Fundamental kinetics/transport processes in MEAs

Abstract

The results of fundamental and applied research on the development of dispersed catalysts, gas‐diffusion electrodes and membrane and electrode assemblies (MEAs) for polymer electrolyte fuel cells (PEFCs) are discussed. In the first part, the electrocatalysis of the oxygen reduction reaction on dispersed platinum catalysts used for the preparation of fuel cell electrodes is briefly considered. The issue is analyzed mainly in terms of the size and structure of the catalyst particles. Next, efforts on the development and single cell testing of low catalyst loading gas‐diffusion electrodes for PEFCs are reported in conjunction with the main parameters relating to the properties of the MEAs. The fuel cell polarization behavior is analyzed considering the effects of the structure and composition of the diffusion and catalytic layers of the gas‐diffusion electrode, the cell temperature and gas pressure and the thickness and the water transport through the membrane.

Dynamic Performance of Fuel Cell Power Module for Mobility Applications

“…Nart et al (2009) have noticed that in catalysis, the important parameter is the active surface area, which is given by the active material [19]. Than Ticianelli et al (2010) have renowned that for such applications, in order to provide the best performance with minimum content of platinum, the most important metallic material employed for the catalysis, one cm 2 of the active surface area contain a value of 2 mg of the noble metal catalyst load, can be maximised for supporting about 20 mg of Pt [20] and Ünlü et al (2010) have noticed that it is more difficult to determine the true surface area in a particular operating fuel cell than the superficial area, even they observed the decrease in the active area by flooding due to faster water generation at high current densities and the charge-transfer resistance consists of a purely kinetic term and is inversely proportional to the active surface area [21]. Ho et al (2011) have revealed a new catalyst support, featuring can give a progress: a high surface area and high proton conductivity, efficiency and durability of polymer electrolyte membrane fuel cells [22], Zakrisson (2011) reported that the platinum is expensive and contributes to a large extent to the high price of PEM fuel cells, which makes it desirable to use the platinum as effective as possible.…”

Efeitos da temperatura e da concentração de CO e CO2 sobre a eletrocatálise da oxidação de hidrogênio em eletrodos à base de Pt e Mo

“…O mais comum é a classificação baseada na natureza do eletrólito e, desta forma, temos cinco principais tipos de células, conforme ilustrado na Tabela 1. 4,6,7 Outras pesquisas apontam ainda a possibilidade de utilizar etilenoglicol e glicerol. 8,9 Dentre os principais combustíveis, o H 2 apresenta maior densidade de potência e menor polarização anódica frente aos alcoóis leves.…”

Tolerância ao CO da reação de oxidação de hidrogênio por mecanismos de oxidação: efeitos do substrato do eletrocatalisador

“…Stackpole ® ) e uma suspensão de politetrafluoretileno (PTFE -Teflon T-30, DuPont ® )[14,53]. Para a sua preparação, inicialmente foi feito um tratamento térmico do tecido de carbono a 450°C em atmosfera ambiente e, em seguida, durante o tempo de 1h, foi tratado com uma solução de ácido nítrico 25% V/V a 80°C, diminuindo assim o seu caráter hidrofílico.…”