Carbonaceous Nanomaterials Research Articles

Critical Review on Carbon Nanomaterial Based Electrochemical Sensing of Dopamine the Vital Neurotransmitter

The clinical diagnosis of dopamine biomarkers plays a crucial role in classifying nervous system-related disorders, which are increasingly prevalent across all age groups worldwide. Accurate and thorough diagnosis is essential for administering appropriate drug therapies. However, it has been observed that there is a scarcity of diagnostic methods available in the market, highlighting a significant demand for such tools, particularly as the healthcare system transitions towards personalized medicine. This growing demand has garnered significant attention from researchers working in diagnostics. It is of great therapeutic and pharmacological significance to design and develop diagnostic instruments for the monitoring of dopamine levels both in vivo and in vitro. Extensive research efforts have been dedicated to devising realistic diagnostic techniques for assessing dopamine levels in bodily fluids, with a particular focus on electrochemical sensing methodologies. While studies related to electrochemical sensing of dopamine have shown promising advancements in terms of simplicity, speed, and sensitivity, there remains a notable gap in their application for clinical studies. Thus, this review aims to provide an overview of the latest progress in non-enzymatic (enzyme-free or direct electrochemical) electrochemical sensing of dopamine, specifically focusing on its integration with carbonaceous nanomaterials in electrodes. Additionally, the review discusses the potential for the commercialization of these laboratory-proven techniques soon, emphasizing their feasibility and practicality in real-world applications.

Optimizing Membrane Performance using Various Filler Materials in Membrane Fabrication for Enhancing Gas Separation Efficiency: A Review

The membrane technology has been receiving significant interest in both research and industrial applications, particularly in the separation of CO2/CH4. These methods, as published, aim to overcome the limitations of pure polymeric membranes and offer an alternative approach in separation techniques where membrane technology can overcome the constraints of conventional methods such as Solid Phase Extraction (SPE) and Liquid-Liquid Extraction (LLE). Fabricating membranes using fillers as adsorbents can enhance membrane separation performance due to their porous nature. Hence, the selection of suitable fillers is crucial to maximize membrane efficiency in separating analytes. This paper will review 3 types of fillers-metal-organic frameworks, carbonaceous nanomaterials and mesoporous molecular sieves-from various research papers published in recent years. HIGHLIGHTS Additives introduced to polymeric membrane to increase the membrane performances in terms of selectivity and permeability. Short review of materials used for fabrication of mixed matrix membrane. Modification of selected additives used to study its effects on membrane performances. Recent advancement of hybrid additives materials, combining MOF and carbonaceous materials. GRAPHICAL ABSTRACT

Competitive adsorption of oxytetracycline and sulfamethoxazole by nanosized activated carbon in aquatic environments: Experimental analysis and DFT calculations

Nanosized activated carbon (NAC) is an emerging carbonaceous nanomaterial for water treatment, while oxytetracycline (OTC) and sulfamethoxazole (SMX) coexisting in aquatic environments may undergo competitive adsorption to influence its removal efficiency. This study investigated the competitive adsorption of OTC and SMX onto NAC under different interaction sequence, pH, electrolyte, and water matrix conditions, using experimental analysis and density function theory (DFT) calculations. Adsorption kinetics show that increasing concentration of one antibiotic inhibited the adsorption of another. Faster equilibrium was attained in binary systems than single systems due to competitive adsorption, with pseudo-second-order model providing the best fit in both systems. Adsorption isotherms suggest that NAC exhibited stronger affinity towards OTC (395.26 mg/g) than SMX (232.02 mg/g), with Langmuir model showing satisfactory fitting in both single and binary systems. Sequential adsorption of [NAC + OTC] + SMX was more favored than binary adsorption, aligning with the optimum configuration of SMX--[NAC-OTC±] with binding energy of −57.25 kcal/mol from DFT calculations. Competitive adsorption was preferred within pH 3.2–5.6, where electrostatic attraction existed between NAC and cationic antibiotics. Salting-out, charge screening, and complexation effects from Na+ and Ca2+ influenced competitive adsorption. Optimal removal of OTC and SMX by NAC was achieved in wastewater effluent among four water matrices in both single and binary systems. Hydrogen bonding, π − π electron donor–acceptor interactions, electrostatic interactions, and hydrophobic interactions contributed to adsorption. Sequential change in functional groups of NAC followed − OH → C − H → C − O → C = C and C = C → C − O → C − H → − OH in single and binary systems, respectively. The findings provide valuable insights into the competitive adsorption mechanisms of antibiotics on NAC, highlighting its potential for remediating mixtures of antibiotics in complex aquatic environments.

Surface science studies on electron-induced reactions of NH3 and their perspectives for enhancing nanofabrication processes

Ammonia (NH3) dissociates efficiently when it interacts with an electron beam. This applies not only to single electron-NH3 collisions in the gas phase but also to electron irradiation of NH3 adsorbed on surfaces. The dissociation products include atomic hydrogen which can act as a reducing agent or NH2 radicals that can bind to suitable surfaces or to adsorbed molecules. This chemistry can be exploited in nanofabrication processes that use electron beams for deposition, etching, or modification of materials. This review describes the current state of insight regarding electron-induced reactions of NH3 adsorbed on surfaces and outlines approaches to the use of these reactions for enhancing electron beam induced nanofabrication processes. First, an overview of surface science studies on electron-induced reactions of NH3 adsorbed on single crystal surfaces is given. This is followed by a summary of studies on the use of NH3 for improving the purity of deposits prepared by electron beam induced deposition (EBID) and on the prospects of NH3 to suppress unwanted thermal surface chemistry during EBID. Finally, we discuss electron-induced reactions of NH3 that are fundamental to the modification of carbonaceous nanomaterials as well as potential application scenarios such as the functionalization of self-assembled monolayers and humidity sensing.

Enhancing anaerobic digestion of food waste for biogas production: Impact of graphene nanoparticles and multiwalled nanotubes on direct interspecies electron transfer mechanism

The present research investigated the effect of two carbonaceous materials, multiwalled carbon nanotubes (MWCNTs), and graphene nanoparticles (GNPs), on biogas yield from food waste (FW) in an anaerobic digestion system for 30 days. Lab scale investigations were conducted in batch mode in 250 mL glass reactor bottles and the findings were compared to the control reactor. The performance of the experimental procedure was assessed in terms of biogas output and organic matter reduction. The addition of 100 mg/L multiwalled carbon nanotubes and 100 mg/L GNPs increased the cumulative biogas production (33.55 % and 81.16 %, respectively) while decreasing the total solid content (about 25.95 % and 24.95 %, respectively). However, increasing the concentration of both carbon nanomaterials from 100 mg/L to 500 mg/L reduced the total biogas production compared to the control, which can be attributed to cytotoxic effects. A microbial diversity study was performed using 16S amplicon sequencing to understand the changes occurring in the microbial ecology. The predominant phyla found during diversity analysis were Firmicutes, Proteobacteria, Actinobacteriota, and Bacteroidota. Finally, addition of carbonaceous nanomaterials to the anaerobic reactors favours organic matter degradation through the DIET mechanism. It improves the biogas production kinetics and productivity during the anaerobic digestion of FW up to a certain dose.

Fabrication of Hierarchically Porous “Fish Cage”‐like Carbonaceous Nanomaterials via Soft Template‐assisted Strategy for Cr Removal: Accelerated Stepped Adsorption and Enhanced Coordination Effect

The negative impact of heavy metal pollution, specifically chromium (VI), on human health is well‐documented. To solve this issue, hollow anisotropic hierarchically porous “Fish Cage”‐like carbonaceous nanomaterial (N,S‐HFC‐180) with multi‐active groups is synthesized. Hierarchically porous structure provides stepped adsorption effect. The addition of K2C2O4 leads to the specific surface area of N,S‐HFC‐180 increases to 1914.21 m2·g‐1 (an increase of ~552 times compared to HFC‐180). Thiourea introduces multi‐active groups act as “Barbs” in “Fish Cage” further reducing Cr(VI) to Cr(III) and sequestrating Cr(III) by coordination effect. Subsequent batch studies suggest that N,S‐HFC‐180 exhibits a high removal capacity of 164.29 mg·g‐1 for Cr(VI) at pH = 2. The kinetics and isotherm analyses display an outstanding maximum adsorption capacity of 393.88 mg·g‐1 at 298 K. In addition, even after seven cycles, the removal rate of Cr(VI) using N,S‐HFC‐180 remains > 85.00%, and it effectively reduces the concentration of electroplating wastewater from 55.82 to 0.14 mg·L‐1. Pore filling, chemical reduction and chelation, hydrogen bond and electrostatic attraction are the primary adsorption drivers. The results suggest that, the recoverable N,S‐HFC‐180 highlights its viability for practical applications in wastewater treatment processes.

Carbon nanotubes perpendicularly grown on graphene oxide nanosheets derived from metal-organic frameworks: Synergistic reinforcement of poly(l-lactic acid) scaffold

The construction of the nanohybrid composed of two carbonaceous nanomaterials is a promising strategy to inhibit their aggregation, and effectively exert the advantages of their excellent mechanical properties as reinforcement for polymers. Here, carbon nanotubes (CNTs) were in situ perpendicularly growing on the surface of graphene oxide (GO) through metal-organic frameworks (MOF)-derived strategy by chemical vapor deposition (CVD), aiming to facilitate their dispersion on poly(l-lactic acid) (PLLA) bone scaffold fabricated by selective laser sintering (SLS). Specifically, GO provided nucleation sites for the growth of MOF, and worked as the templates when CNTs grew, in which MOF provided catalysts and carbon sources simultaneously. The precursor was heated to 550 °C and kept for 2 h, then heated to 900 °C and kept for 2 h before cooling. The obtained nanohybrid (GO@CNT) exhibited a superior dispersion state than the pure GO in the scaffold at the same loading, especially when the loading was 0.75 wt%. Adding 0.75 wt% GO@CNT endowed the scaffold with a remarkable increment in tensile strength and compressive strength of 13.36 MPa and 24.72 MPa with enhancement of 55.35% and 18.85%, respectively, compared to the scaffold containing 0.75 wt% GO. A crack extension model combined with experiment results was proposed to better understand reinforcement mechanisms. Additionally, the scaffold containing GO@CNT exhibited benign cytocompatibility with a cell-spreading area of 86.31% and cell density of 564 cells/mm2 after culturing for 5 d according to the results of cell adhesion and immunofluorescence tests, making it a promising candidate for bone defect repair.

Studies on cytocompatibility of human dermal fibroblasts on carbon nanofiber nanoparticle-containing bioprinted constructs

Functional nanocomposite-based printable inks impart strength, mechanical stability, and bioactivity to the printed matrix due to the presence of nanomaterials or nanostructures. Carbonaceous nanomaterials are known to improve the electrical conductivity, osteoconductivity, mechanical, and thermal properties of printed materials. In the current work, we have incorporated carbon nanofiber nanoparticles (CNF NPs) into methacrylated gelatin (GelMA) to investigate whether the resulting nanocomposite printable ink constructs (GelMA-CNF NPs) promote cell proliferation. Two kinds of printable constructs, cell-laden bioink and biomaterial ink, were prepared by incorporating various concentrations of CNF NPs (50, 100, and 150 µg/mL). The CNF NPs improved the mechanical strength and dielectric properties of the printed constructs. The in vitro cell line studies using normal human dermal fibroblasts (nHDF) demonstrated that CNF NPs are involved in cell-material interaction without affecting cellular morphology. Though the presence of NPs did not affect cellular viability on the initial days of treatment, it caused cytotoxicity to the cells on days 4 and 7 of the treatment. A significant level of cytotoxicity was observed in the highly CNF-concentrated bioink scaffolds (100 and 150 µg/mL). The unfavorable outcomes of the current work necessitate further study of employing functionalized CNF NPs to achieve enhanced cell proliferation in GelMA-CNF NPs-based bioprinted constructs and advance the application of skin tissue regeneration.Graphical abstract

Sulfur-Functionalized Carbon Nanotubes with Inlaid Nanographene for 3D-Printing Micro-Supercapacitors and a Flexible Self-Powered Sensing System.

Digital fabrication of miniaturized micro-supercapacitors (MSCs) holds immense promise for advancing customized, integrated microelectronic systems. As potential electrode materials, carbonaceous nanomaterials, such as carbon nanotubes (CNTs), stand out due to their excellent conductivity and mechanical robustness yet suffer from low ionic storage sites, which restrict further applications. Herein, we introduce a sulfur-assisted in situ activating strategy for obtaining sulfur-functionalized carbon nanotube frameworks integrated with inlaid graphene nanosheets (S-CNT/GNS). Specifically, sulfur functionality enriches the surface charge density with improved interfacial hydrophilicity, while the inlaid nanographene sheets provide abundant ionic adsorption sites. By direct 3D printing of the S-CNT/GNS ink, planar MSCs were fabricated with desirable functionality and outstanding electrochemical performance. Notably, the developed MSCs exhibit a high areal capacitance of 0.47 F cm-2, an exceptional energy density of 64.6 μWh cm-2, and a high-power density of 34.2 mW cm-2. Furthermore, an all-flexible self-powered sensing system with photovoltaic cells and a stretchable sensor was built upon the customized S-CNT/GNS MSCs, demonstrating a highly effective capability for real-time monitoring of human physiological signals and body movements. This work not only presents a promising approach for the development of high-performance MSCs but also lays the groundwork for the creation of advanced wearable/flexible microelectronics systems.

Nitrogen-doped carbon dots as a highly efficient photosensitizer for photodynamic therapy to promote apoptosis in oral squamous cell carcinoma

Photodynamic (PDT) is a new strategy for non-invasive tumor therapy and has been studied for the treatment of oral cancer. PDT has the advantages of low damage and high therapeutic efficiency. However, conventional photosensitizers have defects in different degrees, such as low stability and solubility, and low oxygen quantum yield of singlet oxygen. These defects greatly limit the efficiency of PDT. Several studies have shown that carbonaceous nanomaterials, carbon dots (CDs), are promising as a novel nanoscale photosensitizer to mediate PDT for cancer treatment. In this study, we utilized fluorescent CDs doped with nitrogen to optimize their photosensitizing activity to enhance PDT in oral squamous cell carcinoma (OSCC). Nitrogen-doped CDs were able to generate a large amount of reactive oxygen species (ROS) under 660-nm laser irradiation after uptake by cancer cells, effectively inducing apoptosis in the mitochondrial pathway. The in vivo and in vivo experiments verified that CDs-mediated PDT was able to promote apoptosis of tumor cells in terms of DNA damage, inhibition of angiogenesis and cell proliferation, etc. CDs, as a novel photosensitizer, is expected to be an outstanding tool for clinical PDT in the treatment of OSCC.

Direct Observation of Covalently Bound Clusters in Resonantly Stabilized Radical Reactions and Implications for Carbonaceous Particle Growth.

Based on quantum mechanically guided experiments that observed elusive intermediates in the domain of inception that lies between large molecules and soot particles, we provide a new mechanism for the formation of carbonaceous particles from gas-phase molecular precursors. We investigated the clustering behavior of resonantly stabilized radicals (RSRs) and their interactions with unsaturated hydrocarbons through a combination of gas-phase reaction experiments and theoretical calculations. Our research directly observed a sequence of covalently bound clusters (CBCs) as key intermediates in the evolution from small RSRs, such as benzyl (C7H7), indenyl (C9H7), 1-methylnaphthyl (1-C11H9), and 2-methylnaphthyl (2-C11H9), to large polycyclic aromatic hydrocarbons (PAHs) consisting of 28 to 55 carbons. We found that hydrogen abstraction and RSR addition drive the formation and growth of CBCs, leading to progressive H-losses, the generation of large PAHs and PAH radicals, and the formation of white smoke (incipient carbonaceous particles). This mechanism of progressive H-losses from CBCs (PHLCBC) elucidates the crucial relationship among RSRs, CBCs, and PAHs, and this study provides an unprecedentedly seamless path of observed assembly from small RSRs to large nanoparticles. Understanding the PHLCBC mechanism over a wide temperature range may enhance the accuracy of multiscale models of soot formation, guide the synthesis of carbonaceous nanomaterials, and deepen our understanding of the origin and evolution of carbon within our galaxy.

Electrochemical Detection of Cd2+, Pb2+, Cu2+ and Hg2+ with Sensors Based on Carbonaceous Nanomaterials and Fe3O4 Nanoparticles.

Two electrochemical sensors were developed in this study, with their preparations using two nanomaterials with remarkable properties, namely, carbon nanofibers (CNF) modified with Fe3O4 nanoparticles and multilayer carbon nanotubes (MWCNT) modified with Fe3O4 nanoparticles. The modified screen-printed electrodes (SPE) were thus named SPE/Fe3O4-CNF and SPE/Fe3O4-MWCNT and were used for the simultaneous detection of heavy metals (Cd2+, Pb2+, Cu2+ and Hg2+). The sensors have been spectrometrically and electrochemically characterized. The limits of detection of the SPE/Fe3O4-CNF sensor were 0.0615 μM, 0.0154 μM, 0.0320 μM and 0.0148 μM for Cd2+, Pb2+, Cu2+ and Hg2+, respectively, and 0.2719 μM, 0.3187 μM, 1.0436 μM and 0.9076 μM in the case of the SPE/ Fe3O4-MWCNT sensor (following optimization of the working parameters). Due to the modifying material, the results showed superior performance for the SPE/Fe3O4-CNF sensor, with extended linearity ranges and detection limits in the nanomolar range, compared to those of the SPE/Fe3O4-MWCNT sensor. For the quantification of heavy metal ions Cd2+, Pb2+, Cu2+ and Hg2+ with the SPE/Fe3O4-CNF sensor from real samples, the standard addition method was used because the values obtained for the recovery tests were good. The analysis of surface water samples from the Danube River has shown that the obtained values are significantly lower than the maximum limits allowed according to the quality standards specified by the United States Environmental Protection Agency (USEPA) and those of the World Health Organization (WHO). This research provides a complementary method based on electrochemical sensors for in situ monitoring of surface water quality, representing a useful tool in environmental studies.

Optimizing microstructure and mechanical properties of bimodal-structured magnesium matrix composites by regulating the remelting time of powder thixoforming

A kind of bimodal graphene oxide (GO) reinforced ZK60 Mg matrix composite, characterized by the constitutes of fine grain (FG) zones reinforced by GO and coarse grain (CG) zones, was prepared via powder thixoforming, and its microstructure was optimized through adjusting the partial remelting time to achieve a desirable strength-ductility coordination. Both the volume fractions and grain sizes of CGs could be regulated at different levels by changing the heating duration. The composite thixoformed at 60 min, having 30.1 vol% CGs with average grain size of 15.2 μm, achieves the highest yield strength of 192 MPa and ultimate tensile strength of 316 MPa, as well as a high elongation of 21.8% and toughness of 61.9 MJ m−3, possessing the most remarkable coordination of strength and ductility among the as-reported homogeneous-structured Mg-6Zn composites reinforced by carbonaceous nanomaterials. The macroscopic strain of the composites becomes more uniform as the remelting time increases due to the enhanced co-deformation ability between FG and CG constitutes, which contributes to higher ductility. The back stress strengthening makes a large contribution to the strengthening of the composites. Bimodal structure induced toughening, enhanced dislocation storage capability of the FG zones, and crack blunting contribute to the toughness of the composites. This work provides a promising approach for designing and fabricating bimodal-structured metal matrix composites with good comprehensive mechanical performances.

Synthesized rGO/f-MWCNT-architectured 1-D ZnO nanocomposites for azo dyes adsorption, photocatalytic degradation, and biological applications

A study has synthesized a composite of carbonaceous nanomaterials, including functionalized multi-walled carbon nanotubes (f-MWCNT) and reduced graphene oxide (rGO), with 1D-architectured zinc oxide nanorods (ZnO NRs), for applications in adsorption and sunlight-assisted photocatalytic degradation. We modified the composite with 1% w/w rGO and f-MWCNT. We studied the adsorption and photodegradation of azo dyes using ZnO and its nanocomposites. The photocatalysts of RZnO and CZnO nanocomposite degraded RhB, MB, CV, MO, and CR dyes with a degradation percentage of 92 to 97%. The nanocomposite demonstrated superior antimicrobial and antioxidant properties compared to ZnO NRs, highlighting their potential in drug delivery.

Valorization of Plastic Wastes for the Development of Adsorbent Designed for the Removal of Emerging Contaminants in Wastewater

Plastic waste accrual in the environment has been identified as the topmost significant global issue related to modern civilization. Traditional waste disposal methods, such as open burning, landfilling, and incineration, have increased greenhouse gas emissions in economic and material losses. Unless immediate action is made to curtail demand, prolong product lifespans, enhance waste management, and encourage recyclability, plastic pollution will increase due to an almost threefold increase in plastic use spurred by growing populations and affluence. Plastic production primarily is from crude oil or gas despite more than a fourfold growth from ~6.8 million tonnes in 2000 to ~30 million tonnes in 2019; only ~6% of the world’s total plastics production is made from recycled plastics. The competitiveness and profitability of secondary markets may increase with the establishment of recycled content objectives and advancements in recycling technology. In this review, emerging approaches and the creation of value-added materials from waste plastics such as carbon nanotubes and other carbonaceous nanomaterials production, the environmental impacts of plastic waste, African status concerning plastic waste, the importance of modern techniques in plastic waste management, and the circular economy impact on plastic waste utilization are the high points of this study.

Highly luminescent heteroatom codoped carbon dots for multitudinous applications

Carbonaceous nanomaterials have shown great potential in the analytical and environmental domains due to their natural intriguing properties. Rich in quantum yield and reliable performances are necessary for carbon dots to be effectively used in the real-world applications. Carbon dots (CDs) exhibits high blue-emission with a quantum yield (ϕ) of 11% were synthesized through a single-step superficial pyrolysis technique. In this work, the derived carbon dots were employed as reducing and stabilizing agents in a unique one-step approach for the synthesis of AgNPs. The fluorescence of CDs was found to be quenched in the presence of dopamine with greater sensitivity, the minimum limit of detection was determined as 0.35 μM and possible mechanism could be the inner filter effect along with photoinduced electron transfer. In addition to this, the outstanding optical properties of CDs enable them to use as invisible ink in loading secret information and provide enhanced counterfeit protection. The solid-state quenching is successfully prevented when the CDs were dispersed in a polymer matrix for solid-state films preparation. The CDs-polymer composite is packed on top of a 365 nm UV LED chip, which emits blue light, to fabricate blue LED. Hence, we suggest that the synthesized CDs may serve as a future trend setter by as a single molecular probe for multifarious applications such as optoelectronics and forensic fields. Previously, we utilized these CDs for fingerprint detection and now apply them for new emerging applications.

Carbon nanofibers (CNf) cocatalyst-integrated CdS nanoflowers photocatalyst for the deterioration of rhodamine B

In a heterostructure photocatalyst, a proper co-catalyst plays an important role, which is essential for achieving high efficiency in photocatalyst systems for treating organic pollutants. Carbonaceous nanomaterials are recognized as the most effective, economical, and environmentally friendly cocatalyst for various semiconductor-based heterostructure photocatalysts. CNf would be the best carbonaceous semiconducting material to form a heterogeneous photocatalyst. The heterostructure of CNf/CdS nanoflowers is prepared by a solvothermal route and probed for visible-light decomposition of the rhodamine B (RhB) dye. CNf provides a large surface area for dye adsorption, acts as a sink for photogenerated electrons from the semiconductor CdS, and improves the utilization of visible light. As a result, CNf as a co-catalyst significantly improved the photocatalytic performance of semiconductor-based organic pollutant removal systems. The plausible degradation mechanism of RhB is determined on the basis of the scavenger study. The intermediates formed during photodegradation were detected by LCMS analysis. The probable pathway of RhB degradation to CO2 and H2O is presented in this report.

Application of Biomass‐Based Nanomaterials in Energy

The utilization of biomass as a sustainable and renewable resource for nanomaterial synthesis has received considerable attention in recent years. Through the efficient utilization of biomass waste, opportunities for energy production, energy conversion, and the fabrication of nanomaterials can be maximized. The combination of biomass‐based nanomaterials with additional nanomaterials makes the composite system have more remarkable performance, which further facilitates the transformation procedure of biomass‐based nanomaterials for applications. This comprehensive review provides an overview of the preparation and applications of biomass‐based nanomaterials. The preparation section covers a range of methods for synthesizing biomass‐based nanomaterials, including biomass‐based carbonaceous nanomaterials, biomass‐based carbon nitride nanomaterials, nanomaterials derived from biomass templates, biomass‐based nanomaterials as carriers, and the use of biomass for metal ion reduction. The applications section explores the diverse applications of biomass‐based nanomaterials, such as hydrogen production, carbon dioxide reduction, batteries, and supercapacitors. The unique properties and advantages of biomass‐based nanomaterials in each application are discussed. The conclusion summarizes the current progress and presents future perspectives for the development and utilization of biomass‐based nanomaterials. This review emphasizes the potential of biomass as a valuable and sustainable source for nanomaterial synthesis, opening up promising opportunities in various fields.

Valorizing disposable face masks into non-condensable hydrocarbon gases via optimal reactor configurations in thermal pyrolysis

Pyrolysis studies often overlook the potential of pyrolytic gas as a valuable hydrocarbon resource, thereby hindering the production of advanced carbonaceous nanomaterials (CNM). This study aims to explore various configurations of a multi-zone tubular reactor to upcycle disposable face masks into non-condensable hydrocarbons as potential CNM precursors. The highest gas yield (56.2 wt%) was achieved using a 3-zone configuration (Z-1,3,4), attributed to the end chain scission mechanism. The increased abundance of light hydrocarbons (≤C10) in the resulting liquid confirms a greater extent of end chain scission in the optimum reactor configuration with cold zone retainment. Employing this configuration, different face mask types, including 3ply (polypropylene-based), KF94 (polypropylene-based) and N95 (polyester-based), were utilized as individual feedstocks or in various ratios as mixtures to investigate the resultant composition of hydrocarbon gases. This composition was compared with existing literature studies to identify suitable hydrocarbon gas compositions for CNM production. Mixing 3ply and KF94 face masks produced a consistent gas composition predominantly comprising propylene (62.3 – 66.9%) and ethane (15.4 – 16.8%) via thermal pyrolysis at 500 ℃ with a constant heating rate of 20 ℃/min. However, the inclusion of N95 face masks increased CO2 level fivefold, diminishing the gas quality as a CNM precursor. These findings underscore the necessity of segregating polyester face mask material from polypropylene face mask material prior to pyrolysis to ensure a consistent quality and yield of CNM precursors.

Quantitative morphometry of topological graphene-based aerogels and carbon foams by x-ray micro-computed tomography

In this work, we report quantitative morphometry of freeze-dried graphene-based aerogels (i.e., graphene aerogel-GA, nitrogenated GA-NGA, graphene-carbon nanotube hybrid-Gr-MWCNTs, carbon foam-CF, and CF-GA hybrid-CF-GA) and monoliths, prepared by hydrothermal and organic sol-gel methods, respectively. X-ray micro-computed tomography (XMCT) in combination with scanning and transmission electron microscopy allowed visualization of internal microstructures in three-dimensional space. Quantitative morphometry analysis through the reconstructed volume renderings from two-dimensional sliced images revealed hierarchical structures possessing interlaced thin sheets, honeycomb organization, and topological interconnected pore background domains. The influence of small-diameter functionalized multi-walled carbon nanotubes (MWCNTs) inclusions to graphene-like sheets and integration with CF is assessed through quantitative morphometry analysis in terms of volume-weighted pore size, wall thickness, and porosity levels. Hybrid composite porous solids elucidated cross-linking reinforced by a homogeneous distribution of CNTs into complex sheets of GA and CF matrices. A consistent trend impacting porosity and interconnectedness was found following NGA ≥ GA > CF > Gr-MWCNT2:1 > CF-GA > Gr-MWCNT3:1 > Gr-MWCNT5:1, from XMCT image processing and analyses in corroboration with physical properties and reliability. The experimental results provide insights and guide the design of characteristic porous carbonaceous and graphene-based functional nanomaterials for energy sciences, environmental engineering, and fundamental reactive transport of fluids.