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Abstract: This study focused on manganese oxides with a cryptomelane-type octahedral molecular sieve (OMS-2) structure to replace platinum as a cathode catalyst in microbial fuel cells (MFCs). Undoped (ud-OSM-2) and three catalysts doped with cobalt (Co-OMS-2), copper (Cu-OMS-2), and cerium (Ce-OMS-2) to enhance their catalytic performances were investigated. The novel OMS-2 cathodes were examined in granular activated carbon MFC (GACMFC) with sodium acetate as the anode reagent and oxygen in air as the cathode reagent. The results showed that after 400h of operation, the Co-OMS-2 and Cu-OMS-2 exhibited good catalytic performance in an oxygen reduction reaction (ORR). The voltage of the Co-OMS-2 GACMFC was 217mV, and the power density was 180mWm−2. The voltage of the Cu-OMS-2 GACMFC was 214mV and the power density was 165mWm−2. The internal resistance (R in) of the OMS-2 GACMFCs (18±1Ω) was similar to that of the platinum GACMFCs (17Ω). Furthermore, the degradation rates of organic substrates in the OMS-2 GACMFCs were twice those in the platinum GACMFCs, which enhance their wastewater treatment efficiencies. This study indicated that using OMS-2 manganese oxides to replace platinum as a cathodic catalyst enhances power generation, increases contaminant removal, and substantially reduces the cost of MFCs. [Copyright &y& Elsevier]

Abstract: A solution-phase synthesis method was studied to prepare carbon supported Pt-Co alloy catalysts. The organic precursors of Pt acetylacetonate and Co acetylacetonate were reduced in a high boiling point solvent of octyl ether in the presence of oleic acid (OAc) and oleylamine (OAm) to produce fine Pt-Co nanoparticles, which were subsequently deposited on carbon support to obtain Pt-Co/C catalysts. Thermogravimetric analysis suggests that the stabilizers (OAc and OAm) can be removed by copious ethanol washing and subsequent moderate temperature heat-treatment (250°C, under Argon atmosphere). X-ray diffraction patterns indicate that the average particle size is around 2.3nm, and the lattice parameter is 3.868Å for the heat-treated Pt-Co/C (40wt%). Transmission electron microscopy images show very small Pt-Co alloy nanoparticles homogeneously dispersed on the carbon support with a particle size distribution of 2–4nm for all Pt-Co/C samples. The elements composition of Pt and Co in the final Pt-Co/C catalyst can be well controlled, as evidenced by inductively coupled plasma atomic emission spectroscopy and energy dispersive spectroscopy analyses. Proton exchange membrane fuel cell tests show the heat-treated Pt-Co/C cathode catalyst has higher mass activity of oxygen reduction reaction than Pt/C at an operation voltage of 0.9V, this can be attributed to its smaller particle size and reduced lattice parameter. [Copyright &y& Elsevier]

Abstract: A series of Se-modified Ru/C (Se–Ru/C) samples were prepared from a carbon-supported ruthenium precursor. Selenium was incorporated by two different methods; in the first case, Se was incorporated by treating the Ru/C precursor in a selenious acid solution followed by reduction in H2 atmosphere. In the second case, Se was incorporated to Ru/C by means of thermal treatment in a selenium atmosphere. The samples thus obtained were characterized by different techniques: X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. A detailed study has been made of the structural properties and chemical composition of the different Se–Ru/C samples. Microscopy results reveal that Se is incorporated homogeneously, being preferentially located on the surface of the Ru atoms. These results agree well with XRD and XPS data. The incorporation of Se in the lattice results in the formation of RuSe2 only if RuO2 already exists. On the contrary, if Ru is in its metallic form, Se remains as an amorphous layer located on the surface of the Ru particles. The performance of the catalysts on the oxygen reduction reaction was evaluated either in the absence and presence of methanol. Se-containing samples develop more active and methanol tolerant catalysts, particularly when Se is located on the surface of the Ru particles. [Copyright &y& Elsevier]

Abstract: Even though the measured open-circuit voltage in a H2–O2 PEM fuel cell is invariably about 200–250mV lower than that predicted from thermodynamics (1.229V at 25°C), there is no unequivocal explanation of this phenomenon available in the literature, although several hypotheses exist. Based on a theoretical model of mixed potential with a priori parameters, it is shown here that this voltage loss under open-circuit conditions can be attributed exclusively to hydrogen crossover and the resulting oxygen reduction reaction overpotential at the cathode. The analytical model predictions agree well with available experimental results. [Copyright &y& Elsevier]

Abstract: We report a durable electrocatalyst support, highly graphitized mesoporous carbon (GMPC), for oxygen reduction in polymer electrolyte membrane (PEM) fuel cells. GMPC is prepared through graphitizing the self-assembled soft-template mesoporous carbon (MPC) under high temperature. Heat-treatment at 2800°C greatly improves the degree of graphitization while most of the mesoporous structures and the specific surface area of MPC are retained. GMPC is then noncovalently functionalized with poly(diallyldimethylammonium chloride) (PDDA) and loaded with Pt nanoparticles by reducing Pt precursor (H2PtCl6) in ethylene glycol. Pt nanoparticles of ∼3.0nm in diameter are uniformly dispersed on GMPC. Compared to Pt supported on Vulcan XC-72 carbon black (Pt/XC-72), Pt/GMPC exhibits a higher mass activity towards oxygen reduction reaction (ORR) and the mass activity retention (in percentage) is improved by a factor of ∼2 after 44h accelerated degradation test under the potential step (1.4–0.85V) electrochemical stressing condition which focuses on support corrosion. The enhanced activity and durability of Pt/GMPC are attributed to the graphitic structure of GMPC which is more resistant to corrosion. These findings demonstrate that GMPC is a promising oxygen reduction electrocatalyst support for PEM fuel cells. The approach reported in this work provides a facile, eco-friendly promising strategy for synthesizing stable metal nanoparticles on hydrophobic support materials. [Copyright &y& Elsevier]

Abstract: In this work we studied the electrochemical properties of cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) prepared with nanotubes of La0.6Sr0.4CoO3 (LSCO). Their nanostructures consist of agglomerated nanoparticles in tubular structures of sub-micrometric diameter. The resulting cathodes are highly porous both at the micro- and the nanoscale. This fact increases significantly the access to active sites for the oxygen reduction. We investigated the influence of the diameter of the precursor nanotubes on the polarization resistance of the LSCO cathodes on CeO2–10mol.% Sm2O3 (SDC) electrolytes under air atmosphere, evaluated in symmetrical [LSCO/SDC/LSCO] cells. Our results indicate an optimized performance when the diameter of precursor nanotubes is sufficiently small to become dense nanorods after cathode sintering. We present a phenomenological model that successfully explains the behavior observed and considers that a small starting diameter acts as a barrier that prevents grains growth. This is directly related with the lack of contact points between nanotubes in the precursor, which are the only path for the growth of ceramic grains. We also observed that a conventional sintering process (of 1h at 1000°C with heating and cooling rates of 10°Cmin−1) has to be preferred against a fast firing one (1 or 2min at 1100°C with heating and cooling rates of 100°Cmin−1) in order to reach a higher performance. However, a good adhesion of the cathode can be achieved with both methods. Our results suggest that oxygen vacancy diffusion is enhanced while decreasing LSCO particle size. This indicates that the high performance of our nanostructured cathodes is not only related with the increase of the number of active sites for oxygen reduction but also to the fact that the nanotubes are formed by nanoparticles. [Copyright &y& Elsevier]

Abstract: The carbon-supported Pt-modified Au nanoparticles were prepared by two different chemical reduction processes, the simultaneous chemical reduction of Pt and Au on carbon process (A-AuPt/C) and the successive reduction of Au then Pt (B-AuPt/C) on carbon process. These two catalysts were investigated as the anode catalysts for a direct borohydride fuel cell (DBFC) and Au nanoparticles on carbon (Au/C) were also prepared for comparison. The DBFC with B-AuPt/C as the anode catalyst shows the best anode and fuel cell performance. The maximum power density with the B-AuPt/C catalyst is 112mWcm−2 at 40°C, compared to 97mWcm−2 for A-AuPt/C and 65mWcm−2 for Au/C. In addition, the DBFC with the B-AuPt/C catalyst shows the best fuel utilization with a maximum apparent number of electrons (N app) equal to 6.4 in 1M NaBH4 and 7.2 in 0.5M NaBH4 as compared to the value of N app of 8 for complete utilization of borohydride. [Copyright &y& Elsevier]

Abstract: Carbon-supported Pd–Pt bimetallic nanoparticles of different atomic ratios (Pd–Pt/C) have been prepared by a simple procedure involving the complexing of Pd and Pt species with sodium citrate followed by ethylene glycol reduction. As-prepared Pd–Pt alloy nanoparticles evidence a single-phase fcc disordered structure, and the degree of alloying is found to increase with Pd content. Both X-ray diffraction and transmission electron microscopy characterizations indicate that all the Pd–Pt/C catalysts possess a similar mean particle size of ca. 2.8nm. The highest mass and specific activity of the oxygen reduction reaction (ORR) using the Pd–Pt/C catalysts are found with a Pd:Pt atomic ratio of 1:2. Moreover, all Pd–Pt alloy catalysts exhibit significantly enhanced methanol tolerance during the ORR than the Pt/C catalyst, ensuring a higher ORR performance while diminishing Pt utilization. [Copyright &y& Elsevier]

Abstract: The polyol-reduction method is modified for both high metal loading and high dispersion of particles. The catalysts are post-treated with different atmospheres and temperatures. The post-treatment modifies the morphological and crystallographic structures of the catalysts which influence the methanol oxidation activities. The catalysts are characterized by using X-ray diffraction, transmission electron microscopy, and cyclic voltammetry. The post-treatment induces a change of surface areas and a phase separation of Pt and Ru that modify the surface structures along with the intrinsic and mass-specific activities of methanol oxidation. The activities modified by the post-treatment are investigated by using methanol oxidation at room temperature and at 60°C. Comparison with single-cell performance is conducted, and the results are in accord with those for methanol oxidation at 60°C. All synthesized catalysts exhibit higher single-cell performances than the commercial catalyst. [Copyright &y& Elsevier]

Abstract: Carbon-supported PdNi catalysts for the ethanol oxidation reaction in alkaline direct ethanol fuel cells are successfully synthesized by the simultaneous reduction method using NaBH4 as reductant. X-ray diffraction characterization confirms the formation of the face-centered cubic crystalline Pd and Ni(OH)2 on the carbon powder for the PdNi/C catalysts. Transmission electron microscopy images show that the metal particles are well-dispersed on the carbon powder, while energy-dispersive X-ray spectrometer results indicate the uniform distribution of Ni around Pd. X-ray photoelectron spectroscopy analyses reveal the chemical states of Ni, including metallic Ni, NiO, Ni(OH)2 and NiOOH. Cyclic voltammetry and chronopotentiometry tests demonstrate that the Pd2Ni3/C catalyst exhibits higher activity and stability for the ethanol oxidation reaction in an alkaline medium than does the Pd/C catalyst. Fuel cell performance tests show that the application of Pd2Ni3/C as the anode catalyst of an alkaline direct ethanol fuel cell with an anion-exchange membrane can yield a maximum power density of 90mWcm−2 at 60°C. [Copyright &y& Elsevier]

Abstract: A composite cathode, consisting of Ba(Zr0.1Ce0.7Y0.2)O3−δ (BZCY) and La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF), has shown high catalytic activity toward oxygen reduction, demonstrating a peak power density of 855mWcm−2 at 750°C. The chemical compatibility between BZCY and LSCF is excellent since there was no evidence of chemical reaction between the two after being fired at 1100°C for 10h. The stability of the composite cathode is further shown in single cells operated at 750 and 600°C for 100h without observable degradation in performance. [Copyright &y& Elsevier]

Abstract: A lithium-air battery, in which the catalytic reduction of O2 in an alkaline aqueous electrolyte and the metallic lithium in a non-aqueous electrolyte were subtly united together by a super-ionic conductor glass film (LISICON), was established in the present work. For this system, Mn3O4 based air diffusion electrode and metallic lithium were used as positive electrode and negative electrode, respectively. 500h continuous discharge performance indicates that this kind of lithium-air battery has a potential to realize continuous reduction of O2 from air to deliver energy like a fuel cell. During the long-time discharge process, the air electrode has delivered a special capacity of 50,000mAhg−1 based on total mass of catalytic electrode (carbon+binder+catalyst). This result is much higher than that of previous studies about Lithium-air batteries. [Copyright &y& Elsevier]

Abstract: 5wt.% of platinum (Pt) nanoparticles are highly dispersed on the surface of IrO2 by chemical reduction, and the catalyst is mixed with Pt black to be used as a novel bifunctional oxygen electrocatalyst for the unitized regenerative fuel cell (URFC). The novel cell has been evaluated in the hydrogen and oxygen fuel cell and water electrolysis modes, and compared to a similar cell with an oxygen electrode using conventional mixed Pt black and IrO2 catalyst. With the novel oxygen electrode catalyst, the highest fuel cell power density is 1160mWcm−2 at 2600mAcm−2; the overall performance is close to that with the commercial Pt supported on carbon catalyst and about 1.8 times higher than that with the conventional mixed Pt black and IrO2 catalyst. Additionally, the cell performance for water electrolysis is also slightly improved, which is probably the result of lower interparticle catalyst resistance with 5wt.% Pt on IrO2 compared to no Pt on IrO2. [Copyright &y& Elsevier]

Abstract: Carbon nanotube (CNT)/MnO2 composites are synthesized by reduction of potassium permanganate under microwave irradiation. The morphology and microstructure of samples are examined by scanning electron microscopy (SEM), transition electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Electrochemical properties are characterized by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS). Birnessite-type MnO2 homogeneously coats on the surfaces of CNTs. For CNT–15%MnO2 composite, the specific capacitance based on MnO2 is 944 (85% of the theoretical capacitance) and 522Fg−1 at 1 and 500mVs−1, respectively. When the content of MnO2 reaches 57wt%, the composites have the maximum power density (45.4kWkg−1, the energy density is 25.2Whkg−1). Therefore, CNT/MnO2 composites prepared by microwave irradiation are promising electrode materials in hybrid vehicle systems. [Copyright &y& Elsevier]

Abstract: The performance of the positive electrode composed of a mixture of nickel hydroxide (Ni(OH)2) and a small amount of manganese dioxide (MnO2) was investigated for the positive electrode of Fuel Cell/Battery (FCB) system. It was found that the positive electrode can function not only as an active material of secondary batteries when it is charged but also as a catalyst of fuel cells when oxygen is supplied, which was confirmed by the following characterization: electrochemical characterization was performed with cyclic voltammetry (CV) and galvanostatic discharge curve in oxygen and oxygen-free atmosphere. CV of Ni(OH)2/MnO2 positive electrode exhibited the redox reaction of Ni(OH)2 as well as oxygen reduction reaction. It was observed that the discharge curves of positive electrode had two working potentials in half cell test when the electrode was charged and oxygen was supplied: one from the reactions of nickel oxyhydroxide (NiOOH); the other from the fuel cell reactions of manganese dioxide (MnO2). It was also observed that the discharge curves had two working voltages in full cell test when the cell was fully charged and oxygen was supplied: one at 1.2V from the battery reactions of NiOOH; the other at 0.8V from the fuel cell reactions of MnO2. In particular, the discharge capacity of overcharged cell was improved approximately 2 times compared with a battery of the same electrode quantity due to the additional function of this system as a fuel cell by using oxygen generated by water electrolysis. XRD analysis showed that there was no crystal structure change before and after (over)charge–discharge cycles. In summary, these experimental results showed that the novel bi-functional FCB system could provide an improved overall energy density per weight compared with conventional secondary batteries. [Copyright &y& Elsevier]

Abstract: A core–shell structured low-Pt catalyst, PdPt@Pt/C, with high performance towards both methanol anodic oxidation and oxygen cathodic reduction, as well as in a single hydrogen/air fuel cell, is prepared by a novel two-step colloidal approach. For the anodic oxidation of methanol, the catalyst shows three times higher activity than commercial Tanaka 50wt% Pt/C catalyst; furthermore, the ratio of forward current I f to backward current I b is high up to 1.04, whereas for general platinum catalysts the ratio is only ca. 0.70, indicating that this PdPt@Pt/C catalyst has high activity towards methanol anodic oxidation and good tolerance to the intermediates of methanol oxidation. The catalyst is characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The core–shell structure of the catalyst is revealed by XRD and TEM, and is also supported by underpotential deposition of hydrogen (UPDH). The high performance of the PdPt@Pt/C catalyst may make it a promising and competitive low-Pt catalyst for hydrogen fueled polymer electrolyte membrane fuel cell (PEMFC) or direct methanol fuel cell (DMFC) applications. [Copyright &y& Elsevier]

Abstract: The composite cathode system is examined for suitability on a Ce0.9Gd0.1O2−δ electrolyte based solid oxide fuel cell at intermediate temperatures (500–700°C). The cathode is characterized for electronic conductivity and area specific charge transfer resistance. This cathode system is chosen for its excellent thermal expansion match to the electrolyte, its relatively high conductivity (115Scm−1 at 700°C), and its low activation energy for oxygen reduction (99kJmol−1). It is found that the decrease of sintering temperature of the composite cathode system produces a significant decrease in charge transfer resistances to as low as 0.25Ωcm2. The conductivity of the cathode systems is between 40 and 88Scm−1 for open porosities of 30–40%. [Copyright &y& Elsevier]

Abstract: Two kinds of Pt–Au/CNT catalysts with different structures are prepared by synthesizing the formerly separated Pt/Au (Au separating Pt) in separate solutions, and PtAu nanoparticles in mixed solution using the borohydride reduction method with trisodium citrate as the stabilizing agent, and then depositing the metal colloid nanoparticles on the carbon nanotubes supporting material. The structural information and particle size are characterized by UV–vis absorption spectra, transmission electron microscopy (TEM), and X-ray diffraction (XRD). The results confirm the formation of Pt–Au nanoparticles with PtAu and separated Pt/Au structures. The catalytic activities for methanol oxidation reaction and oxygen reduction reaction are examined by electrochemical measurements. Compared with the Pt/CNT catalyst, the two Pt–Au/CNT catalysts show a lower overpotential for the oxygen reduction reaction in the presence of methanol, indicating a higher methanol tolerance on Au-modified Pt nanoparticles. Particularly, the Pt/Au/CNT catalyst with Au separating Pt nanoparticles structure exhibits the significantly higher methanol tolerance than PtAu/CNT catalyst. The enhanced methanol tolerance may be attributed to less methanol adsorption on Pt surface due to the effect of Au nanoparticles. [Copyright &y& Elsevier]

Abstract: There are increasing expectations and demands for sufficiently active noble-metal-free catalysts for the electrode reactions in polymer electrolyte fuel cells. One of the most promising candidates for the cathode catalyst is a carbon material with Fe–N x moiety embedded on the surface as the active site. We previously found that this carbon-based catalyst was formed by heat treatment of a mixture of Fe lactate, glucose, and amino acids as the nitrogen sources of the active site. In this study, various purine and pyrimidine bases were used as the nitrogen sources for the active site generation in order to obtain fundamental information on the activity enhancement of the carbon-based noble-metal-free cathode catalyst. The specific surface area and the surface Fe concentration of the carbon material formed by heat treatment of the Fe lactate–glucose–base mixture were dependent on the molecular structure and the number of nitrogen atoms contained in the molecule of the base, which then affected the catalytic activity for oxygen reduction and the number of electrons involved in the per oxygen molecule. Especially, the activity increased with an increase in the number of nitrogen atoms contained in the molecule. Efficient generation of the active site was also observed. [Copyright &y& Elsevier]

Abstract: La0.84Sr0.16MnO3−δ –Bi1.4Er0.6O3 (LSM–ESB) composite cathodes are fabricated by impregnating LSM electronic conducting matrix with the ion-conducting ESB for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The performance of LSM–ESB cathodes is investigated at temperatures below 750°C by AC impedance spectroscopy. The ion-impregnation of ESB significantly enhances the electrocatalytic activity of the LSM electrodes for the oxygen reduction reactions, and the ion-impregnated LSM–ESB composite cathodes show excellent performance. At 750°C, the value of the cathode polarization resistance (R p ) is only 0.11Ωcm2 for an ion-impregnated LSM–ESB cathode, which also shows high stability during a period of 200h. For the performance testing of single cells, the maximum power density is 0.74Wcm−2 at 700°C for a cell with the LSM–ESB cathode. The results demonstrate the ion-impregnated LSM–ESB is one of the promising cathode materials for intermediate-temperature solid oxide fuel cells. [Copyright &y& Elsevier]

Abstract: The mesoporous carbons were prepared by the carbonation of the triblock copolymer F127/phloroglucinol-formaldehyde composite self-assembled in an acid medium and employed as the catalyst for triiodide reduction in dye-sensitized solar cells (DSCs). The characteristics of mesoporous carbon were analyzed by scanning electron microscopy, transmission electron microscopy, N2 sorption measurement and X-ray diffraction. The mesoporous carbon with low crystallinity exhibited Brunauer–Emmett–Teller surface area of 400m2 g−1, pore diameter of 6.8nm and pore volume of 0.63cm3 g−1. The photovoltaic performances of DSCs with mesoporous carbon counter electrode were improved by increasing the carbon loading on counter electrode due to the charge-transfer resistance of mesoporous carbon counter electrode decreasing with the increase of the carbon loading. However, further carbon loading increase has no obvious effect on the photovoltaic performance of DSCs with carbon electrode when carbon loading exceeds 300μgcm−2. The overall conversion efficiency of 6.18% was obtained by DSCs composed of mesoporous carbon counter electrode with the carbon loading of 339μgcm−2. This value is comparable to that of DSCs with conventional platinum counter electrode. [Copyright &y& Elsevier]

Abstract: La0.8Sr0.2Co0.5Fe0.5O3−δ (LSCF) cathodes infiltrated with electrocatalytically active Pd and (Gd,Ce)O2 (GDC) nanoparticles are investigated as high performance cathodes for the O2 reduction reaction in intermediate temperature solid oxide fuel cells (IT-SOFCs). Incorporation of nano-sized Pd and GDC particles significantly reduces the electrode area specific resistance (ASR) as compared to the pure LSCF cathode; ASR is 0.1Ωcm2 for the reaction on a LSCF cathode infiltrated with 1.2mgcm−2 Pd and 0.06Ωcm2 on a LSCF cathode infiltrated with 1.5mgcm−2 GDC at 750°C, which are all significantly smaller than 0.22Ωcm2 obtained for the reaction on a conventional LSCF cathode. The activation energy of GDC- and Pd-impregnated LSCF cathodes is 157 and 176kJmol−1, respectively. The GDC-infiltrated LSCF cathode has a lower activation energy and higher electrocatalytic activity for the O2 reduction reaction, showing promising potential for applications in IT-SOFCs. [Copyright &y& Elsevier]

Abstract: Direct-oxidation fuel cells (DOFC) are promising electrochemical devices for various applications. In addition to methanol (MeOH), alternative fuels are being tested in a search for lower toxicity, safer handling, and higher energy density. Ethylene glycol (EG) was employed as one of such fuels. However, DOFCs face several problems, such as fuel crossover through the membrane during its operation. This not only lowers the cell potential but also poisons the catalyst for the oxygen-reduction reaction (ORR). Experiments were performed on the poisoning of Pt and Pt-alloy ORR catalysts (both commercial and homemade, by electroless deposition), by fuels and their oxidation by-products. At 25°C, methanol poisoning was found to be reversible and the catalytic activity measured afterwards in a fuel-free solution and the electrochemical surface area (ECSA) were enhanced. The effect of poisoning by methanol and ethylene glycol and their oxidation intermediates is reported here for the first time. The severity of poisoning was found to be MeOH≪formaldehyde

Abstract: PtRuMoO x and PtRuWO x catalysts supported on multi-wall carbon nanotubes (MWCNTs) are prepared by ultrasonic-assisted chemical reduction method. XRD measurements indicate that Pt exists as face-centered cubic structure, Ru is alloyed with platinum, and the metal oxides exist as an amorphous structure. TEM pictures show that PtRuMoO x and PtRuWO x catalysts are well dispersed on the surface of MWCNTs with the particle size of about 3nm and a narrow particle size distribution. The electrochemical properties of the catalysts for methanol electrooxidation are studied by cyclic voltammetry (CV), chronoamperometry (CA) and chronopotentiometry (CP). The onset potentials for methanol oxidation on PtRuMoO x and PtRuWO x are more negative than that of pure Pt catalyst, shifting negatively by about 0.20V and have better electrocatalytic activities than PtRu/MWCNTs. [Copyright &y& Elsevier]

Abstract: The stability of Sm0.5Sr0.5CoO3 (SSC) under reduction conditions is investigated to determine whether it can be used as a cathode material in on-planar type, single-chamber, solid oxide fuel cells. The techniques of X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy are used to reveal the reduction mechanism of SSC. Impedance spectroscopy analysis also provides a better understanding of the influence of decomposed SSC phases on cathode performance. Decomposition of SSC occurs on the surface by the formation of dot-shaped SrO, Co(OH)2 and CoO on top of the reduced SSC layer at 250°C in 4% H2O–96% H2. The SSC perovskite structure is destroyed at 350°C in pure hydrogen. There is a catastrophic microstructural change in which SSC is completely decomposed to SrO and CoO that cover the surface of Sm2O3. [Copyright &y& Elsevier]

Abstract: The catalytic activity of Ni/La2O3-Al2O3 catalysts modified with noble metals (Pt and Pd) was investigated in the steam reforming of ethanol. The catalysts were characterized by ICP, S BET, X-ray diffraction, temperature-programmed reduction, UV–vis diffuse reflectance spectroscopy and X-ray absorption fine structure (XANES). The results showed that the formation of inactive nickel aluminate was prevented by the presence of La2O3 dispersed on the alumina. The promoting effect of noble metals included a marked decrease in the reduction temperatures of NiO species interacting with the support, due to the hydrogen spillover effect, facilitating greatly the reduction of the promoted catalysts. It was seen that the addition of noble metal stabilized the Ni sites in the reduced state throughout the reaction, increasing ethanol conversion and decreasing coke formation, irrespective of the nature or loading of the noble metal. [Copyright &y& Elsevier]

Abstract: Olivine LiFePO4/C cathode materials were synthesized by carbothermal reduction method at different temperatures. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), particle size analysis and charge–discharge test. The results showed that both the crystallization degree and particle size increased remarkably with the synthesis temperature increasing. The LiFePO4/C synthesized at 750°C showed a highest initial discharge specific capacity of 145mAhg−1 at 1C rate, which decreased to 60mAhg−1 after 500 cycles. However, the sample prepared at 850°C exhibited a lower initial discharge capacity of 135mAhg−1 at 1C rate, whose capacity could also reach 105mAhg−1 after 500 cycles. The material synthesized at lower sintering temperature had lower crystallization degree and plenty of nano-sized microstructure, leading to its higher electrochemical activity and initial discharge capacity. But at the same time, the lower sintering temperature also leads to the instability of the crystal structure and the solution of active materials, which results in the degradation of discharge capacity on long-time cycling. In short, synthesizing the material with perfect crystallization degree and moderate particle size is an effective way to improve the cycling performance of LiFePO4/C cathode materials. [Copyright &y& Elsevier]

Abstract: The geometric parameters of 1, 3-benzodioxol-2-one (BO) and propylene carbonate (PC) was optimized at the B3LYP/6-311++G (d, p) level of density functional theory (DFT) with the polarized continuum models (PCM). The obtained frontier molecular orbital energies and vertical electron affinities indicate that BO is reduced more easily than PC. The transition state (TS) of ring-opening reaction BO −1 →BO −1 was optimized and confirmed by vibrational frequency analysis and intrinsic reaction coordinate (IRC) method. The bond orders and atomic charge distribution of the stable points along the minimum energy path (MEP) were analyzed using the natural bond orbital (NBO) method at the B3LYP/6-311++G(d, p) level of DFT. With these calculated results, the reduction mechanism of BO for the formation of solid electrolyte interface (SEI) film on anode of lithium ion battery can be inferred as: BO+e→BO −1 →BO −1 →⋯→SEI Film. [Copyright &y& Elsevier]

Abstract: In this work, a novel composite consisting of nanosized silicon highly dispersed within the porous, elastic and conductive oxide/carbon matrix has been developed as an anode candidate for lithium ion batteries. The composite was prepared by a mechanochemical reaction between SiO and Li under ball milling followed by a carbon coating using the pyrolysis of poly(vinyl chloride)–co-vinyl acetate. The porous structure can effectively suppress the volume change of silicon during the electrochemically Li-alloying process. No obvious capacity fading was observed up to 100 cycles with a stable capacity of 620mAhg−1. The factors influencing the microstructure and the electrochemical behavior of the composite were discussed. [Copyright &y& Elsevier]

Abstract: The monoclinic-type Li3V2(PO4)3 cathode material was synthesized via calcining amorphous Li3V2(PO4)3 obtained by chemical reduction and lithiation of V2O5 using oxalic acid as reducer and lithium carbonate as lithium source in alcohol solution. The amorphous Li3V2(PO4)3 precursor was characterized by using TG–DSC and XPS. The results showed that the V5+ was reduced to V3+ by oxalic acid at ambient temperature and pressure. The prepared Li3V2(PO4)3 was characterized by XRD and SEM. The results indicated the Li3V2(PO4)3 powder had good crystallinity and mesoporous morphology with an average diameter of about 30nm. The pure Li3V2(PO4)3 exhibits a stable discharge capacity of 130.08mAhg−1 at 0.1C (14mAg−1). [Copyright &y& Elsevier]

Abstract: LiFePO4/C composite cathode materials were synthesized by carbothermal reduction method using inexpensive FePO4 as raw materials and glucose as conductive additive and reducing agent. The precursor of LiFePO4/C was characterized by differential thermal analysis and thermogravimetry. The microstructure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and particle size analysis. Cyclic voltammetry (CV) and charge/discharge cycling performance were used to characterize their electrochemical properties. The results showed that the LiFePO4/C composite synthesized at 650°C for 9h exhibited the most homogeneous particle size distribution. Residual carbon during processing was coated on LiFePO4, resulting in the enhancement of the material''s electronic properties. Electrochemical measurements showed that the discharge capacity first increased and then decreased with the increase of synthesis temperature. The optimal sample synthesized at 650°C for 9h exhibited a highest initial discharge capacity of 151.2mAhg−1 at 0.2C rate and 144.1mAhg−1 at 1C rate with satisfactory capacity retention rate. [Copyright &y& Elsevier]

Abstract: In this paper, the electrochemical reactions of sulfur cathode during discharge–charge process were investigated by EIS technique combining with XRD, SEM and EDS methods. The discharge process of the sulfur cathode could be divided into two discharge regions. These are the first discharge region (2.5–2.05V) where the reduction of elemental sulfur to form soluble polysulfides and further reduction of the soluble polysulfides occurs, and the second discharge region (2.05–1.5V) where the soluble polysulfides are reduced to form a Li2S solid film covered over the carbon matrix. It was found that the EIS can distinguish the individual contributions of charge transfer resistances, ion diffusion impedance and properties originating from Li2S film in the frequency domain of 100kHz to 100mHz. During the upper voltage plateau, the impedance of interfacial charge transfer dominates the reduction reaction, while during the lower voltage plateau, the mass transport in the cathode is a control step. It was also proved that the solid Li2S appeared at the beginning of the lower voltage plateau region and became denser during the following discharge process. [Copyright &y& Elsevier]

Abstract: Nitrogen-modified carbon-based catalysts for oxygen reduction were synthesized by modifying carbon black with nitrogen-containing organic precursors. The electrocatalytic properties of catalysts were studied as a function of surface pre-treatments, nitrogen and oxygen concentrations, and heat-treatment temperatures. On the optimum catalyst, the onset potential for oxygen reduction is approximately 0.76V (NHE) and the amount of hydrogen peroxide produced at 0.5V (NHE) is approximately 3% under our experimental conditions. The characterization studies indicated that pyridinic and graphitic (quaternary) nitrogens may act as active sites of catalysts for oxygen reduction reaction. In particular, pyridinic nitrogen, which possesses one lone pair of electrons in addition to the one electron donated to the conjugated π bond, facilitates the reductive oxygen adsorption. [Copyright &y& Elsevier]

Abstract: Carbon-supported Pd4Au- and Pd2.5Sn-alloyed nanoparticles were prepared by a chemical reduction method, and characterized by a wide array of experimental techniques including mass spectrometry, transmission electron microscopy, and X-ray diffraction spectroscopy. Ethanol electrooxidation on the as-synthesized catalysts and commercial Pt/C was then investigated and compared in alkaline media by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy studies at room temperature. Voltammetric and chronoamperometric measurements showed higher current density and longer term stability in ethanol oxidation with the palladium alloy nanocatalysts than with the commercial one. Electrochemical impedance spectroscopy and Tafel plots were employed to examine the charge-transfer kinetics of ethanol electrooxidation. The results suggest that whereas the reaction kinetics might be somewhat more sluggish on the Pd-based alloy catalysts than on commercial Pt/C, the former appeared to have a higher tolerance to surface poisoning. Overall, the Pd-based alloy catalysts represent promising candidates for the electrocatalytic oxidation of ethanol, and Pd4Au/C displays the best catalytic activity among the series for the ethanol oxidation in alkaline media. [Copyright &y& Elsevier]

Abstract: A comparative study of the electrochemical stability of Pt25Cu75 and Pt20Cu20Co60 alloy nanoparticle electrocatalysts in liquid electrolyte half-cell environment was conducted. The aforementioned catalysts were shown to possess improved resistance to electrochemical surface area (ECSA) loss during voltage cycling relative to commercially available pure Pt electrocatalysts. The difference in ECSA loss was attributed to their initial mean particle size, which varied depending on the temperature at which the alloy catalysts were prepared (e.g. 600, 800 and 950°C). Higher preparation temperatures resulted in larger particles and lead to lower ECSA loss. Liquid electrolyte environment short-term durability testing (5000 voltages cycles) revealed the addition of cobalt to be beneficial as ternary compositions exhibited stability advantages over binary catalysts. Oxygen reduction reaction (ORR) activity and catalyst stability tests were then performed for both Pt25Cu75 and Pt20Cu20Co60 alloy catalysts in membrane electrode assemblies (MEA). ORR activity data, taken both prior to and at the conclusion of 30,000 voltage cycles from 0.5 to 1.0V vs. reversible hydrogen electrode (RHE), revealed that both Pt25Cu75 and Pt20Cu20Co60 were able to retain both their mass and Pt surface area-based activity advantage relative to Pt/C [R. Srivastava, P. Mani, N. Hahn, P. Strasser, Angew. Chem. Int. Ed. 46 (2007), 8988; P. Mani, R. Srivastava, P. Strasser, J. Phys. Chem. C 112 (2008), 2770; S. Koh, P. Strasser, J. Am. Chem. Soc. 129 (2007), 12624]. Further analysis revealed that the Pt surface area-based activity, measured at 0.9V vs. RHE, of commercially available Pt catalysts, as well as that for both Pt25Cu75 and Pt20Cu20Co60 increased on the order of tens of per 1000 voltage cycles. This increase in specific activity combined with a reduced ECSA loss resulted in a negligible change for the Pt mass-based activity of Pt25Cu75 alloys annealed at 950°C. [Copyright &y& Elsevier]

Abstract: Two composite electrode structures for direct methanol fuel cells comprising an outer, middle and an inner catalyst layers, are proposed to suppress methanol crossover and improve the utilization efficiency of methanol fuel. These two composite anodes have structures I and II, and are prepared by a combination of screen-printing, direct-printing and impregnation–reduction (IR) methods. The inner layer of these two composite anodes, which are prepared by IR method, is a layer of nanometer-sized Pt37–Ru63/Pt or Pt37–Ru63/Pt20–Ru80 catalyst particles deposited in the PEM anode side serving as the reactive methanol filter layer. The suppression of methanol crossover and the membrane electrode assembly (MEA) performance of the proposed structures are compared to those of the normal-MEA structure with PEM without IR treatment. The mechanisms of the suppression of methanol crossover are investigated. Experimental results show that the MEA-I and MEA-II improve the suppression of methanol crossover by up to 22% and 33% compared to the normal-MEA structure, respectively, and yield a 12% and 18% better MEA performance than the normal-MEA structure, respectively. The filtering and electrode effects of a layer of nanometer-sized Pt37–Ru63/Pt or Pt37–Ru63/Pt20–Ru80 catalyst particles deposited in the PEM anode side contribute to the suppression of methanol crossover and performance enhancement. [Copyright &y& Elsevier]

Abstract: Composite electrodes composed of a perovskite-type La0.8Sr0.2Sc0.1Mn0.9O3−δ (LSSM) and a fluorite-type scandium-stabilized zirconia (ScSZ) were prepared and evaluated as potential cathodes for intermediate-temperature solid-oxide fuel cells. Characterization was made by phase reaction, electrochemical impedance spectroscopy, step current polarization and I–V tests. The phase reaction between LSSM and ScSZ occurred at 1150°C or higher; however, it had a minor effect on the electrode performance. The formation of a composite electrode led to an obvious improvement in both charge transfer and surface-related processes. With the increase of ScSZ content, the rate-limiting step of oxygen reduction reaction steadily changed from mainly a surface diffusion process to an electron transfer process. The optimal ScSZ content and sintering temperature of the electrode layer were found to be 20wt.% and 1100–1150°C, respectively. Under optimal conditions, an anode-supported single cell with LSSM+ScSZ composite cathode showed high power densities of ∼1211 and 386mWcm−2 at 800 and 650°C, respectively. [Copyright &y& Elsevier]

Abstract: Porous composite cathodes including (La0.74Bi0.10Sr0.16)MnO3−δ (LBSM) and Bi1.4Er0.6O3 (ESB) were fabricated and characterized using AC impedance spectroscopy. In our earlier work, the growth and aggregation of ESB particles were found in LBSM–ESB composite cathodes. In this study, therefore, two approaches were used to restrain the growth and aggregation of ESB particles. First, the sintering temperature of the composite cathode was reduced by introducing a sintering function layer, which caused a 22% reduction in the initial polarization resistance (R), but the cathode polarization resistance decreased at a rate of 2.15×10−4 Ωcm2 h−1 at 700°C during a period of 100h. Second, nano-sized Gd-doped ceria powder (CGO) was added to the composite cathode system. Stability improvement was achieved at 10vol% CGO, and the degradation rate at 700°C was 4.01×10−5 Ωcm2 h−1 during a period of 100h. [Copyright &y& Elsevier]

Abstract: During solid oxide fuel cell operation, re-oxidation of the nickel anode can occur due to a disruption in fuel supply, emergency system shutdown or leakages in the fuel delivery channel. Once oxidation occurs, the anode has to be reduced again in order to be ready for use. Cyclic reduction and oxidation (redox) is known to cause severe expansion and contraction in the anode causing significant changes to the integrity of the material interfaces leading to performance degradation and eventual failure. The redox tolerance of Ni/YSZ anode supported solid oxide fuel cell is investigated at 800°C in partial oxidation and reduction conditions and a total of 52 redox cycles is performed. Partial oxidation is performed by shutting-off the hydrogen supply for 3min to allow atmospheric air to oxidize the anode, while partial reduction proceeded by a flow of 20mlmin−1 hydrogen for 5min. The electrochemical performance of the cell decreased slightly after each redox cycle. An average degradation rate of 0.3% per cycle was calculated. The micro-structural changes that occurred after redox cycling is characterized by both dilatometry and scanning electron microscopy (SEM). The theory that damage was caused by defect growth in the anode was confirmed. [Copyright &y& Elsevier]

Abstract: A platinum/carbon nanofiber (Pt/CNF) nanocomposite with a platinum loading of 15wt% is prepared by a modified electrophoretic deposition (EPD) method, and the as-grown nanocomposite is used as the electrocatalyst for oxygen reduction reaction (ORR). For comparison, a Pt/CNF composite with 40wt% platinum loading is prepared by chemical reduction. High resolution transmission electron microscope (HRTEM) images show that the size of platinum nanoparticles formed by EPD is about 1nm, much smaller than those by chemical reduction (about 3–5nm). Cyclic voltammetric analysis in a nitrogen saturated electrolyte shows that the electrochemical surface area of electrocatalyst by EPD is larger than that by chemical reduction. Moreover, although the electrocatalyst prepared by chemical reduction has a higher electrochemical capacity, it is less active than that prepared by EPD. Analysis of the electrode kinetics using Tafel plot suggests that the electrocatalyst prepared by EPD provides a strong ORR activity. Cyclic voltammetric measurements at different scan rates confirm that the ORR on the nanocomposites prepared by EPD is a diffusion-controlled process. This work demonstrates that the Pt/CNF composites synthesized by EPD are effective for ORR. [Copyright &y& Elsevier]

Abstract: In this work, carbon-supported platinum nanoparticles were synthesized in the presence of varying concentrations of thiourea (TU). Because of the presence of the sulfur atom, thiourea adsorbs strongly on the forming Pt nuclei during the synthesis, affecting the rate and the extent of growth. High-intensity X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) were used to probe the effect on the crystallite size and particle size, respectively, revealing a decrease in both mean crystallite and the mean particle size for increasing concentrations of thiourea during the synthesis. An adsorption isotherm for the adsorption of thiourea on platinum nanoparticles is also discussed. Cyclic voltammetry was used to check the effect of TU on the particles as well as to obtain further knowledge on both adsorption and electrochemical oxidation behavior of thiourea on Pt surfaces. Thermal treatment effectively cleaned the electrode surface, thus providing an easy way to remove adsorbed species from the Pt surface. [Copyright &y& Elsevier]

Abstract: Composite consisting of nanosized silicon, Li4SiO4 and other lithium-rich components was synthesized using high energy mechanical milling (HEMM) method. The reactive milling of SiO with lithium metal resulted in the oxidation of lithium and silicon, and reduction of SiO. X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM) were used to determine the phases present in the composite. In addition, cyclic voltammetry (CV), along with constant current discharge/charge tests, was used to characterize the electrochemical properties of the resultant material. Compared with pure SiO and pure silicon as anode materials, the as-prepared composite demonstrated larger capacity and superior cyclability even at high C-rate. [Copyright &y& Elsevier]

Abstract: A high active Pt/C(b) catalyst was prepared by chemical reduction. The experimental results showed that the Pt/C(b) catalyst formed by reduction of hexachloroplatinic acid with formic acid has excellent catalytic properties for methanol and adsorbed CO(COad) electro-oxidation. The electrocatalytic activity of the catalyst was characterized as having a specific surface activity of 33.38mAcm−2 at 0.6V (versus Ag-AgCl). The Pt in the catalyst was well dispersed on carbon with an electrochemically-active specific surface area (ESA) of 84.16m2 g−1 and a BET specific surface area of 192.34m2 g−1 and an average particle size of about 2.6nm. The catalyst showed a very good stability for 12h. [Copyright &y& Elsevier]

Abstract: Pt on a tungsten carbide nanocrystalline support (Pt-WC/C) has been prepared by the direct reduction of a platinum salt precursor combined with intermittent microwave heating (IMH). The Pt-WC/C electrocatalyst shows better performance for oxygen reduction in acidic media than that of pure Pt/C or Pt-WC/C prepared by a mechanical mixing method. The results reveal that the Pt-WC/C electrocatalyst prepared by present method is very active for oxygen reduction reaction (ORR) with an onset potential of 1.05V versus standard hydrogen electrode (SHE) at ambient temperature, which is over 150mV more positive compared to that of commercial Pt/C electrocatalysts. [Copyright &y& Elsevier]

Abstract: Tin–graphite materials were prepared by chemical reduction of SnCl4 by t-BuONa-activated NaH. TEM imaging showed that the crude material is composed of an amorphous organic matrix containing tin present either as nanosized particles deposited on the graphite surface or as free aggregates. Subsequent washings with ethanol and water allow removal of side products as well as most part of the organic matrix. Electrochemical insertion of lithium occurred in graphite and in tin. The initial reversible massic capacity of 630mAhg−1 decayed to a stable value of 415mAhg−1 after 12 cycles. This capacity value was lower than the expected maximum one of 650mAhg−1 corresponding to a Sn/12C molar composition and assuming the formation of LiC6 and Li22Sn5. Even if this massic capacity is not much improved by comparison with that of graphite, it must be pointed out that the volume capacity of this graphite/Sn material is much larger (2137mAhcm−3) than that corresponding to graphite (837mAhcm−3). It was hypothesized that the part of tin bound to graphite could be responsible for the stable reversible capacity. To the contrary, graphite unsupported tin aggregates would contribute to the observed gradual decline in the storage capacity. Therefore, the improvement in cycleability, compared to that of massive metals, could be attributed both to the nanoscale dimension of the metal particles and to interactions between graphite and metal the nature of which remaining to be precised. [Copyright &y& Elsevier]

Abstract: This work describes a new method of chemical reduction of p-doped polypyrrole (Ppy) to make a graphite/Ppy lithium-ion battery. Several reducing agents are analysed (sodium hydrosulfite (Na2S2O4), sodium hydrogensulfite (Na2S2O5), hydroxymethanesulfinic acid monosodium salt (HOCH2SOONa), sodium borohydride (NaBH4), formamidinesulfinic acid (H2NCNHSO2H), stannous chloride (SnCl2) and hydrazine (N2H4)), obtaining the best results when reducing a Ppy electrode with sodium borohydride (NaBH4): at least 85% of the polymer electrode can be reduced without significant degradation. To verify the feasibility of the reduction method two lithium-ion batteries with a Ppy cathode have been assembled using different ways (4.5cm×1.9cm electrodes having similar active electrode material (mgcm−2) values and thicknesses to commercial inorganic oxide electrodes). In one of them the doped Ppy electrode is previously electrochemically reduced, applying consecutive potentials steps before the cell assembling; it would be accurate and easy at laboratory scale, but from an industrial point of view it is complicated and not viable. In the second battery the doped Ppy electrode is chemically reduced resulting in a similar charge–discharge characteristic to the electrochemically reduced one. Therefore, the chemical reduction method can be a step forward for using Ppy as cathode in lithium-ion batteries at industry level. [Copyright &y& Elsevier]

Abstract: The activity for the oxygen reduction reaction (ORR) on carbon supported Pt–Ni electrocatalysts prepared by reduction of Pt and Ni precursors with NaHB4 was investigated in sulphuric acid both in the absence and in the presence of methanol and compared with that of a commercial Pt/C electrocatalyst. In methanol-free sulphuric acid solution the Pt70Ni30/C alloy electrocatalyst showed a lower specific activity towards oxygen reduction compared to Pt/C. In O2-free H2SO4 the onset potential for methanol oxidation on Pt70Ni30/C was shifted to more positive potentials, which indicates a lower activity for methanol oxidation than platinum. In the methanol containing electrolyte the higher methanol tolerance of the Pt70Ni30/C electrocatalyst for the ORR was ascribed to the lower activity of the binary electrocatalyst for methanol oxidation, arising from a composition effect. [Copyright &y& Elsevier]

Abstract: A new plating process has been developed for the formation of the cathode catalyst of a micro tubular direct methanol fuel cell. By using this method, a thin porous layer of Pt electrocatalyst was firstly bonded onto a tubular polymer electrolyte membrane by chemical reduction of Pt complex impregnated in the membrane. Electroplating was further made to control the loading amount and size of the Pt catalyst particles. The deposited Pt catalyst layer is around 12μm in thickness with the Pt particles size of 10nm. The micro tubular DMFC with a 6mg–Ptcm-2 cathode exhibited a peak power density of 2mWcm-2 under passive and air breathing conditions at ambient temperature and pressure. [Copyright &y& Elsevier]

The effect of an immobilized diffusion layer on the catalyst layer and the oxygen reduction reaction in polymer electrolyte fuel cells (PEMFCs) have been studied. Since, the oxygen reduction reaction is an inhibitive reaction, much effort has been devoted to the improvement of this reaction in PEMFCs. In this work, the effect of an immobilised hydrophobe carbon layer as the diffusion layer in the gas diffusion electrode has been evaluated. The study of various electrochemical methods in this research, as well as the evaluation of cell polarisation curves showed that the efficiency of electrodes with the diffusion layer in the high current density regions is higher than the electrodes with no diffusion layer. While in the lower current density region the electrodes without the diffusion layer are more efficient than the other type. [Copyright &y& Elsevier]

A series of complex oxides REMn2O5 (RE=Dy, Ho, Er, Tm, Yb, and Lu) and Er0.76Zr0.11Ca0.13Mn2O5 with large specific areas and nanoscale grain sizes were prepared by an improved amorphous citric precursor method (IACP). Their electrocatalytic performances were characterized by the polarization curves of gas diffusion electrodes employing the oxides. The measurement of polarization curves indicated that the REMn2O5 containing different rare earth showed a obviously different electrocatalytic performances for oxygen reduction reaction, being the order Tm>Er>Ho>Dy>Lu>Yb. Temperature-programmed reduction (TPR) analysis revealed that the REMn2O5 containing different rare earth showed a significantly different oxygen contents and TPR peak temperatures. Their catalytic activities depended on both the oxygen contents and TPR peak temperatures. These two factors play a plus and a minus role respectively. [Copyright &y& Elsevier]