Tuning the crystal-phase of bimetallic particles enables a precise control of catalytically active sites but is experimentally challenged by the averaging ensemble effects that are caused by the particle communications occurred during the crystal-phase transformation. Here, H₂-treatment at 773–973 K of Pt₃Fe single-nanoparticle, confined by a permeable silica shell, achieved crystal-phase transformation from the disordered A1 phase to the chemically ordered L1₂ phase. Detailed microscopic and spectroscopic characterizations have identified that the disordered A1 particle possessed contiguously connected large Pt domains while the ordered L1₂ particle afforded regularly populated Pt₃ ensembles surrounded by Fe single-atoms. The isolated 3-fold hollow Pt site in the three-atom ensemble efficiently boosted the adsorption of acetylene, yielding a much higher hydrogenation activity. The reaction rate of the L1₂ particle was twice of that for the A1 particle. Moreover, the charge transfer from the neighboring Fe single-atoms to the Pt atoms on the L1₂ particle expedited the desorption of ethylene, promoting the selectivity as well. Overall, both geometric and electronic interactions in the ordered crystal-phase synergistically facilitated the selective hydrogenation of acetylene to ethylene.

调节双金属颗粒的晶相可以精确控制催化活性位点，但在实验上受到晶相转变过程中发生的颗粒通讯引起的平均系综效应的挑战。在这里，在 773–973 K 下对 Pt ₃ Fe 单纳米颗粒进行H _{2处理，由可渗透的二氧化硅壳限制，实现了从无序 A1 相到化学有序 L1 2}相的晶相转变。详细的微观和光谱表征表明，无序的 A1 粒子具有连续连接的大 Pt 域，而有序的 L1 ₂粒子则提供规则分布的 Pt ₃被 Fe 单原子包围的系综。三原子系综中孤立的3倍空心Pt位点有效地促进了乙炔的吸附，产生了更高的加氢活性。L1 ₂颗粒的反应速率是A1颗粒的反应速率的两倍。_{此外，从邻近的 Fe 单原子到 L1 2}颗粒上的 Pt 原子的电荷转移加速了乙烯的解吸，也提高了选择性。总体而言，有序晶相中的几何和电子相互作用协同促进乙炔选择性加氢为乙烯。