The alkaline polyol synthesis of “surfactant-free” Pt nanoparticles (NPs) is a straightforward approach to synthesize NPs as colloids. Even challenges such as size control have been successfully addressed in the recent past, but the reduction mechanism remains poorly understood. This work shows that the reduction of the precursors H₂PtCl₆ and H₂PtBr₆ can be performed at low reaction rates using visible light even though neither the precursor nor the solvent exhibits any detectable absorption in the visible range. The possibility of a slowed down visible-light-induced reduction was used for mechanistic investigation on the alkaline polyol approach and compared with other energy sources (thermal, microwaves, and ultraviolet light) to induce the reaction. The obtained insensitivity of the resulting particle size on the reaction kinetics presented here as well as in previous studies demonstrates a clear dependence on the ratio of free OH^– to Pt precursors revealing strong indications that the well-known LaMer model is not a valid mechanistic picture for the polyol process.

中文翻译：

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可见光诱导的乙二醇中“无表面活性剂”的Pt纳米颗粒的合成作为合成纳米颗粒形成机理的合成方法

“无表面活性剂” Pt纳米颗粒（NPs）的碱性多元醇合成是一种将NPs合成为胶体的直接方法。近年来，即使是诸如尺寸控制之类的挑战也已成功解决，但缩小机制仍知之甚少。这项工作表明前体H ₂ PtCl ₆和H ₂ PtBr ₆的还原即使前体和溶剂在可见光范围内均未显示任何可检测的吸收，因此可以使用可见光以低反应速率进行反应。将减慢可见光引起的还原的可能性用于碱性多元醇方法的机理研究，并将其与其他能源（热，微波和紫外光）进行比较以引发反应。将所得到的对反应动力学所得到的颗粒尺寸的不敏感性这里提出，以及在以前的研究证明了在游离OH的比率的明确依赖性^-与Pt前体揭示明显的迹象表明公知的拉默模型是不是一个有效机制图片用于多元醇工艺。