Promoting atomic ordering of intermetallic fuel cell catalysts by phase transition engineering

High-temperature treatment generally promotes the atomic ordering transition (AOT) of alloys that easily results in the sintering behavior of catalysts. We demonstrate a novel phase transition induction strategy for promoting efficient atomic ordering of small-sized PtCo alloys by the self-carbothermal reduction of ZnO-Carbon nanoreactors. The self-carbothermal reduction from ZnO-Carbon nanoreactors enables the rapid phase reduction transition of oxidized metal-to-alloy, which makes metallic Zn interdiffuse quickly into the PtCo lattice by lowering the energy barrier of atomic diffusion, achieving a significant enhancement in the ordering degree of Pt-based alloys. Experimental designs and theoretical calculations reveal that introducing Zn significantly improves the strength of metallic bonds, and promotes the electronic coupling of Pt sites and O 2 . The optimized PtCo-Zn intermetallic compound exhibits more outstanding oxygen reduction reaction (ORR) performance in practical fuel cells, with a 33.9% improvement in mass activity and a lower peak power density loss rate of 2.1% than their disordered PtCo alloys (7%). This work provides valuable insights into the rational design of efficient intermetallic compounds for fuel cells. • A general phase transition engineering strategy to achieve atomic ordering transformation of Pt-based alloys is developed for efficient fuel cells. • Accelerating the oxidized metal-to-alloy phase transition process significantly promotes the atomic ordering transformation of Pt-based alloys. • The introduction of Zn significantly improves the structural stability of Pt-based alloy catalysts. • The optimal PtCo-Zn@NCS/KB catalyst exhibits excellent activity and stability in half cells and practical fuel cells.