Mass Synthesis of Pt Subnanoparticle Catalysts for Industrial Production

Abstract The PtCln/Fe–N–C catalyst, which features highly dispersed PtCln particles on an Fe- and N-doped carbon (Fe–N–C) support, exhibits high oxygen reduction reaction (ORR) activity and durability in rotating disk electrode (RDE) tests conducted in acidic solutions that simulate the operating environment of polymer electrolyte fuel cells (PEFCs). This high activity is due to the continuous formation of subnanometer Pt particles (Ptsubnano) in situ on Fe–N–C via the process of Pt dissolution and redeposition. This process transforms the PtCln/Fe–N–C into a Ptsubnano/Fe–N–C catalyst. For the practical application of Ptsubnano/Fe–N–C catalysts, it is essential to develop a technology that enables their production in quantities suitable for production lines. Here, we propose a simple and scalable synthesis technology suitable for industrial production, aiming to commercialize the Ptsubnano/Fe–N–C catalyst. The process consists of adding PtCln/Fe–N–C powder to an acidic solution containing Pt mesh and then stirring while alternately supplying oxidizing and reducing gases for a set period. By controlling the open-circuit potential (OCP) of the Pt mesh under a gas atmosphere and applying a potential to the contacted catalyst, the aforementioned PEFC operating environment is simulated (referred to as the OCP treatment). Analysis of the catalyst powder after the OCP treatment confirmed the formation of Ptsubnano particles and demonstrated their catalytic performance. We have demonstrated that the proposed method can function as a practical synthetic approach.