Evolutionary prediction and experimental identification of stable phases in Pd–Ni/_γ-Al₂O₃ bimetallic catalysts

This work presents a combined theoretical and experimental study of the structural features of Pd-Ni bimetallic nanoclusters. A comprehensive exploration of the configurational space of Pd-Ni nanoclusters (13-56 atoms) across a wide range of compositions (Pd:Ni = 1:1 - 50:1) was performed using the evolutionary algorithm USPEX in conjunction with density functional theory (DFT) calculations. Our approach revealed thermodynamically stable and metastable intermetallic phases with a low-symmetry triclinic structure (space group P1), characterized by complex atomic ordering and a propensity for segregation. The predicted structures were used for a detailed interpretation of experimental X-ray diffraction (XRD) data, enabling the identification of the phase composition of synthesized Pd–Ni/_γ-Al₂O₃ samples. We demonstrate that the phase equilibrium in the system non-linearly depends on the overall component ratio, encompassing both single-phase states (e.g., Ni-Pd13 at Pd:Ni = 1:1 and Ni-Pd33 at 10:1) and regions of phase coexistence (e.g., Ni-Pd50 and Ni-Pd33 at 5:1). These findings elucidate the atomistic origins of the synergistic interaction between Pd and Ni and provide a foundation for the rational digital design of highly efficient and selective bimetallic catalysts. Contribution of the authors: the authors contributed equally to this article. The authors declare no conflicts of interests.

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