High Methanol Electro-Oxidation Using PtCo/Reduced Graphene Oxide (rGO) Anode Nanocatalysts in Direct Methanol Fuel Cell (original) (raw)
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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.
International Journal of Hydrogen Energy, 2017
Platinum e cobalt (PtCo) alloy based highly efficient nano electro-catalysts on reduced graphene oxide (rGO) matrix have been synthesized for the electro-oxidation of methanol, by chemical reduction method. Different molar ratio of Pt (IV) and Co (II) ions along with graphene oxide (GO) were reduced using ethylene glycol to obtain PtCo nanoparticles onto rGO sheets (Pt/rGO, PtCo (1:1)/rGO, PtCo (1:5)/rGO, PtCo (1:9)/rGO and PtCo (1:11)/rGO) with 20 wt. % metal and 80 wt. % rGO. The average particle size of PtCo nanoparticles onto rGO support was observed to be 2e5 nm using XRD and TEM analysis. The PtCo (1:9)/rGO nanocomposite catalyst exhibited~23 times higher anodic current density compare to commercially available Pt/C catalyst (1.68 mA/cm 2) for methanol oxidation reaction. The peak power density of 118.4 mW/cm 2 was obtained for PtCo (1:9)/rGO catalyst in direct methanol fuel cell (DMFC) at 100 C, 1 bar, and 2 M methanol as anode feed, which is~3 times higher than that of Pt/C catalyst. The results indicate the potential application of synthesized nanocomposite catalyst in commercial DMFCs.
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.
Applied Catalysis B: Environmental, 2014
Carbon-supported PtPdCo/C ternary electrocatalysts were prepared by using the sodium borohydride method for use as a cathode catalyst in direct methanol fuel cells (DMFCs). The electrocatalyst particles with a size of 2-3 nm were uniformly dispersed on carbon supports. PtPdCo/C showed a similar performance compared to commercial Pt/C in the oxygen reduction reaction (ORR) tests conducted with a rotating disk electrode (RDE). On the other hand, PtPdCo/C showed higher methanol tolerance than Pt/C in acidic media with methanol. In the single-cell tests, the performance of the PtPdCo/C electrocatalyst was approximately 50% higher than that of Pt/C owing to its enhanced methanol tolerance. In the longterm operation test with the single-cell, the maximum power density of PtPdCo/C decreased only by 14% from its initial value. These results indicate that the PtPdCo/C catalyst is potentially an alternative electrocatalyst for the cathode in DMFCs.
PtCo catalyst with modulated surface characteristics for the cathode of direct methanol fuel cells
International Journal of Hydrogen Energy, 2014
A PtCo catalyst with an ordered cubic primitive structure was synthesized and investigated for the application as a cathode in direct methanol fuel cells. The synthesis involved the preparation of an amorphous PtOx/C precursor by the sulfite complex route, an impregnation with Co(NO 3) 2 , a high temperature (800 C) carbothermal reduction and, finally, a leaching procedure. This method led to the occurrence of a Pt 3 Co/C catalyst with a primitive cubic ordered (L1 2) phase and a mean crystallite size of 3.3 nm, as well as a suitable degree of alloying. This electrocatalyst was investigated for the oxygen reduction reaction in a direct methanol fuel cell (DMFC) operating in the range 30e90 C. At 60 C, under atmospheric pressure, a maximum power density of 40 mW cm À2 was obtained with the new PtCo catalyst formulation at low noble metal loading on the electrode (1 mg cm À2). This performance was 2.3 times higher than a benchmark Pt catalyst used for comparison.
Enhanced methanol electro-oxidation activity of PtRu catalysts supported on heteroatom-doped carbon
Electrochimica Acta, 2008
PtRu nanoparticles deposited on a carbon black substrate are catalysts commonly employed for the electrooxidation of methanol and carbon monoxide-containing hydrogen feeds [1,. However, improvement of effective electrocatalysts is an essential goal in the development of a practical DMFC. The use of carbon black as a support for noble metals is frequent in the electrodes of polymer membrane electrolyte fuel cells, but the impact of the chemical and physical properties of the carbon on electrocatalytic performance are not yet sufficiently understood. The presence of oxygen surface groups influences the surface behaviour of carbons to a considerable extent . As examples, the wettability and adsorptive behaviour of a carbon, as well as its catalytic and electrical properties, are influenced by the nature and extent of such surface groups. The varying role of oxygenated functionalities on the formation of the dispersed platinum has been established [5-8], but not with an additional metal such as ruthenium. In the present investigation we report how the performance in methanol electrooxidation of PtRu nanoparticles deposited on a carbon black substrate, previously functionalized with oxygen surface groups, is improved.
Electrochimica Acta, 2019
Methanol crossover is one of the major problems which reduces the performance of direct methanol fuel cells (DMFCs). Utilization of methanol tolerant cathode electrocatalysts with comparable activity, lower cost, and higher durability than those of current Pt-based electrocatalysts is an essential step towards commercialization of DMFCs. In this research, for the first time the performance of hydrothermally produced nitrogen-doped reduced graphene oxide (NRGO) with nitrogen content of 4.6 wt% was compared with that of commercial 20 wt% Pt/C as cathode electrocatalysts of passive DMFC. The polarization curves of cells with various methanol concentrations (1.5, 3.0, and 4.5 M) were recorded. The results suggested the cell with NRGO cathode could operate at higher optimum methanol concentration in contrast to the cell with Pt/C cathode. The results showed that at the same methanol concentration the maximum power density, the fuel efficiency, and the current stability for the cell with NRGO cathode are higher than those of Pt/C cathode about 208%, 269%, and 77%, respectively. Higher temperature of cathode current collector of the cell with Pt/C cathode, in spite of its lower power output, presented an evidence of oxidation of permeated methanol on its cathode surface. Also, EIS measurements clarified that CO ads oxidation reaction, an intermediate of methanol oxidation reaction (MOR), on cathode side of cell with Pt/C cathode implies a relatively huge impedance on the overall cell operation. By contrast, in the case of cell with NRGO cathode due to its inertness towards MOR, the overall cell impedance significantly reduced.