We report a rationally designed one-pot method for the facile synthesis of Pd concave nanocubes in an aqueous solution at room temperature by manipulating the reduction kinetics through the selection of a proper combination of a salt precursor (PdBr₄^2–) and reductant (sodium ascorbate). Our kinetic analysis demonstrates that, through this selection, the nucleation and growth of Pd nanocrystals could be effectively separated into two kinetic regimes involving distinctive reduction pathways: i) solution reduction for the initial formation of single-crystal seeds and ii) surface reduction for the formation of concave nanocrystals via autocatalytic growth from the single-crystal seeds. The suppressed surface diffusion at room temperature, when coupled with the capping effect of bromide ions, ultimately leads to the formation of concave nanocubes with an asymmetric shape and high-index facets, whose synthesis would otherwise require multiple steps and the use of elevated temperatures.

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我们报告了一种合理设计的一锅法，该方法可通过选择适当的盐前体组合（PdBr ₄ ^2–）和还原剂（抗坏血酸钠）。我们的动力学分析表明，通过这种选择，Pd纳米晶体的成核和生长可以有效地分为涉及独特还原途径的两个动力学机制：i）溶液还原，用于单晶晶种的初始形成； ii）表面还原，用于单晶晶种的形成。通过单晶种的自催化生长形成凹形纳米晶体。室温下受抑制的表面扩散，加上溴离子的封端效应，最终导致形成具有不对称形状和高折射率小面的凹形纳米立方体，否则其合成将需要多个步骤并使用高温。

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