Pt/MWCNTs nanocomposite: a durable electrocatalyst for proton exchange membrane fuel cells (original) (raw)
Related papers
2011
A hydrothermal method for preparation of size-controlled Pt nanoparticles dispersed highly on multiwalled carbon nanotubes (Pt/MWCNTs) has been studied to optimize the effective parameters (temperature, time, pH and stirring rate) using Taguchi method. The synthesized Pt/MWCNTs nanocomposite samples were characterized through X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray fluorescence (XRF) analyses to identify mean Pt nanoparticles size and Pt content. The analysis of the primary experimental data and demonstration of the main effect trend of each parameter showed that a reaction temperature of about 140 C, a reaction period of 5 h, a slightly basic reaction pH (w9) and a stirring rate of 500 rpm are the optimum process conditions which give a low mean Pt nanoparticles size (2.8 nm) and a high Pt content (19.4 wt.%) simultaneously. Cyclic voltammetry (CV) analysis showed that under optimum conditions the synthesized sample gives a specific surface area of 99 m 2 g À1. Obtaining the polarization curves for the two fabricated membrane electrode assemblies (MEAs) using the optimized catalyst and a commercial Pt/C catalyst (10 wt.%, Aldrich) with Pt loading of 0.4 mg cm À2 demonstrated that the catalyst prepared under optimum conditions shows a considerably better performance.
Energy, 2017
In this work, a highly dispersed Pt nanoparticles on multi-walled carbon nanotubes catalyst was prepared by hydrothermal method. The synthesized Pt/MWCNT nanocomposite electrocatalyst was characterized using XRD, XRF, FESEM, TEM, and EDX. In the first step, the electrochemical activity and stability of the Pt/MWCNT and Pt/C catalysts were investigated in half cell condition using cyclic voltammetry for 4000 cycles. The Pt/C catalyst showed no activity after 2000 potential cycles, conversely, the Pt/MWCNT catalyst was more active after a potential cycling of 4000 cycles. The cyclic voltammetry results of the first, 1000 th , 2000 th , 3000 th , and 4000 th cycle for synthesized Pt/MWCNTs and commercial Pt/C catalysts showed the Pt/MWCNTs was more stable. Then, the membrane electrode assemblies (MEAs) were fabricated for each catalyst. The accelerated durability test (ADT) was done for the MEAs in the high potential operation in the fuel cell test station. The morphology of the fabricated MEAs was determined by FESEM before and after the accelerated degradation test. The polarization test, impedance, and cyclic voltammetry results for MEAs before and after degradation test in fuel cell test station were reported and the results showed the synthesized Pt/MWCNT is more stable catalyst than commercial Pt/C.
Pt/SWNT−Pt/C Nanocomposite Electrocatalysts for Proton-Exchange Membrane Fuel Cells
The Journal of Physical Chemistry C, 2007
Single-walled carbon nanotubes (SWNT) have been synthesized by pyrolysis of methane over Mm (Mischmetal)-based AB 3 alloy hydride catalyst. Purification of as-grown SWNT was carried out by air oxidation followed by acid treatment. The as-grown and purified SWNT have been characterized by XRD, SEM, TEM, HRTEM, TGA, IR, and Raman spectroscopy studies. Well-dispersed Pt catalysts on SWNT catalyst support for polymer electrolyte membrane fuel cells (PEMFC) have been prepared by a simple chemical reduction method using prefunctionalized SWNT. The anode and cathode electrodes for PEMFC have been fabricated using Pt-supported SWNT and commercial Pt/C electrocatalysts with different compositions of Pt/SWNT and Pt/C. The dependence of the fuel cell performance on the dispersion and accessibility of SWNT support and Pt electrocatalysts in the electrocatalyst mixture for the oxygen reduction reaction in PEMFC has been discussed. These results open up a way to use Pt/SWNT + Pt/C nanocomposites as electrocatalysts in PEMFC.
Electrochimica Acta, 2010
Micelle-encapsulated multi-walled carbon nanotubes (MWCNTs) with sodium dodecyl sulfate (SDS) were used as catalyst support to deposit platinum nanoparticles. High resolution transmission electron microscopy (HRTEM) images reveal the crystalline nature of Pt nanoparticles with a diameter of ∼4 nm on the surface of MWCNTs. A single proton exchange membrane fuel cell (PEMFC) with total catalyst loading of 0.2 mg Pt cm −2 (anode 0.1 and cathode 0.1 mg Pt cm −2 , respectively) has been evaluated at 80 • C with H 2 and O 2 gases using Nafion-212 electrolyte. Pt/MWCNTs synthesized by using modified SDS-MWCNTs with high temperature treatment (250 • C) showed a peak power density of 950 mW cm −2 . Accelerated durability evaluation was carried out by conducting 1500 potential cycles between 0.1 and 1.2 V with 50 mV s −1 scan rate, H 2 /N 2 at 80 • C. The membrane electrode assembly (MEA) with Pt/MWCNTs showed superior performance stability with a power density degradation of only ∼30% compared to commercial Pt/C (70%) after potential cycles.
International Journal of Chemistry
Synthesis of mono-dispersed Pt/MWCNTs has been performed. Platinum nanoparticles (Pt NPs) were grown directly on multiwall carbon nanotubes (MWCNTs) through sol-gel method using NaBH4 as reducing agent. 120 mg of activated MWCNT were weighed and then incorporated into the mixture (1) and sonicated for 2 hours to form the mixture (2). H2PtCl6 was weighed as much as 90 mg and dissolved into 45 mL of ethylene glycol until formed mixture (3). Solution (3) was dropwise every 3 seconds into the mixture (2). After that the mixture was distilled for 12 hours at a rate of 450 rpm. Subsequently the mixture was sonicated for 3 hours, then checked its pH, adjusting the desired pH to 4, 7, or 13 using the mixture 2M NaOH-ethylene glycol. The tests include SEM, EDS, XRD, and TEM for the morphologies and microstructures of the mono-dispersed Pt/MWCNT. The result of SEM observation and the analysis of the element using EDS found that the composite sample looked homogenous and contained elemen...
Synthesis methods of low-Pt-loading electrocatalysts for proton exchange membrane fuel cell systems
Energy, 2010
While the use of a high level of platinum (Pt) loading in proton exchange membrane fuel cells (PEMFCs) can amplify the trade off towards higher performance and longer lifespan for these PEMFCs, the development of PEMFC electrocatalysts with low-Pt-loadings and high-Pt-utilization is critical and the limited supply and high cost of the Pt used in PEMFC electrocatalysts necessitate a reduction in the Pt level. In order to make such electrocatalysts commercially feasible, cost-effective and innovative, catalyst synthesis methods are needed for Pt loading reduction and performance optimization. Since a Pt-deposited carbon nanotube (CNT) shows higher performance than a commercial Pt-deposited carbon black (CB) with reducing 60% Pt load per electrode area in PEMFCs, use of CNTs in preparing electrocatalysts becomes considerable. This paper reviews the literature on the synthesis methods of carbon-supported Pt electrocatalysts for PEMFC catalyst loading reduction through the improvement of catalyst utilization and activity. The features of electroless deposition (ED) method, deposition on sonochemically treated CNTs, polyol process, electrodeposition method, sputter-deposition technique, g-irradiation method, microemulsion method, aerosol assisted deposition (AAD) method, Pechini method, supercritical deposition technique, hydrothermal method and colloid method are discussed and characteristics of each one are considered.
Journal of Porous Materials, 2015
Commercially available multiwalled carbon nanotubes (MWCNTs) were functionalized using a mixture of HNO 3 and H 2 SO 4 in refluxing condition under three different reaction times (1, 3, and 5 h). The Pt loaded on functionalized MWCNTs (f-MWCNTs) (Pt/1f, 3f & 5f-MWCNTs) were prepared by reducing chloroplatinic acid and for comparison Pt loaded on pristine MWCNTs (Pt/MWCNTs) was also prepared. The size of Pt nanoparticles was determined using X-ray diffraction method. The uniform dispersion of the Pt catalyst on CNTs was confirmed by HRSEM and HRTEM. Surface area and pore size were calculated by Brunauer Emmett Teller analysis method. Five membrane electrode assembly sets were prepared (Pt/MWCNTs, Pt/1f, 3f, 5f-MWCNTs and commercial Pt/C) and tested in the fuel cell assembly. The first four were prepared using SPEEK membrane as electrolyte with the synthesized Pt/f-MWCNTs catalysts and the fifth one was prepared using commercial Nafion-117 electrolyte and Pt/C electrode for comparison.
Microwave-assisted synthesis of Pt/CNT nanocomposite electrocatalysts for PEM fuel cells
Nanoscale, 2010
Microwave-assisted heating of functionalized, single-wall carbon nanotubes (FCNTs) in ethylene glycol solution containing H 2 PtCl 6 , led to the reductive deposition of Pt nanoparticles (2.5-4 nm) over the FCNTs, yielding an active catalyst for proton-exchange membrane fuel cells (PEMFCs). In singlecell testing, the Pt/FCNT composites displayed a catalytic performance that was superior to Pt nanoparticles supported by raw (unfunctionalized) CNTs (RCNTs) or by carbon black (C), prepared under identical conditions. The supporting single-wall carbon nanotubes (SWNTs), functionalized with carboxyl groups, were studied by thermogravimetric analysis (TGA), cyclic voltammetry (CV), and Raman spectroscopy. The loading level, morphology, and crystallinity of the Pt/SWNT catalysts were determined using TGA, SEM, and XRD. The electrochemically active catalytic surface area of the Pt/ FCNT catalysts was 72.9 m 2 /g-Pt.