A method for seeded growth of particles with uniform, smooth spherical shape, and narrow size distributions is presented. By using formaldehyde (HCHO) as a reductant and without any stabilizer in an aqueous solution, gold nanoparticles with sizes up to 220 nm were prepared at room temperature. The gold nanoparticles (diameter in the range of 1–3 nm) for the first seeds are synthesized by the reduction of tetrachloroauric acid trihydrate (HAuCl₄) with tetrakis (hydroxymethyl) phosphonium chloride THPC (P(CH₂OH)₄Cl). These seeds are dispersed in the gold plating solution at pH 9.0 in the presence of HCHO. Through multi-step seeding growth, their sizes are precisely controlled just by adjusting the ratio of gold precursor to seeds. The obtained gold nanospheres are characterized by using transmission electron microscopy, a Zetasizer Nano, and UV–VIS absorption spectroscopy. This approach has excellent reproducibility and can significantly improve the monodispersity of nanospheres.

Graphic abstract

中文翻译：

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可控直径达 220 nm 的均匀金纳米颗粒的种子生长合成

提出了一种具有均匀、光滑球形和窄尺寸分布的粒子的种子生长方法。通过在水溶液中使用甲醛 (HCHO) 作为还原剂并且不添加任何稳定剂，在室温下制备了尺寸高达 220 nm 的金纳米粒子。金纳米颗粒（直径为1-3纳米范围内），用于所述第一种子通过四氯金酸三水合物（的HAuCl还原合成₄）用四（羟甲基）氯化鏻THPC（P（CH ₂ OH）₄CL）。在 HCHO 存在下，将这些种子分散在 pH 值为 9.0 的镀金溶液中。通过多步播种生长，只需调整金前体与种子的比例，即可精确控制其大小。通过使用透射电子显微镜、Zetasizer Nano 和 UV-VIS 吸收光谱对获得的金纳米球进行表征。这种方法具有极好的重现性，可以显着提高纳米球的单分散性。

图形摘要