Density Functional Theory / Oxygen Reduction Reaction / Structure Sensitivity / Nanoparticles / Size EffectA simple, first principles-based model of the oxygen reduction reaction (ORR) is used to determine ORR kinetics on the (111), (100), and (211) facets of eleven transition metals (Au, Ag, Pt, Pd, Ir, Cu, Rh, Ni, Ru, Co, Fe). For most metals, the unreconstructed (100) facets are found to have an activity comparable to, or slightly higher than, the (111) facets. In contrast, (211) steps are found to be significantly less active than the terraces, with the exception of the most noble metals. These results are combined with simple models of the geometries of catalytic nanoparticles to estimate the average ORR activity of Pt and Au nanoparticles of various sizes. On Pt, a modest decrease in the activity with decreasing particle size is predicted, while for Au, the opposite trend is found.

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The performance of particle‐based products depends on a multiple set of particle properties. To monitor them during particle manufacturing, three novel aerosol measurement techniques were developed: wide‐angle light scattering (WALS), three‐dimensional laser scattering (3D‐LSS), and differential aerodynamic particle sizing (DAPS). They measure particle shape, aggregate structure, and particle size, i.e., radius of gyration and aerodynamic diameter. The techniques were tested for rod‐like organic pigments and partially sintered SiO2 aggregates, which were produced by two new aerosol generators.

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