Catalytic Activity Of Graphene Oxide Research Articles

Photodegradation of methylene blue by metal-nanoparticles-modulated-graphene-based composites: An efficient way of sewage water management

Wastewater that holds a very high ratio of toxic contaminants, such as dyes and various organic compounds, from large cities is often pumped directly into rivers, seas, etc. without any treatment which leads to pollution and health hazards. Our work explains the enhanced degradation of dye by graphene oxide-based nanoparticles in the presence of sunlight. In this study, we describe how metal nanoparticles affect the photocatalytic activity of nanocomposites based on graphene oxide (GO). The hydrothermal method was used to create the Fe-doped GO@ZnO nanocomposites successfully. The different percentage of Fe ions doping inside the composites elicits methylene blue (MB) dye degradation efficiency. The catalytic activity of GO (32% in 1hr) is enhanced to 82% (in 1hr) for GO@ZnO composites. A further enhancement is achieved up to 99% after Fe doping inside the GO@ZnO composites. There is an increment of catalytic activity of GO@ZnO as the doping percentage of Fe increases. Interestingly the enhanced photocatalytic activity is not linear with the doping percentage of Fe. The highest activity is observed for 5% Fe doping. The degradation of MB is nearly 96% by the Fe-doped composites upon testing in the actual sample using river water. Thus, synthesized composite is a potential candidate for being an effective adaptable photocatalyst for removing organic dyes from wastewater because of its excellent stability and reusability.

Chemical etching of InP assisted by graphene oxide

Chemical etching of semiconductor surfaces assisted by various types of carbon-based materials is drawing much attention for the fabrication of those micro-nano structures. We herein demonstrated to apply graphene oxide (GO), a 2D nano-carbon material, as a catalyst for the InP etching reaction, and a possible mechanism of GO-assisted InP etching was suggested by combining XPS analyses. The solubility of the InP oxide layer towards the etching solution affected the rate-determining step of InP etching reaction. When the oxidant reduction reaction catalyzed by GO was the rate-determining step, the etching reaction under GO was enhanced. Furthermore, the etching behavior was different in utilizing different oxidants, which means that the catalytic activity of GO for the oxidant reduction also affects the etching behavior.

Catalytic applications of graphene oxide towards the synthesis of bioactive scaffolds through the formation of carbon–carbon and carbon–heteroatom bonds

Abstract During the past several decades, metal-based catalysis is one of the major and direct approaches for the synthesis of organic molecules. Nowadays, materials containing predominantly carbon element which are termed as carbocatalysts, become the most promising area of research to replace transition metal catalysts. In this context of carbocatalysis, the use of graphene oxide (GO) and GO-based materials are under spotlight due to their sustainability, environmental benignity and large scale-availability. The presence of oxygen containing functional groups in GO makes it benign oxidant and slightly acidic catalyst. This chapter provides a broad discussion on graphene oxide (GO) as well as its preparation, properties and vast area of application. The catalytic activity of GO has been explored in different organic transformations and it has been recognized as an oxidation catalyst for various organic reactions.

Evaluation of the catalytic activity of graphene oxide and zinc oxide nanoparticles on the electrochemical sensing of T1R2-Rebaudioside A complex supported by in silico methods

Abstract Herein, we report on the performance of graphene oxide (GOx) and zinc oxide nanoparticles (ZnONPs) on a platinum (Pt) electrode, immobilized with the human T1R2 sweet taste receptor subunit for the detection of rebaudioside A (Reb-A). The characterization studies performed in this work confirmed the thin-layered structure of GOx and the polydispersed nature of ZnONPs. The elucidation of the mass loss observed by TGA demonstrates the stability of GOx. The cyclic voltammetry results for Pt/GOx revealed good catalytic activity over Pt/ZnONPs for adsorption of the T1R2-Reb-A complex. In addition, a series of computational modelling studies were carried out to better understand the surface adsorption phenomena of GOx and ZnONPs to mimic the layer-by-layer electrode modification strategies independently. The strongest interaction energy observed (−573 kcal mol−1) for the direct interaction of ZnONPs onto the Pt electrode surface, demonstrates a stronger adsorption in contrast to the GOx modified Pt electrode (−23 kcal mol−1). However, the overall results for the layered-nanocomposite revealed that the GOx (−256 kcal mol−1) were more strongly adsorbed in contrast to ZnONPs (−231 kcal mol−1) for the detection of the T1R2-ReB-A complex, demonstrating the reliability of our GOx electrode functionalization strategy. The results of this study can potentially be used to improve the design of rapid Reb-A sensors for the food and beverage industry.

Primary amine coupling on nanocarbon catalysts: Reaction mechanism and kinetics via fluorescence probe analysis

Non-metallic nanocarbon materials catalyzed coupling reactions of primary amines to produce imine is an efficient, green and sustainable synthetic route, which has a wide application prospect in fine chemicals or pharmaceutical molecules. In the present study, we show firstly the relatively high catalytic activity of graphene oxide in the reaction of oxidative coupling of benzylamine (OCB), which is even comparable with typical metal-based catalysts, indicating the great potential of nanocarbon materials in this reaction system. More importantly, a novel two-photon fluorescence probe molecule (N-propyl-4-hydrazinyl-1, 8-naphthalimide, NA) with special chemical structure of hydrazine functionality was synthesized. The probe NA could selectively react with aldehyde or ketone compounds, leading to the photoluminescence enhancement via inhibition of photo induced electron transfer (PET) process. The synthesized NA was applied as probe in carbon catalyzed OCB system to predict the existence of reaction intermediate benzaldehyde (BA), indicating the reaction pathway of oxidation-deamination-condensation in nanocarbon catalyzed OCB process. The proposed luminescence-probe strategy for revealing the kinetics and mechanism may also shed light in other reaction systems concerning the intermediates or products of ketones or aldehydes.

Improvement of catalytic activity of graphene oxide by plasma treatment

A considerable enhancement of the catalytic activity of graphene oxide (GO) was achieved as a result of plasma treatment in a hydrogen glow discharge. The results obtained for the hydroisomerization of 1-octene, together with the catalyst characterization showed that plasma exposure leads to the formation of defects in the material and of surface acidic species. Optical emission spectroscopy diagnostics of the plasma revealed that the electron temperature and the dissociation of molecular hydrogen are important parameters that can be tuned for optimization of the treatment process.

Photothermal oxidation of cyclohexane by graphene oxide-based composites with high selectivity to KA oil

Designing high-performance catalyst for the oxidation of cyclohexane (CyH) into value-added products like cyclohexanol and cyclohexanone (the mixture called KA oil) is of paramount significance in chemical industry. Herein, the catalytic activity of graphene oxide coupled with Ag and Fe3O4 nanopaticles composites (GO-Ag&Fe3O4 NPs) was investigated to understand the synergistic effect between Ag and Fe3O4 NPs in photothermal oxidation of CyH. The comparative experiments between thermal and photothermal catalysis indicated that: (a) Conversion efficiency was facilitated by temperature rise, but less than 50 % of selectivity to KA oil was obtained at high temperature (140 °C); (b) Higher selectivity and milder condition were achieved by photothermal catalysis comparing to that of the thermal catalysis; (c) Ag NPs played more important role in photocatalysis, while thermocatalysis was intensified by Fe3O4 NPs. Using 1.5 MPa of dry air as oxidant, 6.6 % of CyH conversion with over 98 % of selectivity was gained by GO-Ag&Fe3O4 NPs. Additionally, no obvious decline in catalytic efficiency was observed after 5 cycles. The concept of photothermal cooperation for CyH oxidation over GO-Ag&Fe3O4 NPs may provide a new approach for the partial oxidation of saturated CH and the design of high-performance catalysts.

Facile Synthesis of Naphtha-quinoxaline Derivatives from β-lapachone Using Graphene Oxide as Catalyst.

To develop efficient method for the synthesis of naphtha-quinoxaline derivatives via the reaction of β-lapachone with various 1,2-diamines. A mixture of β-lapachone (1mmol), 1,2-diamine (1mmol) and graphene oxide (20mg) in methanol (3mL) was heated at 60°C, under constant stirring for appropriate time. After completion of the reaction, the catalyst was filtered off, washed with ethyl acetate (3x3mL) and the combined filtrate was washed with H2O, dried (anhy. Na2SO4) and concentrated under vacuum. The residue was chromatographed over a column of silica gel eluting with a mixture of hexane and ethyl acetate in different ratios, to afford the desired product. All synthesized compounds were assigned with the help of analytical and 1H, 13C NMR, IR, and mass spectral studies. To establish the catalytic role of GO in the synthesis of naphtha-quinoxaline derivatives, the reaction of β-lapachone with 3,4-diaminotoluene was selected as a model reaction. The catalytic activity of graphene oxide in comparison with other catalysts like acidic resin amberlyst-15 and solid acid catalyst like montmorillonite K-10 were studied. The reaction was also observed in various solvents such as water, acetonitrile, toluene, dichloromethane, ethanol and 1,4-dioxane using GO as a catalyst. Excellent yields were obtained at 60°C in methanol. The efficacy of the present protocol was investigated by the reaction of β- lapachone with other 1,2-diamines. An attractive green metal free carbocatalyst Graphene Oxide (GO) has been successfully utilized for the expedient synthesis of naphtha-quinoxaline derivatives. GO showed high catalytic activity which is attested by the desired products being produced in shorter time. The main advantage of this method is the reusability of the catalyst which makes the procedure sustainable.

Graphene Oxide and Oxidized Carbon Black as Catalyst for Crosslinking of Phenolic Resins

Influence of different graphite-based nanofillers on crosslinking reaction of resorcinol, as induced by hexa(methoxymethyl)melamine, is studied. Curing reactions leading from low molecular mass compounds to crosslinked insoluble networks are studied by indirect methods based on Differential Scanning Calorimetry. Reported results show a catalytic activity of graphene oxide (eGO) on this reaction, comparable to that one already described in the literature for curing of benzoxazine. For instance, for an eGO content of 2 wt %, the exothermic crosslinking DSC peak (upon heating at 10 °C/min) shifted 6 °C. More relevantly, oxidized carbon black (oCB) is much more effective as catalyst of the considered curing reaction. In fact, for an oCB content of 2 wt %, the crosslinking DSC peak can be shifted more than 30 °C and a nearly complete crosslinking is already achieved by thermal treatment at 120 °C. The possible origin of the higher catalytic activity of oCB with respect to eGO is discussed.

Water splitting activity of oxygen-containing groups in graphene oxide catalyst in bipolar membranes

Graphene oxide (GO) is a very effective catalyst for splitting water into H+ and OH− ions in bipolar membranes. This research investigated the catalytic activity of six oxygenated functional groups in GO for water splitting. Møller-Plesset second order perturbation method (MP2) simulations were performed to calculate activation barriers for proton acceptance and release reactions with and without an applied electric field. The relative catalytic activity for the functional groups on GO was independent of the electric field intensity and dielectric constant. The catalytic activity for accepting and releasing a proton linearly correlated with the pKa of the functional groups. The edge carboxylate site had the highest catalytic activity for water splitting, and had activation barriers that were 0.2 to 0.4 kcal/mol higher than a model tertiary amine. This suggests that the high catalytic activity of GO results from a high catalytic site density, as opposed to a chemical effect.

Study on the thermal decomposition mechanism of graphene oxide functionalized with triaminoguanidine (GO-TAG) by molecular reactive dynamics and experiments.

Graphene oxide (GO) has a catalytic effect on the thermal decomposition of energetic materials above the melting point. To further enhance the catalytic activity of GO, it has been functionalized with the high nitrogen ligand triaminoguanidine (TAG). However, theoretical studies on the reactivity of functionalized GO (e.g., GO-TAG) have not been carried out. Therefore, the thermal decomposition of each TAG, GO and GO-TAG is studied by molecular dynamic simulations using a reactive force-field (ReaxFF) with experimental verification, and the results are reported herein. The results show that the GO nanolayer has a tendency to aggregate into a large carbon cluster during its degradation. The main decomposition products of TAG are NH3, N2 and H2. For GO-TAG, the main decomposition products are H2O, NH3, N2 and H2. GO has a significant acceleration effect on the decomposition process of TAG by decreasing the decomposition temperature of TAG. This phenomenon is in agreement with the experimental results. The initial decomposition of TAG is mainly caused by hydrogen transfer in the molecule. The edge carbon atoms of GO promote the decomposition of TAG molecules and reduce the decomposition activation energy of TAG by 15.4 kJ mol−1. Therefore, TAG will quickly decompose due to the catalytic effect of GO. This process produces a “new” GO that catalyzes the decomposition of components such as TAG. At the same time, many free radicals (HN2, H2N and free H) are generated during the decomposition of TAG to catalyze the decomposition of other components, which in turn, enhance the catalytic capability of GO.

Catalytic activity of graphene oxide hybridized ZnWO4 for dyes degradation and oxidation of functionalized benzyl alcohols

Catalytic activity of graphene oxide hybridized ZnWO4 for dyes degradation and oxidation of functionalized benzyl alcohols

Catalytic performance of sulfate-grafted graphene oxide for esterification of acetic acid with methanol

Graphene oxide possesses tremendous mechanical and electronic properties in combination with large surface area and accessible active sites leading to the development of novel innovative heterogeneous catalysts. The present study elaborates the catalytic activity of graphene oxide, enhanced by grafting active sulfate groups on its surface to result as a superior catalyst. The catalyst was evaluated in the model acetic acid esterification reaction with methanol in terms of acid conversion. Catalysts consisting of varied sulfate concentrations and calcination time were synthesized and optimized for its best catalytic activity. The prepared catalysts (GO-SO4) were characterized using XRD, FT-IR, SEM-EDS, XPS, and BET. A 44% enhancement in catalyst activity was observed using sulfate-grafted graphene oxide (GO-SO4) catalyst over bare GO due to the synergistic effect of sulfate ions. The catalyst can be separated out by simple filtration. Further, the influence of operating process parameters including catalyst loading, and the reaction temperature was evaluated toward the maximum acid conversion. In addition, the detailed kinetic study was also done in this system using Pseudo-homogeneous model.

Graphene Oxide Promoted Oxidative Bromination of Anilines and Phenols in Water.

The mildly acidic and oxidative nature of graphene oxide, with its large surface area available for catalytic activity, has been explored in aromatic nuclear bromination chemistry for the first time. The versatile catalytic activity of graphene oxide (GO) has been used to selectively and rapidly brominate anilines and phenols in water. The best results were obtained at ambient temperatures using molecular bromine in a protocol promoted by oxidative bromination catalyzed by GO; these transformations proceeded with 100% atom economy with respect to bromine and high selectivities for the tribromoanilines and -phenols. Reduced graphene oxide (r-GO) was observed to form after the second recycle (third use) of GO. This technique is also effective with N-bromosuccinimide (NBS) as the brominating reagent. In the case of NBS, reactions were instantaneous and the GO displayed excellent recyclability without any loss of activity over several cycles.

Graphene‐Based Carbocatalysts for Thermoset Polymers and for Diastereoselective and Enantioselective Organic Synthesis

AbstractThis review reports on the catalytic activity of graphene oxide (GO) and high‐surface‐area graphite (HSAG) for some relevant organic reactions. It is shown that the main drawbacks of graphite‐based catalysts, that is, high catalyst loading and generally poor selectivity, can often be removed by operating under solvent‐free conditions. Moreover, some reactions that are catalyzed by GO as well as HSAG are presented. For these reactions, π stacking of the aromatic substrates with the graphitic planes plays a predominant role in the catalytic activity and the unexpected diastereoselective and enantioselective behaviors.

Enhanced photo catalytic activity of graphene oxide /MoO3 nanocomposites in the degradation of Victoria Blue Dye under visible light irradiation

We show the enhanced photocatalytic activity of graphene oxide –Molybdenum trioxide nanocomposites in the visible range synthesized by a simple dispersion method in two steps. In the first step α-Molybdenum trioxide was synthesized by acidified Sonochemical method. Then the nanocomposites were prepared by loading α-MoO3 on GO. Thus prepared samples were subjected to XRD, UV, PL, Raman, SEM and TEM for structural, optical and morphological studies respectively. The 2-D structure of graphene oxide was confirmed by SEM and TEM. The Raman analysis reveals the presence of D and G peaks of Graphene oxide and also that of MoO3. The X-Ray diffractogram of the nanocomposite indicates the good crystalline nature of the sample and all the peaks were indexed. XPS data conveys the elemental composition of the GO-MoO3 nanocomposite. The BET study reveals a pore size of 4.3 nm for the composite. The as synthesized composites were recognized as a photo catalyst for the photo catalytic dye degradation of Victoria blue dye under various experimental conditions. An explicit control over light harvesting and an enhancement in photo catalytic efficiency was seen by the presence of Graphene oxide. The as synthesized photocatalysts remains chemically and thermally stable and contribute excellent electron transfer mechanism during photocatalytic reactions. The thermal stability of the composites was confirmed by TG-DTA analysis. This work provides new conceit that the as synthesized GO-MoO3 nanocomposites can be efficiently used as high performance photocatalyst for enhancing the degradation of Victoria blue dye under visible light irradiation.

Access of Diverse 2-Pyrrolidinone, 3,4,5-Substituted Furanone and 2-Oxo-dihydropyrroles Applying Graphene Oxide Nanosheet: Unraveling of Solvent Selectivity

Eco benign catalyst graphene oxide (GO) has been effectively exploited in one pot synthesis of 2-pyrrolidinone, 3,4,5-substituted furanone and 2-oxodihydropyrrole derivatives, three important pharmacophores, via one-pot domino reactions (MCR) among easily accessible amines, aldehydes and acetylinic esters. These small heterocyclic molecules have been well diversified employing a wide variety of amines and aldehyde derivatives establishing the broad catalytic activity of graphene oxide towards the synthesis of three potential pharmacophores in good to excellent yields. The protocol features inherent solvent selectivity generating two different heterocyclic core (2-pyrrolidinone and 3,4,5-substituted furanones) starting from common substrates under similar reaction condition. This carbocatalyst prompted protocol demonstrates a rapid and efficient route for the design of biologically diverse heterocycles under mild condition.

Green Catalytic Process for Click Synthesis Promoted by Copper Oxide Nanocomposite Supported on Graphene Oxide

AbstractThe catalytic activity of graphene oxide supported copper oxide (CuO–GO) has been investigated in Click synthesis of 1,2,3‐triazole derivatives under green reaction conditions. In the context of green approach, water is used as solvent under ligand free and aerobic conditions at room temperature, with low catalyst loading (0.2 mol %) while ensuring the recovery and reusability of the catalyst. The catalyst affords excellent selectivity in formation of the desired products in good to excellent yields. Further, the work‐up procedure adopted here is clean and simple, while recycling the organic solvents that one used for work‐up procedure. It is proposed that the functional groups present on the GO surface are effective for preventing the aggregation of the catalytically active copper oxide species during the reaction. Moreover, the excellent performance of CuO–GO nanocomposite is ascribed to the excellent dispersity of the catalyst in water, hydrophilic nature of the GO for the accumulation of organic substrates in water and the “Breslow effect.”magnified image

Graphene Oxide as Recyclable Catalyst for One-Pot Synthesis of α-Aminophosphonates

We report the synthesis of α-aminophosphonates from aromatic aldehydes, aromatic and aliphatic amines, and trimethylphosphite (Kabachnik–Fields reaction) using a “carbocatalyst,” graphene oxide, at room temperature with excellent yield and recyclability. Enhanced catalytic activity of graphene oxide as compared to other catalysts studied is possibly due to the presence of carboxylic acid and hydroxyl groups.

Highly efficient colorimetric detection of ATP utilizing a split aptamer target binding strategy and superior catalytic activity of graphene oxide–platinum/gold nanoparticles

The specific binding of ATP and its aptamer linked the split aptamer-modified GO/PDDA/PtAuNPs and magnetic beads together. Using magnetic separation, TMB was catalyzed into a colored product by nanocomposites, which enabled rapid detection of ATP.