Reduction Of L-ascorbic Acid Research Articles

Fabrication of r-GO/GO/α-Fe2O3/Fe2TiO5 Nanocomposite Using Natural Ilmenite and Graphite for Efficient Photocatalysis in Visible Light

Hematite (α-Fe2O3) and pseudobrookite (Fe2TiO5) suffer from poor charge transport and a high recombination effect under visible light irradiation. This study investigates the design and production of a 2D graphene-like r-GO/GO coupled α-Fe2O3/Fe2TiO5 heterojunction composite with better charge separation. It uses a simple sonochemical and hydrothermal approach followed by L-ascorbic acid chemical reduction pathway. The advantageous band offset of the α-Fe2O3/Fe2TiO5 (TF) nanocomposite between α-Fe2O3 and Fe2TiO5 forms a Type-II heterojunction at the Fe2O3/Fe2TiO5 interface, which efficiently promotes electron-hole separation. Importantly, very corrosive acid leachate resulting from the hydrochloric acid leaching of ilmenite sand, was successfully exploited to fabricate α-Fe2O3/Fe2TiO5 heterojunction. In this paper, a straightforward synthesis strategy was employed to create 2D graphene-like reduced graphene oxide (r-GO) from Ceylon graphite. The two-step process comprises oxidation of graphite to graphene oxide (GO) using the improved Hummer's method, followed by controlled reduction of GO to r-GO using L-ascorbic acid. Before the reduction of GO to the r-GO, the surface of TF heterojunction was coupled with GO and was allowed for the controlled L-ascorbic acid reduction to yield r-GO/GO/α-Fe2O3/Fe2TiO5 nanocomposite. Under visible light illumination, the photocatalytic performance of the 30% GO/TF loaded composite material greatly improved (1240 Wcm-2). Field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) examined the morphological characteristics of fabricated composites. X-ray photoelectron spectroscopy (XPS), Raman, X-ray diffraction (XRD), X-ray fluorescence (XRF), and diffuse reflectance spectroscopy (DRS) served to analyze the structural features of the produced composites.

Chemically reduced graphene oxide/chitosan hybrid; a nanoscale “Fabric Starch”

This work reports on the formation of reduced graphene oxide/chitosan, RGO/CS, (0.1–10 wt%) hybrids via L-ascorbic acid reduction of GO-CS aqueous suspensions. Hybrids at different synthesis steps and the constituent modifications are characterized by microstructural, spectroscopic and physical methods. CS undergoes chemical-structural changes, both by interaction with GO and in the course of the chemical reduction, so that eventually, whilst there is no evidence of CS presence in the final product, we find convincing proof of its transformation to a starch-like phase via a critical examination of XRD and ATR-FTIR analysis. Hybrids show significant modifications of morphology, pore texture, apparent surface area, conductivity, and packing density vs. the pristine RGO. We elucidate more subtle effects, affecting stacking and packing behavior, by examining the capacitive storage behavior of hybrid electrodes. The electrochemical study highlights, at the best composition, a remarkable enhancement of specific/volumetric capacitance (up to 30% and 90% increase, respectively) and of rate behavior, compared to pure RGO. Overall, we show that the functioning of CS in hybrid formation can be explained through the reactive attachment of CS molecules onto RGO sheets, forming a starch-like phase, which stiffens graphene layers mitigating crumpling, and allowing a denser packing without re-stacking.

Optimizing Reduced Graphene Oxide Aerogel for a Supercapacitor

Reduce graphene oxide (rGO) aerogels with different precursor graphene oxide sheet sizes are synthesized using L-ascorbic acid reduction followed by an ambient pressure drying method. The sheet sizes determine the oxygen functionality content during aerogel formation, which subsequently affect its structural properties. The optimized sheet size renders strong parallel sheet stacking to provide mechanical strength that withstands capillary action during aerogel formation with a high surface area (190.40 m2 g−1) and pore volume (0.261 cm3 g−1). Such surface properties enhance the electrochemical properties of rGO aerogel (182 F g−1 at 0.75 A g−1) and render it to be an excellent electrode material for a supercapacitor.

Two-step process for synthesizing wheat-like silver nanoparticles by using facile wet-chemical method

Wheat-like silver nanoparticles (AgNPs) have been facilely synthesized by using two-step reduction method. The initial AgNPs are reduced from silver nitrate in the first step. Effects of ethyl cellulose concentration on the structure and morphology evolution of AgNPs are systematically investigated in the second step. With increasing the concentrations of ethyl cellulose, the AgNPs evolves from cauliflower-like particles to wheat-like species via a transitional shape of slender particles. The trade-off between oxidation of nitric acid and reduction of L-ascorbic acid under the induction of ethyl cellulose dispersant modifies the morphology of AgNPs, contributing to forming various shapes. The phase structure of synthesized AgNPs remains crystalline and independent of ethyl cellulose concentration. Our works indicate that such a wet-chemical method provides an easy-to-do approach for preparing AgNPs with specific shapes.

Adsorption of phenanthrene and 1-naphthol to graphene oxide and L-ascorbic-acid-reduced graphene oxide: effects of pH and surfactants.

In this study, reduced graphene oxide (RGO) was synthesized by L-ascorbic acid reduction, which was a relatively mild and environmental friendly reduction method, and the adsorption of organic contaminants was compared to graphene oxide (GO) to probe the potential adsorption mechanisms. The morphology properties of GO and RGO were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared transmission (FTIR), Raman spectrometer, transmission electron microscope (TEM), and scanning electron microscopy (SEM). The adsorption affinities of GO and RGO for phenanthrene and 1-naphthol were studied in batch experiments. The effects of pH and surfactants were also assessed. The results demonstrated that RGO reduced by L-ascorbic acid show significantly greater adsorption affinity for both phenanthrene and 1-naphthol than GO, and even greater than most of RGOs that reduced by the strong reductive reagents. This was mainly attributed to the hydrophobic interaction, π-π interaction, and H-bonding between graphene sheets and organic contaminants. Both GO and RGO showed stronger adsorption to phenanthrene than to 1-naphthol. The adsorption of 1-naphthol increased with decreasing pH and reached a maximum around pH = 7.34. The surfactants, sodium dodecyl benzene sulfaonate (SDBS) and cetyltrimethyl ammonium bromide (CTAB), had negligible influence on adsorption to GO. Note that CTAB significantly inhibited the adsorption of phenanthrene/1-naphthol on RGO, which could be attributed to the pore blockage effect. In addition, RGO could be regenerated and reused with high recyclability over five cycles. The present study suggests that RGO obtained via L-ascorbic acid reduction can be deemed as a promising material for organic contaminated wastewater treatment.

A comparison study of graphene-cyclodextrin conjugates for enhanced electrochemical performance of tyramine compounds

The present work describes the comparison of the abilities of graphene-cyclodextrin conjugates to enhance the electrochemical performance of four tyramine-related compounds. First, cyclodextrin (CD)-modified graphene conjugates were synthesized via the amine-epoxy reaction between graphene oxide (GO) and 6-deoxy-6-ethylenediamino-β-CD, followed by l-ascorbic acid reduction. The resulting conjugates were characterized using UV–vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Subsequently, for the comparative study, glass carbon electrode electrochemical sensors modified with these conjugates were prepared to detect four structurally similar analytes (tyramine, l-tyrosine, dopamine and levodopa). The sensor sensitivities of the modified electrodes were markedly higher than that of the bare electrode. Based on the results of the comparative study, several crucial factors for improving the performance of the electrodes were proposed, including the binding affinity and the binding orientation of CD toward analytes. The conclusions drawn in this study could provide theoretical foundation for the design and optimization of versatile electrochemical platforms with excellent properties.

Ultralong Fe3O4 nanowires embedded graphene aerogel composite anodes for lithium ion batteries

Fe3O4 nanowires/graphene aerogel composite is prepared for the first time via a simple two-step method, including a hydrothermal and self-assembly water-bath l-ascorbic acid reduction process. Structural and morphological characterizations confirm that the ultralong Fe3O4 nanowires are embedded into the networks of graphene nanosheets. When exploited as an anode material for lithium ion batteries, Fe3O4 nanowires/graphene aerogel composite exhibits good rate capability (557 mAh g−1 at a current density 2000 mA g−1) and excellent cycling performance (900 mAh g−1 at a current density of 200 mA g−1 after 100 cycles) together with good rate performance. This work offers a simple and large-scale preparation process for Fe3O4 nanowires/graphene aerogel composite as an advanced anode material for lithium ion batteries.

One-pot self-assembly of graphene/carbon nanotube/sulfur hybrid with three dimensionally interconnected structure for lithium–sulfur batteries

A graphene/carbon nanotube (CNT)/sulfur (denoted GCS) hybrid with interconnected structure is prepared through a one-pot self-assembly approach initiated by l-ascorbic acid reduction under a mild condition. In such a solution-based assembly process, the formation of an interconnected graphene/CNT conductive network is accompanied by the uniform loading of sulfur, whose fraction is as high as of 70 wt%. The as-prepared GCS hybrid delivers an initial capacity of 1008 mAh g−1 at 0.3C and maintains 704 mAh g−1 after 100 cycles. Remarkably, at a high rate of 1.0C, the cathode shows an excellent cyclic performance with a capacity of 657 mAh g−1 after 450 ycles and the capacity decay is only 0.04% per cycle. Moreover, the superior rate performance of GCS hybrid is attributed to the conductive network formed by interconnected graphene sheets and CNT, which supply an unimpeded and continuous path for electron and Li ion transfer and accommodate the volume variation of sulfur during charge/discharge cycling. In addition, the residual functional groups on GCS can retain intimate contact of the conducting matrix with sulfur and effectively confine the diffusion of polysulfides. This study gives an eco-friendly and highly effective solution-based approach for carbon–sulfur electrode for lithium–sulfur battery.

Preparation and Characterization of Palladium Nanoparticles Supported on Nickel Hexacyanoferrate for Fuel Cell Application

Nickel hexacyanoferrate supported palladium nanoparticles (Pd-NiHCF NPs) were synthesized and studied for oxygen reduction reactions in direct methanol fuel cell. The NiHCF support was readily synthesized by a comixing of <TEX>$Ni(OCOCH_3)_2$</TEX> and equimolar <TEX>$K_3[Fe(CN)_6]$</TEX> solution into DI water under rigorous stirring. After the preparation of NiHCF support, Pd NPs were loaded on NiHCF via L-ascorbic acid reduction method at <TEX>$80^{\circ}C$</TEX>. Pd-NiHCF NPs were electrochemically active for oxygen reduction reaction in 0.1 M <TEX>$HClO_4$</TEX> solution. X-ray absorption near edge structure analysis was conducted to measure the white line intensity of Pd-NiHCF to verify the OH adsorption. As a comparison, carbon supported Pd NPs exhibited same white line intensity. This study provides a general synthetic approach to easily load Pd NPs on porous coordination polymers such as NiHCF and can provide further light to load Pd based alloy NPs on NiHCF framework.

Chemically amplified current response of vitamin C based on the cyclic reaction between l-ascorbic acid and dehydroascorbic acid, using dithiothreithol and ascorbate oxidase

A cyclic reaction between the reduced and the oxidized forms of vitamin C takes place by combining the ascorbate oxidase reaction and the reduction of l-ascorbic acid to dehydroascorbic acid by dithiothreithol. l-Ascorbic acid is oxidized by the dissolved oxygen and its consumption is not compensated by the chemical regeneration of l-ascorbic acid from dehydroascorbic acid. The dissolved oxygen then continues to decrease during the cyclic reaction, consequently, the decrease of the reduction current of oxygen is amplified. The amplification factor of 5 × 10 −5 M l-ascorbic acid at 5 × 10 −3 M dithiothreithol and pH 7.5 was found to be 10.6 when enzyme activity is 0.64 units/ml and the reaction time is 10 min.

On Mechanistic Implications in L-Ascorbic Acid Reduction Reactions: Differential Reactivities of Ascorbic Acid and Acid Ascorbate Monoanion Species Compared vis-a-vis Mechanistic Types

Article On Mechanistic Implications in L-Ascorbic Acid Reduction Reactions: Differential Reactivities of Ascorbic Acid and Acid Ascorbate Monoanion Species Compared vis-a-vis Mechanistic Types was published on January 1, 1986 in the journal Zeitschrift für Physikalische Chemie (volume 267O, issue 1).

Stereoselective, catalytic reduction of L-ascorbic acid: a convenient synthesis of L-gulono-1,4-lactone

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereoselective, catalytic reduction of L-ascorbic acid: a convenient synthesis of L-gulono-1,4-lactoneGlenn C. Andrews, Thomas C. Crawford, and Bradley E. BaconCite this: J. Org. Chem. 1981, 46, 14, 2976–2977Publication Date (Print):July 1, 1981Publication History Published online1 May 2002Published inissue 1 July 1981https://doi.org/10.1021/jo00327a029RIGHTS & PERMISSIONSArticle Views1148Altmetric-Citations52LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (338 KB) Get e-Alerts Get e-Alerts