Promoter Effects of Rare Earth Ions on Electrocatalytic Oxidation of Methanol

The promoter effects of rare earth ions on the electrocatalytic oxidation of methanol at the Pt electrode were studied using the cyclic voltammetry and stable polarization techniques. It was found for the first time that Eu、Ho、Dy ions could accelerate the electrocatalytic oxidation of methanol at the Pt electrode, while Lu、Pr、Yb、Sm ions showed inhibitor effects.

Green bio-synthesis of Ni/montmorillonite nanocomposite using extract of Allium jesdianum as the nano-catalyst for electrocatalytic oxidation of methanol

In this work,synthesis of Ni nanoparticles was carried out successfully by water extract of Allium jesdianum as a biochemical reducing agent in the presence of montmorillonite clay(MMT)as a natural solid support for the first time.Then the electrochemical activity of the synthesized nanocomposite was investigated in methanol electrocatalytic oxidation.MMT with high cation exchange capacity and nano layer structure was exposed to ion exchange conditions in nickel solution.Then Ni^2+ion exchanged form was used in this process as a source of ions and also capping agent.Water extract of Allium jesdianum used as a reducing agent due to abundant availability of phenolic and flavonoid contents.The synthesized Ni/MMT nanocomposite was characterized using UV–Vis spectroscopy(UV–Vis),Fourier Transform Infrared Spectroscopy(FT-IR),X-ray diffraction(XRD),Scanning Electron Microscopy(SEM),Transmission electron microscopy(TEM)and Energy-dispersive X-ray spectroscopy(EDX).The surface of prepared modified electrode has been characterized using SEM to evaluate the morphology,showing uniform dispersion of Ni nanoparticles with mean diameter of 12 to 20 nm.The modified carbon paste electrode was then used in methanol electrocatalytic oxidation reaction.Methanol oxidation on the proposed modified electrode surface occurs at 0.6 V and 0.3 V in alkaline and acidic medium respectively.Also,the results showed the better performance of modified electrode toward methanol electrocatalytic oxidation in comparison with carbon paste electrode that is modified by ion exchanged MMT.Charge transfer coefficients and apparent charge transfer rate constant for the modified electrode in the absence of methanol in alkaline medium were respectively found as:αa=0.53,αc=0.37 and ks=1.6×10^-1 s^-1.Also,the average value of catalytic rate constant for the electrocatalytic oxidation of methanol by the prepared nano-catalyst was estimated to be about 0.9 L·mol^-1·s^-1 by chronoamperometry technique.The prepared electrode was also effective for electrocatalytic oxidation of ethanol and formaldehyde in alkaline medium.

Electrocatalytic Oxidation of Ethanol on Electrodcposited Palladium Electrode

The oxidation of ethanol in 1 .0 mol/L NaOH was studied on Pd/GC electrode preparedby electrodeposition. The results show that (1) Pd/GC electrode can also demonstrateclectrocatalytic activity towards the oxidation of cthanolf (2) two backward anodic peaks on thecathodic branch appear when the ethanol concentration is raised up to 0.5 mol/L.

Electrocatalytic Oxidation of Methanol on Glassy Carbon Electrode Modified by Metal Ions (Copper and Nickel) Dispersed into Polyaniline Film

Polyaniline film was prepared by using the repeated potential cycling technique in an acidic solution at the surface of glassy carbon electrode. Then transition metal ions of Ni and Cu were incorporated to the polymer by immersion of the modified electrode. A comparative study of the electrocatalytic oxidation of methanol is made in NaOH, on Ni and Cu on polyaniline film covered glassy carbon electrode (Ni-PANI-GC, Cu-PANI-GC) at 25℃. Catalytic activity for the oxidation of methanol was studied by using cyclic voltammetry.

Electrocatalytic oxidation of gaseous toluene in an all-solid cell using a foam Ti/Sb-SnO2/β-PbO_(2) anode

Mineralization of benzene,toluene,and xylene (BTX) with high efficiency at room temperature is still a challenge for the purification of indoor air.In this work,a foam Ti/Sb-Sn O2/β-Pb O_(2)anode catalyst was prepared for electrocatalytically oxidizing gaseous toluene in an all-solid cell at ambient temperature.The complex Ti/Sb-Sn O_(2)/β-Pb O_(2)anode,which was prepared by sequentially deposing Sb-Sn O_(2)and β-Pb O_(2)on a foam Ti substrate,shows high electrocatalytic oxidation efficiency of toluene (80%) at 7 hr of reaction and high CO_(2)selectivity (94.9%) under an optimized condition,i.e.,a cell voltage of 2.0 V,relative humidity of60%and a flow rate of 100 m L/min.The better catalytic performance can be ascribed to the high production rate of·OH radicals from discharging adsorbed water and the inhibition of oxygen evolution on the surface of foam Ti/Sb-Sn O_(2)/β-Pb O_(2)anode when compared with the foam Ti/Sb-Sn O_(2)anode.Our results demonstrate that prepared complex electrodes can be potentially used for electrocatalytic removal of gaseous toluene at room temperature with a good performance.

In-situ assembly of 2D/3D porous nickel cobalt sulfide solid solution as superior pre-catalysts to boost multi-functional electrocatalytic oxidation

In this work,we fabricated an efficient pre-catalyst based on(Ni,Co)S2solid solution with hierarchical architecture and high porosity to boost urea oxidation reaction and electrocatalytic oxidation of organic small molecules.The interaction between Ni and Co can optimize the electronic structure,resulting in the improved conductivity and accelerated charge transfer rate.The 2D/3D architecture can enrich more active species and endow the mass and electron transport to facilitate the surface oxidation and the following catalytic process.Post-structure and catalytic characterizations confirm the surface oxidation of(Ni,Co)S_(2)during the stability test,and the in-situ formed Co(Ni)based(oxy)hydroxides exhibit superior catalytic activity and facilitated charge transfer ability.As a result,the optimal(Ni,Co)S_(2)solid solution pre-catalyst displays facilitated catalytic behavior and good stability for multifunctional electrocatalytic oxidation,in which a high conversion of benzyl alcohol(97.50%),a good selectivity to benzoic acid(93.78%)and a satisfied faraday efficiency(91.86%)can be achieved.

Carbon materials in electrocatalytic oxidation systems for the treatment of organic pollutants in wastewater:A review

Carbon materials are widely used as catalysts in electrocatalytic oxidative(EO)degradation of wastewater due to their large specific surface area and low cost.Carbon materials can also be used as catalyst carriers for EO reactions due to their ease of functionalization with other heteroatoms and metals/metal oxides.To improve the catalytic activity and current efficiency of carbon materials,modifying the structural and physicochemical properties of conventional carbon materials are common improvement method.This review briefly outlines the recent research progress of carbon materials in EO for organic pollutants degradation.It also discusses the modification strategies and corresponding electrocatalytic properties of various carbon materials(carbon nanomaterials and porous carbon materials),and explores the EO mechanism.Finally,some summaries of the remaining challenges and future developments of carbon materials in the field of electrocatalysis are given.

Electrocatalytic oxidation of 5-hydroxymethylfurfural for sustainable 2,5-furandicarboxylic acid production-From mechanism to catalysts design

Catalytic conversion of biomass-based platform chemicals is one of the significant approaches to utilize renewable biomass resources.2,5-Furandicarboxylic acid(FDCA),obtained by an electrocatalytic oxidation of 5-hydroxymethylfurfural(HMF),has attracted extensive attention due to the potential of replacing terephthalic acid to synthesize high-performance polymeric materials for commercialization.In the present work,the pHdependent reaction pathways and factors influencing the degree of functional group oxidation are first discussed.Then the reaction mechanism of HMF oxidation is further elucidated using the representative examples.In addition,the emerging catalyst design strategies(defects,interface engineering)used in HMF oxidation are generalized,and structure-activity relationships between the abovementioned strategies and catalysts performance are analyzed.Furthermore,cathode pairing reactions,such as hydrogen evolution reaction,CO_(2) reduction reaction(CO_(2)RR),oxygen reduction reaction,and thermodynamically favorable organic reactions to lower the cell voltage of the electrolysis system,are discussed.Finally,the challenges and prospects of the electrochemical oxidation of HMF for FDCA are presented,focusing on deeply investigated reaction mechanism,coupling reaction,reactor design,and downstream product separation/purification.

Oxygen-coordinated low-nucleus cluster catalysts for enhanced electrocatalytic water oxidation

The oxygen evolution reaction(OER)activity of single-atom catalysts(SACs)is closely related to the coordination environment of the active site.Oxygencoordinated atomic metal species bring about unique features beyond nitrogen-coordinated atomic metal species due to the fact that the M-O bond is weaker than the M-N bond.Herein,a series of metal-oxygen-carbon structured low-nucleus clusters(LNCs)are successfully anchored on the surface of multiwalled carbon nanotubes(M-MWCNTs,M=Ni,Co,or Fe)through a foolproof low-temperature gas transfer(300℃)method without any further treatment.The morphology and coordination configuration of the LNCs at the atomic level were confirmed by comprehensive characterizations.The synthetic Ni-MWCNTs electrocatalyst features excellent OER activity and stability under alkaline conditions,transcending the performances of Co-MWCNTs,Fe-MWCNTs and RuO_(2).Density functional theory calculations reveal that the moderate oxidation of low-nucleus Ni clusters changes the unoccupied orbital of Ni atoms,thereby lowering the energy barrier of the OER rate-limiting step and making the OER process more energy-efficient.This study demonstrates a novel versatile platform for large-scale manufacturing of oxygen-coordinated LNC catalysts.

Noble-metal-free cobalt hydroxide nanosheets for efficient electrocatalytic oxidation

Cobalt hydroxide has been emerging as a promising catalyst for the electrocatalytic oxidation reactions,including the oxygen evolution reaction(OER)and glucose oxidation reaction(GOR).Herein,we prepared cobalt hydroxide nanoparticles(CoHP)and cobalt hydroxide nanosheets(CoHS)on nickel foam.In the electrocatalytic OER,CoHS shows an overpotential of 306 mV at a current density of 10 mA·cm^-2.This is enhanced as compared with that of CoHP(367 mV at 10 mA·cm^-2).In addition,CoHS also exhibits an improved performance in the electrocatalytic GOR.The improved electrocatalytic performance of CoHS could be due to the higher ability of the two-dimensional nanosheets on CoHS in electron transfer.These results are useful for fabricating efficient catalysts for electrocatalytic oxidation reactions.

Electrocatalytic Activity of Pt/C Electrodes for Ethanol Oxidation in Vapor Phase

High performance platinized-carbon electrodes have been developed for the electrocatalytic oxidation of ethanol to acetaldehyde in electrogenerative processes. A load current density of the electrode can be achieved as high as 600 mA per square centimeter for oxygen reducing in 3 mol/L sulfuric acid with a good stability. With these electrodes and sulfuric acid as an electrolyte in fuel cells, ethanol vapor carried by nitrogen gas can be oxidized selectively to acetaldehyde. Selectivity of acetaldehyde depends on the potential of the cell and the feed rate of ethanol vapor and it can be more than 80% under optimized conditions. The initial product of ethanol oxidized on a platinized-carbon electrode is acetaldehyde and the ethanol oxidation mechanism is discussed.

Efficient electrooxidation of biomass-derived aldehydes over ultrathin Ni V-layered double hydroxides films

Selective upgrading of C=O bonds to afford carboxylic acid is significant for the petrochemical industry and biomass utilization.Here we declared the efficient electrooxidation of biomass-derived aldehydes family over NiV-layered double hydroxides(LDHs) thin films.Mechanistic studies confirmed the hydroxyl active intermediate(-OH*) generated on the surface of NiV-LDHs films by employing electrochemical impedance spectroscopy and the electron paramagnetic resonance spectroscopy.By using advanced techniques,e.g.,extended X-ray absorption fine structure and high-angle annular dark-field scanning transmission electron microscopy,NiV-LDHs films with 2.6 nm could expose larger specific surface area.Taking benzaldehyde as a model,high current density of 200 mA cm^(-2)at 1.8 V vs.RHE,81.1% conversion,77.6% yield of benzoic acid and 90.8% Faradaic efficiency were reached,which was superior to most of previous studies.Theoretical DFT analysis was well matched with experimental findings and documented that NiV-LDHs had high adsorption capacity for the aldehydes to suppress the side reaction,and the aldehydes were oxidized by the electrophilic hydroxyl radicals formed on NiV-LDHs.Our findings offer a universal strategy for the robust upgrading of diverse biomass-derived platform chemicals.

The Electrochemical Behavior of Au/Au NPs/PNA/ZnS e-QD/ACA Electrode Towards Cy SH Oxidation

This work describes the electrochemical behavior of azodicarboxamide(ACA) film immobilized on the surface of penicillamine(PNA)/Zn Se-quantum dot(Zn Se-QD) gold nanoparticle(Au NPs) Au electrode. Electrocatalytic activity of modified electrode toward the oxidation of cysteine(Cy SH) was investigated. The surface structure and composition of the sensor were characterized by scanning electron microscopy(SEM). Oxidation of Cy SH on the surface of modified electrode was investigated with cyclic voltammetry, electrochemical impedance spectroscopy(EIS),hydrodynamic voltammetry and chronoamperometry methods. The results show that the PNA/Zn Se-QD/ACA film displays excellent electrochemical catalytic activities towards Cy SH oxidation. The modified electrode shows reproducible behavior and high level of stability during the electrochemical experiments. Also it has short response time, low detection limit, high sensitivity and low operation potential, which can be used as an amperometric sensor for monitoring of Cy SH. The proposed modified electrode was successfully used for determination of Cy SH in real sample such as human serum.

Electrochemical oxidation of Rhodamine B with cerium and sodium dodecyl benzene sulfonate co-modified Ti/Pb0_(2)electrodes:Preparation,characterization,optimization,application

Regulation of the electronic structure and interface property becomes a major strategy in the preparation of electrocatalyst.This paper reports the synthesis of cerium(Ce)and sodium dodecyl benzene sulfonate(SDBS)comodified Ti/PbO_(2)electrodes(Ti/PbO2CeSDBS).Ce and SDBS could greatly change the electronic structure and interface property of PbO2.Ti/PbO_(2)CeSDBS exhibited excellent electrocatalytic activity and stability in Rhodamine B(RhB)electrocatalytic oxidation reaction.The improved electrocatalytic activity associates with the synergistic effect of electronic and interface factors.In the electrochemical degradation of RhB,the removal efficiencies of RhB and COD are about 0.880 and 0.694 respectively after the electrolysis of 220 min with Ti/PbO_(2)Ce4SDBS40,which are higher than the contrast Ti/PbO_(2)electrodes.In the meantime,the accelerated lifetime of Ti/PbO_(2)Ce4SDBS40 is more than 6.2 times than that of Ti/PbO_(2).

Electrooxidation of Nitric Oxide at a Glass Carbon Electrode Modified with Functionalized Single-walled Carbon Nanotube

The electrocatalytic oxidation of nitric oxide（NO） at a glass carbon electrode（GC） modified with functionalized single-walled carbon nanotubes（SWCNTs） was investigated by cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）.It was found that the SWCNT modified electrode could speed greatly up the electron transfer rate compared with the bare GC electrode.After the SWCNT was treated with alkali or mixed acids,the reaction rate and activation energy of NO electrooxidation were changed to different extent.Chemical modification of the SWCNT surface is one of the most powerful methods to change the sensitivity of NO electrooxidation reaction.The modified electrode with SWCNT obtained by the firstly alkali treatment and then the mixed acids treatment was the best one for NO electrooxidation,the result of CV was also confirmed by that of EIS.The anodic processes of NO were recognized more clearly by exploring the reaction mechanism of NO electrooxidation at the SWCNT modified electrode.

An α-Fe_(2)O_(3)/Circulating Fluidized Bed Fly Ash Based Geopolymer Composite Anode for Electrocatalytic Degradation of Indigo Carmine Dye Wastewater

Geopolymers have been developed to various catalysts due to their advantages.However,low conductivity restricts their application in the electrocatalysis field.In this study,anα-Fe_(2)O_(3)/circulating fluidized bed fly ash based geopolymer(CFAG)composite anode was fabricated using a facile dip-coating method by loadingα-Fe_(2)O_(3) in the matrix of CFAG.The effects ofα-Fe_(2)O_(3) content on the composition,surface morphology and electrochemical performance ofα-Fe_(2)O_(3)/CFAG composite anode were investigated.The X-ray diffraction(XRD)and scanning electron microscope(SEM)results demonstrated thatα-Fe_(2)O_(3) was successfully inlaid with the surface of amorphous CFAG matrix.The electrochemical measurements indicated thatα-Fe_(2)O_(3)/CFAG composite anode had higher oxygen evolution potential,greater electrochemical activity area,and smaller electrochemical impedance than CFAG.The as-prepared composite anode was applied for electrocatalytic degradation of indigo carmine dye wastewater.It was discovered that the highest degradation efficiency over 10α-Fe_(2)O_(3)/CFAG reached up 92.6%,and the degradation of indigo carmine followed pseudo-first-order kinetics.Furthermore,10α-Fe_(2)O_(3)/CFAG composite anode presented excellent stability after five cycles.The active hydroxyl radical was generated over theα-Fe_(2)O_(3)/CFAG composite anode,which acted as strong oxidizing agents in the electrocatalytic degradation process.

The Catalysis of NAD^+ on Methanol Anode Oxidation Electrode for Direct Methanol Fuel Cell

A tentative idea of developing a liquid-catalytic system on methanol anode oxidation was proposed by analyzing the characteristics of methanol anode oxidation in direct methanol fuel cell. The kinetics of methanol oxidation at a glassy carbon electrode in the presence of nicotinamide adenine dinucleotide (NAD +) was investigated. It is found that the current density of methanol oxidation increases greatly and the electrochemical reaction impedance reduces obviously in the presence of NAD + compared with those in the absence of NAD +. The catalytic activity of NAD + is sensitive to temperature. When the temperature preponderates over 45℃, NAD + is out of function of catalysis for methanol oxidation, which is probably due to the denaturation of NAD + at a relatively high temperature.

Realizing efficient electrochemical oxidation of 5-hydroxymethylfurfural on a freestanding Ni(OH)_(2)/nickel foam catalyst

With the continuous improvement of solar energy production capacity,how to effectively use the electricity generated by renewable solar energy for electrochemical conversion of biomass is a hot topic.Electrochemical conversion of 5-hydroxymethylfurfural(HMF)to biofuels and value-added oxygenated commodity chemicals provides a promising and alternative pathway to convert re-newable electricity into chemicals.Although nickel-based eletrocatalysts are well-known for HMF oxidation,their relatively low intrinsic activity,poor conductivity and stability still limit the poten-tial applications.Here,we report the fabrication of a freestanding nickel-based electrode,in which Ni(OH)2 species were in-situ constructed on Ni foam(NF)support using a facile ac-id-corrosion-induced strategy.The Ni(OH)2/NF electrocatalyst exhibits stable and efficient electro-chemical HMF oxidation into 2,5-furandicarboxylic acid(FDCA)with HMF conversion close to 100%with high Faraday efficiency.In-situ formation strategy results in a compact interface between Ni(OH)2 and NF,which contributes to good conductivity and stability during electrochemical reac-tions.The superior performance benefits from dynamic cyclic evolution of Ni(OH)2 to NiOOH,which acts as the reactive species for HMF oxidation to FDCA.A scaled-up device based on a continu-ous-flow electrolytic cell was also established,giving stable operation with a high FDCA production rate of 27 mg h^(-1)cm^(−2).This job offers a straightforward,economical,and scalable design strategy to design efficient and durable catalysts for electrochemical conversion of valuable chemicals.

碱性介质中(氢)氧化铜修饰电极电催化氧化蔗糖(英文)

A stable copper(hydr)oxide-modified electrode was prepared in 0.5 mol/L NaOH solution by cyclic voltammetry in the range of -250 to 1 000 mV.It can be used for electrochemical studies in the range of -250 to 1000 mV without interfering peaks because there is no oxidation of copper.During an anodic potential sweep,the electro-oxidation of saccharose on Cu occurred by the formation of CuⅢ and this reaction also occurred in the early stages of the reversed cycle until it is stopped by the negative potentials.A mechanism based on the electro-chemical generation of CuⅢ active sites and their subsequent consumption by saccharose was proposed,and the rate law and kinetic parameters were obtained.The charge transfer resistance from theoretical and impedance studies was used to verify the mechanism.Under chronoamperometry regimes,the reaction followed Cottrellian behavior.The transfer of up to 21 electrons was observed in further investigations of the electro-oxidation of saccharose on a(hydr)oxide Cu rotating disk electrode.

Electrochemical Polymerization of Azure Blue II and Its Electrocatalytic Activity toward NADH Oxidation

Poly(azure blue II) (PABII) thin film modified electrode was successfully assembled on the surface of a glassy carbon electrode by means of electrochemical polymerization, which was carried out with cyclic voltammetric sweeping in the potential range of -0.6 to +1.3 V (vs. SCE) in Britton-Robinson buffer solution (pH=9.8) containing 1.25×10 -4 mol/L azure blue II. The effect of pH on the polymerization process of azure blue II and the electrochemical characteristics of the polymer-modified electrodes were studied in detail. The experimental results indicated that the electropolymerization of azure blue II could take place in basic or neutral media. The cyclic voltammograms of poly(azure blue II) thin film modified electrode showed the presence of two couples of redox peaks. The film modified electrode exhibited potent and persistent electrocatalysis for oxidation of dihydronicotiamide adenine dinucleotide (NADH) in phosphate buffer media with a diminution of the overpotential of about 410 mV and an increase in peak current. The presence of some divalent cations in an electrolyte can greatly enhance the electrocatalytic current for oxidation of NADH. The electrocatalytic current increased linearly with NADH concentration from 1.0×10 -5 to 8.0×10 -3 mol/L in the presence of 4.0×10 -2 mol/L Mg 2+ cation. The detection limit (3s b1/S) was 5.0×10 -6 mol/L, and the relative standard deviation of determination results was 4.2% for six successive determinations of 5.0×10 -4 mol/L NADH in the presence of Mg 2+ cation.