Journal of Electrochemistry

Electrochemical and Spectroscopic Studies of Ethanol Oxidation on Nano-Cubic Pt Modified by Tin Adatoms

RAO Lu, ZHANG Bin-wei, LI Yan-yan, JIANG Yan-xia*, SUN Shi-gang

2014, 20(5): 395-400. doi:10.13208/j.electrochem.131177

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The nano-cubic Pt modified by tin (Sn) was synthesized and used to investigate the role of this adatom played in the ethanol oxidation. The onset potential of ethanol oxidation was significantly shifted negatively which can be forward about 300 mV when the coverage of Sn (θSn)was 0.9. The electrtochemical in situ FTIR result demonstrated that the amount of CO2 increased first, and then decreased with θSn increased, and reached the maximun when θSn was 0.38. Furthermore, the formation of acetic acid could be observed at very low potential (-0.05 V) after modifying Sn adatom, and the amount of acetic acid increased with θSn increased. That is, Sn deposited on Pt surfaces has a double effect on the ethanol oxidation. First, it facilitates the oxidation of CO coming from the cleavage of the C—C bond in ethanol by a bifunctiontal mechanism. Second, the Pt–Sn ensemble catalyzes the oxidation of ethanol to acetic acid. This means that the main product in the oxidation of ethanol for the Pt–Sn system should be acetic acid unless the Pt surface structure has some special sites able to break the C—C bond.

Boosting Electrocatalytic Activity of Nitrogen-Doped Graphene/Carbon Nanotube Composite for Oxygen Reduction Reaction

ZHANG Yun, HU Jin-song*, JIANG Wen-jie, GUO Lin, WEI Zi-dong*, WAN Li-jun

2014, 20(5): 401-409. doi:10.13208/j.electrochem.131178

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Bimetallic PtRu nanotubes array electrodes (NTAEs) with varied Pt to Ru atomic ratios have been prepared by electrochemical codeposition in 3-aminopropyltri-methoxysilane modified porous anodic alumina (PAA) membranes. The structure and morphology of the catalysts were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Electrochemical results showed that the NTAEs with varied atomic ratios could be achieved by controlling the precursor concentration for deposition. The prepared nanoarrays composed of Pt or PtRu alloy promoted the mass-normalized activity toward the sluggish electrooxidation reaction of methanol due to the increased catalytic activity and real surface area, as well as the improved mass transport through the catalysts. Correlations between the anode composition and the electrocatalytic activity of the catalysts toward the electrooxidations of CO and CH₃OH were systemically investigated. The PtRu NTAEs containing ca. 50% Ru showed the highest activity for CO electrooxidation, while the PtRu NATEs of 40% Ru for CH₃OH electrooxidation.

Recent Progress in Heteroatoms Doped Carbon Materials as a Catalyst for Oxygen Reduction Reaction

DING Wei, ZHANG Xue, LI Li, WEI Zi-dong*

2014, 20(5): 426-438. doi:10.13208/j.electrochem.131179

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Developing catalytic materials for oxygen reduction reactions (ORR) with high performance and low cost has been one of the major challenges for large-scale applications of fuel cells. In this review, we summarize the recent progress in the heteroatoms doped carbon materials as a catalyst for the catalysis of ORR, with an emphasis on the universal origin of their catalytic mechanisms. The future prospects of the metal-free catalyst were to find precisely controlled doping methods, to explore the role of heteroatoms in the catalysis, and to generate more active catalysts with suitable nanostructure.

Electrochemistry of Glucose Oxidase Modified on Porin-Phospholipid Biomimic Membrane

WANG Kun-qi, ZHANG Zuo-ming*, XING Wei*, LIU Chang-peng, ZHOU Xing

2014, 20(5): 439-443. doi:10.13208/j.electrochem.131176

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Biomimic membrane with nano-channels, which is made up of porin MspA and 1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) is constructed on glassy carbon substrate, and glucose oxidase (GOD) is modified on it. The direct electrochemical reaction and electrocatalytic behavior to oxygen and glucose of GOD on the GOD/MspA-DMPC/GC electreode are expounded by the cyclic voltammetric method. The study shows that GOD immobilized on porin MspA and DMPC biomimic membrane displays direct and surface-controlled electrochemical reaction nearby formal potential (E0′) of the flavoprotein active centre (FAD/FADH), and the electrochemical reaction contains two electrons and two protons exchange in 0.1 mmol?L^-1 phosphate buffer solution (PBS) (pH 7.0). Furthermore, it is also discovered that, GOD immobilized on porin MspA and DMPC biomimic membrane possesses an excellent bioelectrocatalytic activity for the reduction of O₂ and the oxidation of glucose. That is to say, the biomimic nano-channels membrane formed by porin MspA and DMPC provides an ideal living environment for GOD. So, the GOD/MspA-DMPC/GC electrode can be utilized in biosensor and biofuel cell in the future.

On the Origin of the Errors of i_k as Estimated from K-L Equation in Rotating Disk Electrode System

CHEN Wei，LIAO Ling-wen，HE Zheng-da，CHEN Yan-xia*

2014, 20(5): 444-451. doi:10.13208/j.electrochem.131167

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Rotating disk electrode system is mainly used to study the kinetics of reactions whose reactants have very low solubility in the electrolyte. For an irreversible reaction, Koutecky-Levich equation (K-L Eq.) is frequently used to deduce the kinetic current i_k). Since K-L Eq. is derived based on the assumption that a system should conform the steady-state diffusion conditions, the data recoded from the actual system which deviates from such a condition, great error may be induced for the i_k estimated. In this work, polarization curves for oxygen reduction reaction at polycrystalline Pt electrode recorded in solutions with various O₂ concentrations and under various electrode rotation speeds have been analyzed systematically. Our analysis reveals that an error of 30% may be introduced by extrapolation to infinite rotation speed in solution with low O₂ concentration or by including the data recorded under very slow electrode rotation speeds. The origins of the error and the ways to avoid such error are discussed.

Fabrication of Pattern of Graphene Oxide and Au Nanoparticles by Microcontanct Printing Technique

PANG Wen-hui, XIAO Xiao-jian, YE Meng-wei, DENG Kai-chao, TANG Jing*

2014, 20(5): 452-458. doi:10.13208/j.electrochem.131175

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Graphene oxide (GO) was prepared by modified Hummers method. Using the GO solution as "ink", Au nanoparticles (AuNPs) and GO were transferred to the surface of ITO substrate modified with (3-aminopropyl) triethoxysilane (APTES/ITO) in a sequence. The transferred AuNPs and GO could form a uniform and dense composite pattern which was characterized by FE-SEM and AFM. Moreover, using the APTES/ITO substrate surface potential as zero, the sequences of the surface potential were APTES>GO>Au.

Preparation of Pt/DNA-MWCNTs/GC Electrode and Its Electrocatalytic Activity toward H₂O₂ Reduction

FAN Li-li, WU Li-na, QU Zhi-yu, LIU Dan-feng, ZHANG Jun-ming, FAN Si-ming, FAN You-jun*

2014, 20(5): 459-464. doi:10.13208/j.electrochem.131165

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The DNA-multi-walled carbon nanotubes (MWCNTs)/glassy carbon (GC) electrode was prepared by modifying the DNA functionalized MWCNTs composite on a GC electrode. A novel non-enzymatic H₂O₂ sensing electrode was fabricated by electrodepositing Pt nanoparticles on the DNA-MWCNTs/GC electrode. The modified electrodes were characterized by scanning electron microscope (SEM). The response properties of the sensing electrode to H₂O₂were investigated by cyclic voltammetry and chronoamperometry. The results indicated that the sensing electrode exhibited a good linear relationship between response current and H₂O₂concentration in the range of 0.04 ~ 18.07 mmol·L^-1 with a detection limit of 3.85 μmol·L^-1 (S/N = 3), as well as excellent reproducibility, stability and selectivity.

Effect of Imidazole Ionic Liquids on the Electro-Oxidation of p-Methoxy Toluene

CHEN Qiong, ZHU Ying-hong, ZHU Ying, LI Yan-fang, MA Chun-an*

2014, 20(5): 465-469. doi:10.13208/j.electrochem.131029

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The interactions between four Imidazole ionic liquids (EMIMBF₄, BMIMBF₄, BMIMHSO₄, BMIMAc) and p-methoxy toluene were investigated by ultraviolet spectroscopy. The red shifts of absorption peak were obviously observed, and the fine structures of the spectroscopy were disappeared on the long wave district. p-MT producing stable excited state was benefit from the interaction with solvent molecules. The electro-oxidation behavious of p-MT were studied in the four ILs on platinum electrode by cyclic voltammetry (CV) and chronoamperometry (CP), and the diffusion coefficients (D) and activation energies (ED) were calculated. The results indicated that the electro-oxidation process of p-MT was irreversible and controlled by diffusion. The diffusion coefficient of p-MT and the selectivity of electrolytic product were maximum in EMIMBF4 compared to other ionic liquids.

Fabrication and Characterization of the Ni-ScSZ Composite Anodes with a Cu-LSCM-CeO₂ Catalyst Layer in the Thin Film SOFC

LV Yao, HUANG Bo*, GU Xi-zhi, HOU Chun-yi, HU Yi-xing, WANG Xiao-yin, ZHU Xin-jian

2014, 20(5): 470-475. doi:10.13208/j.electrochem.131129

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Solid oxide fuel cell (SOFC) directly operating on hydrocarbon without external reforming has the potential of greatly speeding up the application of SOFCs for transportation. In this paper, a three-layer structure anode was fabricated by tape casting and screen printing method. The addition of Cu-LSCM-CeO₂ to the supported anode surface presented better performance running on H₂ and ethanol. The maximum power densities were 511 and 390 mW?cm^-2, respectively, running on H₂ and ethanol at 750 °C. No significant degradation was observed on the anode. Consequently, the Cu-LSCM-CeO₂ catalyst layer on the surface of the LSCM-YSZ support layer makes it possible to have good stability for long-term operation in ethanol fuel due to free carbon deposition.

Review of Carbon Materials Energy Storage Mechanism in Lead-Carbon Battery

WANG Le-ying, ZHANG Hao*, HU Chen, ZHANG Shu-kai, ZHAO Hai-lei, CAO Gao-ping, ZHANG Wen-feng, YANG Yu-sheng, LAI Xiao-kang

2014, 20(5): 476-481. doi:10.13208/j.electrochem.131209

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The traditional lead-acid batteries are mainly used for automobile and various internal combustion engine starting, wireless communication base stations and renewable energy storage; however, their negative plates are easily sulfated under partial-state-of-charge duty, then their charging capacity and cycle life are greatly reduced. Lead-carbon battery is a new type of lead-acid battery, in which a carbon material with high specific surface area and conductivity is added into a negative plate, and has excellent rate discharge performance and higher PSoC cycle life. Lead-carbon battery has a good application prospect in energy storage and hybrid electric vehicle, so these years the study of the mechanism of carbon materials in lead-carbon battery becomes a hot research topic. This paper reviewed the recent progresses in research on the mechanisms of carbon materials in lead-carbon batteries, mainly focused on the construction of conductive network, double-layer capacitance storage, improvement of pore structure, increase of electrochemical reaction dynamics and other aspects, as well as the research work of our group in Pb-C batteries.

Determination of Folic Acid by Composite Film Electrode Modified with Poly-Alizarin Red and Multi-walled Carbon Nanotubes

DU Xue-ping, LOU Tong-fang, DONG Ying, QU Jian-ying*

2014, 20(5): 482-485. doi:10.13208/j.electrochem.131105

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The novel modified electrode was fabricated by electropolymerizing alizarin red onto the surface of multi-walled carbon nanotubes on glassy carbon electrode surface, which exhibited good electrocatalytic activity for folic acid. The experimental results showed that the reduction peak current of folic acid at -0.63 V was linear to its concentration over the range of 1.25×10^-6 ~ 4.00×10^-5 mol·L^-1 in the optimized experimental conditions (R = 0.9985). Test for recovery was carried out by standard addition method, and the recovery ratios were in the range of 92.0% ~ 102.0%. The modified electrode was prepared simply with excellent stability, which provides a new feasible method for determination of folic acid.

Preparation and Electrochemical Behavior of PbO/GN/AC

GAO Yun-fang*, WANG Yan-ping, YAO Qiu-shi, WANG Fu-hua, REN Dong-lei, XU Xin

2014, 20(5): 486-492. doi:10.13208/j.electrochem.131227

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The lead oxide/graphene/activated carbon (PbO/GN/AC) composite materials were prepared by impregnating commercial activated carbon and graphene in saturated lead nitrate solution followed by calcination. The structures and morphologies of the composite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that PbO crystals (about 200 nm) were dispersed uniformly on the surface of activated carbon and graphene. Electrochemical data indicate that the composite exhibited good electrochemical performances. The PbO/GN/AC composite possessed the higher over-potential of hydrogen evolution and the high specific capacitance of 312.6 F·g^-1, while the internal resistance was 1.56 Ω. The composite electrode also displayed excellent cycling stability, retaining over 92.6% of its initial charge after 6000 cycles. The ultra-battery with 5% (by mass) PbO/GN/AC being added to the negative paste had a cycle life approximately 3.5 times longer than conventional lead-acid batteries.

Electro-Catalytic Properties of β-PbO₂/Sb-SnO₂/Ti Electrode on Phenol Oxidation

LI Peng; ZHAO Yue-min, WANG Li-zhang*, ZHANG Yan-le, LU Zhao-qing

2014, 20(5): 493-498. doi:10.13208/j.electrochem.131021

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The combination technology of brush pyrolysis and electroplating was employed in the preparation of β-PbO₂/Sb-SnO₂/Ti electrode. X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) results showed that the Sb-SnO₂ as an interlayer would restrain the formation of lead fluoride and the crystallization degree on the electrode surface could be as high as 100%. The grain size was calculated by Scherrer formula to be 25.2 nm and the agglomeration of lead dioxide was effectively eliminated. The potential span of diffusion control phase, oxygen evolution potential, Tafel slope for the β-PbO₂/Sb-SnO₂/Ti electrode during the polarization were 1.85 ~ 2.15 V, 2.08 V and 0.84, respectively, which exhibited much better electrochemical properties as compared with those of the β-PbO₂/Ti electrode with the values of 1.40 ~ 1.80 V, 1.75 V and 0.36, respectively. Furthermore, the β-PbO₂/Sb-SnO₂/Ti and β-PbO₂/Ti electrodes were taken as anodes participating in the electrocatalysis degradation of phenol simulated wastewater under current density 9 mA·cm^-2 within 240 min. Experimental results revealed that the efficiencies of chemical oxygen demand (COD) removal and instant current efficiency (ICE) during phenol degradation were 90.1% and 63.28% for the β-PbO₂/Sb-SnO₂/Ti electrode, while 66.9% and 44.96% for the β-PbO₂/Ti electrode. Ultimately, the accelerated life test was performed to evaluate the service time of β-PbO₂/Sb-SnO₂/Ti. The results presented that the industrial life of β-PbO₂/Sb-SnO₂/Ti was 8.6a, which is 10 times longer than that of β-PbO₂/Ti,suggesting that β-PbO₂/Sb-SnO₂/Ti would have a relatively high engineering application value.

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