Preparation of a carbon-supported pt-ni bimetallic catalyst with a Pt-rich shell using a dopamine as protective coating

A carbon-supported Pt₂Ni₁ catalyst with a Pt rich shell was prepared using a high temperature treatment. In this process, polydopamine (PDA) encapsulates whole Pt/C and acts as a protective coating layer to suppress sintering effects of particles during the high temperature treatment. Dopamine, a mussel-inspired substrate, is an effective surface coating material because the polymerization of dopamine takes place easily at room temperature and exhibits a strong adhesive function with almost any surface. With increasing thickness of the PDA coating layer, the particle size became smaller following heat-treatment. However, when excess PDA was used, residue remained on the surface of catalyst. As a result, the active surface area of catalyst was reduced, thereby resulting in lowered catalytic performance. The Pt₂Ni₁/C catalyst prepared with an optimized amount of PDA layer exhibited improved mass activity of 0.43 A mg_Pt⁻¹ at 0.9 V, which is almost two times higher than that of Pt/C.