Electrocatalytic Oxidation Of Benzyl Alcohol Research Articles

Selective electrocatalytic conversion of primary alcohols to nitriles on nickel-cobalt nitride/oxide tandem electrocatalyst

Nitriles are vital precursors in the production of pharmaceuticals, advanced materials and many other commercial chemicals. Conventional approaches for nitrile synthesis are limited by the utilization of highly toxic cyanide ion and harsh conditions. The electrochemical conversion of primary alcohols and ammonia to nitriles offers a cost-effective and green approach to prepare nitriles, which requires highly efficient and selective catalysts to drive the cascade reaction and minimize side reactions. Here, we demonstrate how nitriles can be selectively synthesized by electrocatalytic oxidation of benzyl alcohol and ammonia on NiCo nitride and oxide that are co-localized on carbon cloth (NiCo-N,O/CC) electrode. In this electrocatalyst, the oxidation from alcohols to aldehydes is mainly catalyzed by NiCo oxide, while the oxidation from imine to nitrile is mainly catalyzed by NiCo nitride, endorsing preferential oxidation and cascade reactions on these catalytic interfaces. A total faradaic efficiency of 52%, productivity rate of 35 μmol cm-2h−1 and 70.1% selectivity of nitriles was achieved at 1.53 V vs RHE. The two interface NiCo-N,O/CC tandem electrocatalyst revealed synergistic activity and selectivity superior to NiCo-O/CC with single interface. Our results demonstrate that the utilization of tandem catalytic mechanisms could create new prospects in designing electrocatalysts for cascade reactions.

Fe Electron Center Local Regulation of CoFe‐Layered Double Hydroxides Nanosheets for Enhancing the Electrocatalytic Oxidation of Benzyl Alcohol

AbstractReplacing sluggish oxygen evolution reaction (OER) with electrocatalytic oxidation (ECO) of alcohols was a promising hotspot due to its advantages of requiring low potential, inhibiting mixing of gases, and forming value‐added products. In the ECO of alcohols process, Fe electron centers of Fe‐based layered double hydroxides (LDHs) can regulate the d band of LDHs overlap, optimize the active local structure of LDHs, and then enhance the electrocatalytic oxidation performance. In this work, CoxFey‐LDHs nanosheets with different ratios of Co/Fe were prepared for selective ECO of benzyl alcohol (BA) to benzoic acid (BAC). Comprehensive characterizations revealed that the adjustment of bandgap and OH species adsorption of CoxFey‐LDHs resulted in the appropriate thermodynamic driving force, which improved the electrical conductivity of CoxFey‐LDHs and enhanced their ECO of BA. Especially, the as‐prepared Co3Fe1‐LDH showed intriguing electrocatalytic activity and only required a potential of 1.51 V (vs. RHE) to achieve a total current density of 50 mA cm−2 in alkaline solution containing 10 mM BA with a conversion (96.79 %) of BA and selectivity (94.93 %) of BAC, which was 60 mV lower than that of OER. After six cycles, Co3Fe1‐LDH still achieved 94.74 % conversion of BA and 92.10 % selectivity of BAC without significant degradation.

Oxidant-Free Electrochemical Direct Oxidative Benzyl Alcohols to Benzyl Aldehydes Using Three-Dimensional Printing PPAR Polyoxometalate.

The oxidation of benzyl alcohols is an important reaction in organic synthesis. Traditional methods for benzyl alcohol oxidation have not been widely utilized due to the use of significant amounts of precious metals and environmentally unfriendly reagents. In recent years, electrocatalytic oxidation has gained significant attention, particularly electrochemical anodic oxidation, which offers a sustainable alternative for oxidation without the need for external oxidants or reducing agents. Here, a copper monosubstituted phosphotungstate-based polyacrylate resins (Cu-LPOMs@PPAR) catalyst has been fabricated with immobilization and recyclability using 3D printing technology that can be successfully applied in the electrocatalytic oxidation of benzyl alcohol to benzaldehyde, achieving atom economy and reducing pollution. In this protocol, we obtain benzaldehyde in good yields with excellent functional group toleration under metal-free and oxidant-free conditions. This strategy could provide a new avenue for heterogeneous catalysts in application for enhancing the efficiency and selectivity of electrocatalytic oxidation processes.

In situ construction of NiCo2O4 nanosheets on nickel foam for efficient electrocatalytic oxidation of benzyl alcohol

A NiCo2O4/NF catalyst with a nanosheet structure was designed, and it exhibited excellent catalytic activity and stability for the ECO of benzyl alcohol.

Droplet Flow Assisted Electrocatalytic Oxidation of Selected Alcohols under Ambient Condition.

This study reports using a droplet flow assisted mechanism to enhance the electrocatalytic oxidation of benzyl alcohol, 2-phenoxyethanol, and hydroxymethylfurfural at room temperature. Cobalt phosphide (CoP) was employed as an active electrocatalyst to promote the oxidation of each of the individual substrates. Surface analysis of the CoP electrocatalyst using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), as well as electrochemical characterization, revealed that it had excellent catalytic activity for each of the substrates studied. The combined droplet flow with the continuous flow electrochemical oxidation approach significantly enhanced the conversion and selectivity of the transformation reactions. The results of this investigation show that at an electrolysis potential of 1.3 V and ambient conditions, both the selectivity and yield of aldehyde from substrate conversion can reach 97.0%.

Highly Efficient Electrochemical Oxidation of Alcohols in a Flow Electrochemical Column Cell Modified with Au Nanoparticle Catalyst

Electrosynthesis is a powerful means for obtaining a variety of useful chemical products without employing toxic or otherwise hazardous chemical reagents and under relatively mild conditions. However, conventional batch-type cells suffer from a low productivity due to narrow two-dimensional reaction fields in the electrochemical system. To overcome this problem, we utilized continuous-flow column cell[1]. Although it was developed for a highly sensitive coulometric analysis of trace chemical substances in 1968, it is also expected to conduct rapid and quantitative bulk electrolysis due to its large electrode area and continuous-flow system. This flow cell consisted of a working electrode compartment and a counter electrode compartment, separated by an ion permeable Vycor® glass tube (Figure 1 (a)). A bundle of carbon fiber threads was tightly packed as a working electrode in the continuous-flow column cell, and a Pt spiral wire was used as a counter electrode. During several decades, the bulk gold has been considered as less active material, but at nanoscale, it exhibits surprisingly physicochemical and catalytic properties[2]. Therefore, in this work, the carbon fiber surface was also functionalized with Au nanoparticle catalyst to promote an electrochemical oxidation of alcohols.As a result, we have successfully demonstrated an efficient electrocatalytic oxidation of benzyl alcohol to provide benzaldehyde and benzoic acid with high current efficiencies in alkaline media. Moreover, it was also found that the selectivity of benzaldehyde was influenced by the added base amounts, and increased up to 97% by decreasing the amounts. We will also report the results of electrochemical oxidation of other alcohols.

Platinum decorated polythiophene modified stainless steel for electrocatalytic oxidation of benzyl alcohol

Platinum nanoparticles were electrochemically deposited on conducting polymer polythiophene (PTh)-coated stainless steel (SS) substrate. A thin layer of PTh on the steel substrate facilitates uniform deposition of Pt nanoparticles on the substrate, thereby improving the surface area to a great extent. The electrochemical properties of the modified electrodes were analyzed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The physicochemical properties of the modified electrodes were investigated by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The proposed method has been applied for the electrocatalytic oxidation of benzyl alcohol in the presence of a mediator, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO). Cyclic voltammetric studies reveal that the electrocatalytic activity of Pt–PTh/SS electrode is higher than that of PTh/SS electrode toward the conversion of benzyl alcohol to benzaldehyde.

Study of kinetics aspects of the electrocatalytic oxidation of benzyl alcohol in aqueous solution on AgBr modified carbon paste electrode

When a modified carbon paste electrode (CPE) with AgBr nanoparticles was immersed in a HCl supporting electrolyte at pH 3.5, it showed a well redox peak pair in cyclic voltammetry (CV) (Epa: 220 mV, Epc: 119 mV). Its anodic peak current was increased when benzyl alcohol (BZ) was added into the solution. The electrode response showed an irreversible behavior because the Epa-Epc difference was 109 mV and Ipa/Ipc = 1.09 for the AgIBr/AgIIBr redox process. The electrode had a geometric surface area of 0.03 cm2, while its effective surface area was estimated about 0.16 cm2. The Γ value, the surface coverage concentration of the electrode, was about 10.5 μmol AgBr cm−2. While the charge transfer coefficient, α, was 0.67 in HCl in CV experiments, but it was changed to 0.61 when BZ alcohol was added into the solution. α- values of 0.63 to 0.58 were obtained by Tafel plots in LSV (linear sweep voltammetry) in the absence and presence of BZ alcohol, respectively. The rate constant value (k) was changed from 0.21 s−1 to 0.55 s−1 in CV experiments and from 0.33 s−1 to 0.43 s−1 in LSV experiments by addition of BZ alcohol into the solution, confirming a faster reaction rate in the presence of BZ alcohol.

Correction: Electrocatalytic oxidation of benzyl alcohol for simultaneously promoting H2 evolution by a Co0.83Ni0.17/activated carbon electrocatalyst

Correction for ‘Electrocatalytic oxidation of benzyl alcohol for simultaneously promoting H2 evolution by a Co0.83Ni0.17/activated carbon electrocatalyst’ by Guoqiang Liu et al., New J. Chem., 2018, 42, 6381–6388.

Efficiently electrocatalytic oxidation of benzyl alcohol for energy- saved zinc-air battery using a multifunctional nickel–cobalt alloy electrocatalyst

We investigate the possibility of utilizing benzyl alcohol oxidation reaction to replace sluggish oxygen evolution reaction (OER) for the charging process in a rechargeable zinc-air battery, catalyzed by NiCo alloy nanoparticles supported on activated carbon (NiCo/AC) with the multifunctional electrocatalytic activities of the oxygen reduction, oxygen evolution and benzyl alcohol oxidation reactions. As an electrocatalyst for the oxygen reduction reaction (OER), NiCo/AC exhibits superior catalytic activity with an onset potential of 0.85 V (vs. RHE), a half-wave potential of 0.74 V (vs. RHE) and a large limiting current density of 4.65 mA cm−2 at 0.2 V (vs. RHE). Moreover, NiCo/AC also demonstrates the electrocatalytic oxidation activities toward water and benzyl alcohol, moreover, the benzyl alcohol oxidation reaction is more thermodynamically and kinetically favourable with 254 mV smaller overpotential than water oxidation at 10 mA cm−2. Owing to these advantages, NiCo/AC as air cathode material is assembled into a home-made rechargeable zinc-air battery, resulting an almost 200 mV lower charging voltage at the current density of 50 mA cm−2 in the presence of 0.1 M benzyl alcohol compared to the battery without benzyl alcohol, consequently obtaining 10.5% energy saving at the charging current density of 50 mA cm−2 with high durability.

Electrocatalytic oxidation of benzyl alcohol for simultaneously promoting H2 evolution by a Co0.83Ni0.17/activated carbon electrocatalyst

Co0.83Ni0.17 alloy nanoparticles on activated carbon were successfully fabricated by a simple thermal-treatment method, as electrocatalyst exhibiting superior HER, OER and electrocatalytic oxidation activity toward benzyl alcohol.

Electrocatalysis on Oxide-Stabilized, High-Surface Area Carbon Electrodes

A procedure is described for preparing and derivatizing novel, high surface area electrodes consisting of thin layers of nanostructured ITO (Sn(IV)-doped indium tin oxide, nanoITO) on reticulated vitreous carbon (RVC) to give RVC|nanoITO. The resulting hybrid electrodes are highly stabilized oxidatively. They were surface-derivatized by phosphonate binding of the electrocatalyst, [Ru(Mebimpy)(4,4′-((HO)2OPCH2)2bpy)(OH2)]2+ (Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; bpy = 2,2′-bipyridine) (1-PO3H2) to give RVC|nanoITO-RuII-OH22+. The redox properties of the catalyst are retained on the electrode surface. Electrocatalytic oxidation of benzyl alcohol to benzaldehyde occurs with a 75% Faradaic efficiency compared to 57% on nanoITO. Electrocatalytic water oxidation at 1.4 V vs SCE on derivatized RVC|nanoITO electrode with an internal surface area of 19.5 cm2 produced 7.3 μmoles of O2 in 70% Faradaic yield in 50 min.

Hydroquinone functionalized oriented MCM-41 mesochannels at the electrode surface

The ordered mesoporous silica (MCM-41) thin film has been electrodeposited at the electrode surface by the method known as electrochemically assisted self assembly (EASA). The constructed structures with unique morphology have been functionalized with hydroquinone derivatives as an electron mediator. Three functionalization routes, one co-condensation and two grafting methods, have been examined for the attachment of hydroquinone derivative to the electrode surface. For all electrodes the electroactive group immobilized successfully on deposited MCM-41 thin film and all of the constructed modified electrodes show the adequate and relatively stable currents. The electrochemical behaviors of these electroactive porous electrodes and their performances in electrocatalytic oxidation of benzyl alcohol and hydrazine have been studied by electrochemical methods.

Understanding Electronic Ligand Perturbation over Successive Metal‐Based Redox Potentials in Mononuclear Ruthenium–Aqua Complexes

AbstractA family of new ruthenium complexes containing a combination of polypyridyl and carbene ligands has been prepared and characterized from structural, spectroscopic, and redox viewpoints both experimentally and computationally. Interestingly, a correlation between ΔE1/2, defined as the difference between E1/2(RuIV/III) and E1/2(RuIII/II), and the activity and selectivity of some catalytic oxidation processes has been clearly established. A density functional theory study on the synthesized species has been carried out revealing a correlation between the number of carbene ligands and ΔE1/2, and consequently with the RuIII disproportionation. The reactivity of these complexes has been tested with regard to the electrocatalytic oxidation of benzyl alcohol.

TEMPO coated Au nanoparticles: synthesis and tethering to gold surfaces

Gold nanoparticles covered by derivatives of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) with well-defined coverage and narrow size distribution were synthesized and self-assembled on the gold electrode. The TEMPO nanoparticle-coated electrode was characterized using STM and AFM. The kinetics of oxidation of the nitroxide radicals attached to the nanoparticles was evaluated based on cyclic voltammetry measurements. The TEMPO–nanoparticle modified electrode was found more efficient in electrocatalytic oxidation of benzyl alcohol than the electrode modified with a monolayer of TEMPO molecules directly bound to the gold surface.

Ruthenium(II) nitro-nitroso-bis-{1-(alkyl)-2-(β-napthylazo)imidazole}: Synthesis, spectroscopy, electrochemistry and reactivity

Aquation of blue cis-trans-cis-[RuCl2(β-NaiR)2] (1) leads to the synthesis of solvento species, blue-violet cis-trans-cis-[Ru(OH2)2(β-NaiR)2](ClO4)2 (2), [β-NaiR = C10H7-N=N-C3H2-NN, abbreviated as N,N′-chelator, R = Me] that have been reacted with NaNO2 in warm EtOH resulting in violet dinitro complexes of the type, [Ru(NO2)2(β-NaiR)2] (3). The nitrite complexes are useful synthons of electrophilic nitrosyls, and on triturating the dinitro compounds with cone. HClO4 nitro-nitrosyl derivatives, [Ru(NO2)(NO)(β-NaiR)2]2+ (4) are isolated. The chemical oxidation of aqua complex (2) by excess aqueous eerie solution in 1 (N) H2SO4 leads to the spontaneous formation of a yellow colored species. The electrophilic behaviour of metal bound nitrosyl has been proved by reacting with a bicyclic ketone, camphor, containing an active methylene group and an arylhydrazone with an active methine group. The diazotization of the primary aromatic amines with a strongly electrophilic mononitrosyl complex in acetonotrile and dichloromethane solution was thoroughly studied. Electrocatalytic oxidation of benzyl alcohol was examined.

Electrocatalytic Oxidation of Benzyl Alcohol in an Ionic Liquid and Acetonitrile: Tempo vs. Ar3N as Mediators

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Electrocatalytic activity of surface adsorbed ruthenium–alizarin complexone toward the oxidation of benzyl alcohol

The surface electrochemical behavior of an adsorbed alizarin complexone (abbreviated as AC) and its surface coordination with Ru(II) were studied in aqueous solution at a pH range of 0–6. The surface complex of ruthenium with AC displays strong electrocatalytic activities toward benzyl alcohol. Based on the rotating disk electrode measurement, it is believed that the electrocatalytic oxidation of benzyl alcohol is a two-electron and two-proton process with benzaldehyde as a major product. On the other hand, ruthenium–AC surface complex has also shown catalytic activities toward electro-oxidation of several small organic molecules such as methanol, formic acid, formaldehyde, ethanol, and acetaldehyde.

Crystal structure and electrochemical behavior of Rh polypyridyl complexes

[Rh(tpy)(bpy)(Cl)](ClO 4) 2 and [Rh(tpy)(phen)(Cl)](PF 6) 2 (tpy; 2,2′;6′,2″-terpyridine, bpy; 2,2′-bipyridine, phen; 1,10-phenanthroline) have been determined structurally. Both complexes were identified and characterized by spectroscopic methods. ortep drawings of each complex show three pyridyl rings of the tpy ligand that are nearly coplanar, as are the two rings of bpy. The two ligands are coordinated to the metal atom through their nitrogen atoms in a mutually perpendicular fashion. The interatomic distance between chloride and rhodium atom is 2.300(12) and 2.323(2) Å, respectively. The bond angle formed by the axially positioned nitrogen atom, the rhodium atom, and the chlorine atom is 174.96(8) and 176.32(19)°. The oxidation of each [Rh(tpy)(bpy)(OH 2)] 3+ or [Rh(tpy)(phen)(OH 2)] 3+ with two equivalents of Ce(IV) yielded the corresponding mono-oxo product, [Rh V(tpy)(bpy)(O)](ClO 4) 3 and [Rh V(tpy)(phen)(O)](ClO 4) 3. A cyclic voltammogram of rhodium aqua complex with a scan rate of 5 mV s −1 displays the redox couple at −0.81 V as reversible wave for the first oxidation from Rh(III) to Rh(IV) and the next Rh(IV)/Rh(V) wave at −0.49 V as quasi-reversible. Electrocatalytic oxidation of benzyl alcohol with rhodium aqua complex gave benzaldehyde as a major product with the turnover ratio of 13.

Synthesis, characterization, and electrocatalytic oxidation of benzyl alcohol by a pair of geometric isomers of [Ru(trpy)(4,4′-Me 2dppi)(OH 2)] 2+ where 4,4′-dppi is 3,6-di-(4-methylpyrid-2-yl)pyridazine

The geometric isomers, in-[Ru(trpy)(4,4′-Me 2dppi)Cl] + ( 1a), in-[Ru(trpy)(4,4′-Me 2dppi)OH 2] 2+ ( 1b), and in-[Ru(trpy)(4,4′-Me 2dppi)(NCCH 3)] 2+ ( 1c), out-[Ru(trpy)(4,4′-Me 2dppi)Cl] + ( 2a), out-[Ru(trpy)(4,4′-Me 2dppi)OH 2] 2+ ( 2b), and out-[Ru(trpy)(4,4′-Me 2dppi)(NCCH 3)] 2+ ( 2c), where trpy is 2,2′,2″-terpyridine and 4,4′-Me 2dppi is 3,6-di-(4-methylpyrid-2-yl)pyridazine, were synthesized and characterized by UV–Vis and 1H NMR spectroscopy. The in and out notation refers to the orientation of the non-imine group which is directed towards the center of the complexes in the in complexes and away from the center in the out complexes. Compounds 1a and 2c were additionally characterized by X-ray crystallography. Reaction of 1a or 2a with aqueous silver ion produces the corresponding aqua complexes, 1b and 2b, which after dissolution in acetonitrile produces the analogous acetonitrile complexes, 1c and 2c. The redox properties of 1a, 1b, 2a, and 2b were examined using cyclic voltammetry. In acetonitrile, compounds 1a and 2a display reversible 1e − waves assigned to the Ru(III)/Ru(II) couple, while in aqueous solutions 1b and 2b show pH-dependent 2e − waves corresponding to the formation of Ru(IV)O complexes. Second-order rate constants, k cat, for oxidation of benzyl alcohol derivatives by the Ru(IV)O complex 2b were determined electrochemically. Complex 1b severely passivated the working electrode upon oxidation, and reliable catalytic rate constants could not be measured. This passivation may be related to self oxidation of the Me 2dppi ligand by the electrochemically generated Ru(IV)O complex.