Electrocatalytic Oxidation Of Alcohols Research Articles

Modification with platinum of silver-deposited nickel wire electrodes for electrocatalytic oxidation of alcohols

A silver-deposited nickel (Ag/Ni) wire electrode was prepared via a galvanic replacement reaction between Ag+ and Ni wire in aqueous solution. It was then found that the Ag/Ni wire electrode could be modified with Pt simply by treating it in an aqueous solution of K2PtCl4. Although the deposition of Ag on Ni wire was limited in amount, forming Ag deposits less than 100 nm in size, a considerable increase in the electrocatalytic currents for the oxidation of alcohols could be observed after further modification of the Ag/Ni wire electrodes with Pt. This is in contrast to the fact that it was difficult to produce sufficient electrocatalytic response by modifying Ni wire with Pt directly via a simple galvanic replacement between PtCl42− and Ni wire. Thus, the prior deposition of Ag was found to strongly promote modification with Pt via a simple stepwise treatment using AgNO3 and K2PtCl4. This approach should be effective in modifying various Ni materials with Pt, including Ni microparticles.

Integration of Marigold 3D flower-like Ni-MOF self-assembled on MWCNTs via microwave irradiation for high-performance electrocatalytic alcohol oxidation and oxygen evolution reactions

Fabrication of metal-organic frameworks (MOFs) on carbon nanostructure arrays is extremely challenging. Here, we successfully fabricated three-dimensional (3D) flower-like Ni-MOFs on multiwalled carbon nanotubes (MWCNTs) through a highly efficient and rapid microwave synthetic protocol and studied their applicability in electrocatalytic alcohol oxidation reaction (AOR) and oxygen evolution reaction (OER). Morphological studies using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) images suggested the formation of marigold-like Ni-MOF decorated on the MWCNTs. Surface coverage of Ni-MOF@CNT (1.11 × 10−7 mol g-1) was higher than that of the pristine Ni-MOF (9.35 × 10-8 mol g-1) electrocatalyst. The higher electrochemical active surface area (ECSA) of Ni-MOF@CNT (494.3 cm2) compared to the pristine Ni-MOF (203.5 cm2) electrocatalyst resulted in the availability of large active sites in the Ni-MOF@CNT to catalyze AOR and OER. Ni-MOF@CNT exhibited a higher electrooxidation performance in AOR than the pristine Ni-MOF and its OER activity was far superior.

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.

Electron-Rich Phenoxyl Mediators Improve Thermodynamic Performance of Electrocatalytic Alcohol Oxidation with an Iridium Pincer Complex.

Electron-rich phenols, including α-rac-tocopherol Ar1OH, 2,4,6,-tri-tert-butylphenol Ar3OH, and butylated hydroxy-toluene Ar4OH, are effective electrochemical mediators for the electrocatalytic oxidation of alcohols by an iridium amido dihyride complex (PNP)Ir(H)2 (IrN 1, PNP = bis[2-diisopropylphosphino)ethyl]amide). Addition of phenol mediators leads to a decrease in the onset potential of catalysis from -0.65 V vs Fc+/0 under unmediated conditions to -1.07 V vs Fc+/0 in the presence of phenols. Mechanistic analysis suggests that oxidative turnover of the iridium amino trihydride (PNHP)Ir(H)3 (IrH 2, PNHP = bis[2-diisopropylphosphino)ethyl]amine) to IrN 1 proceeds through two successive hydrogen atom transfers (HAT) to 2 equiv of phenoxyl that are generated transiently at the anode. Isotope studies and comparison to known systems are consistent with initial homolysis of an Ir-H bond being rate-determining. Turnover frequencies up to 14.6 s-1 and an average Faradaic efficiency of 93% are observed. The mediated system shows excellent chemoselectivity in bulk oxidations of 2-propanol and 1,2-benzenedimethanol in THF and is also viable in neat 2-propanol.

Emergence of CO2 electrolyzers including supported molecular catalysts

With access to cheap, sustainable electricity, electrocatalysis is a promising technology for converting electric power into storable chemical fuels or value-added chemical compounds. This has sparked the development of electrocatalysts that need to operate at high product selectivity and high energy efficiency. Electrocatalytic alcohol oxidation, oxygen activation and nitrogen and carbon dioxide (CO 2 ) reduction are examples of reactions with a huge industrial potential. Notably, electrocatalytic reduction of CO 2 has recently developed as a favourable pathway to convert this greenhouse gas into value-added chemicals and fuels. Earth-abundant metals stabilized by carbon/nitrogen macrocycle ligands are well-known efficient and selective catalysts for the electrochemical reduction of CO 2 in homogeneous conditions. Recently, such catalysts have also been used in supported conditions and implemented in flow cell electrolyzers, showing promising performances. This review provides a synopsis for the evolution of CO 2 electrolyzers using molecular catalysts.

Intrinsic Effect of Carbon Supports on the Activity and Stability of Precious Metal Based Catalysts for Electrocatalytic Alcohol Oxidation in Fuel Cells: A Review.

Electrocatalyst supports, in particular carbonaceous materials, play critical roles in the electrocatalytic activity and stability of precious metal group (PMG)-based catalysts such as Pt, Pd, and Au for the electrochemical alcohol oxidation reaction (AOR) of fuels such as methanol and ethanol in polymer electrolyte membrane fuel cells (PEMFCs). Carbonaceous supports such as high surface area carbon provide electronic contact throughout the catalyst layer, isolate PMG nanoparticles (NPs) to maintain high electrochemical surface area, and provide hydrophobic properties to avoid flooding of the catalyst layer by liquid water produced. Compared to high surface area carbon, PMG catalysts supported on 1D and 2D carbon materials such as graphene and carbon nanotubes show enhanced activity and durability due to the intrinsic effect of the underlying carbonaceous supports on the electronic states of PMG NPs. The modification of the electronic environment, in particular the d-band centers of PMG NPs, weakens the adsorption of AOR intermediates, facilitates breaking of the C-C bonds, and thus enhances the electrocatalytic activity of PMG catalysts. The doping of heteroatoms further facilitates the electrocatalytic activity for the AOR through the structural, bifunctional, and electronic effects, in addition to the enhanced dispersion of PMG NPs in the carbon support. The prospects for the development of effective PMG-based catalysts for high-performance alcohol-fuel-based PEMFCs is discussed.

Synergistic effect of Na2Ta2O6 in Pt/sodium tantalate on promoted electrocatalytic ability toward alcohol electro-oxidation

The poor durability of commercial Pt/C catalyst in the electrocatalytic oxidation of alcohols is mainly due to the weak corrosion resistance of carbon carrier to acid and alkali, and the exfoliation/aggregation and weak resistance to CO poisoning of Pt nanoparticles. Herein, sodium tantalate, such as NaTaO3 and Na2Ta2O6, was introduced as carrier material of Pt based electrocatalyst. Various characterizations and density functional theory calculations indicated that Na2Ta2O6 exhibited superior synergistic effect on alcohol electro-oxidation, involving the improvement of electron transport, selective adsorption of CO molecule, and excellent corrosion resistance to acid and alkali. Accordingly, Pt/Na2Ta2O6 catalyst showed the excellent electrocatalytic performances, including enhanced catalytic activity, high durability and strong CO-tolerance, toward methanol and ethanol oxidation reaction in both acid and base environment.

Electrocatalytic Alcohol Oxidation with Iron-Based Acceptorless Alcohol Dehydrogenation Catalyst.

Electrochemical and chemical studies reveal that the amido complex (PNHxP)Fe(CO)(H)(X) (FeN 1, x = 0, X = 0; Fe(H)(NH) 2, x = 1, X = H; PNHP = bis[2-(diisopropylphosphino)ethyl]amine) is active for the electrocatalytic oxidation of isopropanol. At room temperature, the amido FeN 1 dehydrogenates isopropanol to form acetone. The resulting amino hydride complex Fe(H)(NH) 2 is subsequently oxidized by one electron at a low potential (-0.74 V versus ferrocene/ferrocenium, Fc0/+) in tetrahydrofuran. In the presence of strong base (phosphazene base P2-Et, Et-N = P2(dma)5, P2), this oxidation process becomes a two-electron, two-proton process that regenerates FeN 1. FeN 1 is active for the electrooxidation of isopropanol in the presence of strong base (i.e., P2) with an onset potential near -1 V versus Fc0/+. By cyclic voltammetry, fast turnover frequencies of 1.7 s-1 for isopropanol oxidation are achieved with FeN 1. Controlled potential electrolysis studies confirm that the product of isopropanol electrooxidation is acetone, generated with high Faradaic efficiency (∼100%).

Preparation of palladium/nickel hydroxides nanoflakes on carbon cloth support as robust anode catalyst for electrocatalytic alcohol oxidation

Palladium (Pd) based catalysts are one of promising candidate to replace widely used Pt catalyst due to their lower cost and good electrocatalyst ability for ethanol oxidation reaction in alkaline media. However, most of Pd electrocatalysts suffer from limited operational durability and unsatisfying catalytic activity. Herein, a hybrid electrocatalyst consisting of Pd nanoparticles and Ni(OH)2 nanoflakes on the supported carbon cloth is prepared. Owe to the promoting effects of Ni(OH)2 nanoflakes on Pd nanoparticles for electrocatalytic ethanol oxidation, the prepared Pd/Ni(OH)2/CC exhibits high peak anode current of 161 mA/mg, and excellent operational durability in cycling and chronoamperometric testing. After 1 h of chronoamperometric testing, the mass-specific current on Pd/Ni(OH)2/CC hybrid reserves almost 80% of the original value and approaches to about 132 mA/mg. The electrocatalytic activity can remain via recycled cyclic voltammetry. Such high stability and current density is assigned to the synergistic effect between Pd nanoparticles and Ni(OH)2 nanoflakes.

Operando Thin-Layer ATR-FTIR Spectroelectrochemical Radial Flow Cell with Tilt Correction and Borehole Electrode.

A novel spectroelectrochemical ATR-FTIR thin-film cell was designed and applied to elucidate the intermediates during electrocatalytic alcohol oxidation. In the novel cell design, the working electrode is positioned coplanar above the internal reflection element (IRE) to ensure uniform electrolyte film thickness at reaction conditions. The depletion of the reactant (i.e., ethanol or ethylene glycol in the case of electrocatalytic alcohol oxidation) is decreased by a specifically designed flow-through glassy carbon borehole electrode embedded in PEEK. The electrolyte can be pumped through the disk-shaped gap between the ring working electrode and the IRE into the borehole via an external peristaltic pump. To ensure a radially uniform electrolyte flow, the working electrode and the internal reflection element need to be aligned in parallel at a well-controlled distance, which was achieved by a three-microelectrode-assisted tilt correction. Tilt correction of this four-electrode ensemble and the IRE was performed by three step-motor-driven micrometer screws that allow adjustment of the electrode orientation. The effect of electrolyte pumping through the borehole electrode was analyzed by performing anodic ethanol oxidation using nickel boride as electrocatalyst. The applicability, reliability, and functionality of the cell was further assessed by oxidizing ethylene glycol and determining the reaction products as a function of the electrolyte flow rate. It is found to be essential to induce forced electrolyte convection into the thin electrolyte layer to achieve well-defined steady-state conditions, as mass transport by diffusion is by far insufficient, resulting in reactant depletion, product accumulation, and local pH changes.

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.

Specific ion effects directed noble metal aerogels: Versatile manipulation for electrocatalysis and beyond.

Noble metal foams (NMFs) are a new class of functional materials featuring properties of both noble metals and monolithic porous materials, providing impressive prospects in diverse fields. Among reported synthetic methods, the sol-gel approach manifests overwhelming advantages for versatile synthesis of nanostructured NMFs (i.e., noble metal aerogels) under mild conditions. However, limited gelation methods and elusive formation mechanisms retard structure/composition manipulation, hampering on-demand design for practical applications. Here, highly tunable NMFs are fabricated by activating specific ion effects, enabling various single/alloy aerogels with adjustable composition (Au, Ag, Pd, and Pt), ligament sizes (3.1 to 142.0 nm), and special morphologies. Their superior performance in programmable self-propulsion devices and electrocatalytic alcohol oxidation is also demonstrated. This study provides a conceptually new approach to fabricate and manipulate NMFs and an overall framework for understanding the gelation mechanism, paving the way for on-target design of NMFs and investigating structure-performance relationships for versatile applications.

TEMPO-Modified Linear Polyethylenimine (LPEI) As Organic Radical Battery Electrode

With increasing demand for electronic devices and electric vehicles, there is a need for good performance of electrochemical energy storage materials while considering cost, safety, and environmental impact [1][2]. Organic electrodes based on stable organic radicals such as (2,2,6,6,-tetramethylpiperidin-1-yl)oxy (TEMPO) are a promising alternative to conventional inorganic (i.e. metal, metalloid, and metal oxide) battery materials due to their highly reversible, stable electron transfer reaction. Organic radical electrodes have the potential to achieve high power density, low cost, and improved environmental sustainability compared to inorganic electrodes [2][1]. Despite these advantages, organic radical-based electrodes face problems including dissolution of the active material in common battery solvents (thus requiring radical immobilization on polymer supports) and low capacity due to poor electronic conductivity and/or low fractions of active radical material [2][3]. Previous work suggests the support polymer can affect the performance of organic radicals as electrocatalysts, mediators, or energy storage materials. Hickey et al. demonstrated enhanced electrocatalytic activity of TEMPO when immobilized on linear polyethyleneimine (LPEI), a cationic polymer with amine functionality [4] [5]. In this work we explore for the first time LPEI-TEMPO as a cathode material in sodium-ion and lithium-ion organic radical batteries. Figure 1a demonstrates the structure and stable electron transfer mechanism of LPEI-TEMPO. LPEI-TEMPO electrode is prepared by dissolving TEMPO-modified LPEI(prepared according to [3]) in 0.1 M HCl (10 mg/mL) with 2.5:1 wt% carboxylated carbon nanotubes, 2.5 M glutaraldehyde crosslinker (0.25 L in 80 L of solution) and polytetrafluoroethylene (PTFE) binder (5 wt%). This solution is deposited on Toray carbon paper (10L) and a steel current collector (20 L) for cyclic voltammetry and battery testing, respectively. Cyclic voltammetry measurements of LPEI-TEMPO (Figure 1b) confirm the reversible electron transfer of the TEMPO radical when immobilized on LPEI (electrolyte: 0.1 M TBAPF6 in acetonitrile; counter electrode: Pt; reference electrode: Ag/Ag+; scan rate: 100 mV/s). This work will present a detailed characterization of LPEI-TEMPO electrodes in sodium- and lithium-ion battery systems, including cyclic voltammetry, charge-discharge, rate capacity, and electrochemical impedance measurements. A preliminary sodium-ion half-cell charge-discharge test (Figure 1c) indicates a capacity of 30 mAh/g of LPEI-TEMPO (electrolyte: 1 M NaClO4 in 1:1 etheylene carbonate: tetrahydrofuran; Celgard 2340 separator; sodium metal anode). We will explore performance optimization of LPEI-TEMPO organic radical batteries, including a study of LPEI-TEMPO electrode-electrolyte interactions. [1] H. Nishide, S. Iwasa, Y. J. Pu, T. Suga, K. Nakahara, and M. Satoh, “Organic radical battery: Nitroxide polymers as a cathode-active material,” Electrochim. Acta, vol. 50, no. 2–3 SPEC. ISS., pp. 827–831, 2004. [2] D. R. Nevers, F. R. Brushett, and D. R. Wheeler, “Engineering radical polymer electrodes for electrochemical energy storage,” J. Power Sources, vol. 352, pp. 226–244, 2017. [3] M. Miroshnikov et al., “Power from nature: Designing green battery materials from electroactive quinone derivatives and organic polymers,” J. Mater. Chem. A, vol. 4, no. 32, pp. 12370–12386, 2016. [4] D. P. Hickey, R. D. Milton, D. Chen, M. S. Sigman, and S. D. Minteer, “TEMPO-Modified Linear Poly(ethylenimine) for Immobilization-Enhanced Electrocatalytic Oxidation of Alcohols,” ACS Catal., vol. 5, no. 9, pp. 5519–5524, Sep. 2015. [5] Q. Chen, C. Fang, Z. Shen, and M. Li, “Electrochemistry Communications Electrochemical synthesis of nitriles from aldehydes using TEMPO as a mediator,” Electrochem. commun., vol. 64, pp. 51–55, 2016. Figure 1

Electrocatalytic Oxidation of Small Molecule Alcohols over Pt, Pd, and Au Catalysts: The Effect of Alcohol’s Hydrogen Bond Donation Ability and Molecular Structure Properties

The direct alcohol fuel cell is a kind of power generation device that directly converts the chemical energy of small molecule alcohols into electric energy. In this paper, the electro-oxidation behaviors of some typical alcohols (methanol, ethanol, ethylene glycol, n-propanol, 2-propanol, and glycerol) over Pt, Pd, and Au electrodes were investigated in acidic, neutral, and alkaline media, respectively. By analyzing the activity information from a cyclic voltammetry (CV) method and some dynamic tests, several regularities were revealed in those electro-oxidation behaviors. Firstly, alkaline media is the best for the electro-oxidation of all these alcohols over Pt, Pd, and Au catalysts. Secondly, the hydrogen bond donation abilities (HBD) of different alcohols were found have a great relationship with the catalytic performance. In alkaline media, on Pt electrodes, the solute HBD is positively correlated with the ease of electrooxidation within the scope of this experiment. Contrarily, it is negatively correlated on Pd and Au electrodes. Additionally, for Pt catalysts in acidic and neutral media, the relationship becomes negative again as the HBD increases. Finally, the alcohol’s molecular structure properties were found to have a remarkably influence on the activity of different catalysts. Over the Pt electrode in alkaline media, the activation energy of methanol oxidation is 44.1 KJ/mol, and is obviously lower than the oxidation of other alcohols. Under similar conditions, the lowest activation energy was measured in the oxidation of n-propanol (14.4 KJ/mol) over the Pd electrode, and in the oxidation of glycerol (42.2 KJ/mol) over the Au electrode. Totally, among all these electrodes, Pt electrodes showed the best activities on the oxidation of C1 alcohol, Pd electrodes were more active on the oxidation of C2-3 monobasic alcohols, and Au electrodes were more active on the oxidation of polybasic alcohols.

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.

Defect engineering of nickel hydroxide nanosheets by Ostwald ripening for enhanced selective electrocatalytic alcohol oxidation

Selective electrocatalytic oxidation (ECO) of benzyl alcohol to benzoic acid or benzaldehyde over 1.0 h-Ni(OH)2 with excellent conversion, selectivity, and stability in a two compartment H cell is presented.

Nano-Au Catalysts Modified with TiO2: Enhancement of Electrocatalytic Activity for 1-Propanol Oxidation in Alkaline Media

Electrocatalytic activity of the anode for alcohols oxidation is a critical issue in fuel cell which is considered as a clean energy. Performance deterioration of the catalyst takes place due to the adsorption of carbonaceous residues on the electrode surface, which is also known as poisoning of the electrode. Desorption of carbonaceous residues is thought to be an essential solution but not has been studied systematically. In this work, we investigate both the desorption of carbonaceous residues and the promotion of electrocatalytic activity to alcohols oxidation reactions by using Au nanoparticles (NPs)-TiO2/polyaniline (PANI) composite to boost the overall activity of electrocatalytic alcohol oxidation reactions. Desorption of carbonaceous residues and electrocatalytic activity of alcohol oxidation reactions are evaluated by cyclic voltammetry (CV) measurements in various alcohols. The chronoamperometric i-t curves are measured to evaluate the stability. Mechanisms for desorption of carbonaceous residues and enhancement of the electrocatalytic activity are elaborated and summarized. Electrodes with TiO2 decoration show better performance than TiO2-free specimens. In addition, Au NPs-decorated composites not only show an extra characteristic peak of alcohol oxidation reactions but also perform a constructive effect on the already existing oxidation reaction, indicating the promotion of electrocatalytic oxidation of alcohols.

Catalysts for the Steam Reforming and Electrochemical Oxidation of Methanol

Catalysts used for the steam reforming and electrochemical oxidation of methanol in fuel cells are briefly reviewed. The mechanisms of these processes are discussed. Most of the methanol steam reforming catalysts contain noble metals, copper, or their alloys supported on inorganic materials. The main laws governing the steam reforming process are extended to a wider range of alcohols. The electrochemical oxidation of methanol is catalyzed by noble metals and alloys based on them. The catalyst selectivity and activity is largely determined by the nature of the metallic catalyst. However, an equally important role is played by the supports, a variation of which provides not only an increase in the catalyst activity but also an improvement in the on-stream stability of the catalyst. An important role is played by both the chemical nature and the structure and morphology of the support. Using the example of the two processes, it is shown that the catalytic processes in the studied systems have a bifunctional nature. It is shown that the oxide support plays an important role in the water sorption, which accelerates the occurrence of both the steam reforming and electrocatalytic oxidation of alcohols.

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.