Herein,Pd nanoparticles loaded Co_(3)O_(4)catalysts(Pd@Co_(3)O_(4))are constructed from zeolitic imidazolate framework-67(ZIF-67)for the ethanol oxidation reaction(EOR).It is demonstrated for the first time that the e...Herein,Pd nanoparticles loaded Co_(3)O_(4)catalysts(Pd@Co_(3)O_(4))are constructed from zeolitic imidazolate framework-67(ZIF-67)for the ethanol oxidation reaction(EOR).It is demonstrated for the first time that the electrochemical conversion of Co_(3)O_(4)support would result in the charge distribution alignment at the Pd/Co_(3)O_(4)interface and induce the formation of highly reactive Pd-O species(PdO^(*)),which can further catalyze the consequent reactions of the intermediates of the ethanol oxidation.The catalyst,Pd@Co_(3)O_(4)-450,obtained under the optimized conditions exhibits excellent EOR performance with a high mass activity of 590 mA mg-1,prominent operational stability,and extraordinary capability for the electro-oxidation of acetaldehyde intermediates.Importantly,the detailed mechanism investigation reveals that Pd@Co_(3)O_(4)-450 could be benefit to the C-C bond cleavage to promote the desirable C1 pathway for the ethanol oxidation reaction.The present strategy based on the metal-support interaction of the catalyst might provide valuable inspiration for the design of high-performing catalysts for the ethanol oxidation reaction.展开更多
Au nanowires in 4H crystalline phase(4H Au NWs)are synthesized by colloid solution methods.The crys-talline phase and surface structure as well as its performance toward electrochemical oxidation of CO be-fore and aft...Au nanowires in 4H crystalline phase(4H Au NWs)are synthesized by colloid solution methods.The crys-talline phase and surface structure as well as its performance toward electrochemical oxidation of CO be-fore and after removing adsorbed oleylamine molecules(OAs)intro-duced from its synthesis are evaluat-ed by high-resolution transmission electron microscopy(HR-TEM),X-ray diffraction(XRD),underpoten-tial deposition of Pb(Pb-upd)and cyclic voltammetry.Different methods,i.e.acetic acid cleaning,electrochemical oxidation cleaning,and diethylamine replacement,have been tried to remove the adsorbed OAs.For all methods,upon the removal of the adsorbed OAs,the morphology of 4H gold nanoparticles is found to gradually change from nanowires to large dumbbell-shaped nanoparticles,accompanying with a transition from the 4H phase to the face-centered cubic phase.On the other hand,the Pb-upd results show that the sample sur-faces have almost the same facet composition before and after removal of the adsorbed OAs.After electrochemical cleaning with continuous potential scans up to 1.3 V,CO electro-oxida-tion activity of the 4H Au sample is significantly improved.The CO electro-oxidation activi-ty is compared with results on the three basel Au single crystalline surfaces reported in the lit-erature,possible origins for its enhancement are discussed.展开更多
A simple one-pot method was developed to prepare Pt Ni alloy nanoparticles,which can be self-decorated on multiwalled carbon nanotubes in [BMIm][BF4] ionic liquid.The nanohybrids are targeting stable nanocatalysts for...A simple one-pot method was developed to prepare Pt Ni alloy nanoparticles,which can be self-decorated on multiwalled carbon nanotubes in [BMIm][BF4] ionic liquid.The nanohybrids are targeting stable nanocatalysts for fuel cell applications.The sizes of the supported Pt Ni nanoparticles are uniform and as small as 1–2 nm.Pt-to-Ni ratio was controllable by simply selecting a Pt Ni alloy target.The alloy nanoparticles with Pt-to-Ni ratio of 1:1 show high catalytic activity and stability for methanol electro-oxidation.The performance is much higher compared with those of both Pt-only nanoparticles and commercial Pt/C catalyst.The electronic structure characterization on the Pt Ni nanoparticles demonstrates that the electrons are transferred from Ni to Pt,which can suppress the CO poisoning effect.展开更多
Polyvinylpyrrolidone-stabilized graphene(PVP-graphene) was synthesized and investigated as a modifier for the determination of ascorbic acid(AA). With PVP acting as stabilizer and dispersant, the resulting PVP-gra...Polyvinylpyrrolidone-stabilized graphene(PVP-graphene) was synthesized and investigated as a modifier for the determination of ascorbic acid(AA). With PVP acting as stabilizer and dispersant, the resulting PVP-graphene material could disperse well into water. And the PVP-graphene modified glassy carbon electrode(PVP-graphene-GCE) showed an obvious electrocatalytical activity toward the oxidation of AA in a phosphate buffer solution(PBS, pH=7.0) with an oxidation potential of AA at 0.052 V vs. AglAgCl(sat. KCl). The calibration curve for APt was linear in a concentration range from 1.0×10^-5 to 5.0×10^-4 mol/L with a correlation coefficient of 0.9998. And the detection limit was found to be 1 μtmol/L. During the oxidation of AA, the π-π interaction of graphene plane with conjugated hexenoic aeid-lactone in AA molecules might play a key role. As a result, an obvious decrease of overpotential was achieved at such a PVP-graphene electrode through a possible adsorption/enrichment process, which will probably trigger potential applications for the electroanalysis of some aromatic and heterocyclic compounds.展开更多
Alloying degree, particle size and the level of dispersion are the key structural parameters of Pt-Ru/C catalyst in fuel cells. Solvent(s) used in the preparation process can affect the particle size and alloying de...Alloying degree, particle size and the level of dispersion are the key structural parameters of Pt-Ru/C catalyst in fuel cells. Solvent(s) used in the preparation process can affect the particle size and alloying degree of the object substance, which lead to a great positive impact on its properties. In this work, three types of solvents and their mixtures were used in preparation of the Pt-Ru/C catalysts by chemical reduction of metal precursors with sodium borohydride at room temperature. The structure of the catalysts was characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The catalytic activity and stability for methanol electro-oxidation were studied by Cyclic Voltammetry (CV) and Chronoamperometry (CA). Pt-Ru/C catalyst prepared in H2O or binary solvents of H2O and isopropanol had large particle size and low alloying degree leading to low catalytic activity and less stability in methanol electro-oxidation. When tetrahydrofuran was added to the above solvent systems, Pt-Ru/C catalyst prepared had smaller particle size and higher alloying degree which resulted in better catalytic activity, lower onset and peak potentials, compared with the above catalysts. Moreover, the catalyst prepared in ternary solvents of isopropanol, water and tetrahydrofuran had the smallest particle size, and the high alloying degree and the dispersion kept unchanged. Therefore, this kind of catalyst showed the highest catalytic activity and good stability for methanol electro-oxidation.展开更多
Pd@Ru bimetallic nanoparticles deposited on carbon black electro-catalysts have been fabricated by microwave-assisted polyol reduction method and investigated for methanol electro-oxidation (MEO). The structure and ...Pd@Ru bimetallic nanoparticles deposited on carbon black electro-catalysts have been fabricated by microwave-assisted polyol reduction method and investigated for methanol electro-oxidation (MEO). The structure and electro-catalytic properties of the as-prepared catalysts were characterized by XRD, SEM, TEM and cyclic voltammetry (CV) techniques. The results showed that the introduction of Ru element (2-10 wt%) into Pd 20 wt%/C (hereafter, denoted as Pd/C) produced a series of core-shell structured binary catalysts. Pd@Ru 5 wt%/C (hereafter, denoted as Pd@Rus/C) catalyst displayed the highest catalytic activity towards MEO. And the mass activity of Pd@Ru5/C electrode catalyst at E = -0.038 V (vs. Hg/HgO) was 1.42 times higher than that of Pd/C electrode catalyst. In addition, the relationship between the catalytic stability for MEO on Pd@Ru/C catalysts and the value of dbp/dfp (the ratio of MEO peak current density in the negative scan and positive scan) were also investigated. The result demonstrated that Pd@Rus/C offering the smallest value of Jbp/Jfp displayed the best stable catalytic performance.展开更多
Carbon nanotubes-Nafion (CNTs-Nation) composites were prepared by impregnated CNTs with Nation in ethanol solution and characterized by FT-IR. Pt-Ru catalysts supported on CNTs-Nafion composites were synthesized by ...Carbon nanotubes-Nafion (CNTs-Nation) composites were prepared by impregnated CNTs with Nation in ethanol solution and characterized by FT-IR. Pt-Ru catalysts supported on CNTs-Nafion composites were synthesized by microwave-assisted polyol process. The physical and electrochemical properties of the catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), CO stripping voltammetry, cyclic voltammetry (CV) and chronoamperometry (CA). The results showed that the Nation incorporation in CNTs-Nation composites did not significantly alter the oxygen-containing groups on the CNTs surface. The Pt-Ru catalyst supported on CNTs-Nafion composites with 2 wt% Naton showed good dispersion and the best CO oxidation and methanol electro-oxidation activities.展开更多
The effect of irreversibly adsorbed Bi on commercial Pt/C catalyst toward glucose electro-oxidation re- action (GOR) in different electrolytes (acidic, neutral, alkaline) is studied. Bi is successfully deposited o...The effect of irreversibly adsorbed Bi on commercial Pt/C catalyst toward glucose electro-oxidation re- action (GOR) in different electrolytes (acidic, neutral, alkaline) is studied. Bi is successfully deposited on Pt/C from Bi3+ containing acidic solution from 0 to 90% coverage degree. The stability of the Bi layer in acid and alkaline corresponded to previous studies and started to dissolve at 0.7 V and 0.8 V versus re- versible hydrogen electrode (RIIE), respectively. However, in neutral phosphate buffer the layer showed remarkable stability to at least 1.2V versus RHE. Bi modification at low (20%) and high (80%) coverage showed the highest increase in the activity of Pt/C toward GOR by a factor up to 7 due to the increased poisoning resistance of the modified catalyst. The effect of poisoning was especially reduced at high Bi coverage (80%), which shows that adsorbate blocked by Bi through the third-body effect is effective. Finally, with or without Bi modification GOR on PtIC was most active in alkaline conditions.展开更多
To obtain the electrocatalyst with an improved electrocatalytic performance towards formic acid electrooxidation(FAEO), a simple impregnation method is used to prepare Pt3Ni nanoparticles loaded on carbon black, assis...To obtain the electrocatalyst with an improved electrocatalytic performance towards formic acid electrooxidation(FAEO), a simple impregnation method is used to prepare Pt3Ni nanoparticles loaded on carbon black, assisted with electrochemically dealloying process. The X-ray powder diffraction(XRD) results as well as transmission electron microscopy(TEM) analysis of as-synthesized electrocatalyst demonstrates that the reduction temperature has a great influence on the FAEO activity of the dealloyed Pt3Ni nanoparticles. X-ray photoelectron spectroscopy(XPS) analyses confirm the variation in the electronic structure of platinum by incorporation of nickel atoms which reduces chemisorption of toxic carbon monoxide and promotes the dehydrogenation pathway of FAEO. The size of the dealloyed Pt3Ni nanoparticles remains within the range of about 2.7 nm. All electrochemical results illustrate that the performance of the asobtained electrocatalyst towards the FAEO is significantly enhanced. Moreover, the carbon black content,incorporation of Ni atoms, and reduction temperature conditions have been proven to be the key factors for modification of the crystal structure and morphology which leads to enhanced catalytic performance.展开更多
Direct ethanol fuel cells have attracted attention as an alternative energy technology due to several advantages such as high theoretical energy density and abundant supply of ethanol.In spite of the advantages,commer...Direct ethanol fuel cells have attracted attention as an alternative energy technology due to several advantages such as high theoretical energy density and abundant supply of ethanol.In spite of the advantages,commercialization of direct ethanol fuel cells is hampered by the relatively low performance caused by its slow oxidation kinetics and difficulty of complete oxidation.In this study,formate,which has relatively faster oxidation kinetics,was mixed with ethanol to compensate the latter’s sluggish kinetics.Effects of p H,concentration,scan rate,and temperature on the mixed reactants oxidation on Pd were investigated by electrochemical experiments such as potential sweep and potentiostatic methods.Furthermore,the potential of the mixed reactants as fuel was evaluated by single cell experiments.As a result,we demonstrate that mixing formate with ethanol results in enhanced power performance in a single cell system.展开更多
Formic acid electro-oxidation reaction(FAOR)is generally believed that follows a two-pathway mechanism.Herein,we resorted to in situ electrochemical mass spectrometry and successfully captured the trace of H_(2),as th...Formic acid electro-oxidation reaction(FAOR)is generally believed that follows a two-pathway mechanism.Herein,we resorted to in situ electrochemical mass spectrometry and successfully captured the trace of H_(2),as the new intermediate species,during the process of FAOR on both Pt based catalyst and two single atom catalysts(Rh-N-C and Ir-N-C).Inspired by this,we proposed a new reaction path named hydrogen oxidation pathway:at the oxidation potential,formic acid will break the C–H bond and combine with the protons in the solution to form H_(2) species,then hydrogen oxidation reaction(HOR)will occur to generate two protons.This process is accompanied by electron transfer and contributes currently to the whole reaction.展开更多
The small organic molecule electro-oxidation(OMEO) and the hydrogen evolution(HER) are two important half-reactions in direct liquid fuel cells(DLFCs) and water electrolyzers,respectively,whose performance is largely ...The small organic molecule electro-oxidation(OMEO) and the hydrogen evolution(HER) are two important half-reactions in direct liquid fuel cells(DLFCs) and water electrolyzers,respectively,whose performance is largely hindered by the low activity and poor stability of electrocatalysts.Herein,we demonstrate that a simple phosphorization treatment of commercially available palladium-nickel(PdNi) catalysts results in multifunctional ternary palladium nickel phosphide(PdNiP) catalysts,which exhibit substantially enhanced electrocatalytic activity and stability for HER and OMEO of a number of molecules including formic acid,methanol,ethanol,and ethylene glycol,in acidic and/or alkaline media.The improved performance results from the modification of electronic structure of palladium and nickel by the introduced phosphorus and the enhanced corrosion resistance of PdNiP.The simple phosphorization approach reported here allows for mass production of highly-active OMEO and HER electrocatalysts,holding substantial promise for their large-scale application in direct liquid fuel cells and water electrolyzers.展开更多
The glassy carbon substrates were bombarded with 5 X 10(17) ions/cm(2) of platinum. The surface composition of implanted electrode and concentration-depth profiles of various elements were measured by AES. The chemica...The glassy carbon substrates were bombarded with 5 X 10(17) ions/cm(2) of platinum. The surface composition of implanted electrode and concentration-depth profiles of various elements were measured by AES. The chemical state of Pt in glassy carbon electrode implanted with platinum (Pt/GC) was detected by X-ray Photoelectron Spectroscopy (XPS). The electro-oxidation of HCOOH and HCHO have been investigated on Pt/CC and smooth Pt electrodes. The results show that the platinum implanted into glassy carbon is much more active than the smooth platinum metal for electro-oxidation of HCOOH and HCHO.展开更多
Carbon nanotubes (CNTs) supported Pt-Ru and Pt-Ru-Ni catalysts were prepared by chemical reduction of metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of ...Carbon nanotubes (CNTs) supported Pt-Ru and Pt-Ru-Ni catalysts were prepared by chemical reduction of metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of the catalysts were characterized by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, and the catalytic activity and stability for methanol electro-oxidation were measured by electrochemical impedance spectroscopy (EIS), linear sweep voltammetries (LSV), and chronoamperometry (CA). The results show that the catalysts exhibit face-centered cubic (fcc) structure. The particle size of Pt-Ru-Ni/CNTs catalyst is about 4.8 nm. The catalytic activity and stability of the Pt-Ru-Ni/CNTs catalyst are higher than those of Pt-Ru/CNTs catalyst.展开更多
The ethanol oxidation reaction(EOR)is crucial in direct alcohol fuel cells and chemical production.However,the electro-oxidation of ethanol molecules to produce acetaldehyde and carbon monoxide can poison the active s...The ethanol oxidation reaction(EOR)is crucial in direct alcohol fuel cells and chemical production.However,the electro-oxidation of ethanol molecules to produce acetaldehyde and carbon monoxide can poison the active sites of nanocatalysts,resulting in reduced performance and posing challenges in achieving high activity and selectivity for ethanol oxidation.In this study,we employed a dynamic seed-mediated method to precisely modify highly dispersed Ru sites onto well-defined Pd nanocrystals.The oxyphilic Ru sites serve as"OH valves",regulating water dissociation,while the surrounding Pd atomic arrangements control electronic states for the oxidation dehydrogenation of carbonaceous intermediates.Specifically,Ru0.040@Pd nanocubes(Ru:Pd=0.04 at.%),featuring(100)facets in Ru-Pd4 configurations,demonstrate an outstanding mass activity of 6.53 A·mgPd^(-1) in EOR under alkaline conditions,which is 6.05 times higher than that of the commercial Pd/C catalyst(1.08 A·mgPd-1).Through in-situ experiments and theoretical investigations,we elucidate that the hydrophilic Ru atoms significantly promote the dynamic evolution of H_(2)O dissociation into OHads species,while the electron redistribution from Ru to adjacent Pd concurrently adjusts the selective oxidation of C_(2) intermediates.This host-guest interaction accelerates the subsequent oxidation of carbonaceous intermediates(CH_(3)CO_(ads))to acetate,while preventing the formation of toxic*CHx and*CO species,which constitutes the rate-determining step.展开更多
Electrocatalytic dehydrogenative cross-coupling of various alcohols in aqueous electrolytes functionalizes alcohols to form structurally diverse long-carbon-chain chemicals.However,it remains challenging to achieve th...Electrocatalytic dehydrogenative cross-coupling of various alcohols in aqueous electrolytes functionalizes alcohols to form structurally diverse long-carbon-chain chemicals.However,it remains challenging to achieve the high selectivity because of the high reactivity of involved carbonyl intermediates and different oxidation rates for the alcohols.Herein,the synthesis ofα,β-unsaturated ketones from alcohols was realized by the electro-oxidation cross-coupling in aqueous solutions by a“salting-out”strategy to engineer the micro-environment at electrocatalytic reaction interfaces.Theoretical calculations and electrochemical measurements demonstrated that concentrated local intermediates could inhibit the over-oxidation of alcohols and accelerate the coupling reaction kinetics between the intermediates.This strategy can couple primary and secondary alcohols to formα,β-unsaturated carbonyl compounds with a selectivity of 87% and be easily scaled up to gram scales.This study provides an attractive strategy for broadening the diversity of organic products in electrocatalysis.展开更多
ZnO doped Pt/CeO2 nanocomposites were prepared by electrospinning and reduction impregnation.Xray diffraction(XRD),transmission electron microscopy(TEM),energy disperse spectroscopy(EDS) and X-ray photoelectron ...ZnO doped Pt/CeO2 nanocomposites were prepared by electrospinning and reduction impregnation.Xray diffraction(XRD),transmission electron microscopy(TEM),energy disperse spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS) were employed to characterize the nanocomposites.It is observed that ZnO and CeO2 form the hexagonal wurtzite phase and cubic fluorite phase in the nanocomposite,respectively,whilst Pt nanoparticles(NPs) with the number-averaged size of ca.3.1 nm are uniformly distributed on the surface of nanofibers.The mass fraction of Pt NPs in the nanocomposites is about 10 wt%.The doping of ZnO is effective to promote reactive oxygen species,surface reaction sites and the interaction between Pt and oxides.The catalytic performance of nanocomposites was evaluated by the methanol electro-oxidation.indexed with the catalytic activity,stability of catalyst.As a result,it is found that the nanocomposite exhibits much higher activity and stability for methanol oxidation than the undoped Pt/CeO2 catalyst.展开更多
Pt:Pd:Co ternary alloy nanoparticles were synthesized by sodium borohydride reduction under nitrogen, and were supported on carbon black as catalysts for methanol and formic acid electro-oxidation. Compared with Pt0...Pt:Pd:Co ternary alloy nanoparticles were synthesized by sodium borohydride reduction under nitrogen, and were supported on carbon black as catalysts for methanol and formic acid electro-oxidation. Compared with Pt0.65C00.35/C, Pt/C, Pd0.65C00.35/C, and Pd/C catalyst, Pt0.35Pd0.35Co0.30/C exhibited relatively high durability and strong poisoning resistance, and the Pt-mass activity was 3.6 times higher than that of Pt/C in methanol oxidation reaction. Meanwhile, the Pt0.35Pd0.35Co0.30/C exhibited excellent activity with higher current density and higher CO tolerance than that of Pt0.6sCo0.35/C, Pt/C, Pd0.65C00.35/ C, and Pd/C in formic acid electro-oxidation.展开更多
Electrochemically producing formate by oxidizing methanol is a promising way to add value to methanol.Noble metal-based electrocatalysts,which have been extensively studied for the methanol oxidation reaction,can cata...Electrochemically producing formate by oxidizing methanol is a promising way to add value to methanol.Noble metal-based electrocatalysts,which have been extensively studied for the methanol oxidation reaction,can catalyze the complete oxidation of methanol to carbon dioxide,but not the mild oxidation to formate.As a result,exploring efficient and earth-abundant electrocatalysts for formate production from methanol is of interest.Herein,we present the electro-oxidation of methanol to formate,catalyzed by iron-substituted lanthanum cobaltite(LaCo_(1-x)Fe_(x)O_(3)).The Fe/Co ratio in the oxides greatly influences the activity and selectivity.This effect is attributed to the higher affinity of Fe and Co to the two reactants:CH3OH and OH,respectively.Because a balance between these affinities is favored,LaCo_(0.5)Fe_(0.5)O_(3) shows the highest formate production rate,at 24.5 mmol h^(-1) g_(oxide)^(-1),and a relatively high Faradaic efficiency of 44.4%in a series of(LaCo_(1-x)Fe_(x)O_(3))samples(x=0.00,0.25,0.50,0.75,1.00)at 1.6 V versus a reversible hydrogen electrode.展开更多
Electrochemically synthesized nanosphere,nanorod and nanotube Fe_(2)(MoO_(4))_(3) at optimized temperature and current density are characterized with XRD,SEM,TEM,XPS.Crystal lattices of the three types Fe_(2)(MoO_(4))...Electrochemically synthesized nanosphere,nanorod and nanotube Fe_(2)(MoO_(4))_(3) at optimized temperature and current density are characterized with XRD,SEM,TEM,XPS.Crystal lattices of the three types Fe_(2)(MoO_(4))_(3) detected by HRTEM are well matched with the simulation analysis results from Materials Studio 6.0 based on the inorganic crystal structure database(ICSD)data and the modified XRD lattice parameters.The ratios of Fe/Mo on the surface resulted from XPS analysis are 1.47,1.63 and 2.22 respectively for nanosphere,nanorod and nanotube.The mixture of Fe_(2)(MoO_(4))_(3) with polytetrafluoroethylene dispersion are coated on glass carbon substrate as electrode for electrocatalytic performance test by cyclic voltammetries in 0.1 mol/L KOH and 1 mol/L methanol electrolyte.Methanol oxidation peak current density of the Nanotube-Fe_(2)(MoO_(4))_(3)/GCEs electrode is 3.27 mA/cm^(2) higher than 2.8 mA/cm^(2) of platinum foil electrode,which shows enhanced catalytic activity of Nanotube-Fe_(2)(MoO_(4))_(3)/GCEs.The cyclic stability in terms of peak current retention are 91%,92%and 88%respectively for Nanosphere-Fe_(2)(MoO_(4))_(3)/GCE,Nanorod-Fe_(2)(MoO_(4))_(3)/GCE and Nanotube-Fe_(2)(MoO_(4))_(3)/GCE electrode after 220 cycles.It is concluded that nanosized Fe_(2)(MoO_(4))_(3) could be promising alternative non-noble electro-catalysts for electro-oxidation of methanol in alkaline medium.展开更多
基金supported by the National Natural Science Foundation of China(21336005)the Ministry of Science and Technology of China(2014EG111224)+1 种基金the National Key R&D Program of China(2021YFB4001200)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX22_3185)。
文摘Herein,Pd nanoparticles loaded Co_(3)O_(4)catalysts(Pd@Co_(3)O_(4))are constructed from zeolitic imidazolate framework-67(ZIF-67)for the ethanol oxidation reaction(EOR).It is demonstrated for the first time that the electrochemical conversion of Co_(3)O_(4)support would result in the charge distribution alignment at the Pd/Co_(3)O_(4)interface and induce the formation of highly reactive Pd-O species(PdO^(*)),which can further catalyze the consequent reactions of the intermediates of the ethanol oxidation.The catalyst,Pd@Co_(3)O_(4)-450,obtained under the optimized conditions exhibits excellent EOR performance with a high mass activity of 590 mA mg-1,prominent operational stability,and extraordinary capability for the electro-oxidation of acetaldehyde intermediates.Importantly,the detailed mechanism investigation reveals that Pd@Co_(3)O_(4)-450 could be benefit to the C-C bond cleavage to promote the desirable C1 pathway for the ethanol oxidation reaction.The present strategy based on the metal-support interaction of the catalyst might provide valuable inspiration for the design of high-performing catalysts for the ethanol oxidation reaction.
基金supported by the National Natural Science Foundation of China(No.22172151 and 21972131).
文摘Au nanowires in 4H crystalline phase(4H Au NWs)are synthesized by colloid solution methods.The crys-talline phase and surface structure as well as its performance toward electrochemical oxidation of CO be-fore and after removing adsorbed oleylamine molecules(OAs)intro-duced from its synthesis are evaluat-ed by high-resolution transmission electron microscopy(HR-TEM),X-ray diffraction(XRD),underpoten-tial deposition of Pb(Pb-upd)and cyclic voltammetry.Different methods,i.e.acetic acid cleaning,electrochemical oxidation cleaning,and diethylamine replacement,have been tried to remove the adsorbed OAs.For all methods,upon the removal of the adsorbed OAs,the morphology of 4H gold nanoparticles is found to gradually change from nanowires to large dumbbell-shaped nanoparticles,accompanying with a transition from the 4H phase to the face-centered cubic phase.On the other hand,the Pb-upd results show that the sample sur-faces have almost the same facet composition before and after removal of the adsorbed OAs.After electrochemical cleaning with continuous potential scans up to 1.3 V,CO electro-oxida-tion activity of the 4H Au sample is significantly improved.The CO electro-oxidation activi-ty is compared with results on the three basel Au single crystalline surfaces reported in the lit-erature,possible origins for its enhancement are discussed.
基金supported by the National Natural Science Foundation of China(No.61274019)the Soochow University-Western University Joint Centre for Synchrotron Radiation Research+1 种基金the Collaborative Innovation Center of Suzhou Nano Science & Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘A simple one-pot method was developed to prepare Pt Ni alloy nanoparticles,which can be self-decorated on multiwalled carbon nanotubes in [BMIm][BF4] ionic liquid.The nanohybrids are targeting stable nanocatalysts for fuel cell applications.The sizes of the supported Pt Ni nanoparticles are uniform and as small as 1–2 nm.Pt-to-Ni ratio was controllable by simply selecting a Pt Ni alloy target.The alloy nanoparticles with Pt-to-Ni ratio of 1:1 show high catalytic activity and stability for methanol electro-oxidation.The performance is much higher compared with those of both Pt-only nanoparticles and commercial Pt/C catalyst.The electronic structure characterization on the Pt Ni nanoparticles demonstrates that the electrons are transferred from Ni to Pt,which can suppress the CO poisoning effect.
基金Supported by the National Natural Science Foundation of China(No.20673109)
文摘Polyvinylpyrrolidone-stabilized graphene(PVP-graphene) was synthesized and investigated as a modifier for the determination of ascorbic acid(AA). With PVP acting as stabilizer and dispersant, the resulting PVP-graphene material could disperse well into water. And the PVP-graphene modified glassy carbon electrode(PVP-graphene-GCE) showed an obvious electrocatalytical activity toward the oxidation of AA in a phosphate buffer solution(PBS, pH=7.0) with an oxidation potential of AA at 0.052 V vs. AglAgCl(sat. KCl). The calibration curve for APt was linear in a concentration range from 1.0×10^-5 to 5.0×10^-4 mol/L with a correlation coefficient of 0.9998. And the detection limit was found to be 1 μtmol/L. During the oxidation of AA, the π-π interaction of graphene plane with conjugated hexenoic aeid-lactone in AA molecules might play a key role. As a result, an obvious decrease of overpotential was achieved at such a PVP-graphene electrode through a possible adsorption/enrichment process, which will probably trigger potential applications for the electroanalysis of some aromatic and heterocyclic compounds.
基金supported by 863 Project(No.2006AA05Z102)the Cultivation Fund of the Key Scientific and Technical Innovation Project,Ministry of Education of China (No.707050)+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education (No.20060610023)Chengdu Natural Science Foundation (Nos.06GGYB449GX-030,and 07GGZD139GX)
文摘Alloying degree, particle size and the level of dispersion are the key structural parameters of Pt-Ru/C catalyst in fuel cells. Solvent(s) used in the preparation process can affect the particle size and alloying degree of the object substance, which lead to a great positive impact on its properties. In this work, three types of solvents and their mixtures were used in preparation of the Pt-Ru/C catalysts by chemical reduction of metal precursors with sodium borohydride at room temperature. The structure of the catalysts was characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The catalytic activity and stability for methanol electro-oxidation were studied by Cyclic Voltammetry (CV) and Chronoamperometry (CA). Pt-Ru/C catalyst prepared in H2O or binary solvents of H2O and isopropanol had large particle size and low alloying degree leading to low catalytic activity and less stability in methanol electro-oxidation. When tetrahydrofuran was added to the above solvent systems, Pt-Ru/C catalyst prepared had smaller particle size and higher alloying degree which resulted in better catalytic activity, lower onset and peak potentials, compared with the above catalysts. Moreover, the catalyst prepared in ternary solvents of isopropanol, water and tetrahydrofuran had the smallest particle size, and the high alloying degree and the dispersion kept unchanged. Therefore, this kind of catalyst showed the highest catalytic activity and good stability for methanol electro-oxidation.
基金supported by the National Basic Research Program of China(2013CB934001)the Natural Science Foundation of Beijing(2051001)the Natural Science Foundation of China(51074011)
文摘Pd@Ru bimetallic nanoparticles deposited on carbon black electro-catalysts have been fabricated by microwave-assisted polyol reduction method and investigated for methanol electro-oxidation (MEO). The structure and electro-catalytic properties of the as-prepared catalysts were characterized by XRD, SEM, TEM and cyclic voltammetry (CV) techniques. The results showed that the introduction of Ru element (2-10 wt%) into Pd 20 wt%/C (hereafter, denoted as Pd/C) produced a series of core-shell structured binary catalysts. Pd@Ru 5 wt%/C (hereafter, denoted as Pd@Rus/C) catalyst displayed the highest catalytic activity towards MEO. And the mass activity of Pd@Ru5/C electrode catalyst at E = -0.038 V (vs. Hg/HgO) was 1.42 times higher than that of Pd/C electrode catalyst. In addition, the relationship between the catalytic stability for MEO on Pd@Ru/C catalysts and the value of dbp/dfp (the ratio of MEO peak current density in the negative scan and positive scan) were also investigated. The result demonstrated that Pd@Rus/C offering the smallest value of Jbp/Jfp displayed the best stable catalytic performance.
基金supported by National Natural Science Foundation of China (NO.0576023)Key Project of Science and Technology Department of Guangdong Province (NO.2008B010800036 NO.2008B010800037)
文摘Carbon nanotubes-Nafion (CNTs-Nation) composites were prepared by impregnated CNTs with Nation in ethanol solution and characterized by FT-IR. Pt-Ru catalysts supported on CNTs-Nafion composites were synthesized by microwave-assisted polyol process. The physical and electrochemical properties of the catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), CO stripping voltammetry, cyclic voltammetry (CV) and chronoamperometry (CA). The results showed that the Nation incorporation in CNTs-Nation composites did not significantly alter the oxygen-containing groups on the CNTs surface. The Pt-Ru catalyst supported on CNTs-Nafion composites with 2 wt% Naton showed good dispersion and the best CO oxidation and methanol electro-oxidation activities.
基金Jane and Aatos Erkko FoundationJenny and Antti Wihuri Foundation for funding
文摘The effect of irreversibly adsorbed Bi on commercial Pt/C catalyst toward glucose electro-oxidation re- action (GOR) in different electrolytes (acidic, neutral, alkaline) is studied. Bi is successfully deposited on Pt/C from Bi3+ containing acidic solution from 0 to 90% coverage degree. The stability of the Bi layer in acid and alkaline corresponded to previous studies and started to dissolve at 0.7 V and 0.8 V versus re- versible hydrogen electrode (RIIE), respectively. However, in neutral phosphate buffer the layer showed remarkable stability to at least 1.2V versus RHE. Bi modification at low (20%) and high (80%) coverage showed the highest increase in the activity of Pt/C toward GOR by a factor up to 7 due to the increased poisoning resistance of the modified catalyst. The effect of poisoning was especially reduced at high Bi coverage (80%), which shows that adsorbate blocked by Bi through the third-body effect is effective. Finally, with or without Bi modification GOR on PtIC was most active in alkaline conditions.
基金supported by the National Natural Science Foundation of China(No.51602209)the Provincial Nature Science Foundation of Sichuan(No.2016GZ0423,2017CC0017,2018FZ0105)the Fundamental Research Funds supported by Ministry of Education of the People’s Republic of China(No.YJ201746,2018SCUH0025)
文摘To obtain the electrocatalyst with an improved electrocatalytic performance towards formic acid electrooxidation(FAEO), a simple impregnation method is used to prepare Pt3Ni nanoparticles loaded on carbon black, assisted with electrochemically dealloying process. The X-ray powder diffraction(XRD) results as well as transmission electron microscopy(TEM) analysis of as-synthesized electrocatalyst demonstrates that the reduction temperature has a great influence on the FAEO activity of the dealloyed Pt3Ni nanoparticles. X-ray photoelectron spectroscopy(XPS) analyses confirm the variation in the electronic structure of platinum by incorporation of nickel atoms which reduces chemisorption of toxic carbon monoxide and promotes the dehydrogenation pathway of FAEO. The size of the dealloyed Pt3Ni nanoparticles remains within the range of about 2.7 nm. All electrochemical results illustrate that the performance of the asobtained electrocatalyst towards the FAEO is significantly enhanced. Moreover, the carbon black content,incorporation of Ni atoms, and reduction temperature conditions have been proven to be the key factors for modification of the crystal structure and morphology which leads to enhanced catalytic performance.
基金supported by the New & Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)granted financial resource from the Ministry of Trade,Industry & Energy,Republic of Korea(20153030031720)
文摘Direct ethanol fuel cells have attracted attention as an alternative energy technology due to several advantages such as high theoretical energy density and abundant supply of ethanol.In spite of the advantages,commercialization of direct ethanol fuel cells is hampered by the relatively low performance caused by its slow oxidation kinetics and difficulty of complete oxidation.In this study,formate,which has relatively faster oxidation kinetics,was mixed with ethanol to compensate the latter’s sluggish kinetics.Effects of p H,concentration,scan rate,and temperature on the mixed reactants oxidation on Pd were investigated by electrochemical experiments such as potential sweep and potentiostatic methods.Furthermore,the potential of the mixed reactants as fuel was evaluated by single cell experiments.As a result,we demonstrate that mixing formate with ethanol results in enhanced power performance in a single cell system.
基金supported by the National Natural Science Foundation of China(21875243,21633008,21673221,U1601211)the Jilin Province Science and Technology Development Program(20190201270JC,20180101030JC)the Special Funds for Guiding Local Scientific and Technological Development by the Central Government(2020JH6/10500021)。
文摘Formic acid electro-oxidation reaction(FAOR)is generally believed that follows a two-pathway mechanism.Herein,we resorted to in situ electrochemical mass spectrometry and successfully captured the trace of H_(2),as the new intermediate species,during the process of FAOR on both Pt based catalyst and two single atom catalysts(Rh-N-C and Ir-N-C).Inspired by this,we proposed a new reaction path named hydrogen oxidation pathway:at the oxidation potential,formic acid will break the C–H bond and combine with the protons in the solution to form H_(2) species,then hydrogen oxidation reaction(HOR)will occur to generate two protons.This process is accompanied by electron transfer and contributes currently to the whole reaction.
基金financial support of China Scholarship Council,China(Grant No.201806150015)the financial support of the Portuguese Foundation of Science and Technology through TACIT project(Grant No.02/SAICT/2017/028837)the National Innovation Agency of Portugal through Baterias 2030 project(Grant No.POCI-01-0247FEDER-046109)to this work。
文摘The small organic molecule electro-oxidation(OMEO) and the hydrogen evolution(HER) are two important half-reactions in direct liquid fuel cells(DLFCs) and water electrolyzers,respectively,whose performance is largely hindered by the low activity and poor stability of electrocatalysts.Herein,we demonstrate that a simple phosphorization treatment of commercially available palladium-nickel(PdNi) catalysts results in multifunctional ternary palladium nickel phosphide(PdNiP) catalysts,which exhibit substantially enhanced electrocatalytic activity and stability for HER and OMEO of a number of molecules including formic acid,methanol,ethanol,and ethylene glycol,in acidic and/or alkaline media.The improved performance results from the modification of electronic structure of palladium and nickel by the introduced phosphorus and the enhanced corrosion resistance of PdNiP.The simple phosphorization approach reported here allows for mass production of highly-active OMEO and HER electrocatalysts,holding substantial promise for their large-scale application in direct liquid fuel cells and water electrolyzers.
文摘The glassy carbon substrates were bombarded with 5 X 10(17) ions/cm(2) of platinum. The surface composition of implanted electrode and concentration-depth profiles of various elements were measured by AES. The chemical state of Pt in glassy carbon electrode implanted with platinum (Pt/GC) was detected by X-ray Photoelectron Spectroscopy (XPS). The electro-oxidation of HCOOH and HCHO have been investigated on Pt/CC and smooth Pt electrodes. The results show that the platinum implanted into glassy carbon is much more active than the smooth platinum metal for electro-oxidation of HCOOH and HCHO.
基金The project is supported by the National Natural Science Foundation of China (20576023)the Science and Technology Project of Guangzhou City (2005 J1-C0361)the Key Project of Education Bureau of Guangzhou City (2052).
文摘Carbon nanotubes (CNTs) supported Pt-Ru and Pt-Ru-Ni catalysts were prepared by chemical reduction of metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of the catalysts were characterized by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, and the catalytic activity and stability for methanol electro-oxidation were measured by electrochemical impedance spectroscopy (EIS), linear sweep voltammetries (LSV), and chronoamperometry (CA). The results show that the catalysts exhibit face-centered cubic (fcc) structure. The particle size of Pt-Ru-Ni/CNTs catalyst is about 4.8 nm. The catalytic activity and stability of the Pt-Ru-Ni/CNTs catalyst are higher than those of Pt-Ru/CNTs catalyst.
基金supported by the National Natural Science Foundation of China(No.22275009)SINOPEC(Contact No.421028)Fundamental Research Funds for the Central Universities(No.XK2020-02).
文摘The ethanol oxidation reaction(EOR)is crucial in direct alcohol fuel cells and chemical production.However,the electro-oxidation of ethanol molecules to produce acetaldehyde and carbon monoxide can poison the active sites of nanocatalysts,resulting in reduced performance and posing challenges in achieving high activity and selectivity for ethanol oxidation.In this study,we employed a dynamic seed-mediated method to precisely modify highly dispersed Ru sites onto well-defined Pd nanocrystals.The oxyphilic Ru sites serve as"OH valves",regulating water dissociation,while the surrounding Pd atomic arrangements control electronic states for the oxidation dehydrogenation of carbonaceous intermediates.Specifically,Ru0.040@Pd nanocubes(Ru:Pd=0.04 at.%),featuring(100)facets in Ru-Pd4 configurations,demonstrate an outstanding mass activity of 6.53 A·mgPd^(-1) in EOR under alkaline conditions,which is 6.05 times higher than that of the commercial Pd/C catalyst(1.08 A·mgPd-1).Through in-situ experiments and theoretical investigations,we elucidate that the hydrophilic Ru atoms significantly promote the dynamic evolution of H_(2)O dissociation into OHads species,while the electron redistribution from Ru to adjacent Pd concurrently adjusts the selective oxidation of C_(2) intermediates.This host-guest interaction accelerates the subsequent oxidation of carbonaceous intermediates(CH_(3)CO_(ads))to acetate,while preventing the formation of toxic*CHx and*CO species,which constitutes the rate-determining step.
基金supported by the National Key R&D Program of China(2020YFA0710000)the National Natural Science Foundation of China(22122901)+2 种基金the Provincial Natural Science Foundation of Hunan(2021JJ0008,2021JJ20024,2021RC3054)the Provincial Natural Science Foundation of Hunan(2022JJ40043)Hunan Provincial Innovation Foundation For Postgraduate(CX20220386)。
文摘Electrocatalytic dehydrogenative cross-coupling of various alcohols in aqueous electrolytes functionalizes alcohols to form structurally diverse long-carbon-chain chemicals.However,it remains challenging to achieve the high selectivity because of the high reactivity of involved carbonyl intermediates and different oxidation rates for the alcohols.Herein,the synthesis ofα,β-unsaturated ketones from alcohols was realized by the electro-oxidation cross-coupling in aqueous solutions by a“salting-out”strategy to engineer the micro-environment at electrocatalytic reaction interfaces.Theoretical calculations and electrochemical measurements demonstrated that concentrated local intermediates could inhibit the over-oxidation of alcohols and accelerate the coupling reaction kinetics between the intermediates.This strategy can couple primary and secondary alcohols to formα,β-unsaturated carbonyl compounds with a selectivity of 87% and be easily scaled up to gram scales.This study provides an attractive strategy for broadening the diversity of organic products in electrocatalysis.
基金Project supported by the National Natural Science Foundation of China(21475021,21427807)the Natural Science Foundation of Jiangsu Province(BK20141331)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘ZnO doped Pt/CeO2 nanocomposites were prepared by electrospinning and reduction impregnation.Xray diffraction(XRD),transmission electron microscopy(TEM),energy disperse spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS) were employed to characterize the nanocomposites.It is observed that ZnO and CeO2 form the hexagonal wurtzite phase and cubic fluorite phase in the nanocomposite,respectively,whilst Pt nanoparticles(NPs) with the number-averaged size of ca.3.1 nm are uniformly distributed on the surface of nanofibers.The mass fraction of Pt NPs in the nanocomposites is about 10 wt%.The doping of ZnO is effective to promote reactive oxygen species,surface reaction sites and the interaction between Pt and oxides.The catalytic performance of nanocomposites was evaluated by the methanol electro-oxidation.indexed with the catalytic activity,stability of catalyst.As a result,it is found that the nanocomposite exhibits much higher activity and stability for methanol oxidation than the undoped Pt/CeO2 catalyst.
基金supported by NSFC(No.21373116)Tianjin Natural Science Research Fund(No.13JCYBJC18300)+1 种基金RFDP(No. 20120031110005)MOE Innovation Team of China(No. IRT13022)
文摘Pt:Pd:Co ternary alloy nanoparticles were synthesized by sodium borohydride reduction under nitrogen, and were supported on carbon black as catalysts for methanol and formic acid electro-oxidation. Compared with Pt0.65C00.35/C, Pt/C, Pd0.65C00.35/C, and Pd/C catalyst, Pt0.35Pd0.35Co0.30/C exhibited relatively high durability and strong poisoning resistance, and the Pt-mass activity was 3.6 times higher than that of Pt/C in methanol oxidation reaction. Meanwhile, the Pt0.35Pd0.35Co0.30/C exhibited excellent activity with higher current density and higher CO tolerance than that of Pt0.6sCo0.35/C, Pt/C, Pd0.65C00.35/ C, and Pd/C in formic acid electro-oxidation.
基金This research was supported by the National Research Foundation,Prime Minister's Office,Singapore,under its Campus for Research Excellence and Technological Enterprise(CREATE)programThe work was partially supported by a Singapore Ministry of Education Tier 1 grant(2019-T1-002-125)and Tier 2 grant(MOE-T2EP10220-0001).
文摘Electrochemically producing formate by oxidizing methanol is a promising way to add value to methanol.Noble metal-based electrocatalysts,which have been extensively studied for the methanol oxidation reaction,can catalyze the complete oxidation of methanol to carbon dioxide,but not the mild oxidation to formate.As a result,exploring efficient and earth-abundant electrocatalysts for formate production from methanol is of interest.Herein,we present the electro-oxidation of methanol to formate,catalyzed by iron-substituted lanthanum cobaltite(LaCo_(1-x)Fe_(x)O_(3)).The Fe/Co ratio in the oxides greatly influences the activity and selectivity.This effect is attributed to the higher affinity of Fe and Co to the two reactants:CH3OH and OH,respectively.Because a balance between these affinities is favored,LaCo_(0.5)Fe_(0.5)O_(3) shows the highest formate production rate,at 24.5 mmol h^(-1) g_(oxide)^(-1),and a relatively high Faradaic efficiency of 44.4%in a series of(LaCo_(1-x)Fe_(x)O_(3))samples(x=0.00,0.25,0.50,0.75,1.00)at 1.6 V versus a reversible hydrogen electrode.
基金This work was supported by the National Natural Science Foundation of China(No.21373137)National 863 program(No.2014AA052202)+1 种基金Shanghai Science and Technology Development Funds(No.13DZ2280200&No.15DZ2282000)SSM also thanks the support of Shenzhen Overseas High-Level Talent Innovation and Entrepreneurship Team special funds(No.1208040050847074).
文摘Electrochemically synthesized nanosphere,nanorod and nanotube Fe_(2)(MoO_(4))_(3) at optimized temperature and current density are characterized with XRD,SEM,TEM,XPS.Crystal lattices of the three types Fe_(2)(MoO_(4))_(3) detected by HRTEM are well matched with the simulation analysis results from Materials Studio 6.0 based on the inorganic crystal structure database(ICSD)data and the modified XRD lattice parameters.The ratios of Fe/Mo on the surface resulted from XPS analysis are 1.47,1.63 and 2.22 respectively for nanosphere,nanorod and nanotube.The mixture of Fe_(2)(MoO_(4))_(3) with polytetrafluoroethylene dispersion are coated on glass carbon substrate as electrode for electrocatalytic performance test by cyclic voltammetries in 0.1 mol/L KOH and 1 mol/L methanol electrolyte.Methanol oxidation peak current density of the Nanotube-Fe_(2)(MoO_(4))_(3)/GCEs electrode is 3.27 mA/cm^(2) higher than 2.8 mA/cm^(2) of platinum foil electrode,which shows enhanced catalytic activity of Nanotube-Fe_(2)(MoO_(4))_(3)/GCEs.The cyclic stability in terms of peak current retention are 91%,92%and 88%respectively for Nanosphere-Fe_(2)(MoO_(4))_(3)/GCE,Nanorod-Fe_(2)(MoO_(4))_(3)/GCE and Nanotube-Fe_(2)(MoO_(4))_(3)/GCE electrode after 220 cycles.It is concluded that nanosized Fe_(2)(MoO_(4))_(3) could be promising alternative non-noble electro-catalysts for electro-oxidation of methanol in alkaline medium.