This document describes a study on the use of PtCo and PtNi nanoparticles supported on graphitic mesoporous carbon (GMC) as electrocatalysts for the electro-oxidation of methanol. The electrocatalysts were prepared using a sequential impregnation reduction method and characterized using various techniques. Their performance for methanol oxidation was evaluated using cyclic voltammetry. The results showed that PtCo/GMC had the highest mass activity and CO tolerance, followed by PtNi/GMC, due to the high metal nanoparticle dispersion and GMC support, which facilitated CO oxidation through a bifunctional mechanism.

1. PtCo AND PtNi NANOPARTICLES SUPPORTED ON GRAPHITIC
MESOPOROUS CARBON FOR ELECTRO-OXIDATION OF METHANOL.
D. Macias Ferrer1
*, J.A. Melo Banda1
, J.Y. Verde Gomez2
, U. Páramo García1
, P. Del Ángel
Vicente3
, M. Lam Maldonado1
, R. Silva Rodrigo1
1
Instituto Tecnológico de Ciudad Madero. Juventino Rosas y Jesús Urueta S/N, Col. Los Mangos,
Cd. Madero, Tamaulipas, C.P. 89440, México.
2
Instituto Tecnológico de Cancún. Ave. Kabah Km. 3, S/N, Cancún, Quintana Roo, C.P. 77500,
México.
3
Instituto Mexicano del Petróleo, Dirección de Investigación y Posgrado, Eje Central Lázaro
Cárdenas 152, México D.F. 07730, Mexico.
*e-mail: maestro_macias@hotmail.com
ABSTRACT
In this work, electrocatalysts based on PtCo and PtNi nanoparticles supported on
graphitic mesoporous carbon (GMC) have been prepared by sequential impregnation reduction
method in which Pt, Co and Ni precursors are chemically reduced by sodium borohydride, citric
acid and Ar-H2 atmosphere [1-2]. GMC sample was synthesized via nanocasting process with
anhydrous pyrolysis at 1273 K using SBA-15 as hard template and purified sugar as carbon
source [3]. SBA-15 was prepared via sol gel using pluronic P-123 as surfactant and TEOS as
silica precursor [4]. The prepared materials were characterized by means of N2 physisorption
analysis, XRD, RAMAN, SEM, EDS and TEM. The performance of electrocatalysts for
methanol oxidation reaction was measured by CV.
Keywords: Electrocatalysts, platinum, cobalt, nickel, graphitic mesoporous carbon, sba-15.

2. XXXI CONGRESO DE LA SOCIEDAD MEXICANA DE ELECTROQUÍMICA
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1. INTRODUCTION
The direct methanol fuel cell (DMFC) is a special form of low-temperature fuel cells based
on PEM technology. DMFC have attracted significant attention because of their high theoretical
power density, high energy conversion efficiency, low environmental pollution and easy
refueling, being one of the potential power source for portable electronic devices. The high
reactivity of platinum with methanol and the excellent catalytic activity towards the electro-
oxidation of methanol, makes this metal is indispensable in DMFC anode electrocatalyst. The Pt
particles quickly poisoned due to the intermediate species formed during oxidation of methanol,
mainly CO, since molecules of CO can adsorb chemically on the surface of Pt, blocking the
active sites and producing a poor kinetics in the process methanol oxidation [5-7].
The electrocatalytic activity toward methanol oxidation of PtCo/GMC and PtNi/GMC as
well as commercial electrocatalyst PtRu/C was evaluated through cyclic voltammetry in a three
electrode cell at 30 mV/s.
2. EXPERIMENTAL METHODOLOGY
2.1. Electrochemical Measurements
2.1.1. Electrochemical System
The performance of electrocatalysts and commercial catalysts (Pt/C and PtRu/C) for room
temperature methanol oxidation reaction was measured in electrochemical work station BASi-
epsilon (potentiostat/galvanostat) with coupled rotating disk electrode. A conventional three-
electrode cell consisting of the glassy carbon (GC) working electrode, Pt wire as counter
electrode and Ag/AgCl reference electrode were used for the cyclic voltammetry studies.
2.1.2. Preparation of the Electrodes
A glassy carbon electrode (3 mm in diameter) was sequentially polished with 0.05 μm
Al2O3 and then washed. The catalyst ink was prepared by ultrasonically dispersing 10 mg
catalyst in 1 mL of ethanol and 60μL Nafion/water (25% Nafion) for 45 min. 10 μL of the
dispersion was transferred on the GC and then dried in the air for 30 min. The electrolyte solution

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9TH MEETING OF THE MEXICAN SECTION ECS
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for methanol oxidation reaction consists of 0.5 M CH3OH and 0.5 M H2SO4 and the CV’s were
recorded at a scanning rate of 30 mV/s and 10 cycles for each.
3. RESULTS AND DISCUSSION
The electrocatalytic activity given by mass activity (the current density is normalized to the
platinum loading on the electrodes), the onset potential and the value of the ratio between the
forward peak maximum current density (If) and the backward peak maximum current density (Ib)
of the electrocatalysts PtCo/GMC, PtNi/GMC and the commercial catalyst PtRu/C for room
temperature methanol oxidation reaction, were obtained by cyclic voltammetry in a conventional
three-electrode cell, using an electrolyte solution that consists of 0.5 M CH3OH and 0.5 M
H2SO4; The potential was swept between -0.2 and 1.0 V at a scanning rate of 30 mV/s and 10
cycles for each. The results of these measurements are shown in Fig. 1 and Table 1.
Figure 1. Cyclic voltammograms in 0.5 M CH3OH + 0.5 M H2SO4 solution at scan rate of 30 mV/s of PtCo/GMC,
PtNi/GMC and PtRu/C.

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Table I. Mass activity, onsetpotential and If/Ib for PtCo/GMC, PtNi/GMC and PtRu/C
Sample
Onset Potential
(V)
Mass Activity
(mA/mgPt)
If/Ib
PtCo/GMC 0.07 337 1.18
PtNi/GMC 0.07 279 1.03
PtRu/C 0.05 254 1.14
The chemisorbed CO specie is considered as a poisoning on pure Pt surface, and are more
difficult to oxidize that all intermediate carbonaceous species formed during the methanol
oxidation reaction (MOR); to free the pure platinum, is necessary to dissociate the water
molecules and cause the oxidation of CO to CO2, however, this is achieved at high values of
potential [8]; it has been shown that the incursion of a second metal can dissociate water
molecules at very low potential (i.e., Ruthenium) [9], and contribute to the release of the active
sites of Pt increasing the electrocatalytic activity in the MOR. Currently this process is known as
bifunctional mechanism theory [10]. According to what explained above and the experimental
results, the electrocatalysts PtCo/GMC and PtNi/GMC had better electrocatalytic activity and
antipoisoning ability relative to MOR, that the catalyst PtRu/C; this can be explained by the
adsorption of water OH species on the Co, CoO, Ni and NiO nanoparticles with very small
particle size, which facilitates release of the Pt nanoparticles (poisoned by CO molecules) leading
to the oxidation of CO to CO2 producing an increment in mass activity and an high level CO-
tolerance in methanol oxidation process [11].
4. CONCLUSIONS
The nanostructured carbon GMC with low graphitization degree and turbostratic structure, was
obtained by the nanomolding procedure using SBA-15 as hard template and purified sugar as
carbon precursor. Characterization techniques applied to all electrocatalysts prepared in this
work, showed that high dispersions of metallic nanoparticles of Pt, Co, Ni and NiO on oxidized
GMC which it was a decisive factor in increasing the electrocatalytic activity towards methanol
oxidation process. According with CV results, the electrochemical activity in MOR has the
following order: PtCo/GMC > PtNi/GMC > PtRu/C, mainly attributed to the high dispersion of

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MONTERREY, NUEVO LEON
metal nanoparticles and the nature of carbon support. The values of ratio If/Ib of our
electrocatalysts showed higher level of CO-tolerance to intermediate carbonaceous species and
higher efficiency to remove them. This study shows that the electrocatalyst synthesized in this
work deserve a deeper analysis on the development of anodic catalysts for direct methanol fuel
cell.
5. ACKNOWLEDGEMENTS
This paper has been supported by the National Council for Science and Technology,
México under contract DGEST 4513.12-P; authors also acknowledge the support of Cancún
Institute of Technology, Madero City Institute of Technology and Mexican Petroleum Institute.
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