介绍了一种用二甘醇（DEG）取代乙二醇（EG）合成18-32纳米立方体纳米银的方法。由于DEG具有较高的粘度和相对于EG较低的还原力，能够实现在成核期突发生成大量的种子，在生产期有一个相对缓慢的生长速率，这两个因素是关键纳米银立方体具有小尺寸的关键。
This article describes a robust method for the facile synthesis of small Ag nanocubes with edge lengths controlled in the range of 18-32 nm. The success of this new method relies on the substitution of ethylene glycol (EG) -- the solvent most commonly used in a polyol synthesis -- with diethylene glycol (DEG). Owing to the increase in hydrocarbon chain length, DEG possesses a higher viscosity and a lower reducing power relative to EG. As a result, we were able to achieve a nucleation burst in the early stage to generate a large number of seeds and a relatively slow growth rate thereafter; both factors are critical to the formation of Ag nanocubes with small sizes and in high purity (>95%). The edge length of the Ag nanocubes could be easily tailored in the range of 18-32 nm by quenching the reaction at different time points. For the first time, we were able to produce uniform sub-20 nm Ag nanocubes in a hydrophilic medium and on a scale of ~20 mg per batch. It is also worth pointing out that the present protocol was remarkably robust, showing good reproducibility between different batches and even for DEGs obtained from different vendors. Our results suggest that the high sensitivity of synthesis outcomes to the trace amounts of impurities in a polyol, a major issue for reproducibility and scale up synthesis, did not exist in the present system.

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