Catalyst Layer Degradation, Diagnosis and Failure Mitigation

Abstract

Faced with rapidly rising air pollution-related health risks, sky-rocketing oil prices, and diminishing natural resources, scientists and engineers are now seeking clean and efficient alternatives to petroleum as energy sources. The hydrogen fuel cell, using hydrogen and oxygen from air as fuel, could achieve efficiencies of electric power generation in the 50-65% range. As a "clean" electric power source, fuel cells can be used to power vehicles, back-up the power supply for electric devices, and store electricity in power stations by converting water into hydrogen and oxygen during off-peak hours. The only by-products are water and heat. The proton exchange membrane fuel cell (also called polymer electrolyte membrane fuel cell, PEMFC) is a highly promising power source candidate for zero emission vehicles, stationary applications, backup power units, materials handling, and small electronics. Fuel cells are currently the only technology that can effectively provide pollution-free energy for both transportation and electric utilities. The use of fuel cell vehicles (FCVs) will partially reduce the global dependency on petroleum as a fuel.In the past several decades, a variety of fuel cells have been developed. These can be classified by the type of electrolyte used in the cells, and include: 1) polymer electrolyte membrane fuel cell, 2) alkaline fuel cell (AFC), 3) phosphoric acid fuel cell (PAFC), 4) molten carbonate fuel cell (MCFC), and 5) solid oxide fuel cell (SOFC). Hydrogen has many merits as a fuel for fuel cells in most applications. It is highly reactivity when suitable catalysts are used. It can be produced from hydrocarbons, obtained as a by-product of chemical plans, or generated by water electrolysis using solar or nuclear power. It also has high energy density. Therefore, hydrogen has been chosen as a PEMFC fuel for many applications. The most common and economical oxidant is gaseous oxygen, which is readily available from air. A typical single PEMFC consists of an anode, a cathode, a proton conductive membrane, and two bipolar plates (Figure 23.1).

Hydrogen spillover effect – harnessing hydrogen evolution reaction from diverse carbon-based supports with a tungsten oxide catalyst

“…8b inset) with no obvious change in the surface structure indicating that the catalyst has undergone oxidation, which is consistent with the XPS outcome. 25,52,55,56 When a portion of the electrocatalyst was scanned for morphological analysis (Fig. S25 †) aer the stability test, results expose the intact nature of the WO 3 /GR composite onto the carbon ber substrate indicating good adherence of the electrocatalyst onto the substrate even aer long hours of electrochemical tests.…”