9529589 Cox This U.S.-Polish Cooperative Research award will study "Electroanalytical Chemistry in the Absence of a Bulk Solution Phase." The principal researchers are Dr. James A. Cox of Miami University, Ohio, and Dr. Pawel J. Kulesza of the University of Warsaw. The general goal of this program is to characterize certain ionically-conducting solids in terms of their ability to serve as media for electrochemical studies in the absence of a contacting solution phase. Of particular interest would be to establish conditions where electrolyses of gas-phase components can be performed at cells using these electrolytes under conditions where the rates and mechanisms of the electrode reaction are not influenced by concomitants in the gas phase. The components of interest in this study are generally electrochemically silent at conventional, bare electrodes, so the investigation of catalysis in the environment of these solids is a required part of this program. The researchers will investigate two general materials as solid electrolytes, glassy substances prepared by sol-gel processes and polyoxometallate powders. The former will be xerogels with known or predicted ionic conductivity such as polymeric vanadium, ruthenium, and iridium oxides. The catalysts will be in the form of surface layers on electrodes coated with films of the xerogels or dispersions with these films. In addition, conversion of selected xerogels into redox mediators by electrochemically generating lower oxides of the metal centers will be explored. Keggin-type heteropoly-12-tungstates will comprise the primary polyoxometallates investigated. The test systems will be selected on the basis of formation of mixed-valent systems. The kinetics of electron self-exchange will be determined along with the effective transport coefficient. Once characterized, the polyoxometallates will be encapsulated in xerogels. Here, the objective is to exploit the catalytic activity of the former in an envi ronment that permits the selected redox reaction to proceed without interference from other components, including water, of the surrounding atmosphere. The studies will be performed with conventional electrochemical instrumentation, including voltammetric and a.c. impedance methodology. The results of this investigation will guide the development of amperometric sensors for hazardous components in air and for the presence of targeted solids or liquids with finite vapor pressures. In addition, these electrochemical systems are projected to be suited to purifying the atmosphere of small environments. Other possible applications include the design of energy-storage devices and microscale electronic components such as bilayer switches. This research in chemistry fulfills the program objectives of bringing together leading experts in the U.S. and Poland to combine complementary efforts and capabilities in areas of strong mutual interest and competence on the basis of equality, reciprocity, and mutuality of benefit.
