Jong-Gil Oh

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 Pt3Co1 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.

Preparation of Pt/C catalyst using alcohol reduction and a polyol process in the presence of urea for oxygen reduction reaction

The effect of urea hydrolysis was studied on the preparation and properties of Pt/C catalyst. The hydrolysis of urea provided hydroxyl ions in a controlled manner that prevented the localized pH change in the solution and only surface precipitation is resulted in a particle growth. From rotating ring disk electrode (RRDE) experiments, the Pt/C prepared in the presence of urea showed better exchange current density toward the oxygen reduction reaction. The rate of H2O2 formation was reduced when urea was used in the alcohol reduction process and it was further decreased in the Pt/C catalyst prepared by the polyol process combined with urea.