Platinum

About: Platinum is a research topic. Over the lifetime, 49675 publications have been published within this topic receiving 1150035 citations. The topic is also known as: Pt & element 78.

High performance platinum single atom electrocatalyst for oxygen reduction reaction

Abstract: For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm-2 at 80 °C with a low platinum loading of 0.09 mgPt cm-2, corresponding to a platinum utilization of 0.13 gPt kW-1 in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.

Methods to Advance Technology of Proton Exchange Membrane Fuel Cells

Abstract: Proton exchange membrane (PEM) fuel cells showing promise of a high level of performance have, up to the present time, used electrodes containing a high platinum loading (4 mg/cm2). We report improvements in performance of PEM fuel cells utilizing electrodes with only one‐tenth of this platinum loading by (i) extension of the three‐dimensional reaction zone by incorporation of a proton conductor (Nafion) into the electrode structure; (ii) optimization of the amount of Nafion impregnated into the electrode structure; (iii) hot‐pressing the impregnated electrodes to the Nafion membrane at 120°C and 50 atm; (iv) optimal humidification of reactant gases at a temperature above that of the cell (5°C for or air and 10°–15°C for ); and (v) operation at elevated temperatures and pressures. The performance of the cells was analyzed from measurements of cell potential vs. current density and of cell potential at constant current density vs. time. Cyclic voltammetry proved to be a useful tool to ascertain the electrochemically active area of the electrodes.

Catalyst–support interactions: Electronic perturbations

Abstract: Oxide materials typically used as supports for the active metal nanoparticles of heterogeneous catalysts are known to influence catalytic activity through strong metal–support interactions. Researchers have now revealed electronic interactions between platinum and ceria that go well beyond known effects and lead to excellent catalytic activity.

Heat-treated Fe/N/C catalysts for O2 electroreduction: are active sites hosted in micropores?

Abstract: Limited availability of platinum is a potential threat to fuel cell commercialization. Since the 1970s, alternative catalysts to the electrochemical reduction of oxygen have been obtained from heat treatment at T > 600 degrees C of carbon with a non-noble metal and a source of nitrogen atoms. However, the process by which the heat treatment activates these materials remains an open question. Here, we report that the activation process of carbon black and iron acetate heat-treated in NH(3) comprises three consecutive steps: (i) incorporation of nitrogen atoms in the carbon, (ii) micropore formation through reaction between carbon and ammonia, and (iii) completion of active sites in the micropores by reaction of iron with ammonia. Step (ii) is the slowest. Moreover, the microporous surface per mass of catalyst controls the macroscopic activity when enough nitrogen atoms are incorporated in the structure of the carbon support. These facts should help in determining the structure of the active sites and in identifying methods to increase the site density of such catalysts.