Nickel phosphides are of particular interest because they are highly active and stable catalysts for petroleum/biorefinery and hydrogen production. Despite their significant catalytic potential, synthesizing various phase-pure nickel phosphide nanoparticles of uniform size remains a challenge. In this work, we develop a robust trioctylphosphine (TOP)-mediated route to make highly uniform phase-pure Ni₁₂P₅, Ni₂P, and Ni₅P₄ nanoparticles. The synthetic route forms amorphous Ni₇₀P₃₀ nanoparticle intermediates. The reactions can be stopped at the amorphous stage when amorphous particles are desired. The amount of P incorporation can be controlled by varying the ratio of TOP to Ni(II). The mechanism for composition control involves the competition of the kinetics of two processes: the addition of the reduced Ni and the incorporation of P into Ni. Uniform Ni₇₀P₃₀ amorphous nanoparticles can be generated at a high TOP-to-Ni(II) ratio, where the P incorporation kinetics is made to dominate. Ni₇₀P₃₀ can later be transformed into phase-pure Ni₁₂P₅, Ni₂P, and Ni₅P₄ nanocrystals of uniform size. The transformation can be controlled precisely by modulating the temperature. A UV–vis study coupled with theoretical modeling reveals Ni(0)-TOP_x complexes along the synthetic path. This approach may be expanded to create other metal compounds, potentially enabling the synthesis of uniform nanoparticles of a greater variety.

中文翻译：

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通过三辛基膦介导的途径合成尺寸均匀的无定形和各种相纯磷化镍纳米颗粒


磷化镍特别受关注，因为它们是石油/生物精炼和制氢的高活性和稳定催化剂。尽管它们具有显著的催化潜力，但合成各种尺寸均匀的相纯磷化镍纳米颗粒仍然是一项挑战。在这项工作中，我们开发了一种稳健的三辛基膦 （TOP） 介导的路线，以制备高度均匀的相纯 Ni₁₂P₅、Ni₂P 和 Ni₅P₄ 纳米颗粒。合成路线形成无定形 Ni₇₀P₃₀ 纳米颗粒中间体。当需要无定形颗粒时，可以在无定形阶段停止反应。可以通过改变 TOP 与 Ni（II） 的比率来控制 P 掺入量。成分控制的机制涉及两个过程的动力学竞争：添加还原的 Ni 和将 P 掺入 Ni 中。均匀的 Ni₇₀P₃₀ 无定形纳米颗粒可以以高 TOP-to-Ni（II） 比率产生，其中 P 掺入动力学占主导地位。Ni₇₀P₃₀ 稍后可以转化为尺寸均匀的相纯 Ni₁₂P₅、Ni₂P 和 Ni₅P₄ 纳米晶体。可以通过调节温度来精确控制转变。紫外-可见光研究与理论模型相结合，揭示了合成路径沿线的 Ni（0）-TOP_x 络合物。这种方法可以扩展到创造其他金属化合物，从而有可能合成更多种类的均匀纳米颗粒。