Tin and Silicon Binary Oxide on the Carbon Support of a Pt Electrocatalyst with Enhanced Activity and Durability

Poor durability is one of the two major problems hindering the commercialization of proton exchange membrane fuel cells, due to Pt nanoparticle aggregation in the electrocatalyst and corrosion of its carbon support. In this paper, we report a Pt electrocatalyst in which carbon black decorated with a tin and silicon binary oxide layer was used as the support, with SnO2 as a promoter and SiO2 as a stabilizer. Transmission electron microscopy revealed that the binary oxide formed a thin layer on the surface of the carbon support particles. The catalyst exhibited significantly enhanced performance toward the oxygen reduction reaction (ORR): at 0.9 V (vs RHE), the ORR current density was similar to 1.5 times higher than that of a commercial JM Pt/C catalyst with the same Pt loading. Furthermore, it showed excellent durability, again better than that of JM Pt/C: after 8000 cyclic voltammetry cycles in 0.5 M H2SO4 solution, the electrochemically active surface area was almost unchanged and the ORR half-wave potential shifted by only 10 mV. We attribute the catalysts high activity and durability to the binary oxide coating the surface of the carbon nanoparticles. We suggest it may play two roles: (1) promoted by tin oxide and thereby enhancing the catalytic activity and (2) preventing the Pt nanoparticles from aggregating and carbon support from corrosion. The high ORR performance and excellent stability of this catalyst make it promising for use in practical fuel cell applications.