Proton exchange membrane fuel cell has advantages of high discharge power and no pollution. Platinum-based intermetallic particles, regarded as the promising commercial oxygen reduction catalyst system of the next generation fuel cell, have advantages in stability because of their long-range ordered structure. However, they have problems such as large particle size. These problems result in the reduction of platinum utilization and mass activity which limits fuel cell performance.
In this study, the researchers synthesized a series of platinum-based intermetallic particles Pt3Co, PtCo, Pt3Ti with an ultra-small size of about 2 nm, by breaking size limitation during ordered atomic transformation in Pt alloy systems.
The power density of fuel cells made from ultra-small Pt3Co intermetallic particle was 530 MW/cm-2, higher than that of the commercial Pt/C. In the durability test, the mass activity of ultra-small Pt3Co particles can still reach 0.75 A/mg after 30000 cycles. Meanwhile, platinum-based intermetallic particle located in mesoporous carbon benefits the optimization of three-phase interface under fuel cell conditions.
Theoretical calculations showed that the mesoporous efficiently completed the transport of protons and oxygen, achieving dynamic equilibrium. Mesoporous greatly reduced the mass transfer resistance of the battery and prevented ionomers from poisoning the catalyst.
Based on the ultra-small size platinum-based intermetallic compounds, the researchers optimized the structure design of the catalyst in the fuel cell membrane electrode from nano to mesoscopic scale. The novel electrocatalyst realized high-performance expression.
This study provides a new idea for the preparation of cathode catalytic materials for fuel cells.
