RESEARCH Analytical Chemistry
The photoexcitation of loosely found electrons on a metal surface is called a surface plasmon polariton for planar surfaces or a localized surface plasmon resonance for nanometer-sized metallic structures. The resonance condition depends on the size, shape, composition, and the chemical environment of the metal. By fine-tuning or designing new metallic nanoparticles, unprecedented analytical methodologies can be developed. Isotropical spherical nanoparticles are common examples in this category, however, more complicated nanoparticles, for example, nanorods and nanoplates with various morphologies, can be readily synthesized through a wet-chemical synthetic route or template-assisted methods.
Nanoparicles in Fuel Cells
SKKU analytical chemists are designing and synthesizing new catalytic materials. Nanostructured platinum is a highly efficient heterogeneous catalyst for fuel cells and many other industrial chemical reactions. The common methodologies for improving catalytic activities of Pt nanostructures include alloying, facet engineering, inter-atom strain tuning, and tailoring interactions between Pt nanostructures and its support. Recently, SKKU analytical chemists developed a new Pt nanostructure like 3-dimenstional hollow nanoframes and found a way of stacking them with a regular ordering, leading to carbon-support-free Pt catalysts.
Electrochemical methods for chemical analysis deal with a variety of ways for determining the chemical compositions of samples. A quantitative analysis especially using a potentiostat provides numerical information about the relative amount of one or more of these components. Recently, Electroanalytical chemistry include the deposition of very thin layers on the substrates, monitored by the total charge past through, in a way of modifying the chemical nature of given materials. Galvanic replacement strategy is a well-known approach to synthesize complicated hollow nanostructures, leading to the new development of sensors, catalysts, and solar cells.
A biosensor is an another form of the analytical tool for qualitative and quantitative measurements although the prefix ‘bio’ in its name is limiting its targeted analytes mainly on biological entities like proteins, genes, virus, bacteria, etc. At the heart of a biosensor is the signal transducer which transforms the existence/concentration of the ‘bio’ analytes to a form of signals readily interpretable by a human interfacing units: optical or electrical ones, for instance. Recent advances in this field of science are achieved frequently through the incorporation of nano-scaled materials and devices. Analytical chemists in SKKU are very much interested in devising novel biosensing elements and also addressing their collections based on chemical and often interdisciplinary insights. One typical example adopted in SKKU analytical chemistry lab is micro tubes used as a micro container of enzymes for bioactive materials and a current collector electrode. After storing enzymes in the tube, the top was covered with electropolymerized EDOT (PEDOT). This assembly is simply used as an amperometric sensor for electoactive biomaterials i. e. glucose, etc.. Now we are adopting alloy-deaolly method to build microstructure for enzyme on a micro needle electrode to make an in vivo tests.
All measurements bear uncertainty. There always is a noise when we use analytical means. Sample preparation methods are hard to be reproducible. We lose signals frequently even though they do exist in our result of measurements. Simply, they are not interpreted as a signal. In some occasions where a signal is missed due to its extreme rarity or irregularity, there might be an alternative route to vitalize it. SKKU analytical chemists are exploring a new field of analytical approach: ‘digitizing signal approach’, searching for a new way of enhancing the analytical capability
Conductive Polymer Ion Separating Membrane
It is very well known that conducting polymer shows extreme changes in electric conductivity during its redox chemistry. The redox chemistry also offers fast doping/dedoping process of counter ions. If we can make a membrane of conducting polymer, we can construct a gate membrane which can control the ion movement by applying potential. In this study, SKKU analytical chemists have found that methylene blue has specific adsorption property than other ions like benzyl amine. Now we are interested in dual membrane system which will show fast ion separation functions.