Carboxyl Graphene Research Articles

Metal–Organic Frameworks with Axial Cobalt–Oxygen Coordination Modulate Polysulfide Redox for Lithium–Sulfur Batteries

AbstractAlthough the ultrahigh theoretical energy density and cost‐effectiveness, lithium–sulfur (Li‐S) batteries suffer from sluggish conversion kinetics and the shuttling effect of soluble lithium polysulfides (LiPSs). Herein, conductive hexagonal cobalt‐organic framework (Co‐HTP) nanosheets are anchored in situ on carboxyl graphene (CG) substrates and serve as host catalysts to modulate the polysulfide redox. Substantial characterizations identify that the local coordination environment of the quadrilateral Co–N4 units transforms into an asymmetric penta‐coordinated O–Co–N4 with axial Co─O coordination, which triggers spin polarization and remarkable electron delocalization of Co 3d orbital. The higher spin state and lower local electron density of the O–Co–N4 sites induce more active electronic states in Co‐HTP/CG and facilitate orbital hybridization with polysulfides to form more stable bond orders. Such optimized electronic structure significantly accelerates redox kinetics and enhances the adsorption strength of polysulfides. These merit the lithium–sulfur battery based on Co‐HTP/CG with a high reversible capacity, impressive rate capability, and prolonged cycling performance over 500 cycles. This work will enrich the design philosophy of modulating the spintronic structure of electrocatalysts for advanced Li–S batteries and beyond.

Lightweight and hierarchical carboxyl chitosan-derived carbon aerogel for electromagnetic wave absorber and heat insulation

In recent years, carbon aerogels derived from biomass have shown promising potential in electromagnetic wave (EMW) absorption field owing to their lightweight nature, controllable structure, environmental friendliness, and abundant pore structure. This study reports a novel type of carbon aerogels based on carboxyl chitosan (CCS) and graphene oxide (GO) with rich pores and a unique three-dimensional interconnected structure through solution mixing, freeze-drying, and pyrolysis process. The EMW absorption performances of the carboxyl chitosan/GO xerogel derived carbon aerogels (CGCAs) are adjusted by varying the content of graphene oxide (GO). The nitrogen elements inherent in chitosan can provide a large number of defects to the carbonized material, effectively capturing and attenuating EMW. Synthesized CGCAs show excellent EMW absorption performance with increasing GO content and the CGCA-6 exhibits the best performance. At a thickness of 1.7 mm, it has RLmin of −61.67 dB, and at a thickness of 1.5 mm, it has the widest effective absorption bandwidth (EAB) of 4.24 GHz (12.96–17.12 GHz). Additionally, under far-field conditions, at a thickness of 1.7 mm, the maximum radar cross-section (RCS) reduction relative to a PEC plate for the prepared CGCA-6 is 22.28 dB m2. Furthermore, the good thermal insulation capability exhibited by CGCA-6 makes it suitable for complex application scenarios. Therefore, this biomass-derived multi-functional carbon aerogel with excellent EMW absorption performance, radar stealth, infrared stealth, and thermal insulation capabilities has broad prospects for applications in EMW protection and aerospace fields.

A multimodal sensing network based on synergistically sensitized polyaniline composites strategy for safety monitoring in pesticide spraying

Ensuring the safety of farmers during pesticide spraying is crucial in smart agricultural practices due to the potential risks of pesticide poison and the associated irreversible damages. However, there is a notable deficiency of efficient monitoring strategies for providing timely and cost-effective safety warnings. In this study, we have devised an advanced and real-time sensing network using polyaniline (PANI) composites to address this pressing concern. To enhance sensing performance, diverse quantum dots (QDs) sensitizers and rigid or flexible substrates are strategically integrated with PANI, resulting in sensors tailored to different sensing capabilities. Specifically, the proton conduction is heightened by incorporating carboxyl graphene QDs (GQDs) into PANI, obtaining the superior gas-sensing performance for NH3 detection. Moreover, a strain sensor employing Ti3C2Tx QDs (MQDs) and a flexible thermoplastic polyurethane (TPU) substrate has been developed for real-time monitoring of physical biosignals. Finally, a smart sensing network with real-time display integrated with the above sensors is designed to detection NH3 concentration released from pesticide volatilization and physiological tracking in cases of mild pesticide poisoning. This sensing network can wirelessly interface with a laptop for convenient safety monitoring of farmers engaged in smart agriculture. The proof of concept demonstrated by this sensing network holds promise for enhancing safety monitoring in smart agriculture.

Study of the microstructure, corrosion behavior, and mechanical properties of AZ91D composites containing various graphene-based nanomaterials

Incorporating two-dimensional carbon materials into magnesium alloys has notably improved both their mechanical strength and resistance to corrosion. This study specifically investigated AZ91D composites containing graphene, carboxyl graphene, and graphene oxide, which were synthesized using spark plasma sintering. Results revealed that AZ91D-0.1 GC exhibited superior mechanical properties, while AZ91D-0.1G showed exceptional resistance to corrosion. Despite being categorized similarly, their distinct structural characteristics led to varying mechanical and corrosion performance. Molecular dynamics simulations were utilized to explore the compression behavior of graphene-reinforced AZ91D alloy, while the phase-field method simulated the sintering of particles. A comprehensive understanding of these materials' behavior is critical for their further application in engineering.

Simultaneous Determination of Magnolol and Honokiol Using a Glassy Carbon Electrode Modified by UIO-66-NH2 and Electroreduced Carboxylated Graphene Oxide

An electrochemical sensor for the simultaneous detection of magnolol (MAG) and honokiol (HON) was constructed based on the metal-organic framework, UIO-66-NH2, and electroreduced carboxylated graphene oxide (ErGO-GOOH). The UIO-66-NH2@ErGO-COOH coating was characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. Cyclic voltammetry was applied to investigate the electrochemical behavior of MAG and HON on UIO-66-NH2@ErGO-COOH/GCE. The electroanalytical method for the simultaneous determination of MAG and HON was established using linear sweep voltammetry. Under optimal experimental conditions, a linear range of 0.05 ∼ 8 μM and limits of detection of 16 and 7.0 nm for MAG and HON, respectively, were obtained. The sensor exhibited good repeatability, reproducibility, stability and anti-interference ability. The sensor was successfully applied to the simultaneous detection of MAG and HON in urine and serum samples with good recovery.

An energy-saving structural optimization strategy for high-performance multifunctional graphene films

Graphene has been widely studied for its excellent properties of outstanding conductivity, strength, and flexibility. However, interlayer defects formed during the macroscopic assembly of graphene nanosheets will severely degrade the performance of graphene films. Herein, a strategy combined with trace carboxyl graphene oxide (GO), mild reduction, and chemical crosslinking is employed to minimize the interlayer defects for enhancing both the conductivity and mechanical strength of graphene films. The trace carboxyl feature of GO allows nanosheets to assemble orderly into highly oriented GO films. Subsequently, the mild chemical reduction preserves the highly oriented and packed microstructure. Coupling with further crosslinking by introducing conjugated molecules with pyrene terminal groups (1-pyrene butyric acid-1,6-hexane diamine, PHD) to provide extra π-π bonds, both the mechanical strength and conductivity of graphene films are improved to 548.4 MPa and 1.7 × 105 S m−1, respectively. In addition, the graphene film with only ∼2 μm in thickness possesses an excellent electromagnetic interference shielding effectiveness (EMI SE) of ∼40 dB and a specific shielding effectiveness of up to 74 278 dB cm2 g−1 in a wide frequency range of 8.2–40.0 GHz. Thus, this study provides an energy-saving fabrication route for mechanically strong, effective thermal management and EMI shielding films.

Conductive GelMA/alginate/polypyrrole/graphene hydrogel as a potential scaffold for cardiac tissue engineering; Physiochemical, mechanical, and biological evaluations

Cardiac failure can be a life-threatening condition that, if left untreated, can have significant consequences. Functional hydrogel has emerged as a promising platform for cardiac tissue engineering. In the proposed study, gelatin methacrylate (GelMA) and alginate, as a primary matrix to maintain cell viability and proliferation, and polypyrrole and carboxyl-graphene, to improve mechanical and electrical properties, are thoroughly evaluated. Initially, a polymer blend of GelMA/Alginate (1:1) was prepared, and then the addition of 2–5 wt% of polypyrrole was evaluated. Next, the effect of incorporating graphene-carboxyl nanosheets (1, 2, and 3 wt%) within the optimized scaffold with 2 wt% polypyrrole was thoroughly studied. The electrical conductivity of the hydrogels was significantly enhanced from 0.0615 ± 0.007 S/cm in GelMA/alginate to 0.124 ± 0.04 S/cm with the addition of 5 wt% polypyrrole. Also, 3 wt% carboxyl graphene improved the electrical conductivity to 0.27 ± 0.09 S/cm. The compressive strength of carboxyl-graphene-containing hydrogel was in the range of 175 to 520 kPa, and tensile strength was 61 and 133 kPa. The simplicity and low-cost fabrication, tunable mechanical properties, optimal electrical conductivity, blood compatibility, and non-cytotoxicity of GelMA/alginate/polypyrrole/graphene biocomposite hydrogel is a promising construct for cardiac tissue engineering.

Removal of Atrazine from contaminated water by functionalized graphene quantum dots

The limitation of clean water supplies and the increment of water pollution resources, like industrial processes, oil pollution, and herbicides, are urgent reasons for introducing new techniques for treating contaminated water. Atrazine is heavily used as a herbicide due to its high effectiveness and low price. However, its environmental persistence causes water contamination, and human exposure to Atrazine is linked to several health effects. This work presents a simulation study of the possibility of removing the Atrazine from water by functionally activated graphene quantum dots (GQDs), using density functional theory (DFT) at B3LYP/3-21G level. The activity of GQDs C46 with a total dipole moment of 0.9 is enhanced by the attachment of chemical groups; for instance, attaching CN and NO2 groups increases the total dipole moment to 8.744 and 9.123, respectively. The effect of the functionalized groups Carboxyl and cyanide was investigated, and confirmed that there was no structure deformation due to the functionalization process. Analysis of the obtained data shows the remarkable adsorption ability of GQDs activated by CN and NO2 groups toward the removal of atrazine herbicides due to positive adsorption energy 1.31, 128, and 1.3 eV obtained from pristine, carboxyl graphene, and cyanide graphene respectively. According to the calculated total charge on the complexes Atrazine and GQDs and Functionalized GQD, charge transfer mainly depends on the interaction pattern. The values of charges were − 0.02, 0.004, and − 0.004 for pristine, carboxyl, and cyanide graphene, respectively. Therefore, the observed results demonstrated the possibility of applying the chemically modified carbon quantum dots as a potential candidate for the treatment of contaminated water.

Mechanical Properties of Epoxy Composites Reinforced Using a Carbon Fiber Film Type Coated with Carboxyl Graphene via an Economical Electrophoretic Deposition Technique

Mechanical Properties of Epoxy Composites Reinforced Using a Carbon Fiber Film Type Coated with Carboxyl Graphene via an Economical Electrophoretic Deposition Technique

Toward the early diagnosis of tuberculosis: A gold particle-decorated graphene-modified paper-based electrochemical biosensor for Hsp16.3 detection

Tuberculosis (TB) currently remains a major life-threatening disease as it can be fatal if not treated properly or in a timely manner. Herein, we first describe a disposable and cost-effective paper-based electrochemical biosensor based on a gold particle-decorated carboxyl graphene (AuPs/GCOOH)-modified electrode for detecting heat shock protein (Hsp16.3), which is a specific biomarker indicating the onset of TB infection. The device pattern was first engineered to facilitate detection procedures and printed on low-cost filter paper to create hydrophobic and hydrophilic regions using a wax printing technique. Immunoassays proceeded in a half-sandwich format because it is a reagent-less approach and requires no labeling step. The fabrication of the immunosensor began with GCOOH drop casting, the electrochemical deposition of AuPs, and the establishment of a biorecognition layer against Hsp16.3 utilizing 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS)-sulfo standard chemistry. The appearance of Hsp16.3 resulted in a substantial decrease in the electrochemical signal response of the redox probe employed [Fe (CN)6]3−/4− due to the created immunocomplexes that possess insulation properties. GCOOH enables direct antibody immobilization, and AuPs enhance the electrochemical properties of the sensor. This proposed immunosensor, while requiring only a miniscule sample volume (5 μL), achieved superior performance in terms of the limit of detection, measuring at 0.01 ng/mL. Our platform was confirmed to be highly specific to Hsp16.3 and can rapidly detect TB-infected sera without necessitating any pre-enrichment (20 min), making it an alternative and particularly suitable for the early diagnosis of TB in resource-scarce countries.

An electrochemical biosensor based on graphene oxide for determination of sertraline hydrochloride as an antidepressant drug

This research was done to develop an electrochemical sensor for the determination of the antidepressant drug sertraline hydrochloride (SH) using carboxylated graphene oxide-modified glassy carbon electrodes and silver vanadate nanoparticles (AgVO3/c-GO/GCE). The modified electrode, made of AgVO3/c-GO nanocomposite, was prepared using a hydrothermal technique. Studying the morphology and structure of changed electrodes revealed that AgVO3 nanowires and c-GO nanosheets formed a 3D hybrid matrix with a significant precise surface area and increased porosity. The prepared AgVO3/c-GO/GCE can be anticipated to be an appropriate platform for selective and sensitive SH sensing, according to studies of the electrochemical properties using CV and DPV techniques. With a detection limit and sensitivity of 25 ± 0.5 nM and 0.01901 μA/μM, respectively, the suggested sensor demonstrated a broad linear response range from concentrations of 0 to 1600 μM. Finally, the design sensor's suitability for accurately and precisely determining the SH in pharmaceutical tablets was assessed.

Hybridisation effect of carboxyl graphene and silica nanofillers on environmentally aged composite acrylonitrile butadiene rubber

Hybridisation effect of carboxyl graphene and silica nanofillers on environmentally aged composite acrylonitrile butadiene rubber

A Microelectrode Modified with Co-electrodeposited Carboxyl Graphene and AuNPs: Characterization and Application in Water Quality Detection

A Microelectrode Modified with Co-electrodeposited Carboxyl Graphene and AuNPs: Characterization and Application in Water Quality Detection

Electrochemical aptasensor based on carboxylated graphene oxide modified carbon paste electrode for strontium ultrasensitive detection

Determination of strontium ions (Sr2+) is crucial with regard to human health and environmental protection. In this work, an electrochemical aptasensor was designed using carboxylated graphene oxide (CGO)-modified carbon paste electrode (CGO/CPE) for ultrasensitive determination of Sr2+ ions. The electrochemical determination was accomplished with employing the constructed G-quadruplex (G4) aptamer at the surface of aptasensor in presence of carmoisine (CA) as an electrochemical label. Moreover, NH2-functionalized aptamer was immobilized onto CGO/CPE via carboxylic group. Hence, differential pulse voltammetry was applied for detection of any possible signal changes of CA on the aptasensor surface. The reduction peak currents of CA in the absence and presence of Sr2+ in solution were different and this difference was linearly dependent to the concentration of Sr2+ in solution. The analytical results revealed that our novel aptasensor showed two appropriate linear ranges (0.1–8.0 pM and 3.0–20.0 nM) versus to Sr2+ ion concentrations with the limit of detection of 0.06 pM (S/N = 3). Excellent stability, selectivity and reproducibility were achieved with this new electrochemical aptasensor. Additionally, the aptasensor showed good achievements in analysis of Sr2+ in aqueous and urine real samples, which making this proposed method a promising candidate for electrochemical detection of Sr2+ in real samples.

Ultralong-Cycling and Free-Standing Carboxylated Graphene/PEDOT:PSS Films as Electrode for Flexible Supercapacitors

The rapid development of current wearable electronics motivates the promotion of energy storage devices. Supercapacitor with flexible, lightweight, highly efficient, and long cycling life is one of the potential and glittering candidates. Here, the composite film of carboxylated graphene (CG) and commercially available poly (3, 4-ethylene dioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) are prepared as electrodes for flexible electrochemical capacitors by ultrasonication and vacuum filtration. The CG/PEDOT:PSS films were roundly characterized by SEM, XPS, FTIR, XRD and Raman spectrometer. The as-prepared free-standing films exhibited high specific capacitance (192.7 F g-1 at 0.5 A g-1), excellent rate capability (up to 80.4% from 0.5 to 20 A g-1), and good electrochemical stability (95.5% of specific capacitance retention after 50000 cycles). Surprisingly, the post treated free-standing films by Dimethyl Formamide (DMF) shows better capacitive properties than those of the pristine electrode, such as higher specific capacitance (204.3 F g-1 at 0.5 A g-1), and ultralong-cycling stability (104.6% retention at a high current density of 20 A g-1 after 50000 cycles). It is expected that the free-standing CG/PEDOT:PSS films can be used as flexible electrodes for various wearable energy storage devices.

A binary composite La(OH)3@Ni(OH)2 nanomaterial on carboxyl graphene for an efficient hybrid supercapacitor electrode.

In this work, we present a binary composite of La(OH)3@Ni(OH)2 on carboxyl graphene (La@Ni/CG) as an electrode material. The layered La@Ni/CG double hydroxides (LDHs) were synthesized by a simple electrodeposition method in which La(OH)3 nanoparticles were first adsorbed onto carboxyl graphene and then coated with Ni(OH)2, with different particle shapes due to the large pH change near the cathodic region. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) were used to characterise the as-prepared La@Ni/CG composite. These results showed that the La@Ni/CG composite exhibited improved electrochemical properties, including large specific capacitance (1334.7 F g-1 at 1.4 A g-1) and capacity retention of 90.6% even after 3000 cycles, and excellent rate capability. The improved electrochemical performance of the composite can be attributed to the synergistic effect of surface adsorption and conductive pathways provided by the multiple active species (Ni, La and C) in the La@Ni/CG composite. The results presented in this work provide advances in the efficient design of nanomaterial based electrochemical energy storage devices.

Carboxyl Graphene Oxide Functionalized Cotton Textile with Superwettable Patterns for Humidity Sensing

In this study, a carboxyl-modified graphene oxide (GO–COOH) was prepared and deposited into flexible superwettable patterned cotton (SPC) for humidity sensing. The morphology of the as-prepared electronic-SPC (ESPC) was characterized by field emission scanning electron microscopy (FESEM). The carboxylation process was investigated by comparing the chemical properties of GO–COOH and the unmodified GO via X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared, and Raman. The as-prepared ESPC was then applied for humidity sensing for the first time, whereby the GO–COOH impregnated into the superwettable patterns of SPC played an important role. The as-prepared ESPC processed a high sensitivity for humidity sensing with a quite short response time (less than 1 s at ΔRH of 60%) and the output current increased with increasing relative humidity (ΔRH). The output current was affected by the thickness of the GO–COOH layer, which could be controlled by varying the effective area (diameter of the dots) as well as the loading amount (concentration of GO–COOH). The as-prepared ESPC showed high stability and durability whereby the output current did not show a significant change after overnight washing. Meanwhile, the high flexibility of ESPC was confirmed by the bending test, and results showed that it could maintain an output current of 25 nA even after 2000 bending cycles. The high performance noncontact ESPC was further applied in human breathing sensing test and the results showed that the ESPC could be a promising material for wearable health monitoring.

An Electrochemical Immunosensor Based on Carboxylated Graphene/SPCE for IgG-SARS-CoV-2 Nucleocapsid Determination

The COVID-19 pandemic has emphasized the importance and urgent need for rapid and accurate diagnostic tests for detecting and screening this infection. Our proposal was to develop a biosensor based on an ELISA immunoassay for monitoring antibodies against SARS-CoV-2 in human serum samples. The nucleocapsid protein (N protein) from SARS-CoV-2 was employed as a specific receptor for the detection of SARS-CoV-2 nucleocapsid immunoglobulin G. N protein was immobilized on the surface of a screen-printed carbon electrode (SPCE) modified with carboxylated graphene (CG). The percentage of IgG-SARS-CoV-2 nucleocapsid present was quantified using a secondary antibody labeled with horseradish peroxidase (HRP) (anti-IgG-HRP) catalyzed using 3,3',5,5'-tetramethylbenzidine (TMB) mediator by chronoamperometry. A linear response was obtained in the range of 1:1000-1:200 v/v in phosphate buffer solution (PBS), and the detection limit calculated was 1:4947 v/v. The chronoamperometric method showed electrical signals directly proportional to antibody concentrations due to antigen-antibody (Ag-Ab) specific and stable binding reaction.

Development of a phage-based electrochemical biosensor for detection of Escherichia coli O157: H7 GXEC-N07

Escherichia coli (E. coli) O157:H7 is one of the most important foodborne pathogens that causing severe foodborne diseases. With the development of foodborne diseases, there is an urgent need to seek new methods for early detection and monitoring of E. coli O157:H7. In this study, an electrochemical biosensor using phage EP01 as the recognition agent for detection of E. coli O157:H7 GXEC-N07 was established due to the specificity and high efficiency of phage EP01 in recognizing GXEC-N07. The biosensor was developed by depositing phages conjugated carboxyl graphene oxide (CFGO) and conductive carbon black (CB) onto the surface of glass carbon electrodes (GCEs). When detecting GXEC-N07 in the concentration range of 102 ∼ 107 CFU/mL, the biosensor showed good linearity with a low detection limit of 11.8 CFU/mL, and the whole progress was in less than 30 min. The biosensor was successfully applied to the quantitative detection of GXEC-N07 in fresh milk and raw pork. The recovery values ranged from 60.8 % to 114.2 %. The biosensor provides a rapid, specific, low cost, and label free tool for E. coli O157:H7 GXEC-N07 detection. It is expected to become a powerful method for the detection of bacteria that threatening food safety and public health security.

Synthesis of carboxylic graphene oxide‐carboxymethyl chitosan composite and its applications toward the remediation of U6+, Pb2+, Cr6+, and Cd2+ ions from aqueous solutions

AbstractThe current research work deals with the synthesis of a novel composite material of carboxylic graphene oxide‐carboxymethyl chitosan (COOH‐GO‐CMC) composite by ultrasound and microwave‐assisted processes. The composite was characterized by Fourier Transform Infra‐red spectroscopy, X‐ray Powder Diffraction, Raman Spectroscopy, Scanning Electron Microscopy, and X‐ray Photoelectron Spectroscopy. The synthesized composite was used to remove heavy toxic metal ions (HTMIs) such as uranium (U6+), lead (Pb2+), chromium (Cr6+), and cadmium (Cd2+) ions from aqueous solutions. The HTMIs removal study was carried out to verify the effects of pH, contact time, amount of adsorbent dose, initial concentration, and temperature. The linear and nonlinear Langmuir and Freundlich adsorption isotherms were fitted to the data of removal studies, and it was observed that the linear Langmuir adsorption isotherm (R2 > 0.99) was the best‐fitted model. The maximum adsorption capacities of COOH‐GO‐CMC were found to be 74.62, 416.66, 76.92, and 53.47 mg g−1 for U6+, Pb2+, Cr6+, and Cd2+ ions, respectively. The kinetics studies, including four types of models (linear and nonlinear pseudo‐first‐order, linear and nonlinear pseudo‐second‐order, Intraparticle diffusion, and Elovich kinetic models), were tested, and the results showed that the linear pseudo‐second‐order kinetics model (R2 > 0.99) was the best‐fitted model. The thermodynamic studies reveal that the adsorption of HTMIs is a spontaneous (ΔG < 0) and exothermic (ΔH < 0 and ΔS > 0) process in nature.