Electrochemical Reduction Of Nitrobenzene Research Articles

Asymmetric Activation of the Nitro Group over a Ag/Graphene Heterointerface to Boost Highly Selective Electrocatalytic Reduction of Nitrobenzene

The electrocatalytic reduction of nitrobenzene to aniline normally faces high overpotential and poor selectivity because of its six-electron redox nature. Herein, a Ag nanoparticles/laser-induced-graphene (LIG) heterointerface was fabricated on polyimide films and employed as an electrode material for an efficient nitrobenzene reduction reaction (NBRR) via a one-step laser direct writing technology. The first-principles calculations reveal that Ag/LIG shows the lowest activation barriers for the NBRR, which could be attributed to the optimum adsorption of the H atom realized by the appropriate interaction between Ag/LIG heterointerfaces and nitrobenzene. As a result, the overpotential of the NBRR is reduced by 217 mV after silver loading, and Ag/LIG shows a high aniline selectivity of 93%. Furthermore, an electrochemical reduction of nitrobenzene in tandem with an electrochemical oxidative polymerization of aniline was designed to serve as an alternative method to remove nitrobenzene from the aqueous solution. This strategy highlights the significance of heterointerfaces for efficient electrocatalysts, which may stimulate the development of novel electrocatalysts to boost the electrocatalytic activity.

Performance of graphitic carbon nitride nanosheets derived from liquid and thermal exfoliations towards the electrochemical reduction of nitrobenzene

The electrocatalytic activity of graphitic carbon nitride nanosheets prepared via thermal and solvent exfoliation is compared towards nitrobenzene reduction.

Flat Graphene-Enhanced Electron Transfer Involved in Redox Reactions.

Graphene is easily warped in the out-of-plane direction because of its high in-plane Young's modulus, and exploring the influence of wrinkled graphene on its properties is essential for the design of graphene-based materials for environmental applications. Herein, we prepared wrinkled graphene (WGN-1 and WGN-2) by thermal treatment and compared their electrochemical properties with those of flat graphene nanosheets (FGN). FGN exhibit activities that are much better than those of wrinkled graphene nanosheets (WGN), not only in the electrochemical oxidation of methylene blue (MB) but also in the electrochemical reduction of nitrobenzene (NB). Transformation ratios of MB and NB in FGN, WGN-1, and WGN-2 were 97.5, 80.1, and 57.9% and 94.6, 92.1, and 81.2%, respectively. Electrochemical impedance spectroscopy and the surface resistance of the graphene samples increased in the following order: FGN < WGN-1 < WGN-2. This suggests that the reaction charges transfer faster across the reaction interfaces and along the surface of FGN than that of WGN, and wrinkles restrict reaction charge transfer and reduce the reaction rates. This study reveals that the morphology of the graphene (flat or wrinkle) greatly affects redox reaction activities and may have important implications for the design of novel graphene-based nanostructures and for our understanding of graphene wrinkle-dependent redox reactions in environmental processes.

A Novel Reaction System for Cogeneration of Chemicals and Electric Energy by Electrochemical Reduction of Nitrobenzene with Iron

A Novel Reaction System for Cogeneration of Chemicals and Electric Energy by Electrochemical Reduction of Nitrobenzene with Iron

Electrochemical Behavior of Nitrobenzene in Aqueous CTAB

A mechanistic study of the electroreduction of nitrobenzene was undertaken following previously reported voltammetric investigations of nitrobenzene reduction on bare and dioctadecyldimethylammonium chloride (DODAC) covered platinum electrode [1]. The electrochemical reduction of nitrobenzene in aqueous micellar solution of cetyltrimethylammonium bromide (CTAB) at platinum electrode using cyclic voltammetry revealed two distinct cathodic and anodic peaks with interpeak separation of about 60-65 mV indicating a reversible/quasi-reversible charge transfer reaction pertaining to one electron couple of ArNO2/ArNO2 .- as reported in literature [2-6]. Additional interpretation of experimental cyclic voltammogram was done by using digital simulation. Diffusion co-efficient values of nitrobenzene calculated using Randle-Sevcik equation were found close to the reported values [5-6]. References (1) Haque, I. U.; Tariq, M. J. Chem. Soc. Pak. 2011, 33, 529-534. (2) Sripriya, R.; Chandrasekaran, M.; Noel, M. Colloid Polym Sci. 2006, 285, 39-48. (3) Ernst, S.; Ward, K. R; Norman, S. E.; Hardacre, C.; Compton, R. G. Phys. Chem. Chem. Phys. 2013, 15, 6382-6389. (4) Jara-Ulloa, P.; Nunez-Vergara, L. J.; Squella, J. A. Electroanal. 2007, 19, 1490-1495. (5) Smith, W. H.; Bard, A. J. J. Am. Chem. Soc. 1975, 97, 5203-5210. (6) Kaifer, A. E.; Bard, A. J. J. Phys. Chem., 1985, 89, 4876-4880.

Binary composite ionic liquids [bmim][BF4] and [bmim][Ac] for electrochemical reduction of nitrobenzene

The binary composite ionic liquid mixtures composed of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) and 1-butyl-3-methylimidazolium acetate ([bmim][Ac]) were studied and used in electroreduction of nitrobenzene for the first time. 1H NMR and Fourier transform infrared (FTIR) spectroscopy were carried out to acquire a deep understanding of the interaction of binary ionic liquids, and UV/Vis spectroscopy was used to study the interaction between the mixture of ionic liquids and nitrobenzene. It was found that chemical shifts of all protons were changed and significant changes in the anion IR bands were induced, and the UV maximum absorption wavelength and absorbance of nitrobenzene in binary ionic liquids were different from those in the neat ionic liquid. The electrochemical reduction behavior of nitrobenzene in binary composite ionic liquids on platinum electrode was studied by cyclic voltammetry, in situ Fourier transform infrared spectroscopy, and constant potential electrolysis. Results indicated that the reduction of nitrobenzene in binary composite ionic liquids demonstrated higher current densities with a more positive potential, and the product (azobenzene) showed higher yield and selectivity in the composite ionic liquids than in the neat ionic liquids; the concentrations of water in the binary mixtures of ionic liquids had great effect on the electrochemical behavior of nitrobenzene. In the end, the mechanism of reduction of nitrobenzene in binary mixtures of ionic liquids was discussed.

Electrochemical reduction of nitrobenzene in ionic liquid BMImAc

Ionic liquid, 1-butyl-3-methylimidazolium acetate(BMImAc), was used in the electrochemical reduction of nitrobenzene. The electro-reduction of nitrobenzene on platinum electrode was studied by cyclic voltammetry(CV), in situ Fourier transform infrared(FTIR) spectroscopy and constant-potential electrolysis. The experimental results show that electrochemical reduction process of nitrobenzene was controlled by diffusion, the main reduction product was azobenzen at −1.45 V, and the influences of scan rate and temperature on the electrochemical behaviors were obviously. A reduction mechanism of nitrobenzene in an ionic liquid was a probable ‘nitrobenzene→nitroso-benzene→azobenzene→aniline’ main reductive reaction route.

Electrochemical sensor for nitrobenzene based on carbon paste electrode modified with a poly(3,4-ethylenedioxythiophene) and carbon nanotube nanocomposite

A sensitive and selective electrochemical sensor for the determination of nitrobenzene (NB) was developed based on a carbon paste electrode (CPE) modified with a nanocomposite prepared from the conducting polymer poly(3,4-ethylenedioxythiophene) and carbon nanotubes. The modified CPE exhibits good conductivity, a large surface area, and excellent catalytic activity towards the electrochemical reduction of NB. Under optimal conditions, the modified CPE is capable of detecting NB in the 0.25 to 43 μM concentration range and with a detection limit at 83 nM. Moreover, the sensor is highly stable and reusable, and free of interferences by other commonly present nitro compounds. It was used to determine NB in wastewater samples.

Cu/CuxO and Pt nanoparticles supported on multi-walled carbon nanotubes as electrocatalysts for the reduction of nitrobenzene

Cu/CuxO and Pt nanoparticles supported on multi-walled carbon nanotubes (MWCNTs) were studied as electrocatalysts for the reduction of nitrobenzene in a half-cell set-up. This reaction not only produces valuable chemicals, but has the potential to generate electricity if applied in a fuel cell device. MWCNTs with and without functional groups were investigated as supports for the nanoparticles, employing either ethylene glycol (EG) or H2 gas as reductant. Cu/CuxO nanoparticles supported on pristine multi-walled carbon nanotubes prepared using H2 as reductant (Cu/MWCNT-H2) were identified as the best electrocatalyst for the reduction of nitrobenzene on the basis of its onset potential and of the number of electrons transferred per nitrobenzene molecule. This material consists of well-dispersed Cu/CuxO nanoparticles with an average size of 8nm. The stability of Cu/MWCNT-H2 was tested by cyclic voltammetry (CV) for 1000 cycles, showing that the activity of this electrocatalyst does not deteriorate over time. The electrochemical reduction of nitrobenzene over Cu/MWCNT-H2 in acidic ethanolic medium at −0.62V vs. Fc/Fc+ led to 44% conversion with an overall selectivity toward azoxybenzene (AOB) of 82%.

Electrochemical study of nitrobenzene reduction using novel Pt nanoparticles/macroporous carbon hybrid nanocomposites

Novel Pt nanoparticles (PN) ensemble on macroporous carbon (MPC) hybrid nanocomposites (PNMPC) were prepared through a rapidly and simple one-step microwave-assisted heating procedure. The obtained PNMPC was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and electrochemical methods. The electrochemical reduction of nitrobenzene (NB) was thoroughly investigated at the PNMPC modified glassy carbon (GC) electrode, and the catalytic rate constant was calculated to be 3.14×104M−1s−1 for NB. A sensitive NB sensor was developed based on the PNMPC/GC electrode, which showed a wide linear range (1–200μM), low detection limit (50nM), high sensitivity (6.93μAμM−1), excellent anti-interference ability and good stability. And moreover, the electrode was successfully applied to the determination of NB in real samples.

Dopant induced effect on electrocatalytic reduction of nitrobenzene using conducting polypyrrole thin film electrodes

AbstractConducting polypyrrole electrodes were prepared by electrochemical polymerization of pyrrole on vacuum‐metallized glass substrates. These electrodes were modified by doping with a range of metal halides as dopant ions having different electronegativity. Electrochemical reduction of nitrobenzene using these electrodes was studied by means of cyclic voltammetry technique in acetonitrile medium containing aqueous HClO4 (0.1M) as supporting electrolyte. It was found that the electronegativity of the dopant ion played a very important role in the electrocatalytic activity. Polypyrrole doped with nickel chloride gave the highest anodic current at the reduction potential of nitrobenzene. The results were explained on the basis of charge transfer efficiency at the electrode–electrolyte interface, which was associated with the acceptor state created by the dopant in the semi‐conducting polymer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Electrochemical Reduction of Nitrobenzene in Different Ionic Liquids

Electrochemical Reduction of Nitrobenzene in Different Ionic Liquids

Electrochemical reduction of nitrobenzene at carbon nanotube electrode

The electrochemical behaviors of nitrobenzene at a pyrolytic graphite electrode modified with carbon nanotubes (CNTs) were studied using cyclic voltammetry and constant-potential electrolysis technique, and the CNT-modified electrode was characterized with Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) measurements. A CNT-modified packed-bed flow reactor was also constructed for electrocatalytic reduction of nitrobenzene. The results showed that CNTs exhibited high activity for nitrobenzene reduction to aniline and the electrochemical reduction of nitrobenzene at CNT-modified electrode followed the pathway of nitrobenzene → phenylhydroxylamine → aniline. CNTs had been functionalized with profuse carboxylic group and other oxygen-containing groups, became open with some lacuna on the wall, and were distributed symmetrically on the electrode with forming a three-dimensional layer, resulting in the high catalytic-activity for nitrobenzene reduction to aniline. The removal of nitrobenzene was over 95% with electrolysis for 50 min at −1.20 V in pH 5 solution using the CNT-modified packed-bed flow reactor, and no other product was obtained except aniline. The removal of nitrobenzene was over 95% with electrolysis for 80 min at −1.20 V in pH 7 solution and was 87% with electrolysis for 120 min in pH 9 solution. A little phenylhydroxylamine besides aniline was obtained during the initial electrolysis stage, and then all reduced to aniline. The average current efficiency at pH 5, 7 and 9 was 46, 51 and 63%, respectively. The electrolysis products were mineralized easily through aerobiotic biodegradation.

Determination of nitrobenzene by differential pulse voltammetry and its application in wastewater analysis

A new method for the determination of nitrobenzene (NB) by differential pulse voltammetry (DPV) based on an adsorptive stripping technique was developed. Cyclic voltammetry (CV) was used in a comparative investigation into the electrochemical reduction of NB at a glassy carbon electrode (GCE). With this electrode, the sharp peak of NB appeared at -0.71 V (vs. Ag/AgCl). The experimental parameters were optimized. Studies on the effect of pH on the peak height and peak potential were carried out over the pH range ca. 9.0-11.5 with sodium carbonate/sodium hydrogen carbonate buffer solution. A solution of pH 9.9 was chosen as analytical medium. Cathodic peak currents were found to be linearly related to the concentration of NB over the range ca. 12.3-1.23 x 10(4) microg L(-1) with relative standard deviations of ca. 3.26-6.75%. The detection limit of NB in water was 5.42 microg L(-1). The interference of organic and inorganic species on the voltammetric response was also studied. The proposed method was applied to the determination of NB in wastewater samples with an average recovery of ca. 95.9-102.4%.

Electrochemical reduction of nitrobenzene and 4-nitrophenol in the room temperature ionic liquid [C4dmim][N(Tf)2

Abstract The reductions of nitrobenzene and 4-nitrophenol were studied by cyclic voltammetry in the room temperature ionic liquid 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide [C 4 dmim][N(Tf) 2 ] on a gold microelectrode. Nitrobenzene was reduced reversibly by one electron and further by two electrons in a chemically irreversible step. The more complicated reduction of 4-nitrophenol revealed three reductive peaks (two irreversible and one reversible) which were successfully simulated using the digital simulation program DigiSim ® using a mechanism of rapid self-protonation, given below. (1) HOC 6 H 4 NO 2 + e ⇋ HOC 6 H 4 NO 2 - (2) HOC 6 H 4 NO 2 - + HOC 6 H 4 NO 2 ⇋ HOC 6 H 4 NO 2 H + - OC 6 H 4 NO 2 (3) HOC 6 H 4 NO 2 H + HOC 6 H 4 NO 2 - → HOC 6 H 4 NO 2 H - + HOC 6 H 4 NO 2 (4) HOC 6 H 4 NO 2 H - + HOC 6 H 4 NO 2 → HOC 6 H 4 NO + - OC 6 H 4 NO 2 + H 2 O Two further anodic peaks were observed and were attributed to the oxidations of 4-hydroxyphenylhydroxylamine and 4-nitrophenolate respectively. For both nitrobenzene and 4-nitrophenol, diffusion coefficients were roughly two orders of magnitude smaller than in conventional solvents. It appears that both species are reduced following the same mechanisms as in conventional aprotic solvents, with differences in the voltammetry primarily due to the viscous nature of the ionic liquid.

Electrochemical Reduction of Nitrobenzene on the WC Electrode in Acidic Solution

Electrochemical Reduction of Nitrobenzene on the WC Electrode in Acidic Solution

Study of the hypophosphite effect on the electrochemical reduction of nitrobenzene on Ni

The effect of the hypophosphite ion on the electrochemical reduction of nitrobenzene on Ni was evaluated from a cyclic voltammetric study and from constant potential electrolysis in an aqueous-ethanol alkaline medium. The results were compared with the data obtained in an hypophosphite-free solution. It was found that in an hypophosphite containing solution an unusual selective reduction of nitrobenzene to nitrosobenzene occurs. It is the first time that nitrosobenzene is detected as the reaction product of the nitrobenzene electrochemical reduction in an aqueous-ethanol solution. It is proposed that the Ni modified surface which is formed upon hypophosphite oxidation is responsible for the non reducibility of nitrosobenzene. The effect of the electrode potential on the nitrobenzene electrolysis on a Ni modified electrode was analysed. It was concluded that the highest nitrosobenzene yield (33%) and selectivity (82%) is achieved at −1.1 V. It was also found that the formation of nitrosobenzene leads to an electrode poisoning effect in the electrolysis process.

Electrochemical Reduction of Nitrobenzene on the Cu/C-Nafion Composite Electrode

The electrochemical reduction of nitrobenzene on the cu/c-nafion composite electrode was investigated. the 1 eduction product was only aniline. the high selectivity was related to the weak acid medium at the electrode/nafion interface and the slow diffusion of intermediates in the membrane. the electrochemical process was controlled by the diffusion of some species, the current efficiency for aniline decreased with the current density and was dependent upon the dissolution of nitrobenzene in the membrane.

Influence of oxidative treatment of copper grid electrodes on the efficiency of conversion to aniline in the electroreduction of nitrobenzene and azobenzene in basic aqueous methanol

The influence of preoxidizing the surface of polycrystalline copper electrodes on the efficiency of the controlled potential electrochemical reduction of nitrobenzene and azobenzene to aniline in basic aqueous methanol has been investigated. Electrodes electrochemically preoxidized to Cu(OH)2 or to Cu2O gave high yields of aniline (90–100%) with high current efficiencies (88–99%) for the electrohydrogenation of nitrobenzene compared to electrodes preoxidized by air (7–29% of aniline, 64–74% current efficiency). For the electrohydrogenation of azobenzene, copper electrodes preoxidized to Cu2O were found to be more active (average yield of aniline of 28%, average current efficiency of 55%) than electrodes preoxidized to Cu(OH)2 (3–11% of aniline, 42–53% current efficiency), and electrodes preoxidized by air were inactive (the electrohydrogenation stopped at hydrazobenzene). The improvement of activity induced by preoxidation of the copper surface is linked to the increase of the surface area.

Electrochemical behaviour of nitrobenzene and phenylhydroxylamine on copper rotating disk electrodes

The electrochemical reduction of nitrobenzene and phenylhydroxylamine on rotating (bulk or electrodeposited) copper electrodes has been investigated as a function of the pH in water + ethanol solutions. A comparison is made with the behaviour on glassy carbon and mercury electrodes. Several types of anomalies were observed: (i) From about pH 2 to 8, the E 1 2 of nitrobenzene is pH-independent. (ii) At all pH values from 2 to 12, the total wave height for the reduction of nitrobenzene is higher than that which would correspond to a 4 e − reduction, which shows that aniline is obtained even in alkaline media. This phenomenon is due to the reducibility of phenylhydroxylamine on copper whatever the pH. Deposited copper is more active than bulk copper, (iii) Hysteresis phenomena are observed in alkaline medium during the reduction of nitrobenzene and phenylhydroxylamine.