Phase-Rearrangement-Induced Atomic Replacement toward Customizing Noble-Metal Intermetallics.

Structurally controlled noble-metal intermetallics are promising for catalytic applications but are significantly hindered by the thermodynamically favored symmetric growth of close-packed structures and by differences in metal redox potentials. Here, we report a phase-rearrangement-induced atomic replacement synthesis in noble-metal chalcogenides that successfully realizes a nondestructive intermetallic nanoarchitecture. By choosing well-defined palladium-tellurium (Pd-Te) hexagonal nanoplates as parent templates, a morphology-preserved atomic replacement transformation from Te atoms to Bi atoms is achieved, enabling tunable compositions, phases, and interfaces at specific spatial locations. Mechanistic studies demonstrate that parent templates (rhombohedral phase Pd20Te7) undergo a phase rearrangement to the thermodynamically stable structure (hexagonal phase PdTe) prior to atomic replacement, effectively reducing lattice mismatch and permitting the atomic replacement process to occur while retaining the original morphology. This design rule is highly generalizable for a series of zero-, one-, and two-dimensional Pd-Bi (antimony (Sb), lead (Pb), and tin (Sn)) nanoarchitectures. Therefore, this work advances the diversity of materials and further investigates the potential effect of different phases and compositions on catalyst performance, in which the hexagonal phase PdBi exhibits superior oxygen reduction reaction activity, stability, and antipoisoning methanol capability. This generalizable atomic replacement strategy enables the exploration of heterostructures and intermetallic nanoarchitectures that are otherwise inaccessible.