Abstract

Abstract A nanoparticle with well‐defined surfaces, prepared through colloidal chemistry, enables it to be studied as a model heterogeneous catalyst. The colloidal synthetic approach provides versatile tools to control the size and shape of nanoparticles. Traditional nucleation and growth mechanisms have been utilized to understand how nanoparticles can be uniformly synthesized and unprecedented shapes can be controlled. Now, the size of metal particles can be controlled to cluster regimes by using dendrimers. By using seeds and foreign atoms, specific synthetic environments such as seeded growth and crystal overgrowth can be induced to generate various shaped mono‐ or bi‐metallic, core/shell, or branched nanostructures. For green chemistry, catalysis in 21 st century is aiming for 100 % selectivity to produce only one desired product at high turnover rates. Recent studies on nanoparticle catalysts clearly demonstrate size and shape dependent selectivity in many catalytic reactions. By combining in situ surface characterization techniques, real‐time monitoring of nanoparticles can be performed under reaction environments, thus identifying several molecular factors affecting catalytic activity and selectivity.