Fabrication Of Graphene Oxide Research Articles

Preparation and in vitro characterization of graphene oxide impregnated superporous hydrogel beads: an effective approach of gastro-retentive drug delivery system

ABSTRACT The remarkable properties of graphene oxide, a shining dynamo, opened new possibilities for delivering the drug. The present work aims to fabricate a graphene-based porous hydrogel system that fades its side effects and encourages its utilization as a drug carrier. Graphene oxide was impregnated in the polymeric matrix for gastro-retentive drug delivery. Porogen was added to create a superporous structure. The extrusion-dripping technique is used to fabricate low density, super porous, and floating hydrogel beads, which were considered a practical approach to target the drug in a controlled and sustained manner in the stomach. The fabricated graphene oxide impregnates superporous beads were characterized by physicochemical analysis, morphological parameters, PXRD, swelling study, drug-release pattern, and in-vitro floating ability. The homogenous nature of fabricated samples was analyzed by weight and size variation. Micrometric properties were estimated to calculate the density and flow ability of superporous beads. The stability and shelf life of prepared hydrogels were performed by accelerated stability analysis according to ICH guidelines. Doxorubicin was chosen as a model anticancer drug. The pi–pi stacking technique is responsible for a considerable loading of the drug onto graphene oxide (GO). However, the successful preparation of low-density graphene oxide impregnates superporous hydrogel beads shows excellent floating ability, thus making it a promising candidate for stomach targeting.

A mild one-step method to fabricate graphene oxide cross-linked with dopamine/polyethyleneimine (GO@DA/PEI) composite membranes with an ultrahigh flux for heavy metal ion removal

Heavy metal ion contamination poses a significant threat to both our environment and human health. Consequently, there is a need for proficient and environmentally friendly remediation techniques to tackle this issue. Among various strategies, membrane-based separation using graphene oxide (GO) laminate membranes has emerged as a promising solution. However, traditional GO membranes have low water permeance, poor selectivity, structural instability, and inconsistent layer spacing. In this study, we cross-linked GO with polydopamine/polyethyleneimine (DA/PEI) using a mild one-step strategy to prepare a GO@DA/PEI membrane for heavy metal ion removal and evaluated the effect of cross-linking duration on the interlayer structure, membrane properties, and heavy metal ion removal performance. The successful formation of a cross-linked network between DA/PEI and GO was proven by various characterization methods. Compared with previously reported GO-based membranes, the prepared GO@DA/PEI40 membrane exhibited excellent performance, including a peak pure water flux of 326.7 L/m2h and ion rejection of 99.6 % for Cu2+, 93.5 % for Pb2+, and 96.6 % for Zn2+, thereby overcoming the conventional trade-off” effect. The mechanism for the high flux was discussed. The cross-linking reaction between the oxygen-containing functional groups at the edges and basal planes of the GO flakes and DA/PEI were crucial to the high flux. In addition, the GO@DA/PEI40 membrane had excellent anti-fouling performance in the presence of humic acid and long-term stability under different conditions. Overall, the GO@DA/PEI membrane has good potential for heavy metal ion removal.

Ni7S6 decorated g-C3N4/graphene oxide composites for enhanced visible light photocatalytic hydrogen evolution

Rationally designing high-efficient g-C3N4 based photocatalysts still remains a big challenge. Herein, Ni7S6 decorated K-doped g-C3N4/graphene oxide photocatalyst was synthesized. Interestingly, amorphous conductive carbon black and urea are simultaneously transferred to graphene oxide and K-doped g-C3N4, which achieves in-situ coupled K-g-C3N4/graphene oxide composite. The in-situ fabricated graphene oxide acts as a charge transfer substrate for the rapid photocarriers migration. Ni7S6 forms Schottky heterojunction with K-g-C3N4 photocatalyst, promoting photocarriers separation. The Ni7S6/K-g-C3N4/graphene oxide composite achieves a visible light hydrogen production rate of 487.59 μmol·g−1·h−1, which is about 7.5 times higher than that of K-g-C3N4 (65.4 μmol·g−1·h−1). This work provides a novel strategy for preparing high-efficient g-C3N4 based photocatalysts.

Fabrication, Characterization, Antibacterial and Biocompatibility Studies of Graphene Oxide Loaded Alginate Chitosan Scaffolds for Potential Biomedical Applications

Graphene oxide nanomaterial possesses greater biocompatibility. Chitosan alginate is produced from chitin by deacetylation, it is a biodegradable and biocompatible biomaterial. Graphene has a large specific surface area that enhances the antibacterial effect by enabling biocompatible interactions with bacterial membranes. To fabricate a biocompatible graphene oxide loaded alginate chitosan scaffold for potential biomedical uses and perform the characterization, antibacterial, and biocompatibility properties of ALG-CHI-GO scaffolds. The scaffolds were prepared by mixing the solution of ChitosanHCl (5 %) and graphene oxide-oxidized alginate (10 %). This gelled mixture is freeze-dried (lyophilization) to form the scaffold and is later characterized using FTIR and SEM, The scaffolds were then tested for in biocompatibility towards peripheral blood mononuclear cells and antibacterial properties against Enterococcus faecalis and Streptococcus mutans. The biocompatibility towards peripheral blood mononuclear was checked using the annexin V PI assay. To conclude that the fabricated Graphene oxide loaded chitosan alginate scaffold was found to be biocompatible and showed antibacterial properties. Keywords: Antibacterial activity, Biocompatibility, Chitosan alginate scaffolds, Graphene oxide.

Titanium doped cobalt ferrite fabricated graphene oxide nanocomposite for efficient photocatalytic and antibacterial activities

Dyes and microbes are the main sources of water pollution and their treatment with titanium doped cobalt ferrite nanoparticles (CoTixFe2-xO4 NPs) is highly challenging due to the recombination ability of their electron-hole pairs which could be mitigated by making their composite with graphene oxide (GO). In the present study, titanium doped cobalt ferrite was fabricated on GO (CoTi0.2Fe1.8O4/GO NC) via the facile ultrasonication method and its confirmation was done by various analytical studies. Homogeneous dispersion of spherical CoTi0.2Fe1.8O4 NPs on the GO surface was realized by SEM analysis. Excellent crystallinity was corroborated by XRD while a Zeta Potential value −21.52 mV depicted exceptional stability. The photocatalytic power of CoTi0.2Fe1.8O/GO NC against Congo Red (CR) dye showed 91% degradation efficiency after 120 min visible light irradiation under optimum conditions of pH 9 and dye concentration 1 mg L−1 which was reasonably higher as compared to bare CoTi0.2Fe1.8O NPs (78% degradation efficiency). The improved photocatalytic performance is accredited to its narrow bandgap value (1.07 eV) and enhanced charge separation as indicated by the Tauc plot and Photoluminescence analysis, respectively. Additionally, CoTi0.2Fe1.8O/GO NC could be readily regenerated and reused five times with only ∼2% performance loss. Meanwhile, MICs of CoTi0.2Fe1.8O4/GO NC against P. aeruginosa and S. aureus were 0.046 and 0.093 mg mL−1 while MBCs were 0.093 and 0.187 mg mL−1, respectively. Thereby, optimized NC can open new avenues for the degradation of dyes from polluted water besides acting as a promising antimicrobial agent by rupturing the cell walls of pathogens.

Electrochemically Exfoliated Graphene Oxide for Simple Fabrication of Cocaine Aptasensors.

Transducers made from graphene-type materials are widely used in sensing applications. However, utilization of graphene oxide obtained from electrochemical exfoliation of graphite (EGO) has remained relatively unexplored. In this study, electrochemical cocaine aptasensors based on large-size EGO flakes were investigated. In particular, the influence of the following parameters on the sensor performance was examined: (i) aptamer's terminal group (-NH2 vs -OH), (ii) functionalization of EGO with the aptamer via physical adsorption and covalent immobilization, and (iii) intrinsic electrochemical properties of EGO such as the electrochemical surface area (ESA) and standard rate constant of electron transfer (k0). The results demonstrate that EGO-based electrochemical aptasensors fabricated by physical adsorption with an NH2-modified aptamer have very good reproducibility, shelf-life stability, and high sensitivity for detecting cocaine with a detection limit of 50 nM. Their performance is comparable to that of the aptasensors prepared using the covalent immobilization. Additionally, it is shown that EGO materials with high ESA and k0 can enhance the sensing performance. The fast (less than 10 min) and strong adsorption of the NH2-modified cocaine aptamer on the surface of large EGO flakes makes the fabrication of the sensing platform simple and rapid. This simple approach has the potential to simplify the fabrication of sensors.

Hydrothermal Fabrication of GO Decorated Dy2WO6-ZnO Ternary Nanocomposites: An Efficient Photocatalyst for the Degradation of Organic Dye

Environmental and human health are seriously threatened by organic dye pollution. Many efforts have been made to find effective and safe methods of eliminating these contaminants. To mitigate these effects, the hydrothermal method was used to effectively generate a ternary kind of Dy2WO6-ZnO embedded in graphene oxide (DWZG) nanocomposites, which were used to degrade the pollutant. Powder X-ray diffraction (XRD) investigation confirms the crystalline character of the as-prepared DWZG nanocomposite. The Dy2WO6-ZnO composition on the graphene oxide (GO) layer is shaped like a combination of algae (Dy2WO6) and clusters (ZnO), as shown by scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS) investigation revealed the composition of elements and oxidation state of C, Dy, O, W and Zn elements. Methylene blue (MB) was chosen as the organic dye target for photocatalytic degradation using the produced nanocomposites. MB is degraded with a photocatalytic efficiency of 98.2% in about 30 min using a DWZG catalyst. Based on the result of the research entitled “Reactive Oxidative Species,” the primary reactive species involved in the MB degradation are photo-generated •OH and O2•− radicals. The recycle test was also successful in evaluating the catalysts’ long-term viability as well as their reusability.

Biocompatible polysaccharide fabricated graphene oxide nanoparticles: A versatile nanodrug carrier to deliver κ- carrageenan against cancer cells

A graphene oxide mediated hybrid nano system for pH stimuli-responsive and in vitro drug delivery targeted for cancer was described in this study. Graphene oxide (GO) functionalized Chitosan (CS) mediated nanocarrier capped with xyloglucan (XG) was fabricated with and without Kappa carrageenan (κ-C) from red seaweed, Kappaphycus alverzii, as an active drug. FTIR, EDAX, XPS, XRD, SEM and HR-TEM studies were carried out for GO-CS-XG nanocarrier loaded with and without active drugs to understand the physicochemical properties. XPS (C1s, N1s and O1s) confirmed the fabrications of XG and functionalization of GO by CS via the binding energies at 284.2 eV, 399.4 eV and 531.3 eV, respectively. The amount of drug loaded in vitro was 0.422 mg/mL. The GO-CS-XG nanocarrier showed a cumulative drug release of 77 % at acidic pH 5.3. In contrast to physiological conditions, the release rate of κ-C from the GO-CS-XG nanocarrier was considerably higher in the acidic condition. Thus, a pH stimuli-responsive anticancer drug release was successfully achieved with the GO-CS-XG-κ-C nanocarrier system for the first time. The drug release mechanism was carried out using various kinetic models that showed a mixed release behavior depending on concentration and diffusion/swelling mechanism. The best-fitting model which supports our release mechanism are zero order, first order and Higuchi models. GO-CS-XG and κ-C loaded nanocarrier biocompatibility were determined by in vitro hemolysis and membrane stabilization studies. MCF-7 and U937 cancer cell lines were used to study the cytotoxicity of the nanocarrier by MTT assay, which indicates excellent cytocompatibility. These findings support the versatile use of a green renewable biocompatible GO-CS-XG nanocarrier as targeted drug delivery and potential anticancer agent for therapeutic purposes.

A novel label-free graphene oxide nano-wall surface decorated with gold nano-flower biosensor for electrochemical detection of brucellosis antibodies in human serum

Conventional serological methods to detect brucellosis are time-consuming, expensive, and require special equipment, but they are less sensitive than newly developed approaches. To overcome these drawbacks, in addition to the ultrasensitive, rapid, easy, and early detection of brucellosis biomarkers, more emphasis on novel methods through electrochemical nanostructured platforms is needed. A novel nanostructured platform made of graphene oxide (GO) nanosheet and gold nanoparticles (AuNPs), with field emission scanning electron microscopy (FESEM) scanning revealing that the GO is vertically arranged on the surface like nano-walls (GONW) and the AuNPs are decorated in the shape of nanoflowers. FESEM, energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) were used to characterize the successfully fabricated nanostructured surface. The electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and cyclic voltammetry (CV) techniques applied to the fabricated graphene oxide nanowall-gold nanoflower (GONW@Au-NF) platform indicated excellent electroactivity (more than a 40% increase) and valuable antifouling properties, which make it more sensitive than bare fluorine-doped tin oxide (FTO) electrodes. The limit of detection (LOD) using different concentrations of Brucella–against antibody (Br-Ab) is estimated at 9.3 fg mL−1. The selectivity of the biosensor was tested using E.coli antibody and bovine serum albumin (BSA). The results revealed good selectivity (significant difference) and acceptable reproducibility (not exceeding 12% RSD). Rapid and early detection of Br-Ab in both PBS and real samples (serum), with excellent sensitivity and selectivity, proposed our fabricated biosensor as an ideal candidate for brucellosis biomarker detection.

A novel biomineralization regulation strategy to fabricate schwertmannite/graphene oxide composite for effective light-assisted oxidative degradation of sulfathiazole

Iron-based heterogeneous catalysts exhibit great peroxymonosulfate (PMS) activation ability to degrade persistent antibiotic pollutants, but the catalytic efficiency of this process is significantly affected by Fe(III)/Fe(II) conversion rate. Herein, we designed a novel biomineralization regulation process to fabricate graphene oxide modified schwertmannite composites (Sch-GOx) as light-assisted PMS activator for enhancing sulfathiazole (STZ) degradation. More specifically, the introduction of GO in biomineralization process not only facilitated the dispersion of Sch, but also accelerated the regeneration of available surface-bound Fe(II) in resultant Sch-GOx through intramolecular electron transfer, thus promoting the activation of PMS. Compared with biosynthesized Sch without modification, the prepared Sch-GO100 sample exhibited superior catalytic activity in light-assisted PMS activation process, 99.90 % removal efficiency of 78 μM STZ has been achieved within 30 min without pH adjustment (initial pH = 7.20). Abundant reactive oxygen species including SO4−, OH, O2− and 1O2 were responsible for the effective elimination of STZ. The potential degradation intermediates of STZ were investigated by liquid chromatography-mass spectrometry (LC-MS) and demonstrated to be less toxic than STZ using the ecological structure activity relationship program (ECOSAR). This study provided a facile and environmental-benign strategy of biomineralization regulation to fabricate effective iron-based PMS activator for environmental remediation.

Facile fabrication of the hybrid of amorphous FePO4·2H2O and GO toward high performance sodium-ion batteries

Iron phosphate (FePO4) with moderate working voltage is an appealing cathode material for room temperature rechargeable sodium-ion batteries (SIBs), while the low electronic conductivity and poor cycle performance remarkably impede its possible energy storage applications. In this work, we report a simple route to fabricate graphene oxide (GO) hybridized amorphous FePO4·2H2O composite for SIBs. By directly mixing FeCl3·6H2O and GO (mass controlled by x wt% of the mass of FeCl3·6H2O) in an agate mortar with pestle, Fe3+ ions could be bound by the oxygen-containing functionalities on the surface of GO nanosheets. After adding NH4H2PO4 powder to the above mixture, a direct room temperature solid state reaction between the GO-confined Fe3+ ions and PO43− polyanions results in an in-situ hybridization of amorphous FePO4·2H2O and GO, i.e. the target electroactive material (denoted as FePO4@GO-x) is attained. In-depth mechanism for the solid state reaction is demonstrated by FTIR and XPS techniques. The optimized hybrid of amorphous FePO4·2H2O and GO (FePO4@GO-15 composite) exhibits the best sodium storage performance. A high reversible charge capacity of 129.0 mAh g−1 is delivered at a current density of 100 mA g−1 for the first cycle, which is around 90% of the theoretical capacity (144 mAh g−1) of FePO4·2H2O. The composite also exhibits outstanding rate performance, superior reversibility, and satisfactory long-lasting cycle stability. When cycled at a high current density (800 mA g−1 at 31 °C), the composite cathode still delivers a charge capacity of 51 mAh g−1 over 1000 cycles, corresponding to 67% of the first charge capacity. The results presented clearly indicate that the hybrid of amorphous FePO4·2H2O and GO is a promising cathode material for SIBs.

3D printed membranes of polylactic acid and graphene oxide for guided bone regeneration.

We fabricated graphene oxide (GO)-incorporated polylactic acid (PLA) (GO-PLA) films by using three-dimensional (3D) printing to explore their potential benefits as barrier membranes for guided bone regeneration (GBR). Our results showed that the 3D printed GO-PLA films provided highly favorable matrices for preosteoblasts and accelerated new bone formation in rat calvarial bone defect models.

Enhanced Graphene Oxide Electrical Properties for Thin-Film Electronics Using an Active/Shrinkable Substrate.

The advances in material science along with the development of fabrication techniques have enabled the realization of thin-film-based electronics on active substrates. This has substantially enhanced and supported the deployment of electronic devices in several emerging applications with flexible functionality. In this work, we report a novel fabrication of graphene oxide (GO)-based memristor devices on an active/shrinkable substrate. The standard lithography process is used to fabricate planar Au-rGO-Au devices on a polymer substrate that has the ability to shrink at a certain temperature (i.e., 170 °C). Upon heating, the devices are shrunk to 50% of their original size. A detailed electrical characterization has been carried out to study the switching behavior of the fabricated devices before and after shrinking. The results prove that upon shrinking, the device preserves its switching ability with enhanced electrical parameters (i.e., switching voltage). Also, material characterization performed for the deposited GO on the active substrate shows improved properties of the GO film due to the enhanced arrangement of GO flakes after shrinking. The novel approach proposed in this work provides new insights into and offers the ability to scale thin-film electronics postfabrication and thus overcome some of the device scaling challenges due to manufacturing limitations. It also unfolds a new path for the realization of GO-based electronic devices with improved electrical properties, which is a crucial aspect of the development of highly flexible and lightweight green electronics.

Viscosity-Controllable Graphene Oxide Colloids Using Electrophoretically Deposited Graphene Oxide Sheets.

Graphene oxide (GO) is one of the interesting ink materials owing to its fascinating properties, such as high dissolubility in water and high controllable electric properties. For versatile printing application, the viscosity of GO colloids should be controlled in order to meet the specific process requirements. Here, we report on the relatively rapid fabrication of viscosity-increased GO (VIGO) colloids mixed with electrophoretically deposited GO sheets (EPD-GO). As the GO colloid concentration, applied voltage, and deposition time increase, the viscosity of the GO colloids becomes high. The reason for the improved viscosity of GO colloids is because EPD-GO has parallel stacked GO sheets. The GO and VIGO colloids are compared and characterized using various chemical and structural analyzers. Consequently, our simple and fast method for the fabrication of GO colloids with enhanced viscosity can be used for producing inks for flexible and printed electronics.

Ethylenediaminetetraacetic acid-functionalized graphene oxide for fabrication of a strong laminated film by ionic cross-linking

Graphene oxide is functionalized with ethylenediaminetetraacetic acid groups to investigate the effect of ethylenediaminetetraacetic acid groups on its colloidal, assembly, and ionic cross-linking behaviors. Ethylenediaminetetraacetic acid-functionalized graphene oxide exhibits a high aqueous dispersibility for presenting a nematic liquid-crystalline phase which is an important factor for fabrication of the well-ordered laminated films. Ethylenediaminetetraacetic acid-graphene oxide films show a distinct internal structure from graphene oxide films owing to the heterogeneous surface of ethylenediaminetetraacetic acid-graphene oxide sheets composed of partially reduced and ethylenediaminetetraacetic acid decorated regions. In addition, the mechanical properties of ethylenediaminetetraacetic acid-graphene oxide films are more enhanced by ionic cross-linking with divalent cations, and their degree of mechanical enhancement is also more dependent on the type of cations than graphene oxide films. The interesting behaviors of ethylenediaminetetraacetic acid-graphene oxide suggest the ethylenediaminetetraacetic acid functionalization can greatly improve the potential of graphene oxide derivatives to develop a high-performance structural material.

Preparation of graphene oxide membrane-daptomycin/epidermal growth factor dressing and its effect on wound healing

Herein, a series of environmentally friendly dressings were specially fabricated from graphene oxide (GO) membrane (a high quality substrate with antibacterial function) and Daptomycin (antibacterial function)/Epidermal growth factor (EGF, wound healing function) for the purpose of antibacterial applications. A performance comparison was designed by employing four dressing samples, including the neat GO membrane (Group A), GO membrane-Daptomycin (Group B), GO membrane-EGF (Group C), and GO membrane-Daptomycin/EGF (Group D). The results analyzed using Fourier transform infrared spectroscopy suggested that Daptomycin and EGF might be adhered to the GO membrane. The contact angle test showed that the hydrophilicity of material gradually increased from Group A to Group D. Groups B and D displayed similar in vitro antibacterial activities, better than those of Groups A and C (their antibacterial performances were similar to each other); all the four experimental groups outperformed the control group (P > 0.05). On the other hand, Groups C and D could promote the proliferation effectively within 1–7 days (P < 0.05), and they also showed similar activities in the cell migration, which were higher than those of Groups A and B (close to each other); all the experimental groups outdid the control group (P < 0.05). Moreover, by monitoring the expression levels of PCNA and CD31 , samples from Group D could promote both angiogenesis and cell reproduction when covering the skin defects (P < 0.05). At the seventh days after the injury, the control and experimental groups of A, B, C, and D displayed healing rates of 40.6%, 53.0%, 66.8%, 60.1%, and 68.3%, respectively. Based on a successful fabrication of GO membrane-Daptomycin/EGF dressings, antibacterial effects as well as growth-promoting performance were well realized by samples in Group D. This is benifitial for the wound healing to a great extent.

Fabrication of graphene-oxide and zeolite loaded polyvinylidene fluoride reverse osmosis membrane for saltwater remediation

Incorporation of inorganic and organic materials in polymer has contributed well towards the development of advanced reverse-osmosis membranes; with greater permeation, and salt rejection potential. We are reporting, Zeolite/GO/PVDF based thin-film composite membranes that were successfully synthesized by solution casting process, an eco-friendly, low-cost, and biocompatible technique. PVDF membranes modified with different ratios of GO/Zeo (0.03, 0.05 and 0.07) were characterized by FTIR, SEM, XRD, TGA, and DSC. Membranes were then tested for its potential for water permeation and salt rejection abilities. As prepared membranes owe better pore-distribution, a moderate degree of crystallinity and high absorption capability that is highly needed for micro-filtration phenomena used for desalination of saline water. The modified membranes exhibited enhanced water permeability up to 28.9 L/m2h as compared to pure PVDF membrane having water permeability flux of 15.6 L/m2h. Salt-rejection ability was found increasing for the membranes (up to 98%) modified with different concentration of GO/Zeo, as compare to pure PVDF membrane (82%). During water permeation and salt rejection studies, no deleterious impact was noted for modified PVDF membranes. This development will entail an efficient approach to furnish high-level performance reverse-osmosis membranes, with greater osmotic-pressure bearing capacity and higher stability.

Novel Way to Turn Spent Li-Ion Battery Graphite into Valuable and Active Catalyst for Electrochemical Oxygen Reduction

Battery technology has been recognized as one of the main driving forces and key technologies required to create a carbon-neutral economy and, therefore, batteries are currently one of the most rapidly growing technology sectors due to the rapid rise in the number of electric vehicles (EV´s). Additionally, the employment of Li-ion batteries (LIBs) in portable electronics has become a necessity in the modern world. This produces spend Li-ion batteries (SLIBs) in substantial volumes, it was estimated that in 2019 188,000 tonnes of SLIBs were available for recycling and it is expected that this number will rise to 125 million in 2030.1,2 To obtain the full benefits of electrification the value chain associated with batteries needs to become more sustainable, which strongly depends on the ability of SLIBs recycling to maximize the components return back to materials circulation. However, current SLIBs recycling strategies has been focused on cathode materials alone while largely overlooking the anode of the battery. In turn, anode recycling has so far concentrated mostly on the metal in the electrode and only very recently has the focus shifted towards the recycling of graphite powders.In this work, a novel strategy for recycling SLIB graphite and reforming it as a valuable catalyst material for electrochemical oxygen reduction reaction (ORR) is proposed. A modified Hummers method was applied to fabricate graphene oxide (GO) from SLIB graphite powder. The GO reduction and doping with nitrogen was achieved by pyrolyzing sample at 800 °C in the presence of DCDA. The prepared nitrogen-doped graphene (NG-Bat) was characterised by various physicochemical (SEM, TEM, XRD, Raman and XPS) and electrochemical characterization methods (LSV, EIS, chronoamperometry). For electrochemical characterisation RDE setup with the glassy carbon working electrode, modified with studied catalyst, in 0.1 M KOH solution was used. The physical and electrochemical characteristics of NG-Bat were compared with commercially available nitrogen doped graphene (NG-Com) sample.Based on XRD and Raman data, SLIB-derived graphite maintains its high quality, even after intense exploitation in the batteries and is therefore a valuable material that is worth recycling.3 Homogeneous distribution of carbon, nitrogen, and oxygen in NG-Bat sample was achieved and the overall nitrogen content was found to be 18.4 at%, based on XPS analysis. The onset potential of the ORR for the NG-Bat catalyst material is 0.867 V, and for the NG-Com catalyst 0.797 V. The NG-Bat shows a larger oxygen reduction current and higher electrocatalytic activity than the catalyst based on NG-Com (Figure 1). Based on EIS fitting very different charge transfer resistance and double-layer capacitance values are found, probably caused by different conductivities of the catalyst materials. NG-Bat showed much high electrocatalytic activity towards the ORR than commercial NG-Com based-catalyst material, caused probably by a higher content of active nitrogen species and the presence of carbon vacancies on the surface of graphene, as confirmed by XRD, Raman and XPS experiments.The findings demonstrate that SLIB graphite is still a valuable material and a promising precursor for GO fabrication. One of the potential applications of the SLIB-derived graphene could be the production of catalyst material for the oxygen reduction reaction (ORR), thereby open new avenues to the fuel cell, metal-air battery, and sensor industries.

Concerted catalysis of Ni-Pd/GO for selective nitriles hydrogenation to secondary amines

A novel explosion-assistant strategy was developed to fabricate graphene oxide supported nickel and palladium three-component catalyst Pd/Ni/NiO/GO for hydrogenation of nitriles to secondary amines. The explosion during the synthesis of catalyst was essential to the well-dispersion of palladium and the decomposition of metal salt precursors. Palladium component was well anchored on nickel oxide and graphene oxide sheets, which regulated the catalytic performance of palladium. This special structure facilitated the spillover of active hydrogen species generated on palladium component to nickel (oxide) and graphene oxide sheets, enhancing the catalytic activity of the bimetallic catalyst. This work developed an effective strategy to fabricate multi-component metal catalyst with low-cost transition metal as main composition for selective hydrogenation of nitriles to secondary amines.

Chitosan mediated layer-by-layer assembly based graphene oxide decorated surface plasmon resonance biosensor for highly sensitive detection of β-amyloid

Alzheimer's disease (AD), and its consequent effect primarily clinical dementia, Parkinson’s disease dementia, etc. currently bring potential avenues for diagnosis centered on identification of beta-amyloid1–42 (Aβ1–42). Unfortunately, techniques engaged in AD core biomarker (Aβ1–42) detection are majorly suffering from poor sensitivity and selectivity. Thus, we fabricated graphene oxide (GO) surface decorated chitosan (CS) mediated layer-by-layer (LbL) assembly based surface plasmon resonance (SPR) biosensor for highly sensitive and selective recognition of Aβ1–42. Briefly, silver nanoparticles (AgNPs) and GO synthesis were achieved through a greener approach. LbL assembly was designed using CS and polystyrene sulphonate (PSS) on surface of AgNPs (AgNPs-CS-PSS-CS) and then antibodies of Aβ (anti-Aβ) were fixed on LbL assembly (AgNPs-CS-PSS-CS@anti-Aβ). Herein, amine functionality of CS offers a plethora of sites for anti-Aβ antibody immobilization that gives specific direction, high selectivity, and an adequate amount of antibody immobilization. For fabrication, synthesized GO was immobilized on an amine-modified gold-coated sensor chip via carbodiimide chemistry followed by AgNPs-CS-PSS-CS@anti-Aβ immobilization on an activated GO surface. Inimitable features of LbL assembly showed improved selectivity towards Aβ peptide whereas utilization of affinity biotransducer with a combination of plasmonic and non-plasmonic nanomaterial improved sensitivity and selectivity. Consequently, linearity range and limit of detection (LOD) of Aβ1–42 antigens were found to be 2 fg/mL to 400 ng/mL and 1.21 fg/mL, respectively. Moreover, analysis of Aβ1–42 in AD-induced rats confirmed the real-time-applicability of the designed SPR biosensor. Hence, GO surface decorated AgNPs-CS-PSS-CS@anti-Aβ mediated SPR biosensor would provide a novel approach for exceptionally sensitive and selective Aβ detection.