CO oxidation reaction on Au, Ag and Cu nanoparticles as catalytic substrates

G. S. OTERO; B. PASCUCCI; P. G. BELELLI; M. M. BRANDA

Montevideo

Congreso; QUITEL 2016, 42nd International Congress of Theoretical Chemists of Latin Expression; 2016

Quitel 2016

The carbon monoxide (CO) oxidation has been the main task of many experimental and theoretical research groups. The industry continues looking for alternatives to catalyze CO oxidation. The need of newer, faster and more efficient forms to eliminate one of the more abundant and pollutant gas has been the motivation of this work. In this sense, we proposed to study catalysts based on Au, Ag and Cu nanoparticles (NPs) designed with 19, 38 and 55 atoms (Figure 1). They expose (111) and (110) planes and show corners and edges with many low coordination atoms.By means of the geometry optimization, we evaluated the CO+O and O+O co-adsorptions and the CO2 and O2 adsorptions on the metal NPs (Me NPs) and on the corresponding Me (111) surfaces. Besides, the reaction energies, as well as reaction paths and their activation barriers were obtained with the density functional theory (DFT) calculations [1], using the VASP (Vienna ab-initio simulation package) code [2,3]. For these systems, a proper dispersion-corrected method (DFT-D) was employed.CO and O are preferably adsorbed on top and hollow sites respectively on the three (111) surfaces and on the nanoparticles, while the formed CO2 prefers mostly bridge sites of metal nanoparticles, and hollow sites on extended surfaces. The CO oxidation is an exothermic reaction over all the metallic substrates evaluated. Their magnitud is increased on Me19 and Me38, with respect to the Me(111) surfaces. The reaction energy order found on Me19 and on Me38 was Ag > Au > Cu, meanwhile on Me(111) was Au > Ag > Cu. The lowest energy barrier was found on the Cu19 nanoparticle.