Stability For Methanol Oxidation Reaction Research Articles

Electrochemical fabrication of platinum nanoflakes on fulleropyrrolidine nanosheets and their enhanced electrocatalytic activity and stability for methanol oxidation reaction

Pyridine-functionalized fulleropyrrolidine nanosheets are prepared by a fast reprecipitation method under ultrasonication, and used as a novel nanostructured support materials to fabricate Pt catalyst nanoflakes by a simple electrodeposition approach. The as-prepared novel Pt-fullerene hybrid catalyst (Pt/PyC60) exhibits much enhanced electrocatalytic activity and stability for methanol oxidation reaction compared to the unsupported Pt nanoflakes and commercial Pt/C. The introduction of nanostructured fulleropyrrolidine as new support materials not only increases the electrochemically active surface area of catalyst, but also significantly improves the long-term stability. This will contribute to developing functionalized fullerenes as new nanostructured support materials for advanced electrocatalysts in fuel cells.

Impact of Ultrasonic Waves in Direct Electrodeposition of Nanostructured AuPt Alloy Catalyst on Carbon Substrate: Structural Characterization and Its Superior Electrocatalytic Activity for Methanol Oxidation Reaction

We have successfully developed a facile, fast, and efficient synthetic methodology for direct fabrication of stable AuPt alloy nanostructure catalyst on Toray carbon (TC) as well as glassy carbon substrates without involving any additional stabilizer or surfactant through ultrasonic-wave-assisted electrodeposition (USA-ED) using simple Au and Pt metal salt precursors in electrolyte solution. To know the real effect of ultrasonic waves on deposited particles, the same experimental methods also followed without ultrasonic waves. Size, morphology, surface composition, and surface structure of AuPt alloy nanostructures were investigated by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS), and cyclic voltammetric techniques. The observed results clearly reveal that the USA-ED method yields densely packed Pt-rich AuPt alloy nanostructure, which is a more active electrocatalyst for methanol oxidation, whereas the normal (i.e., without ultrasonic wave) ED method shows loosely packed homogeneous alloy AuPt nanostructure, which is very poor for methanol oxidation. More significantly, USA-ED of Pt-rich AuPt alloy nanostructured surface showed profound enhancement of both electrocatalytic activity and long-term stability of methanol oxidation when compared to ED of Pt nanoparticles, USA-ED of Pt nanoparticle surfaces, and also state-of-the-art commercial electrocatalysts with 30 wt % loading of Pt/C (E-TEK). These obtained results confirm that our synthetic methodology of USA-ED is effective for preparing Pt-rich AuPt alloy nanostructured electrocatalyst with excellent activity and stability in methanol oxidation reaction.

Facile synthesis of platinum–gold alloyed string-bead nanochain networks with the assistance of allantoin and their enhanced electrocatalytic performance for oxygen reduction and methanol oxidation reactions

In this work, a facile one-pot wet-chemical method is developed for preparation of bimetallic platinum–gold (Pt–Au) alloyed string-bead nanochain networks, using allantoin as a structure-directing agent, without any template, surfactant, or seed. The characterization experiments are mainly performed by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) spectroscopy. The as-prepared Pt–Au nanocrystals show enhanced electrocatalytic performance toward oxygen reduction reaction (ORR) mainly predominated by a four-electron pathway, and display improved catalytic activity and high stability for methanol oxidation reaction (MOR) over commercial Pt black and Pt–Ru black.

Novel-Phase Structural High-Efficiency Anode Catalyst for Methanol Fuel Cells: α-(NiCu)3Pd Nanoalloy

An approach has been explored to highly improve the catalytic activity and stability for methanol oxidation reaction (MOR) by using dominant α-(NiCu)3Pd phase-structural NiCuPd nanoparticles (NPs) as anode catalysts. The NiCuPd alloy NPs are monodispersed with the diameter of ∼10 nm and have been prepared by the reduction of Pd(acac)2, Ni(acac)2, and Cu(acac)2 following alloying growth process. In the Ni–Cu–Pd alloy system, Ni atoms fused in Cu3Pd phase to form α-(NiCu)3Pd phase together with NiCuPd solid solution phase. As Ni concentration gradually enriched, the crystallinity of α-(NiCu)3Pd became higher, while its percentage decreased by one degree. Owing to the synergistic effect between components and facet atom arrangement, the catalytic activity and stability of NiCuPd NPs can be adjusted toward the MOR in alkaline media. The maximized crystallinity of α-(NiCu)3Pd results in the largest catalytic activity. Compared with commercial Pd/C with (111) facets, α-(NiCu)3Pd phase with (117) facets afforded...

One-step microwave synthesis of Pt (Pd)/Cu2O/GNs composites and their electro-photo-synergistic catalytic properties for methanol oxidation

A facile one-pot method was used to synthesize Pt/Cu2O/GNs and Pd/Cu2O/GNs composites. Pt or Pd nanoparticles are deposited onto graphene sheets (GNs) and Cu2O via synchronous reduction of K2PtCl4 (K2PdCl4), Cu(OH)2 and graphene oxide (GO) with glucose as a reducing agent under microwave irradiation. The formation of Cu2O promotes the nucleation of Pt(0) or Pd(0) particles and favors more complete reduction of PtCl42− or PdCl42−. Catalytic properties of as-prepared composites for methanol oxidation reaction (MOR) were evaluated by cyclic voltammetry (CV), chronoamperometry, COads stripping voltammetry and electrochemical impedance spectrum (EIS). Electrochemical experiments showed that Pt/Cu2O/GNs and Pd/Cu2O/GNs had much higher catalytic activity and stability for MOR and better resistance to CO poisoning compared with the commercially available Johnson Matthey 20% Pt/C catalyst (Pt/C-JM) and Sigma-Aldrich 20% Pd/C catalyst (Pd/C-SA). Especially under the UV irradiation, the total peak current density and catalytic stability of Pt/Cu2O/GNs and Pd/Cu2O/GNs drastically increase, which may result from the synergistic effect between the electro-catalytic and photo-catalytic properties. In brief, the cooperation among Pt (Pd), Cu2O and GNs promotes remarkably the catalytic performance for MOR on Pt/Cu2O/GNs and Pd/Cu2O/GNs either without light or with UV irradiation.

Caffeine-assisted facile synthesis of platinum@palladium core-shell nanoparticles supported on reduced graphene oxide with enhanced electrocatalytic activity for methanol oxidation

A facile, rapid, and wet-chemical co-reduction method is developed for synthesis of platinum@palladium core-shell nanoparticles supported on reduced graphene oxide (denoted as Pt@Pd/RGO) with the assistance of caffeine, without any seed or template. Caffeine is used here as a structure-directing agent and a capping agent, which is critical to the formation of Pt@Pd core-shell nanoparticles. Furthermore, the as-synthesized Pt@Pd/RGO shows the enlarged electrochemically active surface area, remarkably enhanced catalytic activity, and improved stability for methanol oxidation reaction (MOR), compared to Pt/RGO, Pd/RGO, commercial Pt black and Pd black.

Tuning the Electronic Structure of Titanium Oxide Support to Enhance the Electrochemical Activity of Platinum Nanoparticles

Two times higher activity and three times higher stability in methanol oxidation reaction, a 0.12 V negative shift of the CO oxidation peak potential, and a 0.07 V positive shift of the oxygen reaction potential compared to Pt nanoparticles on pristine TiO2 support were achieved by tuning the electronic structure of the titanium oxide support of Pt nanoparticle catalysts. This was accomplished by adding oxygen vacancies or doping with fluorine. Experimental trends are interpreted in the context of an electronic structure model, showing an improvement in electrochemical activity when the Fermi level of the support material in Pt/TiOx systems is close to the Pt Fermi level and the redox potential of the reaction. The present approach provides guidance for the selection of the support material of Pt/TiOx systems and may be applied to other metal-oxide support materials, thus having direct implications in the design and optimization of fuel cell catalyst supports.

Enhancing the catalytic activity of Pt nanoparticles using poly sodium styrene sulfonate stabilized graphene supports for methanol oxidation

Pt NPs were in situ synthesised on poly(sodium styrene sulfonate) functionalized graphene supports (PSS–G) in aqueous solution. We investigate the reduction of graphene oxide, PSS adsorption on reduced graphene, and Pt NP functionalization by X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure studies (XAFS), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy. The as-prepared Pt on PSS–G sample (Pt–PSS–G) was used directly as a catalyst ink without further treatment. The use of PSS as a stabilizer prevents stacking of reduced graphene sheets, binds Pt NPs, and promotes mass transport of reaction species. The as-prepared Pt–PSS–G exhibits higher activity and stability for methanol oxidation reaction than Pt NPs supported on pristine graphene sheets (Pt–G). The higher activity is due to the presence of Pt NPs on the surface of the PSS–G support, which provides an integrated electron and mass transport pathway for every Pt NP. This work realizes both scalable and greener production of highly efficient catalysts, and would be valuable for practical applications of graphene based fuel cell catalysts.

Highly stable and active PtNiFe dandelion-like alloys for methanol electrooxidation

Novel PtNiFe dandelion-like alloys are fabricated by a facile etching strategy. The ternary alloys and single-walled carbon nanotube (SWNT) immobilized PtNiFe alloys exhibit high activity and poison tolerance with remarkable stability for methanol oxidation reaction (MOR). The excellent electro-catalytic performance is ascribed to the unique dandelion-like nanostructure.

Synthesis of Ultrathin FePtPd Nanowires and Their Use as Catalysts for Methanol Oxidation Reaction

We report a facile synthesis of ultrathin (2.5 nm) trimetallic FePtPd alloy nanowires (NWs) with tunable compositions and controlled length (<100 nm). The NWs were made by thermal decomposition of Fe(CO)(5) and sequential reduction of Pt(acac)(2) (acac = acetylacetonate) and Pd(acac)(2) at temperatures from 160 to 240 °C. These FePtPd NWs showed composition-dependent catalytic activity and stability for methanol oxidation reaction. Among FePtPd and FePt NWs as well as Pd, Pt, and PtPd nanoparticles (NPs) studied in 0.2 M methanol and 0.1 M HClO(4) solution, the Fe(28)Pt(38)Pd(34) NWs showed the highest activity, with their mass current density reaching 488.7 mA/mg Pt and peak potential for methanol oxidation decreasing to 0.614 V from 0.665 V (Pt NP catalyst). The NW catalysts were also more stable than the NP catalysts, with the Fe(28)Pt(38)Pd(34) NWs retaining the highest mass current density (98.1 mA/mg Pt) after a 2 h current-time test at 0.4 V. These trimetallic NWs are a promising new class of catalyst for methanol oxidation reaction and for direct methanol fuel cell applications.