Electrocatalytic activity of binary Palladium Ruthenium anode catalyst on Ni-support for ethanol alkaline fuel cells

In search for a cheaper anode catalyst for the oxidation of ethanol for development of direct alcohol fuel cells, Pd has been considered here as an interesting substitute for Pt in Pt Ru binary electrodeposite. The binary catalyst when co-deposited on nickel support has been found to increase the current density and decrease the anodic overvoltage significantly with respect to pure Pt, Pd and Ni. Its electrocatalytic capability is also comparable with that of the Pt-Ru binary electrocatalyst on Ni-support, when studied in 1 M EtOH containing 1 M NaOH solution. The effect of loading of Pd Ru electrocatalyst on Ni support has also been tested. The electrocatalytic activity of the electrodes for oxidation of ethanol has been explained by studies of cyclic voltammetry, chronopotentiometry, steady-state polarization, and conjugated scanning electron microscopy–energy dispersion X-ray spectroscopy. It has been found that electrode containing the higher amount of deposit are less affected by carbonaceous poisons.     

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.     

Hollow carbon spheres with wide size distribution as anode catalyst support for direct methanol fuel cells

Hollow carbonaceous composites (HCCs) possessing sphere and hemisphere shape, which had wide size distribution between several tens of nanometers and several micrometers, were prepared through a facile hydrothermal method using glucose as carbon source with the assistance of sodium dodecyl sulfate (SDS). Pyrolysis of these hollow carbonaceous composites at 900 °C under nitrogen flow produced carbonized hollow carbon spheres (HCSs) without changing their structures. Platinum (Pt) was directly deposited on the surface of the HCSs by incipient wet method, using the NaBH₄ as the reductant. TEM, SEM, powder XRD and FT-IR were utilized to characterize all these samples. It was found that Pt nanoparticles were uniformly anchored on the outer and the inner surface of HCSs. The electrocatalytic properties of the Pt/HCS electrode for methanol oxidation have been investigated through cyclic voltammetry and chronoamperometry. The Pt/HCS electrode showed significantly higher electrocatalytic activity and more stability for methanol oxidation compared with Pt supported carbon microspheres (Pt/CMs) and commercial carbon (Pt/XC-72) electrode. The excellent performance for the Pt/HCS might be attributed to the high dispersion of platinum catalysts and the particular hollow structure of HCSs.     

Performance study of palladium modified platinum anode in direct ethanol fuel cells: A green power source

The direct ethanol fuel cell is a green and renewable power source alternative to fossil fuels and produces less emissions compared to a combustion engine. Ethanol can be generated in great quantity from renewable resources like biomass through a fermentation process. Bio-generated ethanol is thus attractive fuel since growing crops for biofuels absorbs much of the carbon dioxide emitted into the atmosphere from the oxidation of ethanol. The platinum and palladium were co-deposited on graphite substrate by the galvanostatic technique and employed as anode catalyst for ethanol electrooxidation. The information on surface morphology, structural characteristics and bulk composition of the catalyst was obtained using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) spectroscopy. The cyclic voltammetry (CV) were used for the estimation of the electrochemically active surface area (ECSA) of the synthesized catalysts in alkaline medium. The CVs for ethanol oxidation revealed superior catalytic activity of Pt–Pd/C compared to Pd/C and Pt/C. The effect of OH^? on ethanol oxidation at Pt–Pd/C catalyst was studied using cyclic voltammetry, quasisteady-state polarization, chronoamperometry, and electrochemical impedance spectroscopy (EIS). The Pt–Pd/C catalyst shows good stability and enhanced electrocatalytic activity is ascribed to the synergistic effect of higher electrochemical surface area, preferred OH^? adsorption on the surface and palladium ad-atom contribution on the alloyed surface.     

Preparation and characterization of long-lived anode catalyst for direct methanol fuel cells

Entry of direct methanol fuel cells into the market requires anode catalyst with stable activity. This paper presents a novel method for stabilizing the activity by immobilizing silica on the catalytic PtRu nanoparticles. Characterization was performed by STEM-EDX, XRD, and ICP. The silica-immobilized PtRu nanoparticles showed high and stable activity toward methanol oxidation. The activity was maintained for 1000 h in sulfuric acidic solution, while the activity of the catalyst with "bare" PtRu nanoparticles decayed after 100 h, showing high durability of the silica-immobilized PtRu nanoparticles catalyst in quasi-anodic acidic environment.     

Synthesis and electrocatalytic performance of La0.3Ce0.1Sr0.5Ba0.1TiO3 anode catalyst for solid oxide fuel cells

Ce-doped La_0.4Sr_0.5Ba_0.1TiO_3–δ (LCSBT) perovskite anode catalysts in solid oxide fuel cells were successfully synthesized by a modified rheological phase reaction for the first time. Pure LCSBT could be obtained under a reducing atmosphere and nano-CeO₂ particles could be exsoluted from LCSBT after being sintered in air. The catalytic activity and electrochemical performance of LCSBT anodes for the H₂ oxidation were obviously improved comparing with the pure La_0.4Sr_0.5Ba_0.1TiO_3–δ (LSBT) and LSBT&CeO₂ admixture anodes. The improved performance could be attributed to the nanostructure of LCSBT and the exsoluted nano-CeO₂ particles.     

Mn-N-C催化剂的制备及其在碱性介质中对氧还原反应的电催化性能

选用壳聚糖(CS)为原料制备了壳聚糖水杨醛席夫碱锰配合物(Mn-CS-sal)。将Mn-CS-sal配合物负载于石墨碳上得到碳载配合物(Mn-CS-sal/C),后经高温热处理得到Mn-N-C目标催化剂(Mn-N-C-t,t=200、400、600、800、1 000℃)。采用FT-IR、XRD、XPS和电化学等方法对催化剂的组成和结构进行了表征,对其在氧还原反应中的电催化性能进行了研究。结果表明,所得到的Mn-N-C催化剂对氧还原反应(ORR)具有很好的催化作用,但以600℃热处理制备的催化剂其活性最好。催化剂中Mn-N-C结构是催化ORR的活性位。采用循环伏安法获得了Mn-N-C-t催化ORR的动力学参数,即总的转移电子数n和电子传递系数αnα;具有最佳活性的Mn-N-C-600催化剂的总转移电子数为3.63,说明在此条件下,Mn-N-C-600催化ORR主要以4e转移途径为主,由此提出了可能的氧还原反应的机理。     

新型碳纤维负载直接乙醇燃料电池Pt-SnO_2阳极催化剂的性能研究

采用静电纺丝技术制备了碳纤维基纳米Pt-SnO2阳极催化剂(Pt/Sn原子比为3)。通过X射线衍射(XRD)、红外光谱(FT-IR)、扫描电子显微镜(SEM)等技术对该催化剂进行了表征,并采用循环伏安法对其在乙醇燃料电池中的阳极催化活性进行了评价。结果表明,纳米Pt-SnO2催化剂均匀地分散在碳纤维骨架上;随着烧结温度的升高,碳纤维载体的致密度越高、导电性能越好。电催化性能测试表明,烧结温度为800℃时催化剂的峰电流密度最大,达到0.11 A/cm2,抗中毒能力也最强。单电池的发电性能表明,在一定的乙醇浓度下,1.0 mL/min进样流速具有最优的发电效率。     

Synthesis and electrocatalytic activity of Au/Pt bimetallic nanodendrites for ethanol oxidation in alkaline medium

Gold/Platinum (Au/Pt) bimetallic nanodendrites were successfully synthesized through seeded growth method using preformed Au nanodendrites as seeds and ascorbic acid as reductant. Cyclic voltammograms (CVs) of a series of Au/Pt nanodendrites modified electrodes in 1M KOH solution containing 1M ethanol showed that the electrocatalyst with a molar ratio (Au:Pt) of 3 exhibited the highest peak current density and the lowest onset potential. The peak current density of ethanol electro-oxidation on the Au(3)Pt(1) nanodendrites modified glassy carbon electrode (Au(3)Pt(1) electrode) is about 16, 12.5, and 4.5 times higher than those on the polycrystalline Pt electrode, polycrystalline Au electrode, and Au nanodendrites modified glassy carbon electrode (Au dendrites electrode), respectively. The oxidation peak potential of ethanol electro-oxidation on the Au(3)Pt(1) electrode is about 299 and 276 mV lower than those on the polycrystalline Au electrode and Au dendrites electrode, respectively. These results demonstrated that the Au/Pt bimetallic nanodendrites may find potential application in alkaline direct ethanol fuel cells (ADEFCs).     

Adsorption of ethanol on the modified ruthenium catalysts in alkaline media

Regularities of ethanol adsorption in alkaline medium on the surface of the monoruthenium Ru/C catalyst and systems promoted by nickel and vanadium oxides, Ru-VO _x /C and Ru-NiO _x /C, were studied by non-stationary voltammetry techniques. An analysis of the kinetic and concentration dependences of adsorption showed that an increase in the content of the promoting component in the bimetallic systems enhances the energy heterogeneity of the catalyst surface. The data on adsorption measurements were compared with the results of previous studies of the kinetics and depth of ethanol electrooxidation on the examined catalysts. The larger quantity of electricity consumed for the oxidation of adsorbed particles formed on the surface of the metallooxide systems corresponds to higher extents of electrooxidation and rate than those for the monoruthenium catalyst.     

活性炭和石墨混合载体的Pt催化剂(Pt/CG)对乙醇氧化电催化活性的影响

用化学沉积法制备炭载Pt(Pt/C)和以活性炭与石墨作混合载体的Pt(Pt/CG)催化剂。实验结果表明,活性炭与石墨质量比影响Pt/CG催化剂对乙醇氧化的电催化活性。当活性炭与石墨的质量比为15∶1时,制得的Pt/CG催化剂对乙醇氧化的电催化活性最高。     

碳纤维基PtPb阳极催化剂的制备及其电催化性能

以静电纺丝技术与烧结工艺相结合的方式制备了碳纤维基PtPb纳米催化剂,并采用X射线衍射（XRD）、红外光谱（FT-IR）、扫描电镜（SEM）等分析测试手段对其进行了表征。结果表明,在预氧化温度为300 ℃、碳化温度为800 ℃的条件下,所制备的PtPb阳极纳米催化剂结晶程度好、比表面积大,粒径约为3.05 nm,催化活性颗粒均匀分散在多孔碳纤维骨架上。采用循环伏安法（CV）及交流阻抗（EIS）评价了该催化剂对乙醇氧化反应的电催化性能。结果表明,最大峰电流密度达到125 mA/cm²,电荷转移电阻相较于700 ℃下降了近60%。     

Controllable pt nanoparticle deposition on carbon nanotubes as an anode catalyst for direct methanol fuel cells

We report a novel process to prepare well-dispersed Pt nanoparticles on CNTs. Pt nanoparticles, which were modified by the organic molecule triphenylphosphine, were deposited on multiwalled carbon nanotubes by the organic molecule, which acts as a cross linker. By manipulating the relative ratio of Pt nanoparticles and multiwalled carbon nanotubes in solution, Pt/CNT composites with different Pt content were achieved. The so-prepared Pt/CNT composite materials show higher electrocatalytic activity and better tolerance to poisoning species in methanol oxidation than the commercial E-TEK catalyst, which can be ascribed to the high dispersion of Pt nanoparticles on the multiwalled carbon nanotube surface.     

Carbon nanotubes as efficient catalyst supports for fuel cells with direct ethanol oxidation

Several carbon materials, namely, single-walled nanotubes (CNT1), two-walled nanotubes (CNT2), multiwalled nanotubes (CNT3), and nanofibers (CNF) are synthesized by methane pyrolysis. The resulting nanomaterials are characterized by physical (BET) and electrochemical (charging curves) methods. A catalyst of ethanol electrooxidation PtSn (3: 1, 40 wt % Pt) that involves the mentioned nanomaterials as the supports is synthesized. The catalyst formed on two-walled nanotubes demonstrates the highest activity in ethanol oxidation under model conditions. X-ray diffraction analysis is used in studying the PtSn (3: 1, 40 wt % Pt)/CNT2 catalyst structure. The attained depth of ethanol oxidation is determined by the gas-liquid chromatography. Tests of an ethanol-oxygen fuel cell (FC) with the anodic active layer (AL) based on this catalyst are carried out.     

Steam activation of Fe-N-C catalyst for advanced power performance of alkaline hydrazine fuel cells

Alkaline hydrazine liquid fuel cells(AHFC) have been highlighted in terms of high power performance with non-precious metal catalysts.Although Fe-N-C is a promising non-Pt electrocatalyst for oxygen reduction reaction(ORR),the surface density of the active site is very low and the catalyst layer should be thick to acquire the necessary number of catalytic active sites.With this thick catalyst layer,it is important to have an optimum pore structure for effective reactant conveyance to active site...     

Synthesis and electrocatalytic activity of palladium nanoparticles on porous silicon

Palladium was combined with porous silicon into catalytically active functional electrode nanocomposites. Palladium nanoparticles were examined by transmission electron microscopy and atomic force microscopy; their catalytic activity was estimated using cyclic voltammetry.     

碳纤维基PtSn催化剂直接乙醇燃料电池制备及性能研究

采用自制的碳纤维基PtSn催化剂薄膜作为阳极催化剂,商用Pt/C作为阴极催化剂,Nafion 115膜作为质子交换膜,通过热压制成膜电极,组装平板型直接乙醇燃料单电池,搭建测试系统并进行性能的测试,研究了温度、乙醇浓度、溶液流量、进气流量等参数对DEFC的影响。结果表明,当乙醇溶液浓度为1.0 mol/L、溶液进样流量为1.0 mL/min、溶液温度为80 ℃、氧气进样流量为100 mL/min时结果较优,单电池的最高功率密度达18.2 mW/cm²。     

FexC–C hybrid material as a support for Pt anode catalyst in direct formic acid fuel cell

Fe_xC–C hybrid material as a support for Pt anode catalyst in direct formic acid fuel cell was investigated for the first time. The resultant Pt/Fe_xC–C catalysts were prepared by using a simple reduction reaction to load Pt on Fe_xC–C hybrid material, which was synthesized through the carbonization of sucrose and Fe(NO₃)₃. It was found that the Pt/Fe_xC–C catalysts exhibited excellent catalytic activity for formic acid electrooxidation. The great improvement in the catalytic performance is attributed to the fact that Fe_xC–C hybrid material ameliorated the tolerance to CO adsorption of Pt and facilitated the uniform dispersion of Pt.     

Partially unzipped carbon nanotubes as a superior catalyst support for PEM fuel cells

Partially unzipped carbon nanotubes prepared by strong oxidation and thermal expansion of carbon nanotubes were explored as an advanced catalyst support for PEM fuel cells. The unique hybrid structure of 1D nanotube and 2D double-side graphene resulted in an outstanding electrocatalytic performance.     

Influence of bi modification of pt anode catalyst in direct formic acid fuel cells

The influence of Bi modification of Pt anode catalyst on the performance of direct formic acid fuel cells was investigated. Compared with the unmodified Pt anode, the Bi modified Pt (PtBi(m)) electrode prepared by under-potential deposition (UPD) caused faster electrocatalytic oxidation of formic acid at the same value of the overpotential, and thus, PtBi(m) resulted in an increase in the power performance of direct formic acid fuel cells. Electrochemical impedance spectra helped to explain the difference of performance between the unmodified Pt and Bi modified Pt electrodes. Solution conductivity and dehydration phenomena occurring in highly concentrated formic acid solutions can also explain the higher power performance of PtBi(m).