Efficient electro-oxidation of methanol using PtCo nanocatalysts supported reduced graphene oxide matrix as anode for DMFC (original) (raw)
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Journal of Nanoscience and Nanotechnology, 2019
The higher methanol utilization efficiency in direct methanol fuel cell (DMFC) is one of the key parameter to show the performance of an anode catalyst. Here in, we have synthesized a highly efficient and stable PtCo anode nanocatalysts (2-4 nm size) supported on reduced graphene oxide (rGO) for the electro-oxidation of methanol in a DMFC. Three different compositions of anode catalysts PtCo (1:7)/rGO, PtCo (1:9)/rGO and PtCo (1:11)/rGO comprising of 20% metal loading by weight of rGO are being investigated for methanol electro-oxidation in acidic medium with different methanol concentration using cyclic voltammetry. The electrochemical response from three different catalysts revealed that the PtCo (1:9)/rGO catalyst has efficiently oxidized 5 M methanol in a half cell configuration. A peak anodic current density of 46.8 mA/cm 2 and a power density of 136.8 mW/cm 2 are achieved using PtCo (1:9)/rGO anode catalyst at 100 C for DMFC with 5 M methanol supply with negligible amount of methanol crossover. About 34% Faradaic efficiency and 22% energy efficiency is attained using PtCo (1:9)/rGO anode catalyst for a DMFC. Further, the 3% methanol oxidation reaction (MOR) efficiency is attained as revealed by evaluating the MOR by-products i.e., formic acid and formaldehyde formation. The results indicate excellent catalytic behavior of PtCo (1:9)/rGO towards MOR and its potential application as anode catalyst in DMFC.
Materials for Renewable and Sustainable Energy, 2018
The higher methanol utilization efficiency in direct methanol fuel cell (DMFC) is one of the key factors that determine the performance of DMFC. Herein, we have synthesized bimetallic PtCo nano-particles (with optimized Pt:Co ratio) decorated reduced graphene oxide (rGO) nano-composite as anode catalyst. The electrochemical response of optimized PtCo (1:9)/ rGO catalyst revealed efficient oxidation of 5 M methanol in half-cell configuration with ~ 60% Faradaic efficiency. A current density of 463.5 mA/cm 2 and a power density of 136.8 mW/cm 2 were achieved using PtCo (1:9)/rGO anode catalyst in a complete DMFC setup at 100 °C with 5 M methanol supply which is ~ three times greater as compared to commercial Pt/C (48.03 mW/cm 2). The low activation energy of 9.88 kJ/mol indicates the faster methanol oxidation reduction (MOR) kinetics of PtCo (1:9)/rGO anode catalyst. Furthermore, the higher methanol utilization and open-circuit voltage in complete DMFC using PtCo (1:9)/rGO as compared to commercial Pt/C indicate the reduced methanol crossover. The excellent catalytic behavior of PtCo (1:9)/rGO towards MOR and high methanol utilization warrant its potential application as anode catalyst in DMFC.
Electrochimica Acta, 2009
Carbon-supported Pt and Pt 3 Co catalysts with a mean crystallite size of 2.5 nm were prepared by a colloidal procedure followed by a carbothermal reduction. The catalysts with same particle size were investigated for the oxygen reduction in a direct methanol fuel cell (DMFC) to ascertain the effect of composition. The electrochemical investigations were carried out in a temperature range from 40 to 80 • C and the methanol concentration feed was varied in the range 1-10 mol dm −3 to evaluate the cathode performance in the presence of different conditions of methanol crossover. Despite the good performance of the Pt 3 Co catalyst for the oxygen reduction, it appeared less performing than the Pt catalyst of the same particle size for the cathodic process in the presence of significant methanol crossover. Cyclic voltammetry analysis indicated that the Pt 3 Co catalyst has a lower overpotential for methanol oxidation than the Pt catalyst, and thus a lower methanol tolerance. Electrochemical impedance spectroscopy (EIS) analysis showed that the charge transfer resistance for the oxygen reduction reaction dominated the overall DMFC response in the presence of high methanol concentrations fed to the anode. This effect was more significant for the Pt 3 Co/KB catalyst, confirming the lower methanol tolerance of this catalyst compared to Pt/KB. Such properties were interpreted as the result of the enhanced metallic character of Pt in the Pt 3 Co catalyst due to an intra-alloy electron transfer from Co to Pt, and to the adsorption of oxygen species on the more electropositive element (Co) that promotes methanol oxidation according to the bifunctional theory.
Carbon, 2007
The geometric effect of graphite nanofibers (GNFs) as a support for PtRu electrocatalysts on the oxidation of methanol for direct methanol fuel cells (DMFCs) was studied using X-ray diffraction, field emission transmission electron microscopy (FETEM) and electrochemical measurements. A high loading of 60 wt% PtRu catalyst, which is readily applicable to DMFCs, was well dispersed on GNFs. Further, the shape of the supported metal particles was affected by interactions with the GNFs. Electrochemical analysis indicated that GNF-supported PtRu catalysts resulted in an increased catalytic activity of about 100% over that of Vulcan XC-72 supported catalysts. FETEM data indicate that the enhanced activities result from a geometric modification of the catalyst particles by specific interactions between the GNFs and the supported PtRu nanoparticles.
Journal of Applied Electrochemistry, 2009
This work tries to study the problem of methanol crossover through the polymer electrolyte in direct methanol fuel cells (DMFCs) by developing new cathode electrocatalysts. For this purpose, a series of gas diffusion electrodes (GDEs) were prepared by using single-walled carbon nanotubes (SWCNTs) supported Pt-Pd (Pt-Pd/ SWCNT) with different Pd contents at the fixed metal loading of 50 wt%, as bimetallic electrocatalysts, in the catalyst layer. Pt-Pd/SWCNT was prepared by depositing the Pt and Pd nanoparticles on a SWCNTs support. The elemental compositions of bimetallic catalysts were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES) system. The performances of the GDEs in the methanol oxidation reaction (MOR) and in the oxygen reduction reaction with/without the effect of methanol oxidation reaction were investigated by means of electrochemical techniques: cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). The results indicated that GDEs with Pt-Pd/SWCNT possess excellent electrocatalytic properties for oxygen reduction reaction in the presence of methanol, which can originate from the presence of Pd atoms and from the composition effect.
Journal of The Electrochemical Society, 2007
The carbon-supported nanoparticles of Pd-Co-M ͑M = Pt, Au, Ag͒ catalysts for direct methanol fuel cells ͑DMFCs͒ in a ratio of ͑70:20:10͒ were prepared through reverse microemulsion method. The X-ray diffraction ͑XRD͒ analysis showed well-defined reflections corresponding to a face centered cubic phase of palladium. From transmission electron microscopy analysis, the particle size after heat-treatment at 500°C was found to be approximately 20 nm, which was also confirmed by XRD analysis. Polarization data indicated Pd-Co-Pt to have better oxygen reduction reaction ͑ORR͒ activity than the other combinations with Ag and Au, in terms of shift in onset potential to a positive value of more than 100 mV and increased reduction current. The ORR kinetics on Pd-Co-Pt was analyzed by using rotating disk electrode to follow a 4 electron pathway, the order of the reaction being unity. The peroxide formation estimated from the rotating ring disk electrode measurements was found to be a negligibly small amount of 1.1%. An additional advantage observed with Pd-Co-Pt was its high methanol tolerance and ORR activity nearly equal to Pt.
Journal of Alloys and Compounds, 2019
In this article, we report a wet reflux strategy for the synthesis of reduced graphene oxide (rGO) /polyaniline (PANI)/ Pt-Pd composite, which was exploited as a potential anode catalyst with enhanced methanol oxidation capacity for direct methanol fuel cells (DMFCs). The construction of rGO/PANI/Pt-Pd involves two steps such as synthesis of PANI on GO and in-situ reduction of GO and metal precursors. The spherical shaped Pt-Pd particles with the average size of 3.5 nm are scattered throughout the surface of rGO/PANI, as observed from transmission electron microscope (TEM). PANI tailors the surface of rGO to allow the uniform scattering of Pt-Pd, which is beneficial for adsorption and decomposition of methanol. Besides, PANI assists the water absorption on the catalyst and promotes CO oxidation to CO 2 , thereby enhances the durability of composite. The cumulative features of rGO/PANI/Pt-Pd include active carbon support, extended architecture of electron conducting channels and number of methanol oxidation centers endows excellent DMFC power density of 117.45 mW/cm 2 and concrete cell durability over 70 h.
In this study, a series of graphene-supported Pt-Ni nanoparticles are successfully synthesized by a simple modified polyol method and used as electrocatalysts for methanol oxidation. In this method, graphene oxide is reduced to graphene and Pt-Ni alloy nanoparticles are deposited on graphene sheets simultaneously in ethylene glycol, which acts as a reducing agent. The electrocatalysts are physically characterized using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), thermal gravimetric analysis (TGA), high-resolution transmission electron microscopy (HRTEM), and scanning electron microscopy (SEM). The cyclic voltammetry and chro-noamperometry electrochemical measurements in acidic and alkaline media are promising. The electrocatalysts containing Ni (G/Pt 75-Ni 25 , G/Pt 54-Ni 46 and G/Pt 40-Ni 60) have higher catalytic activity and stability for the MOR than pure G/Pt in both acidic and alkaline media. G/Pt 54-Ni 46 has the highest performance in acidic and alkaline media, and its activity in alkaline media (2732 A/g Pt) is nearly 10 times higher than that in acidic media (260 A/ g Pt). The superior catalytic performance in alkaline media may be because Ni is more stable in alkaline media. These electrocatalysts are promising candidates for direct methanol fuel cell (DMFC) anode catalysts.
Pt decorated PdFe/C: Extremely High Electrocatalytic Activity for Methanol Oxidation
International journal of electrochemical science
A carbon supported Pt-decorated PdFe alloy nano-core catalysts (Pt-PdFe/C) for methanol oxidation is prepared via metathetical reaction between PdFe alloy nanoparticles (deposited on carbon) and PtCl 4 2in aqueous solution. Morphology and composition of the synthesized catalyst are characterized by Transmission Electron Microscope and X-ray diffraction. Experimental results show the electrochemical active surface area of the Pt-PdFe/C catalyst is much larger than those of the PdFe/C and Pt/C catalysts. Furthermore, the mass specific peak current is 1.01 A mg -1 for methanol oxidation on the Pt-PdFe/C electrode, an increase by a factor of 3.5 times and 12.6 times as compared to PtRu/C and Pt/C, respectively. The facile fabrication and high electrochemical performance of Pt-PdFe/C highlight its potential application as anode for DMFCs.