Synthesizing a Novel Janus Carbon Nano-Onions Modified As a Catalyst Support for Oxygen Reduction Reaction

Abstract

Carbon materials have been awakening scientific interest for research because it allows chemical functionalization for multiple applications in the sciences, especially in energy applications. Carbon Nano-onions (CNO) are spherical structures composed of multilayers of fullerenes, these layers are connected in a way that shows a shape of an onion. Its development begins with the use of nano-diamonds, a carbon material of strong structure which it forms in a very violent environment. The nano-diamonds are taken to a furnace at a temperature of 1650°C to finally obtain the CNO. Janus particles are receiving increasing attention because of their dual properties, where each side can be functionalized to have distinctive characteristics. The modifications on the surface of these nanoparticles can provide different chemical and physical properties. The interesting properties of Janus nanoparticles are that they have different sizes and shapes which have now been able to be studied in more detail. The purpose of this project is to use asymmetrically modified CNO as a support for metal nanoparticles to avoid agglomeration and, thus, increase their surface area and efficiency. Janus nanoparticles will be designed by a wax-paraffin Pickering emulsion process using CNO on its surface. The deposition of Platinum (Pt) it was carried out by a chemical process using sodium borohydride. The removal process of the paraffin involves a treatment with chloroform and rinse with ethanol to finally obtain the amphiphilic nanoparticle. The differences on the surface of the particles before and after removing the paraffin were observed by Scanning Electron Microscopy. The Energy-Dispersive Spectroscopy was used to validate the elemental information of the particles and assure the deposition of Pt on the surface of the particles. Cyclic Voltammetry was used to characterize the CNO/Pt ink, providing information about the Pt deposition on the surface of the CNO. Oxygen Reduction Reaction experiments were conducted to test the efficiency of this catalyst using the Rotating Ring-Disk Electrode at rotations of 100, 400, 900, 1600, and 2500 rpm. The polarization curves of CNO/Pt and Pt/Vulcan were compared. Thermogravimetric Analysis were used as a characterization technique to corroborate the percent of Pt on the CNO/Pt particles. Characterization techniques as X-ray Diffraction and Raman Spectroscopy were used to validate the deposition of Pt and confirm the removal of paraffin.