Design and synthesis of Pd decorated rGO-MoSe2 2D hybrid network as high performance electrocatalyst toward methanol electrooxidation

Direct methanol fuel cells (DMFCs) have attracted profound interest for development of future green energy sources, which are being powered by methanol as a fuel. The critical problem identified with DMFCs is the deactivation of electrocatalysts resulting from the adsorption of CO during methanol oxidation. In this work, we have employed a new synthetic approach by a green microwave method for the synthesis of hybrid Pd-MoSe₂-rGO and Pd-rGO nanocomposites. The synthesized electrocatalysts were successfully characterized by XRD, which is used to identify the crystalline phases, FESEM and TEM analyses for morphological features, XPS for analyzing the elements constituting the composites surface and Raman spectroscopy for the analysis of molecular structural bonding. Electrocatalytic activity was explored by cyclic voltammetry (CV), chronoamperometry (CA) and CO stripping techniques. Electroactive surface area (EASA) of the developed hybrid electrocatalyst Pd-MoSe₂-rGO (51.81 m² g⁻¹_Pd) was more than 3.4 times superior activity than that of Pd-rGO catalyst (15.30 m² g⁻¹_Pd). It was observed that the synthesized catalyst with 3D cross-linked hybrid network facilitated even distribution of metal nanoparticles and exhibited nearly four times enhanced electrocatalytic activity (1935 mA mg⁻¹_Pd) towards methanol oxidation reaction (MOR) in alkaline medium, compared to Pd-rGO (546 mA mg⁻¹_Pd). Under constant applied potential investigations, catalytic activity of Pd-MoSe₂-rGO was nearly 50 times higher than that of Pd-rGO at the end of about 1 h. The ease of the availability of more active sites and high tolerance against CO poisoning resulted by the insertion of MoSe₂ led to enhanced catalytic activity of Pd-MoSe₂-rGO towards MOR. It is conceived that this synthetic strategy by employing a combination of 2D materials like MoSe₂, graphene and Pd nanoparticles together as building blocks for 3D hybrid network led to efficient electrocatalysts with high surface area and long-term stability towards methanol oxidation. This synthetic strategy exhibits a promising prospect to develop durable and stable electrocatalyst for DMFC applications.     

Methanol electro-oxidation reaction at the interface of (bi)-metallic (PtNi) synthesized nanoparticles supported on carbon Vulcan

Ni-rich PtNi bi-metallic catalyst and its counterpart free of nickel supported on carbon Vulcan have been synthesized by the impregnation methodology from Na₂PtCl₆ and Ni(C₅H₇O₂)₂ as precursors. The obtained materials Pt/C and PtNi/C were used as electrocatalysts for the methanol oxidation reaction (MOR) in acid conditions. Electrochemical evaluations demonstrated that the addition of Ni in the Pt-Vulcan matrix promotes an important increment in the faradic current during MOR of one order of magnitude, even though the platinum load is lower in the bi-metallic catalyst. These results suggest that the incorporation of nickel promotes some structural and electronic modifications that enhance a better reaction performance at the electrode interface. Morphological characterization using scanning electron microscopy and transmission electron microscopy with energy dispersive spectroscopy (SEM-TEM-EDS) showed Pt/C and PtNi/C catalysts have a particle size of 5.7 nm and 4.4 nm, respectively. X-ray diffraction (XRD) reveals the formation of Ni₃Pt from the synthesis of PtNi catalysts. Additionally, X-ray photoelectron spectroscopy (XPS) confirmed the presence of Pt and Ni in their metallic-oxidation states on the carbon surface.     

Preparation of PtNi hollow nanospheres for the electrocatalytic oxidation of methanol

We report the synthesis and characterization of hollow PtNi nanospheres by chemical successive-reduction method. The results of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) account for the alloy formation between Pt and Ni and electronic structure change of Pt in the alloy. The prepared nanospheres show a high activity and stability for electrocatalytic oxidation of methanol as compared to the commercial Pt/C catalyst and the co-reduced PtNi nanoparticles. The reasons of the high electrocatalytic activity of the hollow PtNi nanospheres were discussed.     

Tungsten(VI) oxide as a versatile support for Pd nanocatalysts for alkaline direct alcohol fuel cells

The instability of carbon support materials has motivated the development of metal oxides supports which are stable under the fuel cell environment. In this study, tungsten (VI) oxide (WO₃) is utilized as a secondary support and cocatalyst for the electrooxidation of methanol and ethanol. Functionalized carbon nanodots employed as primary supports were blended with WO₃ nanoparticles to form a composite support onto which Pd nanoparticles were deposited by a borohydride reduction method. The synthesized Pd/fCNDs-WO₃ electrocatalysts were characterized by Transmission Electron microscopy (TEM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy. XRD results proved that incorporating WO₃ into Pd/fCNDs electrocatalyst shifts the Pd diffraction peaks to lower 2Ɵ value due to lattice relaxation. XPS results revealed that W exist in oxidised form and confirmed the strong interaction between the support material and the catalyst. The Pd/fCNDs-WO₃ electrocatalysts exhibited a remarkable catalytic activity towards methanol and ethanol oxidation. High current densities of 87.24 mA cm⁻² and 44.23 mA cm⁻² were obtained for ethanol and methanol oxidation, respectively, using a catalyst with 2.5% Pd loading. EIS, CA and stability tests revealed that the presence of WO₃ in Pd/fCNDs electrocatalyst improves the kinetics, tolerance to poisoning and long-term durability in alkaline conditions. This superior performance is attributed to the electronic coupling between Pd and WO₃ nanoparticles.     

Pt support of multidimensional active sites and radial channels formed by SnO2 flower-like crystals for methanol and ethanol oxidation

SnO₂ nanoflowers and nanorods have been synthesized by the hydrothermal method without using any capping agent. Both types of SnO₂ nanostructures are selected as a support of Pt catalyst for methanol and ethanol electrooxidation. The synthesized SnO₂ nanostructures and SnO₂ supported platinum (Pt/SnO₂) catalysts are characterized by X-ray diffraction, scanning electron microscope and high resolution transmission electron microscope. The electrocatalytic properties of the Pt/SnO₂ and Pt/C catalysts for methanol and ethanol oxidation have been investigated systematically by typical electrochemical methods. The influence of SnO₂ morphology on its electrocatalytic activity is comparatively investigated. The Pt/SnO₂ flower-shaped catalyst shows higher electrocatalytic activity and better long-term cycle stability compared with other electrocatalysts owing to the multidimensional active sites and radial channels of liquid diffusion.     

The potential of novel carbon nanocages as a carbon support for an enhanced methanol electro-oxidation reaction in a direct methanol fuel cell

In this study, we introduce the potential for a new catalyst support, namely, carbon nanocages (CNCs) for anodic direct methanol fuel cell (DMFC). The synthesis, characterization and catalytic activities of four electrocatalysts, PtRu/CNC, PtNi/CNC, PtFe/CNC and PtCo/CNC, have been investigated. These electrocatalysts are synthesized using pyrolysis, followed by a microwave-assisted ethylene glycol reduction method. From X-ray diffraction analysis, PtNi/CNC and PtRu/CNC showed the smallest crystallite particle size of Pt-alloy, which corresponded to the (111) plane. The Raman spectra confirmed the presence of the carbon support material in all prepared electrocatalysts. The ratio value of the D band and G band (I_D/I_G) of all prepared samples was not much different within the electrocatalyst and CNC. The I_D/I_G values calculated for the CNC, PtNi/CNC, PtRu/CNC, PtCo/CNC and PtFe/CNC electrocatalysts were 0.90, 0.89, 0.83, 0.78 and 0.77, respectively. Therefore, the number of defects of graphitization in increasing order (I_D/I_G) was PtFe/CNC < PtCo/CNC < PtRu/CNC < PtNi/CNC < CNC. Brunauer-Emmett-Teller analysis revealed that the CNC support has a mesoporous-type structure with a high surface area of 416 m² g⁻¹, which indicates that this support has a high potential to act as an excellent catalyst support. From the cyclic voltammetry curve, PtRu/CNC showed the highest catalytic activity in methanol electro-oxidation and reached a value of 427 mA mg⁻¹, followed by PtNi/CNC (384.11 mA mg⁻¹), PtCo/CNC (150.53 mA mg⁻¹) and PtFe/CNC (144.11 mA mg⁻¹). PtFe/CNC exhibited a higher ratio value of I_f/I_b (3.24) compared with PtRu/CNC (2.34), PtNi/CNC (1.43) and PtCo/CNC (1.62). These values show that the combination of Pt and Fe catalysts in PtFe/CNC had better CO tolerance than PtRu/CNC, PtNi/CNC and PtCo/CNC electrocatalysts. The higher performance of PtRu/CNC was attributed to the fact that it had the smallest bimetallic-Pt crystallite; there was a smooth distribution of bimetallic-Pt on its CNC support, as shown by field emission scanning electron microscopy; it had the highest electrochemical surface area value (16.23 m² g⁻¹); and it had an overall catalytic performance enhanced by the advantages of the unique and large surface area from the CNC as support material. In passive DMFC mode, PtRu/CNC showed a maximum power density of 3.35 mW cm⁻², which is 1.72 times higher than that of the PtRu/C commercial electrocatalyst.     

The formation of wrapping type Pt–Ni alloy on three-dimensional carbon nanosheet for electrocatalytic oxidation of methanol

In this paper, the PtNi alloy was embedded into the surface layer of three-dimensional carbon nanosheets (CNSs) with a special layered structure. We controllably adjusted the ratio of Pt/Ni to form large particle alloy with Pt coating Ni and a small number of hollow PtNi alloy pellets. The electro-catalytic methanol oxidation activity and durability of the catalysts were estimated by cyclic voltammetry and chronoamperometric techniques. The results indicated that the doping of Ni effectively improved the activity and anti-poisoning of the catalyst in the methanol electrocatalytic oxidation reaction (MOR). Transmission electron microscopy (TEM), Raman spectroscopy, nitrogen adsorption-desorption techniques, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to explore the composition, morphology and structure of these catalysts. It is discovered that the Pt–Ni/CNSs (2:1) sample exhibits the best MOR activity with a peak current density of 15.03 mA cm^?2 at the forward scan due to the excellent lamellar structure, good crystallinity and abundant pore structure of CNSs, which is benefit to form ultrahigh specific surface area, superb electron and ionic conductivity.     

Platinum-antimony doped tin oxide nanoparticles supported on carbon black as anode catalysts for direct methanol fuel cells

Antimony doped tin oxide supported on carbon black (ATO/C) has been synthesized using an in situ co-precipitation method, and platinum-ATO/C nanoparticles have been prepared using a consecutive polyol process to enhance the catalyst activity for the methanol oxidation reaction. The Pt-ATO/C electrocatalyst is characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microcopy (SEM), energy dispersive X-ray spectroscopy (EDS) and cyclic voltammetry. The Pt-ATO/C catalyst exhibits a relatively high activity for the methanol oxidation reaction compared to Pt-SnO₂/C or commercial Pt/C catalyst. This activity can be attributed to the high electrical conductivities of the Sb-doped SnO₂, which induces the electronic effects with Pt catalysts. Pt-ATO/C is a promising methanol oxidation catalyst with high activity for the reaction in direct methanol fuel cells.     

An advantageous method for methanol oxidation: Design and fabrication of a nanoporous PtRuNi trimetallic electrocatalyst

In this study, an advantageous method of methanol oxidation is developed using a nanoporous structured PtRuNi trimetallic catalyst fabricated by dealloying Ni from a high Ni-content PtRuNi alloy precursor. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) are used for catalyst characterization. The nanoporous PtRuNi trimetallic catalyst shows enhanced CO oxidation, higher activity and better stability than solid commercial PtRu/C catalyst. The method developed in this study is well suited to synthesize other high performance, nanoporous-structured, multimetallic electrocatalysts for fuel cells.     

Platinum nanoparticles anchored on aminated silica@PEDOT-PSS hybrid for enhanced methanol oxidation electrocatalysis

Direct methanol fuel cell (DMFC) with near-zero pollution emission, large energy density, and low operating temperature provides a beneficial and sustainable way for alleviating fossil energy crisis and ecological pollution issues. In this work, a systematic protocol was explored for the design of novel electrocatalyst based on PEDOT-PSS coated amino-functionalized SiO₂ microspheres (SiO₂–NH₂@PEDOT-PSS) support, and then Pt nano-particles (NPs) were uniformly anchored for the anodic process of DMFCs. Characterization techniques, e.g. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed that the dispersity and homogeneity of Pt NPs on the surface of SiO₂–NH₂@PEDOT-PSS were markedly improved due to PEDOT-PSS modification, and the distribution of Pt NPs was in a smaller mean-size ~2.8 nm. Subsequently, X-ray photoelectron spectroscopy (XPS) study exposed fast electron shift phenomenon from SiO₂–NH₂@PEDOT-PSS support to Pt NPs in the catalyst. The various electrochemical tests such as cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (EIS) revealed that the prepared Pt/SiO₂–NH₂@PEDOT-PSS catalyst presented higher electrocatalytic efficacy, excellent durability with improved CO-tolerance towards methanol oxidation reaction rather than commercial Pt/C catalyst. These distinctive physical and chemical features of designed catalyst raise the spirit to design an efficient electrocatalyst based on Pt/SiO₂–NH₂@PEDOT-PSS in DMFC applications.     

Ultrafine palladium nanoparticles anchored on NH2-functionalized reduced graphene oxide as efficient catalyst towards formic acid dehydrogenation

The development of active and stable catalyst is of significance for hydrogen generation from formic acid. Herein, a novel palladium catalyst with ultrafine metallic nanoparticles anchored on NH₂-functionalized reduced graphene oxide (NH₂-rGO) was synthesized by a facile wet chemical reduction process using sodium borohydride as the reducing agent. The TEM and XPS characterization results confirmed the successful functionalization of rGO with 3-aminopropyltriethoxysilane (APTES), which plays a very important role in evenly dispersing ultrafine Pd nanoparticles with a small average size of about 2.3 nm. As a result, the as-prepared Pd/NH₂-rGO catalyst exhibited excellent activity with a high initial turnover frequency of 767 h⁻¹ and 100% hydrogen selectivity, which was predominant among the currently available pure Pd catalysts towards formic acid dehydrogenation under room temperature.     

Highly efficient methanol electrooxidation catalyzed by co-action of PdY2O3 in alkaline solution for fuel cells

Catalytic activity improvement by Pd-based catalyst for methanol oxidation is significant to the development of alkaline direct methanol fuel cells. Herein, we demonstrate the performance of methanol oxidation on Pd catalyst could be greatly increased by Y₂O₃. The promotion effect is discussed with the help of physical and electrochemical characterization techniques by comparing with a home-made Pd/C catalyst in the identical condition. The presence of Y₂O₃ in the system is well confirmed by the characteristic peaks indicated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy(XPS); and a strong electronic effect between the Pd and Y₂O₃ is reflected by an evident shift of binding energy to the lower direction as shown in the XPS spectrum. The catalytic activity expressed by current density reveled by cyclic voltammetry is about 145 mA cm^?2, 1.5 times higher than that of the reference catalyst; current retaining ability of 5 times higher than that of the reference catalyst is revealed by Chronoamperometry. Higher catalytic activity and stability for methanol oxidation is discussed due to the relatively well dispersed Pd particle size, increased electroactive surface area and the synergistic interaction of Pd and Y₂O₃. The work demonstrates the hybrid PdY₂O₃/C as a newly effective catalyst for alkaline direct methanol fuel cells.     

Electrochemically synthesized polypyrrole/MWCNTs-Al2O3 ternary nanocomposites supported Pt nanoparticles toward methanol oxidation

As known, a good support enhances the activity and durability of any catalyst. In the current study, polypyrrole (PPY)/nanocomposite (MWCNTs and Al₂O₃) films were fabricated by electrochemical polymerization of pyrrole solution with a certain amount of nanoparticles on titanium substrates and were used as new support materials for Pt catalyst. The modified electrodes were characterized by Fourier transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX) techniques. High catalytic activity and long-time stability toward methanol oxidation of Pt/PPY–MWNTs-αAl₂O₃ catalyst have also been verified by cyclic voltammetry results and chronoamperometric response measurements. This catalyst exhibits a vehemently high current density (345.03 mA cm^?2) and low peak potential (0.74 v) for methanol oxidation. Other electrochemical measurements (electrochemical impedance spectroscopy (EIS), CO stripping voltammetry and Tafel test) clearly confirmed that Pt/PPY–MWNTs-αAl₂O₃/Ti electrode has a better performance toward methanol oxidation compared to the other electrodes and that can be used as a promising electrode material for application in direct methanol fuel cells (DMFCs).     

Three dimensional nitrogen,phosphorus and sulfur doped porous graphene as efficient bifunctional electrocatalysts for direct methanol fuel cell

The development of efficient and durable bifunctional catalysts for oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) is desirable but remains a great challenge. Herein, a series of new three-dimensional (3D) nitrogen, phosphorus and sulfur doped porous graphene (NPS G) were fabricated by facile and cost-effective strategy, as efficient bifunctional electrocatalysts for direct methanol fuel cell. To obtain superior ORR and MOR bifunctional catalytic activities, we optimized the doping amount of nitrogen, phosphorus and sulfur in catalysts. The resulting metal-free NPS G₂ catalyst had a long-term stability, desirable four electron pathway and excellent methanol poisoning tolerance. Moreover, NPS G₂ exhibited higher onset potential compared to other metal-free NPS G, and close to commerical Pt/C catalyst current density under the same conditions. In addition, a series of NPS G used as good supports for Pt nanoparticles. Pt/NPS G₂ catalyst displayed remarkable electrochemical performance, better cyclic stability and tolerance in methanol electrooxidation reaction.     

Pt nanoparticles supported on titanium iron nitride nanotubes prepared as a superior electrocatalysts for methanol electrooxidation

Titanium iron nitride (Ti_0.95Fe_0.05N) supports with one-dimensional (1D) hollow and porous nanotubes(Ti_0.95Fe_0.05N NTs)are prepared by a two-step method, including hydrothermal method followed post-nitriding treatment. Pt nanoparticles (NPs) are further supported on Ti_0.95Fe_0.05N NTs for methanol electrooxidation. The experimental results reveal that the prepared material is Ti_0.95Fe_0.05N NTs with high purity, and this support is characterized by a porous tubular structure with hollow walls and large specific surface area. The X-ray photoelectron spectroscopy (XPS) pattern shows the strong interaction between the robust Ti_0.95Fe_0.05N NTs support and uniform Pt NPs catalyst. In addition, the electrochemical data demonstrate that Ti_0.95Fe_0.05N NTs loaded Pt NPs (Pt/Ti_0.95Fe_0.05N) display greatly improved activity and stability than that of Pt/C catalyst. The significantly enhanced durability of the hybrid electrocatalysts and electrochemical surface area (ECSA) preservation of the catalyst are observed after the accelerated durability test (ADT). The experimental data verify that the introducing of Fe can tune the electronic structure of Pt atoms, which contributes to the strengthened activity and stability of the Pt catalyst for the methanol oxidation reaction.     

A novel co-precipitation method for preparation of Pt-CeO2 composites on multi-walled carbon nanotubes for direct methanol fuel cells

Ceria (CeO₂) as co-catalytic material with Pt on multi-walled carbon nanotubes (Pt-CeO₂/MWCNT) is synthesized by a co-precipitation method. The physicochemical characterizations of the catalysts are carried out by using transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) techniques. Electrocatalytic activities of the catalysts for methanol oxidation is examined by cyclic voltammetry and chronoamperometry techniques and it is found that Pt-CeO₂/MWCNT catalysts exhibited a better activity and stability than did the unmodified Pt/MWCNT catalyst. CO-stripping results indicate the facile removal of intermediate poisoning species CO in the presence of CeO₂, which is helpful for CO and methanol electro-oxidation.     

Preparation and characterization of Pt nanoparticles supported on a Fe-doped hydroxyapatite-activated Vulcan XC72 composite material

In this research, the hydroxyapatite (HAp) could be directly deposited on carbon black (CB), which was the modified surface to generate more OH⁻ free radicals to strengthen the bond between HAp and CB, before adding ((NH₄)₂Fe(SO₄)₂·6H₂O) to engage the ion exchange with Fe²⁺ and Ca²⁺ to obtain FeHAp-CB composites. The Pt nanoparticles were then reduced on the FeHAp-CB composite surface to derive a Pt/FeHAp-CB catalyst of dual function. The catalyst revealed a steep desorption peak at −0.180 V (vs Ag/AgCl) in a hydrogen oxidation reaction ascribed to the characteristics of Pt (110) facet and the CO detoxication function in the methanol oxidation reaction. The superior performance of Pt/FeHAp-CB/CB catalyst was apparently related to the Pt (110) surface, the Fe concentration, and the homogeneous dispersion of Pt particles on the FeHAp-CB composites. And, the ratio of coexisting Pt⁰ and Pt²⁺ within Pt/FeHAp-CB/CB catalyst would definitely affect chemical stability and mass activity. By X-ray photoelectron spectroscopy (XPS), it was found that a high quantity of Pt⁰ could improve mass activity, while a high quantity of Pt²⁺ contributed to chemical stability.     

Controllable electrodeposition synthesis of Pd/TMxOy-rGO/CFP composite electrode for highly efficient methanol electro-oxidation

A novel and high-efficiency Pd/TM_xO_y-rGO/CFP (TM_xO_y = Co₃O₄, Mn₃O₄, Ni(OH)₂) electrocatalyst for directly integrated membrane electrode was synthesized by controllable cyclic voltammetry electrodeposition combined with hydrothermal process. The results showed excellent performance towards methanol oxidation reduction. The Pd/Co₃O₄-rGO/CFP as-prepared catalyst has the best electrocatalytic activity, and mass activity is 5181 mA·mg⁻¹_Pd, which is about 40 times and 4.3 times that of the commercial Pd/C and Pt/C catalyst (JM). It can be attributed that the small size of Pd nanoparticle, uniformity of distribution, and the synergistic interaction between transition metal oxide on the support surface and Pd nanoparticles. The prepared Pd/TM_xO_y-rGO/CFP composite electrode is a promising catalyst for integrated membrane electrode assembly of proton exchange membrane fuel cells in the future.     

Effect of noble metal species and compositions on manganese dioxide-modified carbon nanotubes for enhancement of alcohol oxidation

By integrating the effects of alloying, chemical composition and support, a series of mono- and bi-metallic catalyst nanoparticles electrodeposited on α-manganese dioxide (MnO₂)-modified carbon nanotube (CNT) supports were synthesized to improve the efficiency of direct alcohol fuel cells. Small and dispersed nanoparticles on the CNT/MnO₂ surfaces with high electrochemically active surface area (ECSA) were successfully obtained in this work. The support materials were characterized by Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD), while the as-prepared catalysts were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) and chronoamperometry (CA) were used to study the activity and stability of the catalysts, respectively. The results showed that a combination of Pt, Pd, Au and MnO₂ on the CNTs significantly affected the topography of the composite catalyst surfaces, and their electrochemical measurements showed excellent electrocatalytic activity toward the reaction. For methanol and ethanol oxidation in acid solution, CNT/MnO₂/1M3Pt (M = Pd or Au) catalysts revealed greater activity improvement compared to the other prepared catalysts. For the bimetallic CNT/MnO₂/xMyPt catalysts, the values of the forward peak current (I_f)) and the ratio of the forward peak current to the reverse peak current (I_f/I_b) were higher, while their onset potentials (E_o) were lower compared to those of the monometallic CNT/MnO₂/4Pt catalyst. Moreover, CO oxidation on these bimetallic catalysts was also confirmed to be poisoning resistant. These results indicate that our prepared catalyst showed excellent electrocatalytic performance, reliability, and stability. The catalytic activity improvement was based upon the unique integrated structural and functional properties and the synergistic effect of different compositions in the catalyst system.     

Nanoporous PtCo and PtNi alloy ribbons for methanol electrooxidation

Nanoporous (NP) PtCo and PtNi alloy ribbons with predetermined bimetallic compositions are easily fabricated by one step of mild dealloying, which are characterized by uniform three-dimensional bicontinuous network architecture with the ligament size as small as 3 nm. Compared with E-TEK Pt/C catalyst, the as-made NP-PtCo(Ni) alloys exhibit superior specific activity with the lower peak potential and enhanced CO-tolerance toward methanol electrooxidation. More importantly, these nanomaterials also show much higher structure stability with little loss of the electrochemical surface area of Pt upon 5000 potential cycles in acid solution. X-ray photoelectron spectroscopy and DFT calculations revealed that alloying with Co or Ni modifies the electronic structure of Pt with the downshift of Pt d-band center, thus resulting in the improved methanol oxidation activity and decreased CO poisoning.