Current Density For Methanol Oxidation Research Articles

Pd nanoparticles-embedded carbon nanotube interface for electrocatalytic oxidation of methanol toward DMFC applications

Pd nanoparticles-embedded multiwalled carbon nanotubes (Pd–MWCNTs) were synthesized via in situ chemical reduction method, which provided promising results for preparing finely divided and uniform sized Pd nanoparticles supported on MWCNTs. The Pd–MWCNT catalysts were synthesized in three different weight (wt) ratios of Pd and MWCNT (1:5, 2:5 and 3:5). Morphology and crystallinity of the catalysts were studied by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Electrocatalytic activity of these catalysts toward methanol oxidation was analyzed with two different dispersing agents, such as chitosan (CS, 0.1% w/v) and Nafion (Nf, 0.05% w/v), for the preparation of catalytic inks. Dramatic increases in the electrocatalytic activity of Pd–MWCNT–CS catalysts compared to Pd–MWCNT–Nf catalysts toward methanol oxidation were revealed from cyclic voltammetric, chronoamperometric and CO stripping analysis studies. The anodic peak current densities of the Pd–MWCNT (2:5 wt ratio) interface prepared with chitosan and Nafion inks in alkaline 1 M CH3OH were 2541 and $$1 0 4 1\,\,{\text{A}}\,\,\mathop {{\text{g}}^{ - 1} }\nolimits_{\text{Pd}}$$ , respectively. High CO tolerance of the Pd–MWCNT catalysts was ascertained from the ratio of peak currents and coulombic charges of forward and reverse scans (I f/I b and Q f/Q b) of CV studies and from the less positive potentials for CO stripping, as low as − 0.2 V versus Ag|AgCl. The steady-state current density for methanol oxidation at Pd–MWCNT–CS electrode is nearly five times higher than that of Pd–MWCNT–Nf electrode.

Pt electrocatalyst supported on metal ion-templated hierarchical porous nitrogen-doped carbon from chitosan for methanol electrooxidation

Hierarchical porous nitrogen-doped carbon (HPNC) derived from chitosan is synthesized through a novel metal ion-templated strategy. In this process, the absorbed Cu(II)-loaded chitosan was calcined at various temperatures which results in carbon/Cu composites. After removal of Cu particles with acid medium, hierarchical porous carbon forms which includes macropores, mesopores and micropores. The specific surface area of HPNC900 reaches 755 m2 g−1. The XPS results show that all the carbon materials contain nitrogen as the doped element due to the use of chitosan as a nitrogen-containing carbon source. Furthermore, highly dispersed Pt nanoparticles have been successfully deposited on the as-prepared HPNC through the in-situ reduction method. The average size of Pt nanoparticles anchored on HPNC900 is only 2.76 ± 0.33 nm. The synthesized products are characterized by TEM, SEM and XRD analysis techniques. Among the studied electrocatalysts, the as-prepared Pt/HPNC900 electrocatalyst (HPNC fabricated at 900 °C) shows superior electrocatalytic activity and stability towards methanol oxidation in comparison with Pt/Vulcan XC-72 catalyst. The current density of methanol oxidation on Pt/HPNC900 is ∼2.5 times higher than that of Pt/Vulcan XC-72 catalyst. The enhanced electrocatalytic activity is ascribed to hierarchical porous structures, nitrogen-doped surface characteristic and high BET specific surface area of HPNC. Therefore, the present method is very useful for fabrication of high-performance electrocatalyst for methanol oxidation.

Enhanced Methanol Oxidation on Strained Pt Films

We report a systematic investigation into the effect of strain on the electrocatalytic activity of films of Pt. We use an electroless deposition process to deposit the Pt onto sputtered Au substrates and characterize their structural and electrochemical properties. We found a direct correlation between the rate of methanol oxidation and the fractional surface coverage of methanol on the compressively strained catalyst surfaces. The fractional methanol surface coverage, ΘM, varied on the Pt surfaces with values ranging from 20.5 to 61.7%, depending on the level of compressive strain. A compressive strain of about e = −0.110% resulted in a high fractional surface coverage of 61.7% with highest peak current density for methanol oxidation of 0.46 mA cm–2 and earliest peak potential of 0.67 V vs Ag/AgCl. As the absolute value of the compressive strain increased, the fractional surface coverage and peak current density for methanol oxidation decreased. Therefore, the adsorption of molecular methanol was control...

Effect of the Dendrimer Generation Used in the Synthesis of Pt-Ru Nanoparticles Supported on Carbon Nanofibers on the Catalytic Activity towards Methanol Oxidation

Pt-Ru nanoparticles supported on carbon nanofibers (CNF) were synthesized by the sodium borohydride reduction method, using different generation dendrimers (zero, one, two and three generations). After the synthesis process, these materials were submitted to a heat treatment at 350 °C, in order to clean the nanoparticle surface of organic residues. TEM characterization showed that the Pt-Ru nanoparticles size ranged between 1.9 and 5.5 nm. The use of dendrimers did not totally avoid the formation of aggregates, although monodisperse sizes were observed. The heat treatment produces the desired surface cleaning, although promoted the formation of agglomerates and crystalline Ru oxides. The study of the electrochemical activity towards the methanol oxidation displayed some clues about the influence of both the dendrimer generation and the presence of Ru oxides. Moreover, the apparent activation energy Eap for this reaction was determined. The results showed a beneficial effect of the heat treatment on the methanol oxidation current densities for the materials synthesized with the biggest dendrimers, being the methanol deprotonation and COad diffusion the predominant rate determining steps (rds).

Platinized titanium nitride/graphene ternary hybrids for direct methanol fuel cells and titanium nitride/graphene composites for high performance supercapacitors

A titanium nitride/reduced graphene oxide nanocomposite (TiN/rGO) was fabricated by a two-step process. The resulting TiN particles had a mean diameter of less than 10nm and were densely decorated onto the rGO surface. The TiN/rGO composite was used as a support matrix to anchor platinum (Pt) nanoparticles by the polyol method to fabricate a Pt@TiN/rGO ternary hybrid catalyst for methanol oxidation. An increase in the methanol oxidation current density was observed for Pt@TiN/rGO when compared to Pt/rGO and Pt/Vulcan, confirming that the inclusion of TiN along with rGO improved the electrocatalytic activity. The electrochemical surface area was also significantly higher for the Pt@TiN/rGO catalyst (84.5m2g−1) than for Pt/rGO (51.7m2g−1) and Pt/Vulcan (33.7m2g−1), highlighting the importance of TiN. The Pt@TiN/rGO hybrid showed excellent electrocatalytic activity, long-term stability, and better carbon monoxide tolerance for the electrooxidation of methanol when compared to more traditional catalysts, namely Pt/rGO and Pt/Vulcan with same Pt content. Conversely, the TiN/rGO composite (without Pt) showed a higher capacitance of 415Fg‐1 and a long cycle life, with 7.0% capacitance loss after 10,000 cycles. The capacitance was as high as 275Fg‐1 at a current density of 5Ag‐1.

Investigation of CeO2/Graphene and Nb2O5/Graphene Supported Pt and PtCo Catalysts Towards Methanol and Ethanol Oxidation and Oxygen Reduction Reactions

In this study the CeO2/graphene and Nb2O5/graphene supported Pt and PtCo catalysts denoted as PtCeO2/GR, PtNb2O5/GR, PtCoCeO2/GR and PtCoNb2O5/GR were prepared by polyol method using the simple and rapid microwave heating method. To obtain the catalysts, required amounts of CeO2/graphene or Nb2O5/graphene, H2PtCl6 and CoCl2 were heated in ethylene glycol at 170 oC for 30 min in the microwave reactor. It was found that Pt nanoparticles were successively deposited onto the surfaces of CeO2/graphene and Nb2O5/graphene. For comparison, the PtCo/graphene (PtCo/GR) and Pt/carbon (Pt/C) catalysts were prepared in the same manner. The composition and morphology of catalysts were detected by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM). The synthesized PtCeO2/GR, PtNb2O5/GR, PtCoCeO2/GR, PtCoNb2O5/GR, PtCo/GR and Pt/C catalysts were examined as electrocatalysts towards the electro-oxidation of methanol and ethanol, and the reduction of oxygen. It has been found that the CeO2/GR or Nb2O5/GR supported Pt and PtCo catalysts show an enhanced electrocatalytic activity towards the oxidation of ethanol and methanol in an alkaline medium as compared with that of the Pt/C catalyst. Depending on catalysts composition, ethanol and methanol oxidation current densities were found to be ca. 3 – 12 times higher at the CeO2/GR and Nb2O5/GR catalysts, respectively, in comparison with those at the Pt/C catalyst. In the case of oxygen reduction, the PtCoCeO2/GR and PtCoNb2O5/GR catalysts outperform the PtCeO2/GR, PtNb2O5/GR, PtCo/GR and Pt/C catalysts towards oxygen reduction and shows higher onset potential, as well as higher current density towards the oxygen reduction reaction as compared with those at the aforementioned catalysts.

Palladium–nickel catalysts supported on different chemically-treated carbon blacks for methanol oxidation in alkaline media

Palladium–nickel catalysts supported on carbon blacks containing similar metal contents (25 wt. %) and Pd:Ni atomic ratios (1:1 and 1:2) were synthesized. Carbon supports were chemically treated to create different oxygen and nitrogen groups on surface. X ray patterns revealed a weak alloying between Pd and Ni, whereas crystallite sizes were between 2.1 and 3.2 nm, being consistent with the values detected by transmission electron microscopy (TEM). CO strippings demonstrated a higher poisoning tolerance of the Pd–Ni catalysts than that observed for a Pd catalyst supported on Vulcan carbon black. The methanol oxidation on Pd–Ni catalysts suggested that presence of Ni increase the activity of the materials, considering that Pd/CB exhibited the lowest methanol oxidation current densities. Nevertheless, no effects associated to the presence of surface functional groups on carbon supports were observed in the performance of this reaction.

Electrocatalytic activity of Pt–ZrO2 supported on different carbon materials for methanol oxidation in H2SO4 solution

Different carbon supports are considered to prepare Pt–ZrO2/XC-72R carbon black, Pt–ZrO2/SWCNTs and Pt–ZrO2/MWCNTs electrocatalysts by a solid–state reaction under intermittent microwave heating method using ethylene glycol and NaBH4 as mixed reducing agents. The prepared electrocatalysts are physically characterized using X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM). Pt particle size decreases in the order: Pt–ZrO2/C > Pt–ZrO2/MWCNTs > Pt–ZrO2/SWCNTs. Cyclic voltammetry, chronoamperometry, chronopotentiometry and electrochemical impedance spectroscopy are applied to investigate the electrochemical performance of the three electrocatalysts for methanol oxidation in H2SO4 solution. CNTs supported electrocatalysts achieve increased methanol oxidation current density and improved stability behaviour during long-time operation when compared to the one containing carbon black. Pt–ZrO2/CNTs electrocatalyst also displays lower resistance and higher electrolyte diffusion rate to infer a faster charge transfer process and better electrode accessibility for methanol oxidation. Therefore, carbon nanotubes are suggested as ideal anode electrocatalyst supporting material for the practical application of direct methanol fuel cells.

The use of a hierarchically platinum-free electrode composed of tin oxide decorated polypyrrole on nanoporous copper in catalysis of methanol electrooxidation

Tin oxide nanoparticles were synthesized through a galvanostatic pathway on polypyrrole, PPy, coated nanoporous copper. The morphology and surface analysis of the assemblies were evaluated by field emission scanning electron microscopy, FESEM, and energy dispersive X-ray, EDX, analysis, respectively. The electrocatalytic behavior of electrodes was studied by cyclic voltammetry and chronoamperometry tests in methanol solution. FESEM results showed that uniformly distributed nanoparticles with diameters of about 20–30nm have been dispersed on PPy matrix. Cyclic voltammetry and chronoamperometry tests in methanol solution showed a significant enhancement in the catalytic action of PPy after decoration of tin oxide nanoparticles. Porous Cu/PPy/SnOx electrodes showed enhanced anodic peak current density for methanol oxidation compared to smooth Cu/PPy/SnOx and porous Cu/PPy. The effects of synthesis current density and time on the electrocatalytic behavior of the electrodes were evaluated. The significant enhancement of electrocatalytic behavior of the Cu/PPy electrode after decoration of SnOx overlayer was attributed to the effect of tin oxide on the adsorption of intermediates of methanol oxidation as well as oxidation of bi-products such as CO; huge tendency of tin oxides for dehydrogenation of the alcohols and the increase in microscopic surface area of the electrodes were introduced as other affecting factors.

Synthesis, Characterization and Properties of the Graphene Supported Pt-Co Nanocatalysts Towards the Electro-Oxidation of Methanol

Among the different types of fuel cell technologies, direct methanol fuel cells (DMFCs) are the most suitable for mobile and portable electronic applications. The development of cost-effective, active, and stable catalysts, able to substitute Pt or allow reducing the amount of it in low temperature fuel cell anodes is still in progress. In our previous works [1, 2] it has been shown that the graphene supported platinum-cobalt catalysts prepared by means of microwave synthesis enhance electrocatalytic activity towards the oxidation of borohydride and ethanol in an alkaline medium and are promising anode materials for direct borohydride fuel cells (DBFCs) and ethanol fuel cells (DEFCs). In this study investigation of activity of the graphene supported platinum-cobalt catalysts with the different Pt:Co molar ratios, fabricated by the rapid microwave heating method, towards the electro-oxidation of methanol in an acidic medium is presented. The Pt-Co/GR catalysts with the Pt:Co molar ratios equal to 1:3, 1:6, 1:20, 1:50 and 1:60 were prepared by microwave-assisted heating of required amounts of Pt(IV), Co(II) and ethylene glycol at a temperature 170 oC for 30 min. For comparison, the graphene supported Pt catalyst was also prepared at 170 oC for 30 s. The Pt loading in the synthesized catalysts was near 0.1 mg Pt cm-2. The electrochemically active surface areas of Pt in the synthesized Pt/GR and Pt-Co/GR catalysts were determined from the cyclic voltammograms of the mentioned catalysts recorded in a deaerated 0.5 M H2SO4 solution at a sweep rate 50 mV s-1 by calculating the charge associated with hydrogen adsorption (220 µCcm-2) and are 0.7 cm2 for Pt/GR and 5.2, 2.9, 1.6, 1.0 and 0.5 cm2for the Pt-Co/GR catalysts with the Pt:Co molar ratios equal to 1:3, 1:6, 1:20, 1:50 and 1:60, respectively. Values of the electrochemically active surface areas of the investigated Pt-Co/GR catalysts are 1.4-7.5 times higher than those of the Pt/GR catalyst. Electrochemical properties of Pt-Co/GR were investigated towards the electro-oxidation of methanol in acidic medium by means of cyclic voltammetry and chronoamperometry and compared with those of the bare graphene supported Pt catalyst. It has been determined that the Pt-Co/GR catalysts with the Pt:Co molar ratios equal to 1:3, 1:6, 1:20 exhibit an enhanced electrocatalytic performance for methanol electro-oxidation as compared with that of bare graphene supported platinum catalyst. Methanol oxidation current density values are ca. 2.1-3.2 times higher at the Pt-Co/GR catalysts with the above mention Pt:Co molar ratios than those at the Pt/GR catalyst. Highest electrocatalytic activity towards the electro-oxidation of methanol in acidic medium shows the graphene supported Pt-Co catalyst with the Pt:Co molar ratios equal to 1:3 and 1:6 as compared with that of catalysts with higher Pt:Co molar ratios and Pt/GR. These results obtained show that the Pt-Co/GR catalysts with the different Pt:Co molar ratios could have promising future as catalysts for DMFC.

Methanol Oxidation on Pd-Ru/C Nanocatalysts: Role of Electronic Properties and FTIR Studies

In this work, methanol oxidation in alkaline solution was studied on carbon-supported Pd-Ru nanocatalysts of nominal Pd:Ru atomic composition 1:1. The synthesis of the catalysts involved the preparation of nanoparticles in colloidal state by a modified polyol method using two reducers. The nanoparticles were separated from the reaction medium and thoroughly cleaned by a sequence of centrifugation and redispersion steps. After that, the particles were supported on high surface area carbon powder (Vulcan XC-72, Cabot). The total metal load was 20 wt%. The carbon-supported catalyst obtained was repeatedly washed with dilute solution of KOH in ethanol, dilute solution of H2SO4, and hot water. After filtration, the catalyst was dried at 80o C. One sample of Pd/C prepared by the same method was used as reference material. Portions of the as-prepared Pd-Ru/C sample were thermally treated at 200 and 400oC during 4 hours in argon, aiming to verify if the degree of alloying could be increased. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) in solutions devoid of alcohol was used to evaluate the general electrochemical behavior. The CV curves showed a quite thick double layer region indicating the presence of Ru species. The electrocatalytic activities towards methanol oxidation were studied by linear potential sweeps and chronoamperometry. Oxidation of adsorbed CO was also measured. The charges of CO stripping curves allowed determining the Pd electrochemically active areas that were used for calculating current densities. It was observed that the catalytic activity was slightly improved after heat treatment at 200oC, while the treatment at higher temperature had a detrimental effect. Measurements of X-ray absorption spectroscopy were carried out around the Pd L3 edge (3173 eV) in order to evaluate the relevance of electronic effects. Despite the fact that these experiments could only be made in high vacuum conditions, it was found that current densities of methanol oxidation measured at 0.5 V vs RHE can be correlated with the Pd 4d band vacancy. It was observed that the methanol oxidation current density increases as the Pd 4d band vacancy becomes larger, in a way similar to what was observed for methanol oxidation in acid solution on Pt-Ru catalysts [1,2]. In situ Fourier transform infrared spectroscopy (in situ FTIR) experiments were performed in order to determine the distribution of reaction products as a function of the applied potential. In a general manner, data showed the formation of formate and the presence of small amounts of adsorbed CO between 0.3 and 0.7 V. The formation of CO2was only observed above 0.7 V as result of the acidification of the thin layer of solution in contact with the catalyst that is caused by the production of protons during methanol oxidation. Acknowledgments Thanks are due to the Brazilian Agencies FAPESP (2014/12255-6; 2013/50206-4; 2013/01822-4) and CNPq (407143/2013-0) for financial support and fellowships. Thanks are also due to the Brazilian Synchrotron Light Laboratory (LNLS) for assisting XAS measurements.

Preparation and electrocatalytic oxidation performance of Pt/MnO2–graphene oxide nanocomposites

A simple and eco-friendly approach was developed to prepare manganese dioxide functionalized reduced graphene oxide supported Pt nanocomposites (Pt/MnO2–RGO) via chemical reduction process. The morphology and structure of as-prepared catalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR) and X-ray diffraction (XRD). Subsequently, electrochemical properties of catalysts were systematically investigated by cyclic voltammetry (CV). As a result, the ultrafine Pt nanoparticles with an average diameter of 2.9nm were uniformly dispersed on the MnO2–RGO surface. The Pt/MnO2–RGO catalysts exhibited the superior electrochemical active surface area (79.4m2g−1) and specific peak current density for methanol oxidation (24.7mAcm−2), compared to Pt/reduced graphene oxide (Pt/RGO) and Pt/carbon black (Pt/CB). The improved electrocatalytic activity was mainly attributed to the better dispersion of Pt nanoparticles as well as the synergistic effect of the modified supports.

Direct synthesis of few-layer graphene supported platinum nanocatalyst for methanol oxidation

High-crystalline few-layer graphene supported Pt nanoparticles have been synthesized by arc discharge evaporation of carbon electrodes containing Pt element. A high-temperature treatment under hydrogen atmosphere has been carried out to obtain a new type of Pt/graphene catalyst for methanol oxidation in direct methanol fuel cell. The morphology and structure characterizations of as-grown few-layer graphene supported Pt nanoparticles and Pt/graphene catalysts have been studied by Raman spectroscopy, scanning electron microscopy with energy-dispersive spectroscopy, and high-resolution transmission electron microscopy. Cyclic voltammograms and chronoamperometric curves show that our present Pt/graphene catalysts have larger current density for methanol oxidation, higher tolerance to carbon monoxide poisoning, and better stability during the operating procedure, compared to commercial Pt/C catalysts.

Enhanced Catalytic Efficiency and CO Tolerance of Novel Pt Nanostructures Prepared by Pulsed Electrodeposition for Methanol Oxidation

Innovative platinum (Pt) nanostructures were developed in this study for enhancing the anode catalyst activities for proton exchange membrane fuel cell application. The platinum nanostructures were directly grown on carbon paper by a pulsed electrodeposition technique. The morphology of Pt nanostructures shown as dendritic structures. The sizes of the dendritic structures are 2-4 μm in length. A cyclic voltammetry analysis was carried out for characterizing the behavior of methanol oxidation on specimen bearing the Pt dendritic nanostructures. It was found that the peak current density of methanol oxidation was 277.5 mA/cm2. Due to its unique morphology, the Pt dendritic nanostructures could exhibit a good carbon monoxide tolerance and high efficiency without the joined Ruthenium catalyst. It is noteworthy that the if/ib value of the Pt dendritic nanostructures is higher than 1.4. The catalytic efficiency of prepared Pt dendritic nanostructures was much better than that of a commercial Pt-black catalyst.

One-step synthesis of nanocrystalline TiO2-coated carbon nanotube support for Pt electrocatalyst in direct methanol fuel cell

One-step synthesis of nanocrystalline TiO2-coated carbon nanotube (TiO2/CNT) was conducted using a non-boiling isothermal hydrolyzing process without post-heating treatment for crystallization, followed by dispersed Pt nanoparticles (NPs) on it employing a conventional microwave-assisted ethylene glycol method. The coating of TiO2 was thin and uniform, Pt NPs homogeneously dispersing on the surface of TiO2. The TiO2/CNT supported Pt electrocatalyst exhibited an excellent electrocatalytic performance toward methanol oxidation. Especially under UV irradiation, the peak current density of methanol oxidation jumped up to 4.65mA cm−2, about 2.5 times as that in the dark. The excellent performance was mainly ascribed to the synergistic effect between Pt and anatase TiO2.

Graphene-Manganite-Pd Hybrids as Highly Active and Stable Electrocatalysts for Methanol Oxidation and Oxygen Reduction

Hybrids of graphene nanosheets (GNSs) with Pd and MMn2O4 (M=Mn & Co) have been prepared and investigated as electrocatalysts for the methanol oxidation (MOR) and oxygen reduction (ORR) reactions in 1M KOH at 25°C. Results show that incorporation of Mn3O4 (or CoMn2O4) into 40wt%Pd/GNS increases the electrocatalytic activity toward both the reactions (MOR and ORR) greatly; the observed enhancement in the activity being much higher with CoMn2O4 addition. It is observed that at an anodic potential, E=0.610V vs RHE, 8wt% CoMn2O4 addition improves the methanol oxidation current density of 40wt%Pd/GNS by more than 3 times. Similarly, at E=0.90V vs RHE, 5wt% CoMn2O4 addition improves the ORR activity of 40wt%Pd/GNS nearly two times. The stability of the active hybrid electrode is also found to be outstanding under both MOR and ORR conditions. Similar stabilities have not been found with other fuel cell catalysts. In a chronoamperometry experiment at E=0.626V vs RHE, the methanol oxidation current observed on Pd-8%CoMn2O4/GNS at 2min decreased by only ∼5% at 120min.

Enhanced Catalytic Efficiency and CO Tolerance of Novel Pt Nanostructures Prepared By Pulsed Electrodeposition for Methanol Oxidation

Innovative support-free platinum (Pt) nanostructures were developed in this study for enhancing the anode catalyst activities for proton exchange membrane fuel cell (PEMFC) application. The platinum nanostructures were directly grown on carbon paper by a pulsed electrodeposition technique. The morphology of Pt nanostructures were investigated by SEM, and shown as dendritic structures instead of nanoparticles. The sizes of the dendritic structures are 2-4 μm in length and 400-600 nm in diameter. A cyclic voltammetry analysis was carried out for characterizing the behavior of methanol oxidation on specimen bearing the Pt dendritic nanostructures in mixed 1 M methanol and 0.5 M sulfuric acid solutions. It was found that the peak current density of methanol oxidation obtained from the cyclic voltammogram on the new Pt dendritic nanostructures specimen was 263 mA/cm2. Due to its unique morphology, the Pt dendritic nanostructures could exhibit a good carbon monoxide tolerance and high efficiency without the joined Ruthenium (Ru) catalyst. The catalytic efficiency of prepared Pt dendritic nanostructures was much better than that of a commercial Pt-black catalyst. It is noteworthy that the if/ib value of the Pt dendritic nanostructures is higher than 1.4, which is very different from pure Pt nanoparticles. The outcome signified that the novel catalyst morphology of the Pt dendritic nanostructures have remarkable CO tolerance even if Ru or other metal catalyst were not joined.

Enhanced methanol oxidation performance on platinum with butterfly-scale architectures: toward structural design of efficient electrocatalysts

Enhanced methanol oxidation performance was achieved by combining elaborate butterfly-scale architectures into platinum electrocatalysts using an electroless deposition-detemplating method. The electrochemically active surface area and the forward peak current density for methanol oxidation were dramatically increased by 5 and 5.2 times, respectively, for lamellar-ridge architectured Pt compared to its unarchitectured counterpart. Excellent mass transport properties and efficient catalytic surface accessibility were further demonstrated by finite element simulation.

Palladium Nanoparticles Loaded on Carbon Modified TiO2 Nanobelts for Enhanced Methanol Electrooxidation

AbstractCarbon modified TiO2nanobelts (TiO2-C) were synthesized using a hydrothermal growth method, as a support material for palladium (Pd) nanoparticles (Pd/TiO2-C) to improve the electrocatalytic performance for methanol electrooxidation by comparison to Pd nanoparticles on bare TiO2nanobelts (Pd/TiO2) and activated carbon (Pd/AC). Cyclic voltammetry characterization was conducted with respect to saturated calomel electrode (SCE) in an alkaline methanol solution, and the results indicate that the specific activity of Pd/TiO2-C is 2.2 times that of Pd/AC and 1.5 times that of Pd/TiO2. Chronoamperometry results revealed that the TiO2-C support was comparable in stability to activated carbon, but possesses an enhanced current density for methanol oxidation at a potential of −0.2 V vs. SCE. The current study demonstrates the potential of Pd nanoparticle loaded on hierarchical TiO2-C nanobelts for electrocatalytic applications such as fuel cells and batteries.

Carboxylic Graphene-Supported Platinum and Platinum-Palladium Nanoparticles with High Electrocatalytic Activity for Methanol Oxidation

Pt, Pd and Pt-Pd nanoparticles (NPs) were synthesized on carboxylic graphene (CGR) sheets. The nanocomposites were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR) and UVvis absorption spectroscopy. Their electrocatalytic activity for methanol oxidation was also investigated. The results showed the peak current density of methanol oxidation of Pt NPs-Graphite oxide (GO), Pd NPs-CGR, Pt NPs-CGR and Pt-Pd NPs-CGR is 12.2μA/cm2, 14.1μA/cm2, 15.1μA/cm2and 21.5μA/cm2respectively. The nanocomposite of CGR as catalyst supports and Pt-Pd NPs as catalyzers is promising for direct methanol fuel cells.