Does nickel prevent the high performance of state-of-the-art catalysts in hydrogen fuel cells?

The primary efficiency-limiting factor in proton exchange membrane fuel cells (PEMFCs) is the inefficient catalyst for the oxygen reduction reaction. Advanced octahedra oh-PtNiIr nanoparticles (NPs) exhibit a 10-fold increase in activity compared to commercial Pt catalysts. However, when coated on the membrane, they suffer from Pt and Ni dissolution during PEMFC operation. Dissolved Ni might redeposit on NP's surface or migrate into the membrane, affecting protons' transport and reducing the fuel cell's performance. Knowing Ni migration dynamics is highly important, as it will help to understand why the 10-fold activity enhancement of advanced bimetallic catalysts measured in a laboratory does not translate to real PEMFC devices. For this reason, we designed a PEMFC capable of both high current densities and operando XAS depth profiling of Ni in the membrane, which allows following nickel in the membrane electrode assembly and correlating its movement with the operation parameters.