碱性介质中多孔纳米结构镍/钯-镍电极上甲醇电氧化反应(英文)

A nanostructured Ni/Pd-Ni catalyst with high activity for methanol oxidation in alkaline solution was prepared by electrodeposition followed by galvanic replacement, that is, electrodeposition of Ni-Zn on a Ni coating with subsequent replacement of the Zn by Pd at the open circuit potential in a Pd-containing alkaline solution. The surface morphology and composition of the coatings were examined by energy dispersive X-ray spectroscopy and scanning electron microscopy. The Ni/Pd-Ni coatings were porous and were composed of discrete Pd nanoparticles of about 58 nm. The electrocatalytic activity of the Ni/Pd-Ni electrodes for the oxidation of methanol was examined by cyclic voltammetry and electrochemical impedance spectroscopy. The onset potentials for methanol oxidation on Ni/Pd-Ni were 0.077 V and 0.884 V, which were lower than those for flat Pd and smooth Ni electrodes, respectively. The anodic peak current densities of these electrodes were 4.33 and 8.34 times higher than those of flat Pd (58.4 mA/cm2 vs 13.47 mA/cm2) and smooth Ni (58.4 mA/cm2 vs 7 mA/cm2). The nanostructured Ni/Pd-Ni electrode is a promising catalyst for methanol oxidation in alkaline media for fuel cell application.     

Physical and electrochemical characterizations of microwave-assisted polyol preparation of carbon-supported PtRu nanoparticles

PtRu nanoparticles supported on Vulcan XC-72 carbon and carbon nanotubes were prepared by a microwave-assisted polyol process. The catalysts were characterized by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). The PtRu nanoparticles, which were uniformly dispersed on carbon, were 2-6 nm in diameter. All PtRu/C catalysts prepared as such displayed the characteristic diffraction peaks of a Pt face-centered cubic structure, excepting that the 2theta values were shifted to slightly higher values. XPS analysis revealed that the catalysts contained mostly Pt(0) and Ru(0), with traces of Pt(II), Pt(IV), and Ru(IV). The electro-oxidation of methanol was studied by cyclic voltammetry, linear sweep voltammetry, and chronoamperometry. It was found that both PtRu/C catalysts had high and more durable electrocatalytic activities for methanol oxidation than a comparative Pt/C catalyst. Preliminary data from a direct methanol fuel cell single stack test cell using the Vulcan-carbon-supported PtRu alloy as the anode catalyst showed high power density.     

聚乙酰苯胺修饰碳纳米管载铂催化剂对甲醇电催化氧化

以原位化学聚合的聚乙酰苯胺/多壁碳纳米管(PAANI-MWCNTs)复合纳米材料作为载体,采用硼氢化钠还原法将Pt纳米粒子担载到PAANI-MWCNTs复合纳米材料表面,制备了Pt/PAANI-MWCNTs复合纳米催化剂.样品的结构和形貌用紫外-可见(UV-Vis)光谱、拉曼光谱、扫描电镜(SEM)、透射电镜(TEM)和X射线衍射(XRD)进行了表征.结果表明,聚乙酰苯胺与碳纳米管之间存在较强的π-π相互作用,使其能牢固地吸附于多壁碳纳米管表面,对碳纳米管的结构完整性和导电性有一定的改善作用.同时,金属Pt纳米颗粒较为均匀地分散在PAANI-MWCNTs表面,粒径分布范围较窄.采用循环伏安法和计时电流法在酸性溶液中研究了Pt/PAANI-MWCNTs催化剂对甲醇的电催化氧化活性,结果表明Pt/PAANI-MWCNTs复合纳米催化剂比用混酸处理的碳纳米管载铂催化剂对甲醇呈现出更高的电催化氧化活性和更好的抗中毒能力及稳定性.     

High electrocatalytic activity of non-noble Ni-Co/graphene catalyst for direct ethanol fuel cells

The electrocatalytic oxidation of ethanol is studied on the non-noble catalysts Ni-Co/graphene and Ni/graphene supported on glass carbon electrode (GCE) in alkaline medium. The synthesized materials are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning transmission electron microscopy. The elements of Ni-Co/graphene and Ni/graphene catalysts are characterized using energy-dispersive X-ray spectroscopy. The electrocatalytic properties of Ni-Co/graphene and Ni/graphene for ethanol oxidation are investigated by cyclic voltammetry, chronoamperometry, and Tafel plot. Compared with Ni/graphene catalyst, Ni-Co/graphene has the higher electroactivity and better stability for ethanol oxidation. The rate constant (k _s) and charge-transfer coefficient (α) are calculated for the electron exchange reaction of the modified GCE. The results indicate that Co addition could promote the oxidation reaction at the Ni/graphene catalyst. Our study demonstrates that the low-cost electrocatalyst Ni-Co/graphene has a great potential for real direct ethanol fuel cells’ application.     

高分散PtRu/C催化剂的制备及对甲醇及吸附态CO的电催化氧化

采用化学还原浸渍法在两种不同条件下制备炭载PtRu催化剂,通过XRD和TEM技术对催化剂的晶体结构及微观形貌进行了分析,运用循环伏安法、线性扫描法来检测不同条件下制备的催化剂对甲醇及吸附态CO(COad)电催化氧化活性的影响.结果表明,不同条件下制备的催化剂Pt和Ru形成合金的程度不同,Pt-Ru合金原子的颗粒在载体炭上的粒径大小和分布不同,导致催化剂对甲醇及COad的电氧化催化活性不同.其中以甲醛为还原剂在乙二醇体系中制备的催化剂PtRu/C-2能形成较好的合金状态,粒径小,分布均匀,对甲醇及COad的氧化具有较高的电催化活性.     

Electrocatalytic oxidation of methanol on Ni modified polyaniline electrode in alkaline medium

Electrolytically deposited Ni on polyaniline film covered carbon paste electrode (Ni/PANI/CPE) was used as anode for the electrooxidation of methanol in alkaline medium. The electrochemical behavior and electrocatalytic activity of the electrode were studied using cyclic voltammetry, impedance spectroscopy, chronomethods, and polarization studies. The morphology and composition of the modified film were obtained using scanning electron microscope and energy dispersive X-ray analysis techniques. The electrooxidation of methanol in NaOH was found to be more efficient on Ni/PANI/CPE than on bare Ni, electrodeposited Ni on Pt, Ni on glassy carbon, and Ni on CPE substrates. Partial chemical displacement of dispersed Ni on PANI with Pt or Pd further improved its performance towards methanol oxidation.     

Synthesis and characterization of a new Schiff base derived from 2,3-diaminopyridine and 5-methoxysalicylaldehyde and its Ni(II), Cu(II) and Zn(II) complexes. Electrochemical and electrocatalytical studies

We describe the synthesis and characterization of a new tetradentate Schiff base ligand obtained from 2,3-diaminopyridine and 5-methoxysalicylaldehyde. This ligand (H₂L) reacted with nickel(II), copper(II), and zinc(II) acetates to give complexes. The ligand and its metal complexes were characterized using analytical, spectral data (UV–vis, IR, and mass spectroscopy), and cyclic voltammetry (CV). The crystal structure of the copper complex was elucidated by X-ray diffraction studies. The electrochemical behavior of these compounds, using CV, revealed that metal centers were distinguished by their intrinsic redox systems, e.g. Ni(II)/Ni(I), Cu(II)/Cu(I), and Zn(II)/Zn(I). Moreover, the electrocatalytic reactions of Ni(II) and Cu(II) complexes catalyze the oxidation of methanol and benzylic alcohol.     

Exploration of electrodeposited platinum alloy catalysts for methanol electro-oxidation in 0.5 M H<Subscript>2</Subscript>SO<Subscript>4</Subscript>: Pt-Ni system

In this work, we examine the electrocatalytic activity of electrodeposited Platinum (Pt)-Nickel (Ni) alloy layers on an inert substrate electrode for methanol oxidation reaction. Analyses using energy-dispersive fluorescent X-ray analysis and powder X-ray diffractometry confirm alloying of Pt with Ni in a range of compositions. Steady-state polarisation measurements in 0.5 M methanol+0.5 M H₂SO₄ solutions clearly show that the onset of electro-oxidation shifts to less anodic potential values (approximately 160 mV), while also exhibiting current enhancements up to ~15 times the currents obtained for the pure Pt electrodeposit. A linear relationship between the cyclic voltammetric peak (oxidation) current and [MeOH] is observed at a scan rate of 50 mVs^–1, thus indicating reduced influence of adsorbed CO (CO_ads) surface poison. A critical composition, Pt (92%)/Ni (8%) [denoted Pt-Ni(3) alloy] is found to exhibit maximum electrocatalytic activity, beyond which the activity drops, whereas pure Ni does not catalyse the reaction. While the promotion of electro-oxidation is understood to be largely due to the alloy catalyst, surface redox species of Ni oxide formed during the electro-oxidation process may also contribute to the oxygenation of CO_ads, thereby enhancing the oxidation current. Plausible mechanisms of methanol oxidation on Pt/ transition metal alloy electrocatalysts are discussed in terms of electron transfer (in the alloy) and the role of Ni oxide species.     

Pt纳米空球粒径的可控制备及其甲醇电催化氧化

利用表面活性剂十二烷基磺酸钠（SDSN）的调控合成不同粒径的硒模板和铂纳米空球（Pthollow）,并将其修饰于玻碳（GC）基底即可制得Pthollow/GC电极;采用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、高分辨透射电子显微镜（HR-TEM）和X射线光电子能谱等观察表征了Pthollow样品的形貌与组成;以甲醇为探针分子,研究Pthollow/GC和电沉积铂电极（Ptnano/GC）对甲醇氧化的电催化活性. 结果表明,由铂原子簇团构筑的多孔铂纳米空球粒径均匀,分散性好;用4 μmol·L^-1 SDSN控制合成的直径为130 nm的Pthollow制备的Pthollow/GC电极对甲醇氧化的电催化活性最佳.     

Nickel modified ionic liquid/carbon paste electrode for highly efficient electrocatalytic oxidation of methanol in alkaline medium

In this study, the electrocatalytic oxidation of methanol at nickel modified ionic liquid/carbon paste electrode (Ni/IL/CPE) in alkaline medium is presented. The ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, is incorporated into the electrode as a binder. Electrochemical impedance spectroscopy is employed to evaluate the electron transfer rate of this electrode. Ni(II) ions are incorporated into the electrode by immersion of this electrode in 1.0?M nickel sulfate solution. Cyclic voltammetry and chronoamperometry techniques are used for the electrochemical study of this modified electrode in the absence and the presence of methanol. The effect of methanol concentration on the anodic peak current shows an increase in the anodic peak current up to 1.25?M. Current density of Ni/IL/CPE for methanol oxidation in alkaline media is investigated by comparison with some of the previously reported electrodes. Results show that this electrode exhibits a high efficient electrocatalytic activity toward the oxidation of methanol with the current density of 17.6?mA?cm^?2. The rate constant for chemical reaction between methanol and redox sites of electrode is calculated. This new proposed electrode is simple and efficient enough, and it can be widely used as anode in direct methanol fuel cell.     

氮掺杂还原氧化石墨烯负载铂催化剂的制备及甲醇电氧化性能

采用高温热解聚苯胺修饰的氧化石墨烯（PANI-GO）,得到了氮掺杂的还原氧化石墨烯碳材料（N-RGO）,以其负载Pt 制备了Pt/N-RGO纳米结构电催化剂. 采用透射电镜（TEM）、X射线光电子能谱（XPS）、X 射线衍射（XRD）谱及拉曼光谱等技术对N-RGO和Pt/N-RGO的形貌及结构进行了表征,用循环伏安、计时电流等电化学技术研究了Pt/N-RGO电极催化剂对CO溶出反应和甲醇电氧化反应的催化性能. 结果表明：高温热解PANIGO可同时实现GO的还原及其氮掺杂的过程,氮掺杂引起还原氧化石墨烯碳材料表面缺陷结构和导电性的增加;与相应的未掺杂氮样品Pt/RGO相比较,Pt/N-RGO样品上Pt 颗粒的分散更均匀,显示出更强的抗CO毒化能力和更高的甲醇电氧化催化活性及稳定性.     

氮掺杂还原氧化石墨烯负载铂催化剂的制备及甲醇电氧化性能

采用高温热解聚苯胺修饰的氧化石墨烯(PANI-GO),得到了氮掺杂的还原氧化石墨烯碳材料(N-RGO),以其负载Pt制备了Pt/N-RGO纳米结构电催化剂.采用透射电镜(TEM)、X射线光电子能谱(XPS)、X射线衍射(XRD)谱及拉曼光谱等技术对N-RGO和Pt/N-RGO的形貌及结构进行了表征,用循环伏安、计时电流等电化学技术研究了Pt/N-RGO电极催化剂对CO溶出反应和甲醇电氧化反应的催化性能.结果表明:高温热解PANIGO可同时实现GO的还原及其氮掺杂的过程,氮掺杂引起还原氧化石墨烯碳材料表面缺陷结构和导电性的增加;与相应的未掺杂氮样品Pt/RGO相比较,Pt/N-RGO样品上Pt颗粒的分散更均匀,显示出更强的抗CO毒化能力和更高的甲醇电氧化催化活性及稳定性.     

炭载Pd-Ni合金纳米粒子对甲酸的电催化氧化

通过液相还原法制备了具有不同原子比例的Pd-Ni/C催化剂,并且使用X射线衍射（XRD）、透射电子显微镜(TEM)和X射线光电子能谱(XPS) 等表征手段对制备的催化剂进行了表征,总结了Ni的掺杂对Pd-Ni合金纳米粒子的尺寸及晶体结构的影响。电化学测试结果表明：适量的Ni的掺杂不但能够增强催化剂对甲酸催化氧化的活性,而且还能够提高催化剂的稳定性。因此,Pd-Ni/C催化剂是一类具有潜在应用前景的直接甲酸燃料电池阳极催化剂     

Application of phosphotungstic acid–nickel composite-modified carbon paste electrode for electrocatalytic oxidation of methanol in alkaline solution

Phosphotungstic acid (PWA) was used for accumulation of nickel ions at the carbon paste electrode for preparation of PWA-modified CPE (PWA/CPE). The PWA was evenly mixed with graphite powder and paraffin oil. Then, for preparation of Ni/PWA/CPE, Ni ions were included onto the PWA/CPE surface through immersion method at open circuit condition. The scanning electron microscopy (SEM), energy-dispersive spectroscopy and electrochemical methods were used to verify the prepared electrodes. The SEM images reveal that morphology of the CPE was influenced by PWA addition. Application of the Ni/PWA/CPE for methanol oxidation was explored by various electrochemical techniques. Electrochemical response of methanol oxidation at the surface of Ni/PWA/CPE was 2.5 times higher than that Ni/CPE. The obtained results indicated that the modified electrode exhibited high electrocatalytic activity toward methanol oxidation. Then, catalytic rate constant was found to be 8.25 × 10⁴ cm³ mol ^?1 s^?1 using chronoamperometry method. Furthermore, the effects of several parameters, such as PWA loading, NiSO₄ concentration, accumulation time and methanol concentration toward methanol oxidation at the surface of this modified electrode as well as stability, have been investigated.     

一步法制备纳米铂/石墨烯及电催化甲醇的交流阻抗和扩散系数测定

采用绿色还原剂抗坏血酸,一步法制备纳米铂/石墨烯。对其进行X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)形貌结构表征,铂纳米粒子均匀分散于纳米石墨烯片层褶皱间,有效减少了团聚现象。运用循环伏安法(CV)和计时电流法(CA)研究纳米铂/石墨烯对甲醇电催化氧化活性和稳定性,通过交流阻抗(EIS)定量测定,发现铂/石墨烯比铂具有更优异的电荷传输性能,电荷转移阻抗下降了34.8%。计时电量法(CC)测定得到甲醇在铂/石墨烯电极的表面扩散系数为1.42×10~(-9) cm~2·s~(-1)。与铂纳米粒子相比,纳米铂/石墨烯对甲醇电催化氧化具有更高的活性和稳定性,显著提高电极催化活性表面积和电荷传输及转移性能。     

Preparation and characterization of nano-sized Pt-Ru/C catalysts and their superior catalytic activities for methanol and ethanol oxidation

Carbon-supported PtRu nanoparticles (Ru/Pt: 0.25) were prepared by three different methods; simultaneous reduction of PtCl(4) and RuCl(3) (catalyst I) and changing the reduction order of PtCl(4) and RuCl(3) (catalysts II and III) to enhance the performance of the anodic catalysts for methanol and ethanol oxidation. Structure, microstructure and surface characterizations of all the catalysts were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results of the XRD analysis showed that all catalysts had a face-centered cubic (fcc) structure with different and smaller lattice parameters than that of pure platinum, showing that the Ru incorporates into the Pt fcc structure by different ratios in all the catalysts. The typical particle sizes of all catalysts were in the range of 2-3 nm. The most active and stable catalyst for methanol and ethanol oxidation is catalyst III, in which a large amount (more than 90%) of PtRu alloy formation was observed. It has been found that this catalyst is about 8.0 and 33.4 times more active at ～0.60 V towards the methanol and ethanol oxidation reactions, respectively, compared to the commercial Pt catalyst.     

壳聚糖修饰炭黑负载Pt-Au催化剂对甲醇氧化的电催化性能

以炭黑及自制的壳聚糖-炭黑(CHI-C)复合材料为载体,采用溶胶负载法制备了Pt_m＾Au/C及Pt_m＾Au/CHI-C催化剂(＾ 代表Au、Pt为分步负载,m代表Pt/Au原子比),通过紫外-可见吸收光谱、X射线衍射、透射电镜及X射线光电子能谱对催化剂进行了表征。利用循环伏安法和计时电流法分别测定了Pt-Au催化剂对甲醇电催化氧化反应的活性和稳定性,考查了Pt/Au原子比及CHI改性对电催化活性和稳定性的影响。结果表明,Pt_1.0＾Au/C具有最高的催化活性,炭黑中加入少量CHI能提高Pt_1.0＾Au/C催化剂的稳定性。     

Highly efficient and stable electrooxidation of methanol and ethanol on 3D Pt catalyst by thermal decomposition of In_2O_3 nanoshells

In this paper In_2O_3 nanoshells have been synthesized via a facile hydrothermal approach.The nanoshells can be completely cracked into pony-size nanocubes by annealing,which are then used as a support of Pt catalyst for methanol and ethanol electrocatalytic oxidation.The prepared In_2O_3 and supported Pt catalysts(Pt/In_2O_3) were characterized by X-ray diffraction(XRD),energy dispersive X-ray spectroscopy(EDS),X-ray photoelectron spectroscopy(XPS),field effect scanning electron microscopy(FESEM),and transmission electron microscopy(TEM).Cyclic voltammetry(CV),linear sweep voltammetry(LSV),chronoamperometry and electrochemical impedance spectroscopy(EIS) were carried out,indicating the excellent catalytic performance for alcohol electrooxidation can be achieved on Pt/In_2O_3 nanocatalysts due to the multiple active sites,high conductivity and a mass of microchannels and micropores for reactant diffusions arising from 3D frame structures compared with that on the Pt/C catalysts.     

Synthesis of graphene oxide nanosheet: A novel glucose sensor based on nickel-graphene oxide composite film

The graphene oxide (GO) nanosheets were produced by chemical conversion of graphite, and were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR). An electrochemical sensor based on Ni/graphene (GR) composite film was developed by incorporating Ni²⁺ into the graphene oxide film modified glassy carbon electrode (Ni/GO/GCE) through the electrostatic interactions with negatively charged graphene oxide. The Ni²⁺/graphene modified glassy carbon electrode (Ni/GR/GCE) was prepared by cyclic voltammetric scanning of Ni/GO/GCE in the potential range from ?1.5 to 0.2 V at 50 mV s^?1 for 5 cycles. The electrochemical activity of Ni/GR/GCE was illustrated in 0.10 M NaOH using cyclic voltammetry. The Ni/GR/GCE exhibits the characteristic of improved reversibility and enhanced current responses of the Ni(III)/Ni(II) couple. The introduction of conductive graphene not only greatly facilitates the electron transfer of Ni²⁺, but also dramatically improves the long-term stability of the sensor by providing the electrostatic interactions. Ni/GR/GCE also shows good electrocatalytic activity toward the oxidation of glucose. The Ni/GR/GCE gives a good linear range over 10 to 2700 μM with a detection limit of 5 μM towards the determination of glucose by amperometry. This sensor keeps over 85% activity towards 0.1 mM glucose after being stored in air for a month, respectively. Furthermore, the modified sensor was successfully applied to the sensitive determination of glucose in blood samples.     

Methanol sensor based on the combined electrocatalytic oxidative effect of chitosan-immobilized nickel(II) and the antibiotic cefixime on the oxidation of methanol in alkaline medium

A sensor for methanol was fabricated by incorporating the antibiotic cefixime (CEF) along with Ni(II) ion into a chitosan membrane matrix. Sensing is based on the electrocatalytic effect that the complex membrane exerts on the electro-oxidation of methanol. The resulting CEF-Ni(II)/chitosan glassy carbon (GC) electrode had a good electrocatalytic activity to the electro-oxidation of methanol in alkaline medium. The modified electrode had an immense electrocatalytic activity on the second process of methanol oxidation (methanol oxidation intermediate(s) to the final product). The modified electrode had a wide linear range from 20 μM to 12 mM for the determination of methanol in alkaline medium, and a detection limit of 5.24 μM based on a signal-to-noise ratio of 3. In addition, the sensor exhibited good stability.