Controlling the Formation of Fast-Growing Silver Nanocubes in Non-Polar Solvents

The key to the most efficient nanostructures is a deep understanding and control of all factors influencing the reaction mechanism. To realize the full potential of a synthesis of Ag nanocubes in a non-polar solvent mixture, the factors that determine the results are thoroughly investigated. In this hot-injection approach, an Ag precursor reacts with a Cl precursor to form AgCl and multiply twinned (MT) Ag nanoparticles. The AgCl is then reduced to single crystalline Ag nanoparticles while the MT nanoparticles are oxidized. As a result, the single crystals grow into nanocubes. Previously unidentified factors like the catalytic influence of Fe(III) ions and the in situ formation of HCl, which leads to an undefined chloride content, are revealed. A high reproducibility is achieved by controlling the amount of Fe(III) ions and adding a stable Cl source. Thoroughly investigating and combining the effects of chloride concentration with temperature and oxidative etching allows for adjusting the edge length of the nanocubes in the range of 40 to 100 nm and improving their uniformity. These findings lead to a robust protocol for producing non-polar silver nanocubes with sharp edges, low polydispersity, tunable size, and thus tunable optical properties in a short reaction time.