Durability For Methanol Oxidation Research Articles

Enhancing methanol oxidation electrocatalysis by Pt/Mo2CTx-rGO ternary hybrid catalyst

Here we report a ternary hybrid catalyst, Pt/Mo2CTx-rGO, for the electrocatalysis of methanol oxidation in direct methanol fuel cells. Two-dimensional Mo2CTx MXene was used to modify reduced graphene oxide (rGO) to obtain a hybrid of Mo2CTx-rGO. Thereafter, ultrafine Pt nanoparticles were dispersed on the hybrid to make a ternary catalyst of Pt/Mo2CTx-rGO. The electrochemical performance of the catalyst was evaluated in 1 M H2SO4 and 2 M methanol electrolyte as a target analyte. Compared with commercial Pt/C, Pt/Mo2CTx-rGO demonstrated 1.5 times larger electrochemically active surface area, 1.9 times higher mass activity, and 33.6 % longer durability. This is because of the strong electronic interaction between Pt and Mo2CTx as well as the large surface area of rGO. This work reports a novel electrocatalyst with high activity and long durability for methanol oxidation, and explore a novel application of Mo2CTx MXene.

Core-Shell Structured PtxMoy@TiO2 Nanoparticles Synthesized by Reverse Microemulsion for Methanol Electrooxidation of Fuel Cells.

The high price of catalyst and poor durability still restrict the development of fuel cells. In this work, core-shell structured PtxMoy@TiO2 nanoparticles with low Pt content are prepared by a reverse microemulsion method. The morphologies, particle size, structure, and composition of PtxMoy@TiO2 nanoparticles are examined by several techniques such as X-ray Diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy, etc. The PtxMoy@TiO2 electrocatalysts show significantly higher catalytic activity and better durability for methanol oxidation than the commercial Pt/C (ETEK). Compared to Pt/C catalyst, the enhancement of the electrochemical performance of PtxMoy@TiO2 electrocatalysts can be attributed to the core-shell structure and the shift of the d-band center of Pt atoms, which can weaken the adsorption strength toward CO molecules, facilitate the removal of the CO groups and improve electrocatalytic activity. The development of PtxMoy@TiO2 electrocatalysts is promising to reduce the use of noble metal Pt and has a great potential for application in fuel cells.

Facile Synthesis Of Composition-Controllable PtPdAuTe Nanowires As Superior Electrocatalysts For Direct Methanol Fuel Cells.

Multicomponent Pt-based nanowires (NWs) have attracted widespread attention as eletrocatalysts toward direct alcohol fuel cells because of their unique one-dimensional structure and high reaction dynamics. Quaternary PtPdAuTe NWs are designed via a facile template method, and NWs with a different composition are obtained by adjusting the feed ratio of metal precursors. The direct displacement reaction of metal precursors with Te NWs and the partial oxidation of Te lead to the formation of quaternary NWs. The rough surface and abundant reactive sites deriving from the rearrangement of metal atoms on the Te NWs surface endow the PtPdAuTe NWs with a superior electrocatalytic property and durability for methanol oxidation. The Pt20 Pd20 Au10 Te50 NWs display the largest mass activity and best stability among all catalysts. The preparation of PtPdAuTe NWs could provide a viable strategy for the preparation of other multicomponent NWs.

Paper-based porous graphene/single-walled carbon nanotubes supported Pt nanoparticles as freestanding catalyst for electro-oxidation of methanol

In this paper, we designed a facile strategy to prepare a freestanding 3D interconnected embossed graphene (e-RGO)-single wall carbon nanotubes (SWCNTs) paper supported Pt nanoparticles (Pt/e-RGO-SWCNT) without binder, which can be used as a flexible and robust electrode for methanol oxidation. The 3D porous e-RGO was prepared by using monodispersed polystyrene (PS) spheres as sacrificial templates to suppress the re-stacking of RGO sheets. Meanwhile, the SWCNTs penetrated through the e-RGO, and thus weaved them into a scalable film to provide an integrative conductive framework. Benefited from their high surface area, 3D porous interconnected architecture, and good electrical conductivity, the Pt/e-RGO-SWCNT catalyst exhibited much higher electrocatalytic activity and durability for methanol oxidation than Pt/e-RGO and Pt/RGO catalysts. More importantly, the Pt/e-RGO-SWCNT is demonstrated to be outstanding flexible electrocatalysts, and the electrocatalytic performances under the different distorted situation (such as folded and rolled states) are almost the same as the normal state.

Carbon-thin-layer protected WP with no passivation supported on acid-treated expanded graphite as efficient Pt Co-catalysts for methanol oxidation and oxygen reduction reactions

Pt-WP-CL/AEG catalysts with particles-encapsulated layer-by-layer structure obtain high activity and durability for methanol oxidation and oxygen reduction reactions.

Pt nanotube network with high activity for methanol oxidation

Electrocatalysts with high performance, increased stability, and high surface area are essential for the widespread commercialization of fuel cells. Nanostructured materials emerge as potential candidates to meet these targets. We report on the synthesis and characterization of a nanostructured platinum electrocatalyst for methanol oxidation. Using a simple, one-step electroless method, an interconnected platinum nanotube network was prepared. The highly ordered, high-surface-area catalyst exhibited enhanced current density and durability for methanol oxidation. The catalyst shows a peak current density of 1.43 mA cm−2 at 50 mV s−1 and retained 25% of its initial activity after 1 h. The high catalytic activity is a result of increased Pt–OH formation on nanocrystal aggregates at lower potentials.

Nanostructured Polyaniline-rGO decorated platinum catalyst with enhanced activity and durability for Methanol oxidation

Addressed herein, a novel composite material is formed between polyaniline and a reduced graphene oxide synthesized by in situ technique in a single step in order to support the platinum nanoparticles. The surface of the reduced graphene oxide layers appeared effectively and stabilized the metal nanoparticles dimensionally. Platinum@reduced graphene oxide-polyaniline (Pt@rGO-PANI) nanoparticles have been characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. All the results show that Pt@rGO-PANI nanocomposite displayed excellent durability and catalytic activity for the alcohol oxidation reaction. Moreover, the resulting nanocomposite can be used in a variety of carbon-polymer applications, which can be improved and this study provides a powerful and universal synthetic strategy for new polymer-carbon composites in the literature. The methanol oxidation reactions current can reach to 47.2 mA and can maintain 68.4% of the initial value even after 100 cycles.

The effect of titanium nickel nitride decorated carbon nanotubes-reduced graphene oxide hybrid support for methanol oxidation

Titanium nickel nitride (TiNiN) decorated three-dimensional (3D) carbon nanotubes-reduced graphene oxide (CNT-rGO), a fancy 3D platinum (Pt)-based catalyst hybrid support, is prepared by a solvothermal process followed by a nitriding process, which is tested as anodic catalyst support for the methanol oxidation reaction (MOR). The structure, morphology and composition of the synthesized TiNiN/CNT-rGO exhibits a uniform particle dispersion with high purity and interpenetrating 3D network structure. Notably, Pt/TiNiN/CNT-rGO catalyst exhibits significantly improved catalytic activity and durability for methanol oxidation in comparison with Pt/CNT-rGO and conventional Pt/C (JM). The outstanding electrochemical performance was attributed to structure and properties. That is, the 3D CNT-rGO provided a fast transport network for charge-transfer and mass-transfer as well as TiNiN NPs with good synergistic effect and the strong electronic coupling between different domains in TiNiN/CNT-rGO, thus the catalytic activity of the novel catalyst is greatly improved. These results evidences 3D TiNiN/CNT-rGO as a promising catalyst support for a wide range of applications in fuel cells.

Hybrid of molybdenum trioxide and carbon as high performance platinum catalyst support for methanol electrooxidation

Molybdenum trioxide (MoO3) has been considered an advanced auxiliary support for Pt nanoparticle anchorage due to its excellent activity and stability. Nevertheless, its non-conductivity property still impedes its applications in electrocatalytic fields. Thus, the MoO3 and carbon composite of a nanostructure is synthesized through sintering process and served as an efficient co-support for Pt-based anode catalyst in this paper. The electrochemical measurements demonstrate that Pt/MoO3-C catalyst shows higher catalytic activity and stability than the as-prepared Pt/C. Significantly, it exhibits 1.95 times higher activity and 2.36 times better durability for methanol oxidation when compared with commercial Pt/C. The remarkably enhanced performance of this novel Pt/MoO3-C catalyst for methanol electrooxidation can be ascribed to the abundant Pt nucleation active sites, uniformly dispersed Pt nanoparticles and the strong metal-support interaction between Pt and MoO3-C. These outstanding properties suggest Pt/MoO3-C a promising catalyst for practical application of fuel cell.

Effect of nitrogen-doped PtRu/graphene catalyst on its activity and durability for methanol oxidation

Pt–Ru catalysts are highly regarded and investigated by many investigators. However, how to reduce Ru dissolution remains a major concern for their applications under realistic operating conditions. In this study, nitrogen-doped graphene supporting PtRu catalyst was synthesized by a mild microwave-assisted ethanol reduction process, which exhibited superior electrocatalytic properties for methanol oxidation. The morphologies and microstructures of the as-prepared catalysts were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. Long-term catalytic stability was evaluated by the accelerated aging cyclic voltammetry test. The results reveal that N-doping is beneficial for the minimization of metal migration and coalescence, and meanwhile it slows Ru dissolution.

Size-tunable palladium nanoparticles synthesized using the solution plasma process and their electrocatalytic activities

In this work, for fuel cell applications, size-tunable Pd nanoparticles were synthesized by adjusting the applied voltage in a range from 2.4 to 3.2 kV in solution plasma. The crystalline structure and morphology of the size-tuned Pd nanoparticles were examined using X-ray diffractometer (XRD) and high-resolution transmission electron microscopy (HR-TEM). The results revealed that the size of the Pd nanoparticles could be varied by tuning the Pd concentration in the plasma, which could be achieved by changing the applied voltages. The size of the Pd nanoparticles gradually decreased with increasing voltage, and the smallest Pd nanoparticles of 4.7 nm in diameter were observed at the highest voltage of 3.2 kV. According to the cyclic voltammetry and chronoamperometry tests, the Pd nanoparticles of 5.7 nm in diameter exhibited the enhanced catalytic activity and durability for methanol oxidation since the Pd surface was less covered by OH species.

Site-Selective Trimetallic Heterogeneous Nanostructures for Enhanced Electrocatalytic Performance.

Trimetallic Au/Ag/Pt hetero-nanostructures (AAPHNs) with distinctive, designed morphology are synthesized by galvanic replacement reaction and a site-selective strategy. The three metals present on the surface are shown to act synergistically to enhance the electro-catalytic performance and durability for methanol oxidation. The described structural modification of the nanocomposites increases the range of potential applications to include both the oxygen reduction reaction in fuel cells and photocatalysis of the hydrogen evolution reaction.

Carbonized phenanthroline functionalized carbon as an alternative support: a strategy to intensify Pt activity and durability for methanol oxidation

In this study, a carbonized phenanthroline functionalized carbon support (CPF-C) has been prepared, which was used to load Pt nanoparticles serve as an electrocatalyst for methanol oxidation.

Porous Hollow Nanorod Arrays Composed of Alternating Pt and Pd Nanocrystals with Superior Electrocatalytic Activity and Durability for Methanol Oxidation

The porous hollow nanorod arrays (PHNRAs) composed of alternating Pt and Pd nanocrystals showed superior electrocatalytic performance, such as high catalytic activity and excellent durability toward methanol electro-oxidation. The special surface and heterogeneous interface effects coming from the nanorod arrays, porous and hollow structures, and alternating Pt and Pd nanocrystals of PtPd PHNRAs are responsible for the significantly enhanced catalytic performance.

Biotemplated synthesis of bark-structured TiC nanowires as Pt catalyst supports with enhanced electrocatalytic activity and durability for methanol oxidation

Unique one-dimensional bark-structured TiC NWs possessing high electrical conductivity, excellent chemical/electrochemical stability and enhanced electrocatalytic properties were synthesised.

Graphene nanosheet-tailored PtPd concave nanocubes with enhanced electrocatalytic activity and durability for methanol oxidation

Here, we demonstrate that graphene oxide (GO) can act as a structure-directing agent for the formation of PtPd alloy concave nanocubes enclosed by high index facets. In the presence of GO, PtPd alloy concave nanocubes could be easily tailored by a simple hydrothermal reaction. In sharp contrast, only cubic PtPd alloy nanocrystals were obtained in the absence of GO. Moreover, compared to the unsupported PtPd nanocubes, the composition ratio of Pt to Pd changed significantly from 1 : 1 to 3 : 1. Due to the exposed high-index facets and the strong interaction between catalysts and graphene support, the as-synthesized PtPd concave nanocubes exhibited enhanced electrocatalytic activity and high durability toward methanol oxidation. The present work highlights the unique role of GO in the formation of metal nanocrystals as not only a catalyst support but also a structure- and/or morphology-directing agent, due to the presence of various functional groups on GO sheets. The present GO-assisted approach provides a new avenue to the synthesis of nanocrystals with high-index facets and initiates new opportunities for the exploration of high-performance graphene-based nanocatalysts.

Improving PEM fuel cell catalyst activity and durability using nitrogen-doped carbon supports: observations from model Pt/HOPG systems

This study presents clear and compelling experimental evidence for the significant beneficial effects of nitrogen-doping on the activity of Pt/C catalyst systems for the methanol oxidation reaction. This evidence is obtained through the deployment of geometrically well-defined model catalytic systems consisting of tunable assemblies of Pt catalyst nanoparticles deposited onto undoped, Ar-doped, and N-doped highly oriented pyrolytic graphite (HOPG) substrates. Both Ar- and N-doping were achieved via ion beam implantation, and Pt was electrodeposited from solutions of H2PtCl6 in aqueous HClO4. Morphology from scanning electron microscopy (SEM) and aqueous electrochemical analysis of catalytic activity was utilized to examine the effect of N-doping compared to the undoped and Ar-doped control samples. The results strongly support the theory that doping nitrogen into a graphite support significantly affects both the morphology and the behavior of the overlying Pt nanoparticles. In particular, nitrogen-doping was observed to cause a significant decrease in the average Pt nanoparticle size, an increase in the Pt nanoparticle dispersion, and a significant increase in catalytic activity and durability for methanol oxidation. The model catalytic systems demonstrated here represent a versatile platform to study catalyst-support interactions in electrocatalytically relevant nanoparticle systems.