(509m) Theoretical / Experimental Investigation Of The Stability And Activity Of Pt Nanoparticles On Pure And Boron-Doped Carbon

A common anode catalyst used in a proton exchange membrane (PEM) fuel cell is platinum on a carbon support. The activity of nanometer-sized catalyst particles may be prolonged by stabilizing the catalysts on various supports. The stability may possibly be increased by strengthening the interaction between the nanoparticles and the support, thus decreasing the mobility and the agglomeration of the catalyst particles. Our density functional theory calculations of Pt and PtRu clusters on carbon supports have shown that the adsorption energies of these metal clusters increased substantially in the presence of substitutional boron defects in carbon lattice. The dynamics of the Pt clusters were studied at elevated temperatures on pristine and boron doped graphite with and without an external electric field. The mean square displacement of the metal atoms on boron-doped graphite was estimated to be lower than pristine graphite even at temperatures of 673 K. The activity of the catalysts was also tested for fuel cell anode reactions such as CO and H2 oxidation. The adsorption energies of the gases, and the activation barrier for various reactions were calculated. To support the simulation results with experiments, boron doped amorphous carbon powders were produced at 1000oC and under 1 atmosphere of pressure using a simple tube furnace apparatus. Characterization of the samples using XPS, XRD and Raman has shown the presence of boron in the carbon lattice. Platinum nanoparticles were deposited on pure and boron-doped carbon and the stability of the nanoparticles were tested using XRD and HRTEM. The activity of the catalysts for reactions such as CO oxidation was also analyzed.