyrolysis temperature, pH, coexisting ions, pollutant concentration, and modification strategies, are also discussed. This review offers guidance for the design of biochar-based soil remediation strategies. Full article

In this work, a comprehensive analysis of the relationship between photoluminescent, thermo-oxidative, and photocatalytic (upon simulated sunlight exposure) properties of ZnO powders is performed. The correlation between the X-ray diffraction and microscopic data is studied. ZnO powders of various sizes and morphologies were used: pseudo-spherical nanoparticles (30–50 nm), submicron faceted crystallites (100–500 nm), and plate- and rod-like microstructures (up to 20 μm). The mean specific surface area values were 32 m²/g, 3.8 m²/g, and 2.6 m²/g for pseudo-spherical nanoparticles, submicron faceted crystallites, and plate- and rod-like microstructures, respectively. According to the XRD data, microstresses and carbon-based impurities were present in ZnO nanoparticles, which is characteristic of nanomaterials synthesized at low temperatures. According to the photoluminescence spectroscopy data, the emission in ZnO was reduced due to high defectiveness, and characteristic emission bands indicated the presence of organic impurities. Upon long signal registration times, an intensive luminescence band with an effective maximum at 579 nm occurred, which indicated the presence of long-term components exhibiting decay times τ ~300 μs. According to the XRD data, the crystal structure parameters of ZnO submicro- and microparticles were close, with no impurities present. In their photoluminescence spectra, pronounced UV and defect-related bands were present with intensity ratios of 11.6 and 6.88, respectively. The decrease in the UV and defect-related luminescence band intensity ratios indicates deviation from the stoichiometry toward an increased Zn over oxygen content. At long signal registration times, in submicron ZnO particles, a luminescence band with maxima at 425 and 490 nm is present, which decays rapidly. An emission band in the 530 nm region is also present, which decays for ≤80 μs, and a weak long-wavelength emission decaying for ~100 μs. At long delay and strobe times (up to milliseconds), only an emission in the 460 nm region is observed, which we connect to the triplet–singlet transition of a defect center (F*, F⁺*). At lower intensities, an emission connected to the surface contamination by organic impurities is observed. In photoluminescence spectra of ZnO microparticles, no long-wavelength emission components are observed. However, upon immersing into methylene blue solution, a modification of the surface and UV region of the spectra is observed with signs of charge carrier recombination rate acceleration. It is shown that the catalytic action of ZnO powders in polyethylene thermo-oxidation processes is determined by a combination of factors. In addition to dispersity and concentration, which are the key parameters, the morphology of ZnO particles, the presence of impurities, the surface state, and the distribution of active sites have a significant influence on catalysis. It has been experimentally demonstrated that these secondary factors can markedly affect the rate of radical formation in polyethylene films and alter their resistance to oxidation. ZnO nanoparticles exhibited low catalytic activity in both photocatalysis (rate constant 0.146 min⁻¹) and thermocatalysis due to the high defect density of the crystallites and the presence of carbon-containing impurities. Submicron ZnO particles, owing to a high carrier generation rate and suppressed recombination (via trapping), demonstrated the highest photoactivity (rate constant 0.729 min⁻¹). Submicron ZnO particles exhibit a catalytic effect on the thermo-oxidation of polyethylene (PE films); however, at concentrations above 8 wt.% a transition to an inhibiting effect is observed. ZnO microparticles catalyzed the oxidation of PE films over a broader concentration range (1–12 wt.%), with oxidation inhibition observed only at 18 wt.%. At the same time, they demonstrated moderate photocatalytic activity (rate constant 0.256 min⁻¹). These characteristics of the samples correlate with data obtained by microscopy, photoluminescence spectroscopy, and X-ray diffraction analysis. Full article

Engineered nanomaterials have been increasingly proposed for the treatment of contaminated soils. Nevertheless, most available evidence has been obtained in water, artificial substrates or short-term laboratory experiments, and performance in real soil is substantially more variable. This review examines nanoscale zero-valent iron, photocatalytic metal oxides, carbon-based nanomaterials, and supported or hybrid formulations, with particular attention to the soil properties and contaminant characteristics that control their mobility, transformation, reactivity, and persistence. Nano-enabled treatments can decrease the mobility of arsenic, chromium, lead, and other potentially toxic elements and can promote the degradation of selected pesticides and hydrocarbons. However, opposite responses have also been reported, including mobilisation of non-target elements, nanoparticle aggregation and passivation, effects on microbial communities and plants, contaminant rebound, and potential transport beyond the treated zone. Environmental assessment should therefore consider both the target contaminant and the applied or transformed nanomaterial, together with ecological and occupational exposure pathways. Current evidence does not support nanoremediation as a general replacement for conventional technologies. Its main value lies in its use as a site-specific component of integrated remediation strategies selected according to soil properties, contaminant behaviour, treatment scale, cost, life-cycle impacts, and future land use. European field experience remains limited, particularly in unsaturated soils, and no harmonised EU-wide authorisation procedure specifically for soil nanoremediation currently exists. Wider implementation will require realistic field trials, long-term monitoring, safer and recoverable formulations, transparent regulatory assessment, and evaluation of soil functions and ecosystem-service recovery. A site-specific decision framework is proposed to support material selection, risk–benefit evaluation, and responsible implementation. Full article

The development of sustainable, high-performance friction composites is critical for the automotive industry, given the environmental and health concerns associated with conventional brake pad materials such as asbestos and copper. This study investigates the effect of incorporating micro- and nano-sized Al₂O₃, SiC, and carbon nanotubes (CNTs) into a novel, eco-friendly, asbestos-free, and copper-free brake pad formulation. Six composite samples were fabricated via a cold-pressing and hot-molding process: five formulations containing a single, size-controlled micro-/nano-sized reinforcement (Al₂O₃, SiC, and CNTs), and one reference formulation (CBP# Reference) containing an unrefined, commercial-grade combination of Al₂O₃ and SiC in place of the size-controlled additive. All formulations were rigorously characterized for their physical, mechanical, and tribological properties. The nano-Al₂O₃ formulation exhibited the highest density (2.197 g/cm³) and compressive strength (249.7 MPa), while the micro-SiC formulation achieved superior wear resistance, recording the lowest weight loss (0.0053 g) and the highest hardness (90 HV). The nano-SiC formulation offered the most balanced overall performance, combining high hardness (86.2 HV) with the highest average friction force (33.65 N) and the most stable friction-time response among all samples. The CNT-reinforced formulation produced the highest maximum friction force (42.07 N) but showed only moderate improvement in density, hardness, and compressive strength relative to the ceramic-reinforced samples. Compared with the CBP# reference, all five developed formulations exhibited higher hardness and coefficient of friction alongside lower weight loss, confirming their potential as durable, sustainable alternatives for automotive brake friction applications. Full article

Graphene oxide (GO) and reduced graphene oxide (rGO) are widely studied two-dimensional carbon nanomaterials for optoelectronic devices. Because the oxygen content and degree of reduction govern the electronic structure of GO-derived films, controlling the reduction process is essential for tailoring their properties. Laser-induced reduction provides a tunable, contact-free route to transparent and conductive graphene-based layers. In this work, 80 nm spray-coated GO layers were reduced using a KrF excimer laser (248 nm, 20 ns) at a fluence of 20 mJ cm⁻², while systematically varying the number of laser pulses (LP) from 1 to 1000. We tuned the degree of GO reduction by stepwise increasing the number of LP and followed the resulting changes in surface composition using X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy. The surface composition evolves non-monotonically with the number of laser pulses, revealing a multi-step reduction mechanism. At low laser doses, epoxide groups are preferentially removed or converted, generating a more disordered distribution of hydroxyl-containing sites on the GO sheets. At intermediate laser doses, oxygen-containing groups are depleted, and sp² conjugation is restored. After extended irradiation in air, however, oxygenated surface species partially re-form. Conductivity measurements show that the sheet resistance reaches a minimum at approximately 300 LP, consistent with efficient chemical reduction and recovery of the conjugated carbon network. These results provide molecular-level guidelines for optimizing laser-induced GO reduction toward graphene-based transparent conductive layers. Full article

In recent years, the rapid development of flexible electronics, smart materials, and micro/nanofabrication technologies has greatly promoted the advancement of flexible pressure sensors. These sensors have achieved significant improvements in sensitivity, detection range, stability, and functional integration, demonstrating great potential for applications in wearable electronics, smart healthcare, and human–machine interaction. This review summarizes recent progress in flexible pressure sensors in terms of sensing mechanisms, functional materials, structural designs, and intelligent applications. First, the working principles and performance characteristics of typical sensing mechanisms, including piezoresistive, capacitive, piezoelectric, triboelectric, iontronic, self-powered, and electrochemical sensing, are introduced and compared. Then, the development of key materials, such as flexible substrates, carbon-based nanomaterials, metal nanostructures, conductive hydrogels, and MXenes, is summarized. The effects of structural designs, including serpentine, three-dimensional porous, crack, wrinkle, and Kirigami structures, on flexibility, stretchability, sensitivity, detection range, and cycling stability are also discussed. Furthermore, the applications of flexible pressure sensors in pulse monitoring, blood pressure monitoring, human motion detection, cardiovascular health assessment, disease diagnosis, gesture recognition, human–machine interaction, and electronic skin are reviewed. Finally, the major challenges and future perspectives of flexible pressure sensors are discussed. Full article

Carbon nanotubes (CNTs) have become one of the most widely investigated nanomaterials for gas sensing because their nearly one-dimensional geometry, large surface-to-volume ratio, hollow structure, and tunable metallic or semiconducting character allow trace adsorption events to be transduced into measurable electrical signals at or near room temperature. This review summarizes CNT-based gas sensors from a system-oriented perspective, linking four interconnected topics: (i) CNT structure, synthesis, and film/device fabrication; (ii) sensing mechanisms, including charge transfer, Schottky-barrier modulation, carrier-lifetime effects, and field-enhanced ionization; (iii) functional interfaces based on noble metals, metal oxides, conducting polymers, and graphene derivatives; and (iv) gas-specific and flexible/wearable device performance. Particular attention is given to recent room-temperature and mechanically compliant CNT-film sensors fabricated on polymer, cellulose, paper, textile, and mask substrates. Rather than cataloguing only individual response values, this review compares representative devices in terms of target gas, operating condition, sensitivity, recovery strategy, selectivity, humidity tolerance, and wearable relevance. The review concludes by discussing remaining challenges in reproducibility, selectivity, humidity compensation, recovery, power consumption, and standardization, and by outlining future directions toward robust, scalable, and intelligent CNT-enabled sensing systems. Full article