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.

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.

Electrochemically reduced graphene oxide with enhanced electrocatalytic activity toward tetracycline detection

An electrochemically reduced graphene oxide sample, ERGO_0.8v, was prepared by electrochemical reduction of graphene oxide （GO） at -0.8 V, which shows unique electrocatalytic activity toward tetracycline （TTC） detection compared to the ERGO-12v （GO applied to a negative potential of-1.2 V）, GO, chemically reduced GO （CRGO）-modified glassy carbon electrode （GC） and bare GC electrodes. The redox peaks of TTC on an ERGO-0.8v-modifled glass carbon electrode （GC/ERGO-0.8v） were within 0-0.5 V in a pH 3.0 buffer solution with the oxidation peak current correlating well with TTC concentration over a wide range from 0.1 to 160 mg/L Physical characterizations with Fourier transform infrared （FT-IR）, Raman, and X-ray photoelectron spectroscopies （XPS） demonstrated that the oxygen-containing functional groups on GO diminished after the electrochemical reduction at -0.8 V, yet still existed in large amounts, and the defect density changed as new sp2 domains were formed. These changes demonstrated that this adjustment in the number of oxygen-containing groups might be the main factor affecting the electrocatalytic behavior of ERGO. Additionally, the defect density and sp2 domains also exert a profound influence on this behavior. A possible mechanism for the TTC redox reaction at the GC/ERGO-0.8v electrode is also presented. This work suggests that the electrochemical reduction is an effective method to establish new catalytic activities of GO by setting appropriate parameters.

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.

Magnetic field assisted electrocatalytic oxidation of organic pollutants in electroplating wastewater

To degrade the organic compounds in the electroplating wastewater,magnetic field was tentatively introduced into electrocatalytic oxidation on Ti-PbO2 anode.The magnetic field assisted electrocatalytic oxidation can promote anion movement and the generation of active species,resulting more organic compounds to be oxidized and degraded.Oxidation parameters such as treatment time,current density and initial pH of the wastewater were systematically discussed and optimized.The mineralization of organic compounds is improved by over 15% under a magnetic density of 22 mT while the current density is 50 A/m2,pH is 1.8 and the reaction time is 1.5 h.The results indicate that the magnetic field assisted electrocatalytic oxidation has considerable potential in electroplating wastewater treatment.

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.

Encapsulation of a nickel Salen complex in nanozeolite LTA as a carbon paste electrode modifier for electrocatalytic oxidation of hydrazine

A nickel salen complex was encapsulated in the supercages of nanozeolite NaA,LTA(linde type A)structure,using the flexible ligand method.The electrochemical behavior and electrocatalytic activity of a carbon paste electrode(CPE)modified with Ni(II)‐Salen‐A(Ni(II)‐SalenA/CPE)for hydrazine oxidation in0.1mol/L NaOH solution were investigated by cyclic voltammetry,chronoamperometry,and chronocoulometry.First,organic‐template‐free synthesis of nanozeolite LTA was performed and the obtained material was characterized by various techniques.The average particle size of the LTA crystals was estimated to be56.1and72nm by X‐ray diffraction and particle size analysis,respectively.The electron transfer coefficient was found to be0.64and the catalytic rate constant for oxidation of hydrazine at the redox sites of Ni(II)‐SalenA/CPE was found to be1.03×105cm3/(mol·s).Investigation of the electrocatalytic mechanism suggested that oxidation of hydrazine occurred through reaction with Ni3+(Salen)O(OH)and also direct electrooxidation.The anodic peak currents revealed a linear dependence on the square root of the scan rate,indicating a diffusion‐controlled process,and the diffusion coefficient of hydrazine was found to be1.18×10?7cm2/s.The results indicated that Ni(II)‐SalenA/CPE displays good electrocatalytic activity toward hydrazine oxidation owing to the porous structure of nanozeolite LTA and the Ni(II)‐Salen complex.Finally,the general reaction mechanism for the electrooxidation of hydrazine on Ni(II)‐SalenA/CPE in alkaline solution involves the transfer of four electrons,in which the first electron transfer reaction acts as the rate‐limiting step followed by a three‐electron process to generate environmentally friendly nitrogen and water as final products.

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.

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 behavior of L-cysteine at Pt microparticles modified nanofibrous polyaniline film electrode

Platinum(Pt)/nanofibrous polyaniline(PANI) electrode was prepared by pulse galvanostatic method and characterized by scanning electron microscopy.The electrochemical behavior of L-cysteine at the Pt/nanofibrous PANI electrode was investigated by cyclic voltammetry.The results indicate that the pH value of the solution and the Pt loading of the electrode have great effect on the electrocatalytic property of the Pt /nanofibrous PANI electrode;the suitable Pt loading of the electrode is 600 μg/cm2 and the suitable pH value of the solution is 4.5 for investigating L-cysteine oxidation.The L-cysteine sensor based on the Pt/nanofibrous PANI electrode has a good selectivity,reproducibility and stability.The Pt/nanofibrous PANI electrode is highly sensitive to L-cysteine,and the linear calibration curve for the oxidation of L-cysteine can be observed in the range of 0.2-5.0 mmol/L.

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.

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.

Recent Progress in Electrocatalytic Conversion of Lignin:From Monomers,Dimers,to Raw Lignin

Lignin,as the second largest renewable biomass resource in nature,has increasingly received significant interest for its potential to be transformed into valuable chemicals,potentially contributing to carbon neutrality.Among different approaches,renewable electricity-driven biomass conversion holds great promise to substitute a petroleum resource-driven one,owing to its characteristics of environmental friendliness,high energy efficiency,and tunable reactivity.The challenges lie on the polymeric structure and complex functional groups in lignin,requiring the development of efficient electrocatalysts for lignin valorization with enhanced activity and selectivity toward targeted chemicals.In this Review,we focus on the advancement of electrocatalytic valorization of lignin,from monomers,to dimers and to raw lignin,toward various valueadded chemicals,with emphasis on catalyst design,reaction innovation,and mechanistic study.The general strategies for catalyst design are also summarized,offering insights into enhancing the activity and selectivity.Finally,challenges and perspectives for the electrocatalytic conversion of lignin are proposed.

Recent Advance in Electrocatalytic Water Splitting for Hydrogen Production by Layered Double Hydroxides

Collecting green hydrogen(H2)from water splitting driven by renewable energy is a new competition to implement the construction of H2 energy industry and promote new economic growth for global governments.The common strategy to enhance the efficiency of H2 production is to reduce the potential of electrolytic cell that is the mainstream way to prepare efficient electrocatalysts.Layered double hydroxides(LDHs)are one of the most active electrocatalysts with adjustable active sites in contemporary research.In this review,we discuss the recent advanced progress of LDHs for hydrogen evolution reaction(HER)on cathode and oxygen evolution reaction(OER)or organic oxidation on anode and emphasize the influence of LDHs structure regulation in water electrolysis process(HER/OER)as well as the current development status of organic oxidation catalyzed by active oxygen species on anode.Finally,we propose the current challenges of LDHs in electrocatalysis and prospect their developing tendency and further application.

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.

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.

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).

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.

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.