Solid state preparation of carbon-supported Pt 2 Ca nanoparticles for the oxygen reduction reaction.

Pt 2 Ca nanoparticles with a mean size diameter of 6 nm can be prepared by heating K 2 PtCl 6 , CaH 2 , carbon black and KCl at 400-500 °C. A mechanism study suggests that the formation of the Pt 2 Ca phase at moderate temperature is enabled by the fast ion transport via the vacancies in the KCl-CaH 2 solid solution. The Pt 2 Ca nanoparticles exhibit high performance for the oxygen reduction reaction in acid due to optimal adsorption energy of the oxygen intermediate.