Preparation of carbon-supported nanosegregated Pt alloy catalysts for the oxygen reduction reaction using a silica encapsulation process to inhibit the sintering effect during heat treatment

The heat treatment of alloy nanoparticles to improve their catalytic properties generally results in severe sintering. In this study, we report a new synthetic process of silica encapsulation to inhibit the sintering of Pt ₃Co₁ alloy particles during heat treatment at high temperature. The silica layer acts as a physical barrier to prevent sintering; thus, the carbon-supported Pt₃Co₁ alloy nanoparticles retained their small particle size after heat treatment. The heat treatment allows the atoms to rearrange themselves, which results in a Pt-rich surface of the alloy nanoparticles. As a result, catalytic activity and stability were improved significantly.