Synthesis and Evaluation of Highly Tolerant Pd Electrocatalysts as Cathodes in Direct Ethylene Glycol Fuel Cells (DEGFC)

Abstract

Abstract:Highly selective Pd electrocatalysts were synthesized by the formic acid (FA) method and evaluated as cathodes for DEGFC applications. In rotating disc measurements in acid medium, the Pd/C cathode showed important catalytic activity for the Oxygen Reduction Reaction (ORR). In the presence of ethylene glycol (EG, C 2 H 6 O 2 ), Pd/C exhibited a noteworthy electrochemical behavior and full tolerance to the organic molecule. No current density peaks associated to the EG oxidation reaction emerged and the shift in onset potential for the ORR (E onset ) toward more negative potentials was negligible on this cathode. As a comparison, commercial Pt/C was tested under the same conditions showing a poor selectivity for the ORR when EG was present. The detrimental effect of EG on the Pt electrocatalysts resulted in high intensity current density peaks due to the oxidation of EG and a significant shift in E onset . The evaluation of Pd/C in a DEGFC operating at 80 °C demonstrated its good performance as cathode material. Given these results, it is expected that highly efficient Pd-based cathodes can find application in DEGFCs.

RRDE and EIS Study of Pt-Co/MWCNT Electrocatalysts as ORR Electrodes in Sulfuric Acid Containing Small Organic Molecules

“…Figure 3 shows the behavior of Pt/C during the ORR in the absence and presence of C 2 H 6 O 2 at the rotating speed of 1600 rpm. The poor capacity of Pt/C to select the ORR under DOFC conditions, in this case with ethylene glycol as the fuel, is clearly demonstrated and is in agreement with previous reports (11,21). The i -E behavior of Pt-Co/MWCNT during the ORR in the presence of EtOH, EG and 2-Prop is shown in Figure 4.…”

“…The expected characteristics of kinetic, mixed and diffusion limited regions for i d are clearly observed. With the Levich equation [1], a relationship between the disc current density (j d ) and the kinetic current density (j k ) can be established (21):…”

“…where 0.2 applies when is expressed in rpm, D is the diffusion coefficient of oxygen in sulfuric acid (1.4×10 −5 cm 2 /s), is the kinematic viscosity of the sulfuric acid (1.0×10 −2 cm/s), c is the bulk concentration of oxygen (1.1×10 −6 mol/cm 3 ), F is the Faraday constant (96,500 C) and n is the number of electrons transferred (21,23). Clearly, the experimental lines in Figure 2 3.6 e -, suggesting that the ORR at the home-prepared Pt-Co/MWCNT alloy may proceed via an overall mechanism that leads almost totally to the formation of H 2 O.…”

“…As a reference, a 20% Pt/C catalyst purchased from E-Tek was also characterized. The experimental details regarding the preparation of the catalytic ink have been described elsewhere (20,21). A brief description is as follows: separate mixtures containing each of the catalysts, DI water and Nafion (5% wt, DuPont) were prepared by ultrasound to form an ink of 5 mg catal /mL.…”

NbC Nanowire-Supported Pt Nanoparticles as a High Performance Catalyst for Methanol Electrooxidation

“…To meet the increased demand of practical, cost-effective direct methanol fuel cells (DMFCs), considerable efforts have been devoted to developing high-performance electrocatalysts for methanol oxidation reaction (MOR). − As we all know, catalyst support materials play a vital role in improving the catalytic activity, reducing the Pt usage to lower the cost of catalysts. − Now, high surface area carbon such as Vulcan XC-72 is the most commonly used support material for dispersing nanosized Pt catalyst in DMFCs. − Unfortunately, Vulcan XC-72 carbon support is susceptible to corrosion because of the operating conditions of DMFCs, which include high water content, acidic electrolyte (pH <1), high temperature (80–100 °C), and high potential (0.6–1.2 V). , …”