Colloidal metal nanocrystals have been used in various applications including catalysis, electronics, photonics, and biomedicine. Despite the large number of successful examples, industrial application of these nanocrystals remains challenging. This is due to the inability to produce the nanocrystals in large quantities while maintaining precise control over their size, shape, and structure.

Younan Xia, Georgia Institute of Technology, Atlanta, USA, and colleagues have developed a practical approach for the continuous and scalable production of nanocrystals based on plug reactors. Air is used as a carrier phase to separate the reaction solution into a series of plugs, which are suitable for a synthesis that requires the constant involvement of O₂. As a proof of concept, the team produced palladium icosahedra with uniform, controllable sizes in these reactors.

The plug reactors hold great promise for the development of continuous production of colloidal nanocrystals. The possible scale-up ability could result in the use of nanocrystals in a variety of applications. As one example, after conformal coating with platinum ultrathin shells, Pd@Pt catalysts showed greatly enhanced activity towards the oxygen reduction reaction (ORR).

• Scalable Synthesis of Palladium Icosahedra in Plug Reactors for the Production of Oxygen Reduction Reaction Catalysts,
  Helan Wang, Guangda Niu, Ming Zhou, Xue Wang, Jinho Park, Shixiong Bao, Miaofang Chi, Zaisheng Cai, and Younan Xia,
  ChemCatChem 2016.
  DOI: 10.1002/cctc.201600060