NON-PLATINUM BIMETALLIC NANOCATALYSTS:

One of the major barriers to the commercialization of fuel cell power systems is high cost which is largely due to the use of platinum (Pt)-containing electrocatalysts. To reduce the cost of electrocatalysts, it is necessary to develop new high performance nanocatalysts based on less expensive non-precious metals. Bimetallic materials have shown great promise for the development of superior catalysts. While mechanisms underlying the synergetic effect are ambiguous, recent evidence suggests that the reactivity of bimetallic metal nanocatalysts can be determined by a complex combination of electronic structure change by metal-metal interactions (ligand effect), creation of unique mixed-metal surface sites (ensemble effect), and surface charge redistribution with varying particle sizes and shapes (size-shape effect). However, little is known about the relative roles of the ligand, ensemble, and size-shape effects in determining the catalytic activity of bimetallic alloy nanoparticles, due to the difficulty of direct characterization of the structure and chemistry of metal nanoparticles. The project aims at developing a fundamental understanding of the molecular mechanisms underlying the alloying effects of bimetallics, through systematic theoretical investigations based on state-of-the-art atomic-level simulation methods.

§ H.-C. Ham, G.S. Hwang, J. Han, S. W. Nam, and T. H. Lim, “On the Role of Pd Ensembles in Selective H₂O₂ Formation on AuPd Alloy Surfaces,” J. Phys. Chem. C 113, 12943 (2009).