Browsing by Author "McFarland, E.W."

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    A Cu2O/TiO2 heterojunction thin film cathode for photoelectrocatalysis
    (Solar Energy Materials and Solar Cells, 2003) Siripala, W.; Ivanovskaya, A.; Jaramillo, T.F.; Baeck Sung-Hyeon; McFarland, E.W.
    A thin film heterojunction photocathode was developed consisting of 100nm of n-type titanium dioxide (TiO2) cathode surface deposited on p-type cuprous oxide (Cu2O). The cuprous oxide was deposited electrochemically on Ti foil. A photocurrent of 0.7mA/cm2(at -1V bias) and an open circuit photovoltage of 460mV were obtained under an illumination of 700W/m2. The photoresponse as a function of pH demonstrated that the TiO2 film protected the Cu2O underlayer against corrosion. These results suggest that using a simple and inexpensive heterostucture configuration, the corrosion limitations of Cu2O alone may be overcome while maintaining a relatively high efficiency for photoelectrolysis.
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    Photoelectrochemical Hydrogen Production Using New Combinatorial Chemistry Derived Materials
    (2002) Baeck Sung-Hyeon; Choi Kyoung-Shin; Ivanovskaya, A.; Jaramillo, T.F.; Siripala, W.; Stucky, G.; McFarland, E.W.
    The overall project objective is the development and application of combinatorial methods to discover an efficient, practical, and economically sensible material for photoelectrochemical production of hydrogen from water and sunlight. We are exploring a shift in the research paradigm from conventional serial chemical research to a combinatorial approach featuring a systematic and deliberate high-speed exploration of the composition-structure-property relationships of new metal-oxide based solid-state aterials. By intelligent and rapid design, synthesis, and analysis of large diverse collections of potential photoelectrochemical materials in libraries we are attempting to discover new and useful energy producing materials as well as better understand fundamental mechanism and composition-structure function relationships of these materials. Since funding began in September 2001 we have remained on or ahead of schedule for milestone completion as outlined in the monthly reports. We have designed and built several prototype systems for automated electrosynthetic deposition of metal oxides including both parallel and serial systems. We now have developed direct cathodic routes to oxides of several metals including W, Ni, Nb, Ti, Fe, Cu, Co, Mo, Zn by stabilization with several ligand types and made preliminary studies with libraries which have shown general trends. Specific improvements in W doped with Ni, Pt, and Ru have been observed. Preliminary work on electrosynthesis of mesoporous WO3 and TiO2 films from a peroxo-stabilized electrolyte using ionic surfactants has not yet shown highly ordered materials, however, increases in photocurrent have been observed which we are attempting to explain. Finally, an important derivative of our work has been from libraries of pulsed electrodeposited Pt doped WO3 whereby a new means of creating nanoparticles has been developed which show high activity for methanol oxidation without the poisoning problems of pure Pt electrodes.