Photoelectrochemically Driven Water-Oxidation Catalysis by Perylene Diimide Plus Cobalt-Oxide Based Photoanodes: Fundamental Studies En Route to Second-Generation Systems

Colorado State University, Fort Collins CO

Investigators

Abstract

The Chemical Catalysis Program of the Chemistry Division supports the project by Professor Richard G. Finke. Professor Finke is a faculty member in the Department of Chemistry at Colorado State University. His research is focused on developing cheap, efficient, earth-element-abundant and hence low cost materials that can collect solar energy, and then use that energy to oxidize water into its oxygen and hydrogen components. The hydrogen then serves as a renewable energy source. The project involves the use of cheap, robust perylene diimide dyes (used, for example, in red to black car paints) to capture the solar energy, plus earth-abundant cobalt oxide as the water-oxidation catalyst. The project is at the interface of inorganic, organic, and materials chemistries plus chemical catalysis, making it ideal for training the next generation of broad-based scientists able to perform energy-related research. Outreach involving college students at the minority serving institutions of Fort Lewis College, a Hispanic Serving institution, and the University of Northern Colorado, a primarily undergraduate university with 15% Hispanic and 34% first-generation students, is an integral part of the project. Looking deeper technically, three main questions are addressed as part of the three specific aims of the research: First, which of seven perylene-type dyes, carefully selected for further investigation, yields the best photoelectrolysis cell and why? Importantly, are phosphonate functional groups present in the perylene diimide dye employed crucial for coupling the organic dye film to the inorganic cobalt oxide water-oxidation catalyst? Second, is the photoelectrolysis cell performance greatly improved if one employs a dye-sensitized photoelectrolysis cell architecture in which a perylene diimide dye monolayer can be adsorbed onto a high-surface-area sintered nanoparticle film of semiconducting metal oxides based on titanium, tin, and tungsten? Or, does the alternative hypothesis prove true that enhanced hole/electron recombination dominates in the dye-sensitized photoelectrolysis cell architecture? If so, why? Third, do organic light-harvesters possess sufficient stability against oxidation to merit an important position in future water-oxidation catalysis and other such photoanodes? Organic dyes have notable advantages over other materials including low cost, synthetic flexibility and easily tunable properties. What are the deactivation pathways active in these photocells and, thus, best strategies for longer photoanode lifetimes based on such organic light-harvesting materials? The education outreach includes lectures that Professor Finke gives to undergraduates and first-year graduate students, at multiple institutions he has been invited to visit, addressing the crucial topic of "Critical Reading and Analysis Skills via a Proper Scientific Method."