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Functional Nanomaterials and Their Applications: From Origins to Unanswered Questions

2012; Wiley; Volume: 13; Issue: 10 Linguagem: Inglês

10.1002/cphc.201200444

1439-7641

Harald Fuchs, Thomas J. Webster, Zhiyong Tang, Florian Banhart,

Nanotechnology research and applications

The control of the physiochemical properties of matter at the molecular and atomic scale is an old dream of mankind. Even though they did not know it, back in ancient Egyptian times, people used nanotechnology as a more effective manner to control skin and hair color. In the Greco–Roman period, organic dyes from plants, such as henna, were commonly used in human hair since they were more potent towards controlling colors than other materials. Medieval church windows derive their color from metal nanoparticles embedded in the glass. Today, we still have the constant urge to develop novel constituent materials that have a greater propensity to more easily control material properties (such as color, magnetic, electric, catalytic, mechanical, etc.). While conventional approaches of creating materials with specific properties have relied on using different chemical compounds and materials, it has become obvious over the last several decades that there is another more promising route for controlling material properties by controlling the size of matter, rather than their chemical composition. Specifically, below a certain size of constituent solids, typically in the range of 1 to 100 nm (so-called nanomaterials), new physical properties have been found due to the spatial confinement of electronic states as predicted by quantum theory. In view of functional properties of condensed matter, this approach complements chemical strategies in the sense that properties which cannot be produced by conventional chemical reactions are now accessible, leading to a large field of applications in biology, medicine, environment, energy, communications, and computer technology. This, of course, is the description of contemporary nanotechnology, which has found a home in numerous applications of materials that can eventually benefit our daily life. Today, a variety of wet-chemical, sol–gel processes, as well as different physical fabrication techniques and biomimetic ways, are available to produce such types of systems. The small size of individual nanoparticles leads, for example, to increased catalytic effects due to the high surface-to-volume ratio of atomic sites of the individual particles. Beyond that, their compression into powders may result in new physical qualities such as a reduced mass density, the shift of the Fermi level, and unique magnetic and optical properties. These are effects which cannot be observed in micrometer scale materials or, for example, in conventional alloys with grain sizes typically larger than 100 nm. Therefore, the field of developing new nanomaterials and controlling their specific properties has become of significant interest in recent years. In parallel to this development, new investigation tools (such as high-resolution transmission electron microscopy, scanning probe microscopy systems including STM and AFM, near-field optics, surface-enhanced Raman spectroscopy and other techniques) have allowed us to explore the origin of the physiochemical properties of these particles—clearly the Egyptians and Greco–Romans did not know. Beyond that, the same characterization techniques can also be used to study potential hazardous effects of nanomaterials, such that depending on their application, nontoxic modifications may be prepared or strategies can be developed to avoid negative effects in technical environments. In this special issue of ChemPhysChem, 23 papers dealing with the synthesis, properties, characterization, and applications of nanomaterials have been assembled, showing a breath-taking variety of highly relevant aspects of nanomaterials from leading laboratories worldwide. The topics cover, for example, special synthesis rules, optical effects, the specific transport properties of solid-state single nanochannels, nanoparticle catalysis, graphene-based photovoltaic devices, and many application aspects that are targeted towards energy storage, biomedical sensing, bacteria elimination and decrease of medical-device infection. In addition, theoretical aspects of nanotechnology are displayed. While a single issue of these series can hardly cover all the areas that are currently being investigated in the field of nanomaterials, this special issue gives an excellent overview on some of the contemporary hot topics in nanotechnology. With the references contained in these individual articles, this special issue opens the gate for more detailed information within individual areas. It also shows the dynamic environment of this diverse field, which is growing rapidly worldwide, and nicely demonstrates that nanoscience and technology are cross-disciplinary areas meeting the combination of physics, chemistry, materials science and biology. Of course, critical questions still need to be answered for the field of nanotechnology to continue to thrive. Specifically, no matter what nanomaterial application is sought, nanomaterials must be manufactured, and through manufacturing, nanomaterial waste is unavoidably exposed to the environment. We know very little about the environmental and health consequences of the tons of nanoparticles that are currently being manufactured across the globe. We also need more information to understand how to make nanoparticles less toxic to the environment and human health if they are found to present a risk. With that in mind, we need to continue to develop environmentally friendly nanomaterials synthesis routes, especially those that are easily scaled up and commercialized. If the field of nanotechnology does not continue to garnish interest from industry, advancements made in the research lab will stop being translated into real commercial products. It has been quite impressive that despite the recent downturn in the global economy, nanotechnology has provided one of the few technological shining lights generating new products and new materials for continued global innovation—something that we all need to continue to thrive towards in order to realize the long-lasting dream of creating materials with tailorable properties for specific applications, which one can argue the ancient Egyptians and Greco–Romans started.