Controlling Particle Size on Carbon Supports with Surface Tension

Mikayla Romero, Nathan Thornburg

University of South Carolina

Mentors: Alaba Ojo and Dr. John R. Regalbuto,

Carbon-supported platinum (Pt) and palladium (Pd) catalysts can be used for converting toxic carbon monoxide to less harmful carbon dioxide and in many catalytic reactions as such, the reactivity of the supported nanoparticles can vary based on the particle size. This work aims at contributing to the method of strong electrostatic adsorption (SEA) to help determine a way to control the particle size of metals on supported metal catalysts like Pt/C and Pd/C. It is hypothesized that the deposited metal size is determined by the size of water nanodroplets that arise during the drying stage of synthesis after electrostatic interaction has occurred, and in turn, particle size can be controlled by the surface tension of the carbon support. To test this theory, we began by performing a series of oxidations on Ketjen Black 300J and Norit SX Ultra carbon supports using nitric acid to introduce more surface oxygen groups, thereby increasing the supports hydrophilicity. A platinum tetraamine nitrate metal precursor was used for the synthesis of the Pt catalyst and a palladium tetraamine nitrate precursor was used for Pd synthesis, each solution was shaken for an adsorption time of 1 hour at 120 rpm and reduced in 10% H₂ / N₂. The resulting particle sizes were then characterized using x-ray diffraction.