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1.
Polyoxometalate anion PMo12O403− (POM) is chemically impregnated into a Pt-supported carbon nanotubes (Pt/CNTs) catalyst that is prepared via a colloidal method. The POM-impregnated Pt/CNTs catalyst system (Pt/CNTs-POM) shows at least 50% higher catalytic mass activity with improved stability for the electrooxidation of methanol than Pt/CNTs or POM-impregnated Pt/C (Pt/C-POM) catalyst systems. The enhancement in electrochemical performance of the Pt/CNTs-POM catalyst system can be attributed to the combined beneficial effects of improved electrical conductivity due to the CNTs support, highly dispersed Pt nanoparticles on the CNTs, and increased oxidation power of the polyoxometalate that can assist oxidative removal of reaction intermediates adsorbed on the Pt catalyst surface.  相似文献   

2.
The application of direct methanol fuel cells (DMFCs) is hampered by not only low activity but also poor stability and poor CO tolerance by the Pt catalyst. Herein, a novel titanium nitride coated multi-walled carbon nanotubes (CNTs@TiN) hybrid support was successfully synthesized by a facile solvothermal process followed by a nitriding process, and this hybrid support was used as Pt support for the oxidation of methanol. The structure, morphology and composition of the synthesized CNTs@TiN exhibits a uniform particle perfect coating with high purity and interpenetrating network structure. Notably, Pt/CNTs@TiN also showed excellent stability, experiencing only a slight performance loss after 5000 potential cycles. The onset potential (0.34 V) of CO oxidation on Pt/CNTs@TiN is obviously more negative than that on the Pt/TiN (0.38 V) and Pt/CNTs (0.48 V) in the first forward scan. In the Pt 4f XPS spectra, plentiful Pt atoms existed as Pt(II) in the Pt/CNTs and Pt/TiN catalysts, while a relatively smaller amount of Pt(II) was observed in the Pt/CNTs@TiN catalyst. The synthetic Pt/CNTs@TiN catalyst was studied with respect to its electrocatalytic activity and durability and CO tolerance toward methanol oxidation might be mainly attributed to the strongly coupled Pt–TiN and the fast electron-transport network structure. This work may provide more insight into developing novel catalyst supports of various transition metal nitrides coated CNTs for DMFCs with high activity and good durability and excellent CO tolerance.  相似文献   

3.
In this study, mesoporous titanium cobalt nitride nanorods (Ti0.9Co0.1N NRs) hybrid as non-carbon platinum supports is successfully prepared by a solvothermal process and subsequent nitridation process. The highly porous materials can provide abundant binding sites for growing well-dispersed Pt. The X-ray photoelectron spectroscopy results indicate that the cobalt element doping promoted the interaction of platinum and support. Notable, the peak current density of Pt/Ti0.9Co0.1N NRs catalyst is 0.85 A mgpt?1, which 3.4-fold of Pt/C catalyst. What's more, the onset potential (0.34 V) of CO oxidation on Pt/Ti0.9Co0.1N NRs is lower than on the Pt/C (0.47 V) and Pt/TiN NRs (0.37 V). The results confirmed the mesoporous Pt/Ti0.9Co0.1N NRs catalyst unfolds a much enhanced catalytic activity and CO tolerance for methanol oxidation. The exceptional electrocatalytic properties are achieved for the Pt/Ti0.9Co0.1N NRs catalysts due to its unique porous structure and the electronic effect of robust Ti0.9Co0.1N NRs introduced by the cobalt element doping.  相似文献   

4.
Pt nanoparticles supported on carbon nanotubes (Pt/CNTs) have been synthesized from sulfur-modified CNTs impregnated with H2PtCl6 as Pt precursor. The dispersion and size of Pt nanoparticles in the synthesized Pt/CNT nanocomposites are remarkably affected by the amount of sulfur modifier (S/CNT ratio). The results of X-ray diffraction and transmission electron microscopy indicate that an S/CNT ratio of 0.3 affords well dispersed Pt nanoparticles on CNTs with an average particle size of less than 3 nm and a narrow size distribution. Among different catalysts, the Pt/CNT nanocomposite synthesized at S/CNT ratio of 0.3 showed highest electrochemically active surface area (88.4 m2 g−1) and highest catalytic activity for methanol oxidation reaction. The mass-normalized methanol oxidation peak current observed for this catalyst (862.8 A g−1) was ∼ 6.5 folds of that for Pt deposited on pristine CNTs (133.2 A g−1) and ∼ 2.3 folds of a commercial Pt/C (381.2 A g−1). The results clearly demonstrate the effectiveness of a relatively simple route for preparation of sulfur-modified CNTs as a precursor for the synthesis of Pt/CNTs, without the need for tedious pretreatment procedures to modify CNTs or complex equipments to achieve high dispersion of Pt nanoparticles on the support.  相似文献   

5.
In this paper, well-dispersed Ni2P-NiP2-Pt/CNTs catalyst promoted by nickel-phosphorus compounds was readily synthesized by a two-step hydrothermal process. The as-synthesized Ni2P-NiP2-Pt/CNTs displayed improved electrocatalytic properties towards electro-oxidation of common small organic fuels such as methanol, ethanol and formic acid in contrast with Pt/CNTs and Pt/CNPs in acidic electrolytes. Meanwhile, the Ni2P-NiP2-Pt/CNTs catalyst also exhibited the excellent performance toward hydrogen evolution reaction with a more negative onset potential (?15 mV) and a smaller Tafel slope (29.8 mV dec?1) when compared with Pt/CNTs (?29 mV, 30.6 mV dec?1) and Pt/CNPs (?32 mV, 31.3 mV dec?1) in 1.0 M H2SO4 solution. The catalytic activity enhancement possibly derives from the induced large specific surface area of carbon nanotubes as well as the strengthened synergistic effect between multiple supporting interactions.  相似文献   

6.
Metal organic frameworks (MOFs) have attracted tremendous attention in recent years owing to their high-specific surface area (SSA) and variable porous structures. Owing to the strong interaction between Pt and CeO2, Pt combined steadily with CeO2. Furthermore, the surface of CeO2 can activate water to produce hydroxyl groups, which can accelerate the removal of catalytic intermediate CO. But the bad conductivity of metal oxide is still a huge obstacle. More importantly, utilizing TiN with excellent conductivity as support can strengthen conductivity of catalyst and improve catalytic activity. Herein, a novel Pt-CeO2/TiN Nanotubes (TiN NTs) catalysts derived from Ce-MOF was fabricated for the first time. In the synthesis process of the targeted catalyst, the compounds of Ce-MOF and TiN NTs was prepared via the hydrothermal method and post-nitriding treatment, and implemented as the Pt support. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen adsorption/desorption and electrochemical measurements were carried out to characterize the catalyst. Notably, the peak current density of Pt-CeO2/TiN NTs (0.67 A mg−1Pt) was approximately 3 times higher than Pt/C (0.28 A mg−1Pt) during methanol oxidation test, showing the exceptional properties toward methanol oxidation reaction (MOR). Remarkably, electrochemical testing data verified the superior tolerance to CO and enhanced catalytical activity of Pt-CeO2/TiN NTs and it could be attributed to the porous structures and the interaction between TiN NTs and CeO2.  相似文献   

7.
Carbon nanotubes (CNTs) supported platinum (Pt) nanoparticles prepared via electrophoretic deposition are used as catalyst layer of a microfluidic direct methanol fuel cell (DMFC), to study the influence of catalyst layer materials and deposition methods on the cell performance. A Y‐shaped channel is designed and microfabricated. It is verified by cyclic voltammetric measurements that shows ca. 317.7% increase in the electrochemical active surface area for the electrode with CNTs over that without CNT. Scanning electron microscopy observations indicate the network formation within the electrode because of a 3‐D structure of CNTs, which could be beneficial to the increasing electrode kinetics and to the improvement in fuel utilization. Comparison between the DMFCs with and without CNTs as support shows that the proof‐of‐concept microfluidic DMFC with Pt/CNTs electrode is able to reach a maximum power density of 5.70 mW cm?2 at 25 °C, while the DMFC with plain Pt electrode only has a maximum power density of 2.75 mW cm?2. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

8.
In this study, it was aimed to synthesize catalytically active, high surface area carbon nanotubes (CNTs) by means of nitrogen doping (N-doping). The synthesized nitrogen doped carbon nanotubes (N-CNTs) were used as Pt catalyst support in order to improve oxygen reduction reaction (ORR) kinetics at the cathode electrode in PEM fuel cell. Polypyrrole (PPy) was served as both carbon and nitrogen source and FeCl3 solution was used as oxidizing agent in the synthesis procedure of N-CNTs. Chemical activation of the materials was made with potassium hydroxide (KOH) solution during 12 and 18 h time periods. It was considered that activation period is of great importance on the properties of the synthesized PPy based N-CNTs. 12 h activated N-CNTs gave higher surface area (1607.2 m2/g) and smaller micropore volume (0.355 cm3/g) in comparison to 18 h activated N-CNTs having smaller surface area (1170.7 m2/g) and higher micropore volume (0.383 cm3/g). PEM fuel cell performance results showed that 12 h activated N-CNTs are better catalyst supports than 18 h activated N-CNTs for Pt nanoparticle decoration.  相似文献   

9.
Direct ethanol fuel cells (DEFCs) offer an attractive alternative to fossil fuel-powered devices due to their high energy density and environmental benignity. However, high cost and poor stability of catalysts are still the main obstacles for the commercialization of DEFCs. Herein, a novel catalyst comprising PtRh alloys anchored on carbon nanotubes that decorated with tungsten nitride (Pt9Rh-WN/CNTs) was synthesized via impregnation-reduction method and followed by thermal annealing in N2. The X-ray powder diffraction (XRD), scanning electron micrograph (SEM) and transmission electron microscopy (TEM) are employed to characterize the corresponding physico-chemical properties of the as-prepared catalysts. Electrocatalytic performance for ethanol oxidation is evaluated by cyclic voltammetry, linear scan voltammetry, CO-stripping voltammograms, chronoamperometry and chronopotentiometry. The current density on Pt9Rh-WN/CNTs is 484.8 mA mgPt?1, which is much higher than that of Pt9Rh/CNTs (305.7 mA mgPt?1) and Pt/CNTs (135.1 mA mgPt?1). Most importantly, the onset potential for CO oxidation on Pt9Rh-WN/CNTs is 0.27 V, which is more negative than that on Pt9Rh/CNTs (0.37 V) and Pt/CNTs (0.40 V). Therefore, the Pt9Rh-WN/CNTs catalyst displays both outstanding catalytic activity and excellent CO-poisoning tolerance for ethanol oxidation. Synergistic effects arising between WN and PtRh alloy along with nitrogen-doping effects of CNTs with ammonia are proposed to contribute to the outstanding performance of this catalyst in ethanol oxidation.  相似文献   

10.
Graphene nanoribbons (GNRs) were first used as a novel support material for Pt nanoparticles (NPs) based catalyst for methanol electro-oxidation. Upon oxidation and cutting of multiwall carbon nanotubes (MWCNTs), highly dispersive graphene oxide nanoribbons (GONRs) were obtained, on which metal ions such as PtCl62− can be homogenously deposited. The hybrid catalyst of GNRs supported Pt NPs (Pt/GNR) was further prepared through facile in-situ chemical co-reduction, with a homogeneous distribution of Pt NPs (2–3 nm) on the nanoribbons. Compared to Pt/MWCNT and commercial Pt/XC72R catalysts, Pt/GNR hybrids show much larger electrochemically active surface area, higher electrochemical stability, and better CO tolerance towards electro-oxidation of methanol. Therefore, GNR is a promising alternative two-dimensional support material for electrocatalysts in direct methanol fuel cells.  相似文献   

11.
In this work, a facile Fe- and N-containing porous carbon derived from sewage sludge was prepared and served as the support of Pt nanoparticles for the electrooxidation of methanol. Both the sludge-derived carbon (denoted as SC) and the resultant Pt/SC catalyst was physically characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The electrocatalytic performance for methanol oxidation reaction (MOR) of the Pt/SC was examined by cyclic voltammetry (CV) and chronoamperometric method. The results showed that the Pt/SC possessed slightly larger Pt particle size (5.5 nm) and lower electrochemical active surface area (ECA) compared to common Pt/C catalyst. However, the mass activity of Pt/SC for MOR was up to 201 mA mg−1, which was much higher than that of Pt/C (93 mA mg−1), indicating the synergistic effect of the sewage sludge-derived carbon with Fe and N species on methanol electrooxidation. Furthermore, Pt/SC showed enhanced durability towards MOR compared to common Pt/C, implying its potential for using in direct methanol fuel cell (DMFC) for energy conversion, which also demonstrated a promising solution for the utilization of sewage sludge resources.  相似文献   

12.
It's a meaningful work to develop a highly active nonprecious SO2 electrooxidation catalyst, replacing the Pt-based ones. Here, a novel Cu-N doped carbon-based catalyst is synthesized by pyrolyzing the imidazole chelated copper ions on the chitosan modified carbon BP2000. During the preparation, metallic Cu is developed and encapsulated in the carbon lattices, and transformed into the CuNx structures on the catalyst surface, simultaneously. Metallic Cu plays significant role in the doping and developing of active sites, which have vital effects on the catalysis activity. The prereduction of Cu2+ by NaBH4 during the preparation of Doping(I)-Cu@N-C makes great contribution to the development of metallic Cu, which highly dispersive anchor in the carbon lattices. This as-synthesized Doping(I) -Cu@N-C catalyst exhibits excellent SO2 electrooxidation activity. Its SO2 oxidation currents are remarkably increased with the elevation of applied potentials, and the oxidation performances prominently surpass the commercial Pt/C, when the potential is above 0.822 V. The peak SO2 oxidation current (ip) of Doping(I)-Cu@N-C is 7.17 mA cm?2 @ 0.684 V, much higher than the 3.03 mA cm?2@ 0.584 V of Pt/C with the same mass loading. In the chronoamperometry tests under 1.2 V, the terminal oxidation current of Doping(I)-Cu@N-C was 1.74 times as high as that of Pt/C, indicating that this prepared catalyst also displays much better SO2 electrooxidation activity than Pt/C under constant applied potentials.  相似文献   

13.
The development of high-performance electrocatalysts for methanol oxidation is an urgent task to enhance the efficiency of direct methanol fuel cells. We report a simple and controllable method to fabricate Pt-decorated TiN electrocatalysts using self-terminated electrodeposition at room temperature and ambient pressure. Under optimized deposition parameters such as electrolyte pH, TiN substrate pretreatment, and pulsed deposition potential, quenching of the Pt electrodeposition facilitates obtaining an extremely low Pt mass loading (0.93 μg/cm2) on the TiN substrate. Repeated deposition potential pulses enable a gradual increase in Pt loading, with a precise control of the loaded Pt mass. Maximum intrinsic and mass activities for the methanol oxidation reaction are achieved for the catalyst with a Pt loading mass of 55.0 μg/cm2, prepared by 20 deposition pulses. The maximum intrinsic activity achieved with the Pt-decorated TiN electrocatalyst is five times higher than that obtained with bulk Pt. The present results thus provide a facile method for the fabrication of cost-effective electrocatalysts.  相似文献   

14.
Titanium carbide (TiC) nanoparticles supported Pt catalyst for methanol electrooxidation is investigated for the first time. The resultant TiC/Pt catalysts are prepared by using a simple electrodeposition to load Pt nanoparticles on TiC nanocomposite. The electrodes are characterized by scanning electron microscopy and cyclic voltammetry. It is found that the TiC/Pt catalysts help alleviate the CO poisoning effect for methanol electrooxidation with a higher ratio of the forward anodic peak current (If) to the reverse anodic peak current (Ib). The improvement in the catalytic performance is attributed to the fact that TiC ameliorates the tolerance to CO adsorption on Pt nanoparticles. One possible mechanism to improve the CO tolerance of Pt taking TiC as supporting material in methanol electrooxidation is also proposed. The results suggest that TiC could be practical supporting materials to prepare electrocatalysts that are suitable for the methanol electrooxidation applications.  相似文献   

15.
Fuel cells are a new type of batteries that produce electricity from a continuous source of alcohols as long as fuel is inserted. In this study, decorated palladium nanoparticles (PdNPs) on dysprosium fluoride (DyF3) nanorods (DyFNRs)‐multiwalled carbon nanotubes (MWCNTs) were used for electrooxidation of methanol. DyFNRs were synthesized by the hydrothermal method, and the proposed multifunctional catalyst (DyFNRs/MWCNT‐PdNPs) was identified by several methods such as X‐ray diffraction, elemental mapping images, field emission scanning electron microscopy, energy dispersive analysis of X‐rays, and transmission electron microscopy which demonstrated a uniform distribution and high dispersion of the PdNPs on the supports. The electrocatalytic activity toward methanol electrooxidation on glassy carbon electrode (GCE) with DyFNRs/MWCNT‐PdNPs (DyFNRs/MWCNT‐PdNPs/GCE) was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). Experimental results showed a high improvement in oxidation potential and peak current of methanol electrooxidation by DyFNRs/MWCNT‐PdNPs in comparison to DyFNRs and PdNPs. The values of the catalytic rate constant (k) and physical dimension (Ds) for methanol oxidation on the DyFNRs/MWCNT‐PdNPs/GCE catalyst were calculated 0.008 s?1 and 1.43, respectively. Moreover, the order of reaction was determined to be 0.43 and 0.13 for CH3OH and NaOH, repectively. Finally, the synthesized catalyst was evaluated in direct methanol fuel cell (DMFC). The single DMFC with proposed anodic catalyst, DyFNRs/MWCNT‐PdNPs, indicated a power density of 4.4 mW·cm?2 at a current density of 18 mA·cm?2 in alcohol (1 M) and NaOH (1 M).  相似文献   

16.
The development of highly active and efficient heterogeneous catalytic oxidation system has become an attractive research field. In this paper, a catalyst (RuCo/N-CNT@PEDOT-OH/Pt) from platinum nanoparticles (Pt NPs) supported on hydroxyl-grafted poly(3,4-ethylenedioxythiophene) (PEDOT–OH)-modified RuCo, N-tridoped bamboo-like carbon nanotubes (RuCo/N-CNT) are used for direct methanol fuel cell (DMFC). The electrocatalytic activity of RuCo/N-CNT@PEDOT-OH/Pt is systematically compared with RuCo/N-CNT/Pt (Pt NPs supported on RuCo/N-CNT without PEDOT-OH) in the methanol oxidation reaction (MOR). The growth mechanism of carbon nanotubes and the role of heteroatom doping in the electrocatalytic process is explored. The catalysts show excellent electrocatalytic performance with high stability for MOR. It is found that the mass activity (MA) of the RuCo/N-CNT@PEDOT-OH/Pt (1961.3 mA mg?1Pt) for MOR was higher than that of RuCo/N-CNT/Pt (1470.1 mA mg?1Pt) and the commercial Pt/C catalysts (281.0 mA mg?1Pt), indicating the positive effect of the PEDOT-OH in the electrocatalytic MOR. In addition, density functional theory (DFT) calculations verify the possible mechanism pathways of the obtained RuCo/N-CNT@PEDOT-OH/Pt catalyst. This presented catalyst offers new inspiration for designing efficient electrocatalysts for methanol oxidation.  相似文献   

17.
Non-noble metal containing catalysts for oxygen reduction reaction (ORR) are being targeted due to their low cost and availability. The rarity, high-cost, and self-poisoning of noble metals are the main drawbacks for the large-scale applications. Herein, a facile and simple synthetic strategy is adopted to prepare non-noble metal-based nitrogen doped carbon nanotubes (N-CNTs). The cobalt oxides (CoOx) nanoparticles are in-situ encapsulated inside these N-CNTs which are then treated with acid (HCl) and phosphidized to obtain CoOx-CoP/N-CNTs. High resolution transmission electron spectroscopy (HR-TEM) results reveal that the ends of N-CNTs are closed with nanoparticles. X-ray photoelectron spectroscopy (XPS) confirms the presence of cobalt oxide and cobalt phosphide nanoparticles. The catalyst CoOx-CoP/N-CNTs2 demonstrated Eonset and E1/2 of 0.96 V and 0.81 V, respectively in alkaline environment which is very much comparable to the state of art catalyst (20 wt% Pt/C). Acid treatment significantly enhances the electrocatalytic activity for ORR in comparison to material synthesized without prior treatment with acid. The catalyst exhibits excellent durability over 10,000 cycles and methanol tolerance to 0.5 M methanol addition. The enhanced ORR activity is attributed to synergistic effect of carbon matrix and encapsulated nanoparticles.  相似文献   

18.
Bucky diamond (BD) with a nanoscale diamond core surrounded by a fullerene shell was used as a support of Pt electrocatalyst for methanol electrooxidation. BDs were prepared by annealing detonation-synthesized nanodiamond (ND) powders in 10−3 Pa vacuum at 900–1100 °C. The electrochemical properties of the BD powders in aqueous solution were investigated. The BDs and NDs supported platinum (Pt) electrocatalysts were prepared using a microwave-assisted reduction method. Higher dispersion of Pt nanoparticles was observed on the BDs than the pristine NDs, indicating a high affinity between BDs and Pt metal. The Pt/BD catalyst had better catalytic activity and higher stability for the methanol electrooxidation in comparison to the Pt/ND prepared at the same conditions. This provides a novel nanoparticle with a high conductivity and a high stability for electrochemical applications.  相似文献   

19.
Cyclic voltammetry (CV), amperometric i − t experiments, and electrochemical impedance spectroscopy (EIS) measurements were carried out by using glassy carbon disk electrode covered with the Pt/C catalyst powder in solutions of 0.5 mol L−1 H2SO4 containing 0.5 mol L−1 CH3OH and 0.5 mol L−1 H2SO4 containing 0.5 mol L−1 HCOOH at 25 °C, respectively. Electrochemical measurements show that the activity of Pt/C for formic acid electrooxidation is prominently higher than for methanol electrooxidation. EIS information also discloses that the electrooxidation of methanol and formic acid on the Pt/C catalyst at various polarization potentials show different impedance behaviors. The mechanisms and the rate-determining steps of formic acid electrooxidation are also changed with the increase of the potential. Simultaneously, the effects of the electrode potentials on the impedance patterns were revealed.  相似文献   

20.
A composite support based on nature clay, i.e. montmorillonite (MMT), shows great promise as support materials for Pt electrocatalyst for the methanol oxidation reaction in fuel cell anodes. The reported composite support (CNx-MMT) was prepared via carbonizing MMT which was covered by N-contented polymer. X-ray diffraction and transmission electron microscopy results showed that Pt nanoparticles can be well-dispersed on the composite support with highly dispersed tiny crystal Pt nanoparticles. Cyclic voltammetry measurements showed that the Pt/CNx-MMT has the enhanced electrocatalytic activity in methanol oxidation reaction. The developed Pt catalyst supported on new composite support is catalytically more active for methanol electrooxidation than Pt supported on the conventional carbon support and shows good stability, offering promising potential for application of MMT as support for fuel cell electrocatalysis.  相似文献   

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