Catalytic Electrode with Gradient Porosity and Catalyst Density for Fuel Cells
In the past decade, huge effort and resource has been devoted to developing proton exchange membrane fuel cells (PEMFCs) technology to realize the wide commercialization in automotive and portable application. However, challenges still remain related to the high cost especially the precious metal cost, relative low performance at low platinum loading, and poor long-term durability.
The technology developed is a membrane electrode assembly (MEA) for a fuel cell comprising a gradient catalyst structure and a method of making the same. The gradient catalyst structure can include a plurality of catalyst nanoparticles, e.g., platinum, disposed on layered buckypaper. The layered buckypaper can include at least a first layer and a second layer and the first layer can have a lower porosity compared to the second layer. The gradient catalyst structure can include single wall nanotubes, carbon nanofibers, or both in the first layer of the layered buckypaper and can include carbon nanofibers in the second layer of the layered buckypaper. The MEA can have a catalyst utilization efficiency of at least 0.35 g,a1/kW or less.
The SWNT/CNF buckypaper based Pt catalyst has shown a good Pt utilization and a good durability under an accelerated degradation test in a mimic cathode environment in our previous patent application. However, this new invention by using the Pt/DLBP with tailored gradient structure was demonstrated even better Pt utilization and stability. Therefore, the fuel cell made with this new structure catalytic electrodes will have better power density and operation time, and low cost.
- Will have significant impact on the structure of future fuel cell
- Will significantly reduce the cost of fuel cells, because the usage of catalytic material (platinum) can be significantly reduced
- Fuel cells are capable of providing high energy efficiency and relatively rapid start-up
- Fuel cells are capable of generating power without generating the types of environmental pollution that characterize many other sources of power
- Thus, fuel cells can be a key to meeting critical energy needs while also mitigating environmental pollution by substituting for conventional power sources