Two of the most critical challenges to commercialization of PEMFCs for automotive applications are the cost of the Pt used in the catalyst layers and the system lifetime. Because the oxygen reduction reaction in the PEMFCs is slow and at low temperatures, finding a suitable replacement for Pt has been incredibly challenging. A recent development of a non-precious metal catalyst that uses iron functionalized by nitrogen starting with a precursor of polyanilane (PANI) has shown remarkable performance. However, electrochemical measurement indicated that this thick catalyst layer may suffer from flooding, a condition that occurs when liquid water clogs the catalyst layer. Two samples were tested, a PANI catalyst and a Pt on carbon catalyst of similar thickness of the PANI. The neutron data shown in Figure 1 revealed that the flooding in the PANI catalyst was not due to the thickness but rather that the interface between the catalyst and membrane was hygroscopic, as evidenced by large amount of water uptake at this interface even when no current was being drawn.
Neutron imaging continues to play a key role in elucidating the role of water in proton exchange membrane fuel cells (PEMFCs) as highlighted by two projects with Los Alamos National Lab.
Rod Borup (Primary Contact)
Los Alamos National Laboratory