Synthesis of Pd₂Ga Nanomeshes via Alloying-Induced Perforation

Metal alloys have been widely exploited as promising catalyst materials owing to their tunable properties and synergistic effects. Herein, perforation-rich Pd₂Ga alloy nanomeshes were synthesized via a facile one-pot solvothermal process. A mechanistic study revealed that the synthesis involved two steps: the initial formation of highly wrinkled Pd nanosheets, followed by an unusual alloy-induced perforation process, in which the Kirkendall effect during alloying led to hole formation within the Pd domains. The size and density of the perforations can be tuned by adjusting the alloying conditions, including the reaction temperature and metal precursor concentrations. Typically, increasing the Ga feeding amount would decrease the difference between the interdiffusion rates of Pd and Ga, resulting in a reduction and eventual disappearance of the perforations. The Pd₂Ga nanomeshes were demonstrated to be excellent alkyne semihydrogenation catalysts. Under ambient conditions, the nanomeshes achieved the semihydrogenation of 4-ethynylbiphenyl to 4-vinylbiphenyl with NaBH₄ in just 5 min with up to 98% selectivity, largely outperforming the pristine Pd nanosheets in both activity and selectivity.