Variations in Electrochemical Characteristics of a Platinum Catalyst Enwrapped by a Carbon Shell According to Carbon Layer Thickness

Enwrapping metal nanoparticles with a carbon shell is a promising method for enhancing the stability of metal catalysts. However, carbon shell thickness control has not been studied extensively. In this study, a Pt catalyst with a carbon shell was synthesized, and the thickness of the carbon shell was controlled via the partial oxidation of the carbon layer. During the cooling step of the carbonization process, various concentrations of oxygen were supplied, and changes in the layer thickness were investigated according to the oxygen concentration. The thickness and characteristics of the carbon shell were examined using transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. The results revealed that the thickness and surface properties of the carbon layer depend on the oxygen concentration. To determine the effect of the carbon shell thickness on the electrochemical characteristics of the catalyst, the activity and durability of the catalyst were studied via an oxygen reduction reaction and an accelerated stress test in both a half-cell and unit cell. Overall, the thin carbon shell enabled the Pt catalyst to maintain its activity and stability, while reducing the activation time required to achieve optimal performance.