Synthesis of Nanomaterials
In conventional materials, the structure determines most properties such as electrical, ionic, thermal conductivity, hardness, and plasticity. However, at the nanoscale, the physical and chemical properties depend mainly on the size, shape, and characteristics of the surface and its interface. The percentage of atoms on the surface grows as the nanomaterials' size decreases. Therefore, the application of nanomaterials depends on precise control of their synthetic processes. In this context, the group is focused on three main strategies:
1) Design of Experiments
Methods of factorial design of experiments and methodology of response surfaces are an alternative to improve the conditions of synthesis and to deepen the knowledge about the mechanism of formation of nanocrystals by colloidal methods. In the factorial design, the experimental conditions important for the product's final characteristics are varied simultaneously to decrease the necessary number of syntheses and provide a multivariate analysis, where the synergistic effect of two or more conditions is evaluated concomitantly.
2) Real-Time Analysis Techniques
Real-time analysis methods such as UV-Vis spectroscopy, infrared spectroscopy, dynamic light scattering, low-angle X-ray scattering (SAXS), and real-time image analysis techniques contribute to the understanding of the formation mechanism of nanocrystals without any intervention in the system, adaptations of the experimental conditions or manipulation of the samples to adapt to the particular ex-situ characterization technique, such as transmission and scanning electron microscopy and atomic force microscopy. Thus, in-situ real-time analysis techniques lead to better control of nanomaterials' synthesis process and, consequently, their properties.
3) Development of New Methods for Synthesis of Two-Dimensional Materials
Mechanical exfoliation is still the most used method for obtaining two-dimensional crystals consisting of one or a few layers. The crystals obtained by this method have high crystallinity and, consequently, better electronic properties. On the other hand, it has low control of the number of layers, low yield, and is not scalable.
Chemical vapor deposition (CVD) synthesis is an alternative for producing large areas of crystalline monolayers. However, the crystallinity control is low, and the crystals have a large number of defects. In addition, the need for methods of transferring crystals from the synthesis substrate to the substrates of interest introduces more defects and contamination, impairing the properties of the materials.
Therefore, it is necessary to search for different synthesis methods of two-dimensional materials to obtain a better performance, better control of defects in the crystalline structure, and an increase in scale.
