Paraffin Removal in the Synthesis of Novel Janus Carbon Nano-Onions

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 the 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) was carried out by a chemical process using sodium borohydride. The removal process of the paraffin involves the dispersion of the wax-paraffin/CNO-Pt particles in Chloroform and rinse with isopropanol 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 (SEM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), and Raman Spectroscopy. Cyclic Voltammetry was used to characterize the proposed catalyst and comparison with the commercial catalyst Pt/Vulcan providing information about their catalytic behavior. It was possible to confirm the deposition of Pt on the surface of the CNO by TEM. The Pt-CNO/CNO catalyst was tested for ORR using the Rotating Ring Disk Electrode (RRDE) and compared its performance with Pt/Vulcan. Thermogravimetric Analysis was used as a characterization technique to corroborate percent of Pt on these particles.