Surface Chemical Structure Research Articles

Improved mechanical properties of carbon fiber/epoxy composites via fiber surface grafting of rigid-flexible chain structure

The surface topography and interface characteristics play a significant role in determining the mechanical properties of carbon fiber reinforced polymer (CFRP) composites. These features are primarily influenced by the surface chemical structures and their interactions with the matrix resin. Here, we developed a rigid-flexible coating consisting of polyetheramine (PEA) and polydopamine (PDA) on the fiber surface to control the interface and improve the mechanical properties of CFRPs. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectrum (FT-IR) results validated the successful introduction of polymeric chains and fiber surface characteristics including rough surfaces, slim polymer layers and uniform dots were examined by scanning electron microscope (SEM) and transmission electron microscopy (TEM). Contact angle tests indicate that the functionalized coating noticeably enhances the interaction force between carbon fibers, promoting improved wettability by the matrix resin. The bending and interlaminar shear strength of CFRP prepared by functional carbon fiber are increased by 45.76 % and 47.63 %, respectively. The drop weight impact (DWI) test confirms the positive effect of improved interfacial properties on the out-of-plane impact resistance of CFRPs.

Advances in the axenic isolation methods of Blastocystis sp. and their applications.

Blastocystis sp. is a prevalent protistan parasite found globally in the gastrointestinal tract of humans and various animals. This review aims to elucidate the advancements in research on axenic isolation techniques for Blastocystis sp. and their diverse applications. Axenic isolation, involving the culture and isolation of Blastocystis sp. free from any other organisms, necessitates the application of specific media and a series of axenic treatment methods. These methods encompass antibiotic treatment, monoclonal culture, differential centrifugation, density gradient separation, micromanipulation and the combined use of culture media. Critical factors influencing axenic isolation effectiveness include medium composition, culture temperature, medium characteristics, antibiotic type and dosage and the subtype (ST) of Blastocystis sp. Applications of axenic isolation encompass exploring pathogenicity, karyotype and ST analysis, immunoassay, characterization of surface chemical structure and lipid composition and understanding drug treatment effects. This review serves as a valuable reference for clinicians and scientists in selecting appropriate axenic isolation methods.

Polymeric ferrite composites as versatile adsorbents for enhanced reactive blue dye removal: a promising solution for treating textile wastewater

ABSTRACT Water contamination caused by the increasing industry and urbanisation is one of the most significant environmental problems that entire planet is facing. Various polymeric ferrite composites synthesised in the current study were employed to remove the synthetic reactive dye blue-248 from wastewater. The polymeric ferrite composites were characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transmission infrared spectroscopy (FTIR) to observe the surface morphology, crystallinity and chemical structure of as-prepared composites. The optimum removal of dye using Ni-CoFe2O4/Chitosan, Zn-NiFe2O4/Starch, CoNiZnFe2O4/Polyaniline, Ni doped CrZnFe2O4/Alginate, Cr doped ZnCoFe2O4/PVA was at (i) pH 2 (32.34 mg/g), 3 (30.31 mgg−1), 3 (21.05 mgg−1), 3 (25.69 mgg−1) and 4 (38.61 mgg−1), (ii) optimum dose (0.03 mg/g) 32.40, 30.27, 21.91, 25.98 and 39.2 mg/g, (iii) Contact time (6090 min) 46.898, 37.70, 43.318, 29.356 and 34.12 mg/g, (iv) Initial dye concentration 32.24 mgg1, 25.79 mgg−1 (120 mg/L), 35.85 mgg−1, 28.37 mgg−1 and 40.37 mgg−1 (150 mg/L) and (v) temperature (65°C) 29.67, 27.08, 21.66, 23.60 and 41.40 mg/g, respectively. Different equilibrium, kinetic and thermodynamic models were used to check the nature of sorption, reaction rate/order of reaction and feasibility of reaction, respectively. The effect of presence of various electrolytes, different metals and surfactants in wastewater were also studied. For dye removal on a large scale, the effects of bed height (1–3 cm), flow rate (1.8–5.4) and initial dye concentration (50–90 ppm) were examined in column study. Different eluents were used for the desorption study of reactive dyes to check the reusability of process.

Unveiling microplastic spectral signatures under weathering and digestive environments through shortwave infrared hyperspectral sensing

Microplastic (MP) pollution presents a novel challenge for marine environmental protection, necessitating comprehensive and long-term monitoring and assessment approaches. Environmental MPs can undergo weathering and microorganism-related digestive processes, altering their original surface properties and chemical structure, thus complicating their quantification and identification. This study aims to establish a comprehensive hyperspectral database for weathered and digestion-degraded MPs, using a wide variety of polymer types collected as either virgin particles or commercial products (within a size range of approximately 3 mm), and to investigate the impact of these processes on their spectral characteristics. Polypropylene (PP) and polyethylene (PE) MPs exhibited significant responses to weathering treatment, as indicated by the formation of new characteristic peaks or slight peak shifts around 1679–1705 nm, which can be attributed to the formation of carbonyl and vinyl functional groups through Norrish reactions. Similarly, polyethylene terephthalate (PET), acrylonitrile butadiene styrene (ABS), and polystyrene (PS) MPs demonstrated notable degradation following digestive treatment, as evidenced by the emergence of new absorption peaks at approximately 1135–1165 nm, possibly associated with alterations involving carbonyl and vinyl functional groups. The results were further validated based on their comparable spectral characteristics of the resultant MPs to reference polymers and possible additives, considering a reasonably accurate match of approximately 80% for the studied MP samples. This study showcases the significant advantage of using shortwave infrared hyperspectral sensing for rapid identification of virgin and exposed MPs with a relatively large scan area after a simple sample preparation. This approach, combined with other complementary characterization techniques, shall provide highly throughput results for MPs identification. This research provides valuable insights into the features extracted from environmental MPs and establishes a foundation for improving their classification efficiency for environmental applications.

Preparation and properties of polyester fibers with polyacrylamide hydrogel grafted by UV‐irradiation

AbstractIt is widely recognized that polyester (PET) fibers with swelling properties are necessary for advanced applications of PET fibers in waterproof fabrics. This study presented the UV‐initiated methods to graft polyacrylamide (PAM) hydrogel on the surface of PET fibers. In the one‐step method, PET fibers are impregnated with a mixed solution of the photoinitiator benzophenone (BP) and the monomer acrylalkylamine (AM). Then, the PET fiber was directly exposed to UV light. In the two‐step method, PET fibers were first impregnated with a photoinitiator solution to generate BP radicals. Then, the fibers impregnated with a monomer solution before being grafted by UV light. Both two methods ultimately achieve PAM gelation‐modified PET fibers. The chemical composition and surface structure were detected by Fourier transform infrared spectroscopy and scanning electron microscope. The findings demonstrate that the PAM hydrogel was successfully grafted on the PET fibers through one‐step method or a two‐step method. In addition, the properties of the grafted PET fibers were evaluated by grafting yield, contact angle, and swelling test. The study indicated that the modified PET fibers via a two‐step method exhibited a superior grafting yield up to 29.3% (PET‐2n) and 54% (PET‐2) compared to the one‐step technique (PET‐1). It was shown that the grafting efficacy of PET fibers modified by two‐step method is better than one‐step method. The static contact angles of PET fibers by UV‐Induced were all reduced. For instance, the contact angles of PET‐2n were decreased from 115° to 62.9°; and the two‐step modified PET fiber after acetone cleaning (PET‐2) decreased from 115° to 60°. It was suggested that the hydrophilicity of the modified PET fibers significantly increased. In addition, the research shows that the gelation‐modified fibers were all possessed swelling properties.

Investigation of structural, optical, and electrical properties of PEDOT:PSS/Au/PEDOT:PSS multilayer films

PEDOT:PSS/Au/PEDOT:PSS multilayer films were successfully prepared and investigated. The PEDOT:PSS and Au layers were prepared using spin coating and DC sputtering, respectively. The thickness of the Au layer was varied within the range of 2–10 nm to investigate its impact on the resulting multilayer films. The amorphous nature of the multilayer films was interpreted from X-ray diffraction analysis. Fourier-transform infrared spectroscopy identified that the multilayer films were the major surface chemical structure of PEDOT:PSS. The optical transmittance and sheet resistance characteristics of the multilayer films exhibited a significant reduction owing to the presence of the Au interlayer. In order to evaluate the optical-electrical properties of the multilayer films, a figure of merit (FOM) was calculated. Remarkably, the multilayer films featuring a thin Au layer of 2 nm yielded the highest FOM value. Therefore, it can be demonstrated that multilayer films of PEDOT:PSS/Au/PEDOT:PSS fabricated with a thin Au layer can be applicable for utilization in optoelectronic devices.

Effect of accelerated weathering on the properties of poly(lactic acid)/poly(butylene adipate-co-terephthalate) blend and composite containing wood flour and wollastonite

The objective of the present work was to explore the effects of accelerated weathering test on properties of poly(lactic acid) (PLA)/poly(butylene adipate- co-terephthalate) (PBAT) blend and PLA)/PBAT/wood flour (WF)/wollastonite (WT) composite. The 70/30 (wt%/wt%) PLA/PBAT blend and its composite with 25 phr WF and 5 phr WT were prepared on a twin screw extruder and injection molding machine. Resulted blend and hybrid composite were exposed to accelerated weathering conditions of UV-irradiation and moisture cycles at 63°C in a laboratory Xenon Weather-Ometer chamber for various periods (250, 500, 750, and 1000 h). The alterations in the surface quality (color change), chemical structure, surface morphology, tensile properties, thermal behaviors, and thermal stability of the specimens were evaluated by spectrocolorimetry, Fourier-transform infrared spectroscopy, scanning electron microscopy (SEM), universal testing machine, differential scanning calorimetry and thermogravimetric analysis, respectively. The photo- and hydrolytic degradations were found to occur during the weathering exposure time. Both blend and composite showed a continuous increase in the total color change with prolonged exposure time, which was mainly due to the degradation of PLA and wood components, especially lignin. The SEM images also confirmed their degradations by illustrating roughness, voids, and cavities on the specimen surfaces after accelerated weathering. Meanwhile, the tensile and thermal properties of both blend and composite were found to decrease. Thus, this study can be used for quality control and material certification.

Visible light driven S-scheme GQDs/BiOBr heterojunction with enhanced photocatalytic degradation of Rhodamine B and mechanism insight

A crucial and desirable objective in the wastewater treatment field is to design photocatalysts that can efficiently remove emerging pollutants while also being environmental-friendly. This work proposed a novel graphene quantum dots/BiOBr (GQDs/BiOBr) heterojunction with strong interfacial interactions through a hydrothermal method. Consequently, in just 140 min, RhB was almost entirely photodegraded by the GQDs/BiOBr and a rate constant 3.26 times higher than pristine BiOBr. The enhanced photocatalytic activity of GQDs/BiOBr was primarily associated with strengthened visible light absorption and improved charge transfer efficiency, as demonstrated through both experimental characterizations and density functional theory (DFT) calculation. Furthermore, with only a minor alteration in the surface chemical structure, GQDs/BiOBr retained strong photocatalytic ability after five cycles (RhB degradation of 85.17 %). The construction mechanism of S-scheme heterojunction, photogenerated carriers' transfer and photocatalytic mechanism were deduced by DFT calculation. The results derived from the radical trapping experiments as well as electron spin resonance (ESR) indicated that the presence of h+ and ·O2− were crucial for the degradation process of RhB. Finally, possible degradation intermediates had been identified and pathways of RhB were proposed, and the results of the toxicity assessment showed that ecotoxicity could be reduced or even eliminated. This effective and reliable visible-light-driven photocatalyst may be applied to build a photocatalytic degradation system for the environmentally friendly and energy-efficient removal of organic pollutants.

The facilitating effect of sulfide treatment coupled sol-gel method on NH3-SCR activity of Fe–Mn/TiO2 catalysts

The 5Fe–3Mn–S/TiO2-SG catalysts were synthesized by sulfide treatment coupled sol-gel method to develop new NH3-SCR catalysts with wide temperature window, good low-temperature activity and environment-friendly. The evolution of catalyst surface chemical state, morphology, structure, acidity and interaction forces were systematically investigated by XPS, BET, XRD, SEM, H2-TPR, NH3-TPD, UV, IR and steady-state kinetic tests. The influence of sulfide treatment coupled sol-gel method on NO conversion was explored. XRD, BET and SEM characterization revealed that sulfide treatment resulted in smaller catalyst particles and higher dispersion, which increased the specific surface area. XPS, NH3-TPD and steady-state kinetic tests results demonstrated that the sulfide treatment catalysts had a higher surface adsorbed oxygen (Oα) content, which could produce more oxygen vacancies on the catalyst surface, thus increasing the number of acid sites. H2-TPR and UV results demonstrated that the 5Fe–3Mn–S/TiO2-SG catalysts exhibited the strongest contact between the carrier and the active component. The 5Fe–3Mn–S/TiO2-SG catalyst obtained more than 80% NO conversion in the operational temperature range of 220–420 °C, according to the NH3-SCR reaction data. The temperature window was expanded by 120 °C compared to conventional Fe–Mn/TiO2 catalysts, and 98% conversion was achieved at 300 °C. Meanwhile, DFT calculations of the SO42--MnFe2O4(311) crystalline surface of the 5Fe–3Mn–S/TiO2-SG catalysts revealed that it could form stronger chemisorption for both NH3 and NO, which promoted the NH3-SCR reaction more effectively. The DFT calculation results and the experimental findings agreed well.

Laser-Induced Graphene Formation on Polyimide Using UV to Mid-Infrared Laser Radiation

Our study presents laser-assisted methods to produce conductive graphene layers on the polymer surface. Specimens were treated using two different lasers at ambient and nitrogen atmospheres. A solid-state picosecond laser generating 355 nm, 532 nm, or 1064 nm wavelengths and a CO2 laser generating mid-infrared 10.6 µm wavelength radiation operating in a pulsed regime were used in experiments. Sheet resistance measurements and microscopic analysis of treated sample surfaces were made. The chemical structure of laser-treated surfaces was investigated using Raman spectroscopy, and it showed the formation of high-quality few-layer graphene structures on the PI surface. The intensity ratios I(2D)/I(G) and I(D)/I(G) of samples treated with 1064 nm wavelength in nitrogen atmosphere were 0.81 and 0.46, respectively. After laser treatment, a conductive laser-induced graphene layer with a sheet resistance as low as 5 Ω was formed. Further, copper layers with a thickness of 3–10 µm were deposited on laser-formed graphene using a galvanic plating. The techniques of forming a conductive graphene layer on a polymer surface have a great perspective in many fields, especially in advanced electronic applications to fabricate copper tracks on 3D materials.

Enhanced paint adhesion of puffed wood-based metal composites via surface treatment with silane coupling agent

ABSTRACT Puffed wood-based metal composite (PWMC) is a lightweight metallic wood material with a high thermal conductivity, having a prospective application as wooden products. Coating with clear waterborne paints increases the grain visibility and prolongs color retention of PWMC, thus providing both decorative and protective functions. However, the poor film adhesion strength of clear waterborne paints limits their industrial wood processing applications. To obtain a better paint films performance, it is necessary to study the effect of silanization treatment on the PWMC’s surface wettability and chemical structures. In this paper, the surface free energy of the metal and wood areas of silane-treated PWMC (S-PWMC) respectively increased by 19.7% and 159.5%, indicating improved surface wettability. S-PWMC showed an improved paint film performance, with a hardness grade of H, paint film adhesion of level 0, and abrasion resistance of 0.04 g/100 r. The excellent paint film performance makes S-PWMC promising for use in wood furnishings.

Electrospun silk nanofibers for numerous adsorption-desorption cycles on Reactive Black 5 and reuse dye for textile coloration

Despite the fact that numerous effective adsorbents have been developed and the fact that adsorption is an appropriate technology for the removal of textile waste, cyclic adsorption-desorption and the reusability of collected waste dye have proven to be difficult to achieve thus far. Therefore, we report the fabrication of electrospun silk nanofibers (ESNFs) membranes for textile dye adsorption, desorption, and reusability. The surface morphology and chemical structure of ESNFs membranes were characterized using FE-SEM, FTIR and XPS techniques. We showed that ESNFs membranes can be efficient adsorbent for Reactive Black 5 (RB5) dye and 40 mg ESNFs have capacity to adsorb up to 98 % of RB5 (dye concentration 100 mg/L) in 5 mL volume of dye solution within 5 min at pH 5. Good physicochemical stability and physical attachment of RB5 on ESNFs membrane, enables a way for 20-time good cyclic adsorption-desorption. The experimental kinetic and isotherm data were well explained by pseudo-second order kinetic model and Langmuir adsorption isotherm model, respectively. Due to simple desorption achieved in alkaline DI water, we proposed a reusability of waste collected dye in textile coloration (cotton fabric coloration). As a result of these findings, we now know that ESNFS are an easy-to-use, cost-effective, resilient, and cyclic adsorbent that may serve as an alternative for various practical applications.

Mechanism analysis of PI/PEEK interface bonding properties enhanced by atmospheric plasma treatment: Experiment and DFT calculation

Due to the increase of service temperature, the bond strength of polyimide composite film will decrease significantly, the continuity of the lapped structure is broken. Therefore, this study proposed a double-layer structure consisting of a polyimide (PI) substrate and Polyetheretherketone (PEEK) coating. The PI/PEEK interface adhesion was improved by using atmospheric plasma treatment. The surface wettability, surface chemical structure, surface element analysis, surface morphology and surface roughness of PI films were studied, respectively. The Materials Studio (MS) was used to model the active groups' grafting mechanism after plasma treatment. The results shown that the surface free energy increased obviously from 27.65 mJ/m2 to 66.93 mJ/m2. Reactive groups containing oxygen, such as C = O, C–O, were generated on the surface of PI film due to etching and addition reactions during the plasma process. The mechanical properties of PI films had little change after plasma treatment. The inorganic particles on the surface of the PI film were exposed by plasma etching, which would increase the adhesion between the PI film and the PEEK coating. MS simulated the sequence, relative energy change, and energy barrier of the three functional groups, revealing that the reactivity sequence of the three groups was: –OH > –COOH > –CO–.

Surface chemical states and structures of epitaxial Mg2Sn thermoelectric thin films

Abstract Evaluation of the surface chemical states and structures of thermoelectric thin films is vital for the successful fabrication and operation of microscale thermoelectric devices incorporating such films. The chemical states and structures present in the surface layers of epitaxially grown Mg2Sn thermoelectric thin films were evaluated by Auger electron spectroscopy and reflection high-energy electron diffraction measurements. An oxide layer about 5 Å thick was shown to form on the surface of epitaxially grown Mg2Sn thermoelectric thin films on exposure to air, giving meaningful insights into potential ways of improving the microfabrication of thin-film-based miniaturized thermoelectric devices.

Study of surface etching of polycarbonate by environmentally friendly alkaline potassium permanganate system

This study examined the surface etching of polycarbonate (PC) using an environmentally friendly etching technique and an alkaline potassium permanganate system. On the surface morphology and roughness, the impacts of swelling circumstances, KMnO4-NaOH concentration, etching temperature, and time were examined. The PC substrate's average surface roughness (Ra) was enhanced by the etching process from 4 nm to 253 nm. The peel strength between the chemically coated copper film and the PC substrate also reached 0.91 KN/m. Using contact angle, Fourier transforms infrared spectrum (FT-IR), and X-ray photoelectron spectroscopy (XPS), the surface chemical structure of the PC substrate was compared before and after treatment. The PC surface turned hydrophilic after the etching process, and the contact angle dropped from 97.2° to 33.2°. The etching process increased the PC surface's roughness and hydrophilicity, which enhanced the adhesion strength between the polycarbonate (PC) substrate and the chemically coated copper film, according to FT-IR absorption spectroscopy, Atomic Force Microscope (AFM) and XPS analysis.

Fabrication of a novel composite nanofiltration membrane with effective treating dye wastewater via integration of phase inversion and interfacial polymerization

In this work, we proposed using the combination of nonsolvent induced phase separation (NIPS) technology and interfacial polymerization (IP) process upon polyvinylidene fluoride (PVDF) substrate as a novel and simple method for preparing high-flux composite nanofiltration membranes. The surface chemical properties, physical structure, hydrophilicity, zeta potential, and permeation experiments of the composite membranes that were prepared with graphene oxide (GO), cyclodextrin (CD), or GO@CD as aqueous monomers were studied. The results indicated that the selective polyester active layer successfully covered the PVDF substrate, and the optimal GO@CD50/PVDF membrane was fabricated using the modification conditions of 1.0 wt% of GO@CD50, 5 min of phase transition time, 0.2 wt% of TMC, and 60 min of IP reaction time, which achieved a high pure water flux (84.8 L m−2 h−1 bar−1) and dye permeation flux (48.7 L m−2 h−1 bar−1 for Rose Bengal); in addition, the dye rejection rate was also high (e.g., 99.6 % for Rose Bengal). Besides, CD nanomaterials can be effectively inserted into the GO lamella to increase the layer spacing of GO sheets and expose more oxygen-containing functional groups; this, in turn, enhances the long-term stability and permeability of the membrane. This study provides practical ways to treat dyes wastewater.

Long-chain amino acids and hydrogen bonding enhanced epoxy thermosets: High latency, thermal and mechanical properties, and its application in recyclable carbon fiber composites

Thermoset carbon fiber reinforced polymer (CFRP) composites are widely used and in increasing demand in composites industries. Among them, CFRP with one-component epoxy matrix can optimize the preparation process. However, high-value carbon fiber (CF) is difficult to recover and no cases of latent CFRP with CF recyclability have been reported. In this study, long aliphatic chains were innovatively introduced into amino acid type latent curing agents to improve the latent performance and the solubility in organic solvents. The latent performance of curing agents improved with the increase of chain length due to the difficulty in proton transfer of ammonium ions along to the long chain. The latent curing agent derived from 1,10-diaminodecane exhibited good solubility in ethanol and good compatibility with epoxy monomers, making it had the potential for industrial use in the preparation of CFRP. Moreover, amide bonds in the synthetic amino acid were prone to form hydrogen bonds to improve the thermal and mechanical properties of cured resin, while ester bonds in the amino acids imparted the resin with degradability in alkaline environments, thereby endowing CFRP with CF recyclability without damaging surface morphology and chemical structure. This work will open a door for the recycling research of latent CFRP.

A nitric oxide-catalytically generating carboxymethyl chitosan/sodium alginate hydrogel coating mimicking endothelium function for improving the biocompatibility

Thanks to their outstanding mechanical properties and corrosion resistance in physiological environments, titanium and its alloys are broadly explored in the field of intravascular devices. However, the biocompatibility is insufficient, causing thrombus formation and even implantation failure. In this study, inspired by the functions of endothelial glycocalyx and the NO-releasing of endothelial cells (ECs), a biomimetic coating (TNTA-Se) with three-dimensional gel-like structures and NO-catalytically generating ability was constructed on the titanium surface. To this end, the titanium alloy was firstly anodized and then annealed to form nanotube structures imitating the three-dimensional villous of glycocalyx, followed by the preparation of the Cu2+-loaded polydopamine intermediate layer for the immobilization of carboxymethyl chitosan and sodium alginate to form the hydrogel structure. Finally, an organoselenium compound (selenocystamine) as an active catalyst was covalently immobilized on the surface to develop a bioactive coating mimicking endothelial function with NO-generating activity. The surface morphologies and chemical structures of the biomimetic coating were characterized by scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and the results indicated that the NO-catalytically generating hydrogel coating was successfully constructed. The results of water contact angle and protein adsorption suggested that the TNTA-Se coating exhibited excellent hydrophilicity, the promotion of bovine serum albumin (BSA) adsorption while the inhibition of fibrinogen (FIB) adsorption. Upon the addition of NO donor S-nitroso glutathione (GSNO) and reducing agent glutathione (GSH), the surface (TNTA-NO) displayed excellent blood compatibility and cytocompatibility to ECs. Compared with other surfaces, the TNTA-NO coating can not only further promote BSA adsorption and inhibit the adhesion and activation of platelets as well as hemolysis, but also significantly enhance ECs adhesion and proliferation and up-regulate VEGF and NO expression of ECs. The current study demonstrated that the NO-catalytically generating hydrogel coating on the titanium alloy can mimic the glycocalyx structure and endothelium function to catalyze a large number of NO donors in human blood to produce NO, and thus simultaneously enhance the surface hemocompatibility and endothelialization, representing a promising strategy for long-term cardiovascular implants of titanium-based devices.

Symmetric Electrochemical Supercapacitors Based on Electrodes of Graphene Nanoribbons/Iron-Doped Lanthanum-Strontium-Manganese Based Perovskite Oxides

The dramatic increase in the world population and industrialization have resulted in unprecedented levels of humanity's hunger for energy. The total global energy production has increased from 23 in 1900 to 548 Exajoules (1018 J = EJ) in 2016.1 A significant contribution of the internment renewable energy resources to the energy production before the mid of this century becomes a necessity to significantly reduce fossil fuel usage and hence limit global warming.1 This creates a great incentive to identify the best ways to store energy when it is not needed.Supercapacitors have gained significant attention due to their fast charging/discharging speed, high power density, and long-term cycling stability in contrast to traditional batteries.2 In recent years, perovskites and graphene nanoribbons have been significantly considered promising materials for electrochemical energy storage. The graphene-based materials have a highly tunable surface area, outstanding electrical conductivity, good chemical stability, and excellent mechanical behavior.3 While the perovskite materials provide the possibility of both anionic and cationic storage mechanisms.4 This presentation reports the in situ preparation of iron-dopped lanthanum-strontium-manganese-based perovskite oxides (La0.7Sr0.3MnxFe1-xO3-δ, LSMFO) in the presence of graphene nanoribbons (GNRs), and the evaluation of the supercapacitive behavior of the synthesized composites. The physical/chemical structure of LSMFO was evaluated using XRD, TEM, FT-IR, Raman spectroscopy, EDS, BET, and XPS. Integrating the perovskite materials that possess redox reaction ability with graphene nanoribbons that exhibit good electronic properties is found to improve the supercapacitor performance in comparison to the single components. The symmetric supercapacitor devices based on LSMFO/GNRs showed good stability (capacitive retention of 95% over 10,000 cycles at a higher current density of 10 A g-1), a wide potential window (up to 1.7 V), and a relatively high capacitance. The best composite with optimum LSMFO:GNRs ratio that shows the highest supercapacitance is identified and explained in correlation with its surface chemical structure. References G. A. Jones and K. J. Warner, Energy Policy, 93, 206–212 (2016).S. Ghosh, K. Anbalagan, U. N. Kumar, T. Thomas, and G. R. Rao, Applied Materials Today, 21, 100872 (2020).O. D. Salahdin et al., Appl. Phys. A, 128, 703 (2022).B.-M. Kim et al., Sci Rep, 12, 10043 (2022).

The Effect of Anionic and Cationic Charge Carriers on the Supercapacitive Behavior of Graphene Nanoribbons

As worldwide energy consumption continues to increase, so too does the demand for improved energy storage technologies. Supercapacitors have attracted a lot of attention due to their quick charging/discharging rate, high power density, and long-term cycling stability in comparison to conventional batteries.1 Graphene nanoribbons (GNRs) with ultrathin two-dimensional structures and unique properties received a lot of attention recently as potential materials for electrochemical energy storage and specifically supercapacitors.2,3 GNRs maintain graphene’s unique lattice structure in one dimension and provide more open-edge structures compared to graphene, thus allowing faster ion diffusion, which makes GNRs highly promising for energy storage systems.2,3 GNRs have unique characteristics such as exceptional electrical conductivity, a highly modifiable surface area, strong chemical stability, low toxicity, great mechanical behavior, and the ability to tune properties for the desired application.This presentation provides an overview of the production of GNRs from carbon nanotubes and their application in supercapacitors. The physical/chemical structure of GNRs was evaluated using XRD, TEM, FT-IR, Raman spectroscopy, and XPS. Since the selection of the cation and anion has been reported to have a dramatic effect on the specific capacitance of the studied materials,4 the supercapacitive behavior of GNR was thoroughly investigated in various media (H2SO4, KOH, K2SO4 ), using different loadings and different evaluation systems (three and two-electrode systems). GNRs, in all of the tested media, showed good stability (retained 95% of their capacitance over 10,000 cycles at a high current density of 10 A/g), a wide potential window (up to 1.7 V), and a relatively high capacitance (≈ 400-800 F/g). The best medium for GNRs highest supercapacitance in correlation with their surface chemical structure will be discussed.