ty H₂, because parts-per-million levels of carbon monoxide (CO) and sulfur poison the precious metal catalysts in the anode.

The species transported through the electrolyte in SOFCs are O^2- ions. This makes SOFCs more fuel flexible, and, in theory, any combustible gas could be used as the fuel. A schematic drawing of an SOFC is shown in Figure 1.

The cell is composed of a thin, dense layer of an oxygen ion-conducting electrolyte, typically yttria-stabilized zirconia (YSZ), and a porous anode and cathode. To obtain appreciable oxygen ion conductivity in the electrolyte, the system must operate at high temperatures. The cathode is composed of an electronically conducting oxide, such as strontium-doped LaMnO₃ (LSM). The cathode is exposed to air and reduces O₂ to O^2- ions using electrons supplied by the external circuit according to the following half-cell reaction:

The anode catalyzes the oxidation of the fuel using O^2- ions delivered through the electrolyte-producing electrons that flow through the external circuit to the cathode. If H₂ is used as the fuel, the anode half-cell reaction is as follows:

Front Matter (R1-R10)

Chemical and Molecular Engineering in the 21st Century (1-28)

Technology for Human Beings (29-52)

The Future of Nuclear Energy (53-90)

Engineering Challenges for Quantum Information Technology (91-108)

Dinner Speech (109-118)

Appendix: Contributors (119-126)

Appendix: Program (127-130)

Appendix: Participants (131-140)