Microwave Heating of Nanocrystals for Rapid, Low-Aggregation Intermetallic Phase Transformations

The use of intermetallic Pt-Co nanocrystals (NCs) for electrocatalytic oxygen reduction reaction is quickly gaining interest thanks to the higher electrochemical stability of the intermetallic L10 phase compared to a random alloy A1 phase. However, the thermal treatment that enables the intermetallic phase transformation also causes significant NC aggregation, resulting in a significant loss of electrochemically active surface area. Herein, we report the use of microwave radiation to induce the intermetallic phase transformation in Cu-doped Pt-Co NCs. We demonstrate that microwave radiation reduces NC aggregation while allowing for a complete phase transformation in only 30 seconds. These microwave-treated NCs demonstrate higher mass activity for oxygen reduction reaction while maintaining electrochemical stability similar to the thermally-annealed samples.