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A team of researchers recently proposed a new method that gives further insight into the synthesis of very important gold nanocrystals.

A Phys.org report said specified that the team, led by Professor Li Yuen from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, along with Professor Cuncheng from the University of Jinan, has recently developed a general route through the kinetic control to a family of Penta-twinned Au NCs.

Gold nanocrystals have enticed substantial attention in recent decades because of their extraordinary size- and shape-reliant optical properties.

For the realization of practical applications, the controlled synthesis of Au NCs is very important. Amidst the application of numerous seedling methods which have been attained to synthesize Au NCs, some of the major struggles that hinder the synthesis of various colloidal nanocrystal types are their multifaceted synthetic approaches, as well as the lack of a universal growth mechanism in a single system.

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Science Times - Gold Nanocrystals: New Method Proposed, An Effective Kinetically Controlled Approach to a Family of Penta-Twinned Au NCs
(Photo : Erik Wetterskog et al. on Wikimedia Commons)
Self-assembly of iron oxide nanocrystals


Seed-Mediated Growth Method

In their research published in the Chemical Science journal, the study authors presented a universal kinetically regulated seed-mediated growth method to have a family of Au Penta-twinned NCs synthesized in one growth system.

With modulation of atom deposition sites and rates through the molar ratio of reductant/AU precursors or R-value, seven different types of Penta-twinned nanocrystals with sizes that can be tuned and have high purity were fabricated.

The researchers said this approach can be further applied in the growth and development of a second metal, specifically silver, on Au decahedral seeds which have tunable optical absorbance "from visible to Near-infrared range."

More essentially, it does not necessitate purification treatment, as well as additional metal ions, substantially simplifying the synthesis procedure.

Penta-Twinned NCs

In a similar report, the Chinese Academy of Sciences said the universal method suggested in this work not just developed an efficient kinetically controlled tactic to the family of Penta-twinned NCs, but provided a deep insight as well, on a general mechanism for their formation, which may lead researchers to synthesize NCs in a designed manner.

Generally, Penta-twinned Au NCs are prepared through a seeded growth procedure in which tiny Penta-twinned seeds are initially prepared and then developed into final products.

Nonetheless, the quality of seed, as well as the growth environment, therefore, have a crucial impact on their synthesis. In early studies, their shape yield was, in general, below 30 percent due to the poor portion of Penta-twinned seed used in the first or original syntheses.

Consequently, time-consuming purification processes of Au decahedral seed, described in the National Library of Medicine, and is also known as the final products, were typically needed.

At first, the research groups reported that the seed thermal treatment activates or allows for the conversion of seeds into much more unwavering Penta-twinned ones, drastically augmenting the yield of products to 90 percent minus purification.

Recently, an innovation in the Penta-twinned seeds' formation mechanism was discovered by in situ high-resolution transmission electron microscopy, unveiling their actual process of formation, as indicated in the study.

Now, the study authors said they could obtain an extensive insight and regulation of decahedral seed formation based on the results they were able to obtain.

Related information about nanocrystals is shown on The Audiopedia's YouTube video below:

 

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