Carbon-supported Pt nanoparticles

Additional experiments were carried out to study the behavior of Pd nanoparticles coated with Pt or with Pt plus M, which more closely reflects the morphology of actual catalyst particles. Figure 9.18a displays the polarization curves for the ORR on commercial carbon-supported Pt nanoparticles (Pt/C), Pd nanoparticles (Pd/C), a monolayer of Pt on Pd/C (PtMu/Pd/C), and mixed (Pto.gIro.a/ML/Pd/C and... 

One of the critical issues with regard to low temperamre fuel cells is the gradual loss of performance due to the degradation of the cathode catalyst layer under the harsh operating conditions, which mainly consist of two aspects electrochemical surface area (ECA) loss of the carbon-supported Pt nanoparticles and corrosion of the carbon support itself. Extensive studies of cathode catalyst layer degradation in phosphoric acid fuel cells (PAECs) have shown that ECA loss is mainly caused by three mechanisms ... 

Methanol, Formaldehyde, and Formic Acid Adsorption/Oxidation on a Carbon-Supported Pt Nanoparticle Fuel Cell Catalyst A Comparative Quantitative OEMS Study... 

Maillard F, Savinova FR, Simonov PA, Zaikovskii VI, Stimnting U. 2004b. Infrared spectroscopic study of CO adsorption and electro-oxidation on carbon-supported Pt nanoparticles Interparticle versus intiaparticle heterogeneity. J Phys Chem B 108 17893-17904. 

Maillard F, Schreier S, Hanzhk M, Savinova FR, Weinkauf S, Stimnting U. 2005. Influence of particle agglomeration on the catalytic activity of carbon-supported Pt nanoparticles in CO monolayer oxidation. Phys Chem Chem Phys 7 385-393. 

The role of metal-support interaction on the catalytic activity of carbon-supported Pt nanoparticles toward oxygen reduction and methanol oxidation was analyzed. It was observed that both dispersion and specific activity are influenced by the interaction of the active phase with the support, determining well-defined relationships that may be used for interpreting the electrochemical behavior of new, more advanced catalytic systems. 

Figure 2. Point-by-point Pt NMR spectra of 3.2 nm carbon-supported Pt nanoparticle after electrochemical cleaning.

We have carried out NMR investigations of (conducting) carbon-supported Pt nanoparticles having an average particle size of... 

Saez A, Exposito E, Solla-Gullon J, Montiel V, Aldaz A (2012) Bismuth-modified carbon supported Pt nanoparticles as electrocatalysts for direct formic acid fuel cells. Electrochim Acta 63 105-111... 

The most frequent use of DBMS is for studies of possible fuels in fuel cells. Figure 5 shows the faradaic and ion currents for CO2 and methylformate during methanol oxidation at carbon-supported Pt nanoparticles. Note that the formation of methylformate starts at a slightly lower potential than that of CO2. The ratio of the CO2 formation rate to the faradaic current yields a current efficiency of 90 % in this case. Under flow and at smooth Pt electrodes, the current efficiency for CO2 remains at 30 % for all flow rates [4]. This proves the parallel reaction mechanism suggested by Bagotsky [30]. One path leads to formaldehyde and formic acid. Under flow, these molecules diffuse away fi om the electrode, while under stagnant conditions as in the pores of a porous electrode, they are further oxidized to CO2. The other path leads to CO2 via adsorbed CO and is independent of flow rate. 

Hydrogen Oxidation and Evolution on Platinum in Acids, Fig. 2 Typical voltammetry black) and polarization curves for the HER/HOR (Wne) and ORR/OER red) reactions measured, respectively, on carbon-supported Pt nanoparticles in Ar-, H2-, and 02-saturated 0.1 M HCIO4 solutions. The vertical dotted lines show the reversible potentials for the HER/HOR and ORR/OER... 

Liu ZL, Gan LM, Hong L, Chen WX, Lee JY. Carbon-supported Pt nanoparticles as catalysts for proton exchange membrane fuel cells. J Power Sources 2005 139 73-8. Colon-Mercado HR, Kim H, Popov BN. Durability study of Pt3Nil catalysts as cathode in PEM fuel cells. Electrochem Comm 2004 6 795-9. 

Chen WX, Lee JY, Liu Z. Microwave-assisted synthesis of carbon supported Pt nanoparticles for fuel cell applications. Chem Commun 2002 2588-89. 

The membrane electrode assembly (MEA) is the heart of a fuel cell stack and most likely to ultimately dictate stack life. Recent studies have shown that a considerable part of the cell performance loss is due to the degradation of the catalyst layer, in addition to membrane degradation. The catalyst layer in PEMFCs typically contains platinum/platinum alloy nanoparticles distributed on a catalyst support to enhance the reaction rate, to reach a maximum utilization ratio and to decrease the cost of fuel cells. The carbon-supported Pt nanoparticle (Pt/C) catalysts are the most popular for PEMFCs. Catalyst support corrosion and Pt dissolution/aggregation are considered as the major contributions to the degradation... 

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