A first-principles investigation of the effect of Pt cluster size on CO and NO oxidation intermediates and energetics.

As catalysis research strives toward designing structurally and functionally well-defined catalytic centers containing as few active metal atoms as possible, the importance of understanding the reactivity of small metal clusters, and in particular of systematic comparisons of reaction types and cluster sizes, has grown concomitantly. Here we report density functional theory calculations (GGA-PW91) that probe the relationship between particle size, intermediate structures, and energetics of CO and NO oxidation by molecular and atomic oxygen on Pt(x) clusters (x = 1-5 and 10). The preferred structures, charge distributions, vibrational spectra, and energetics are systematically examined for oxygen (O(2), 2O, and O), CO, CO(2), NO, and NO(2), for CO/NO co-adsorbed with O(2), 2O, and O, and for CO(2)/NO(2) co-adsorbed with O.

Micellization coupled with facilitation of J-aggregation for poly(1,3-cyclohexadiene)-based amphiphilic block copolymers.

Amphiphilic PS-b-sPCHD copolymers can associate to form micelles with PS blocks as the core surrounded by sPHCD blocks in aqueous media. J-Aggregation of the chromophores in sPCHD blocks is significantly facilitated by the micellization, resulting in a remarkable change in the photophysical properties of PS-b-sPCHD.