Nanometric chemical clocks

Field ion microscopy combined with video techniques and chemical probing reveals the existence of catalytic oscillatory patterns at the nanoscale. This is the case when a rhodium nanosized crystal-conditioned as a field emitter tip-is exposed to hydrogen and oxygen. Here, we show that these nonequilibrium oscillatory patterns find their origin in the different catalytic properties of all of the nanofacets that are simultaneously exposed at the tip's surface. These results suggest that the underlying surface anisotropy, rather than a standard reaction-diffusion mechanism, plays a major role in determining the self-organizational behavior of multifaceted nanostructured surfaces. Surprisingly, this nanoreactor, composed of the tip crystal and a constant molecular flow of reactants, is large enough for the emergence of regular oscillations from the molecular fluctuations. © 2009 by The National Academy of Sciences of the USA.Journal Articleinfo:eu-repo/semantics/publishe

Superior Fischer-Tropsch performance of uniform cobalt nanoparticles deposited into mesoporous SiC

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Oxygen-Induced Thermal Faceting of Pd Nanosized Crystals

The oxygen-induced faceting of [111] and [100] oriented Pd nanosized crystals (“tips”) was studied by field ion microscopy (FIM). Annealing at temperatures of 500 K in the presence of submonolayer amounts of oxygen caused major reconstruction to occur. Regions of the {100} plane broke up into small {100}, {112}, and {012} facets. In addition, only {111} and significantly enlarged {011} facets occurred at the surface of the reconstructed Pd crystal. The faceting behavior is in accordance with recently calculated equilibrium shapes of Pd crystals in the presence of small amounts of adsorbed oxygen.info:eu-repo/semantics/publishe