Investigation of the Oxygen Evolving and Photocurrent Producing Capacity of Mixed Metal Oxides
Mentor:John Kenney, Professor of Chemistry and Chemical Physics, Concordia University, Irvine
The general purpose of this study is to discover an inexpensive, efficient method of solar energy storage through solar water splitting. The specific purpose of this study is to to discover metal oxide catalysts that could be used effectively in such a system, analyzing potential materials both qualitatively and quantitatively. The qualitative part of this study is to analyze different mixed metal oxides (MMOs) for their capacity to catalyze the formation of oxygen gas from water in an electrochemical test cell. In a series of experiments, different metal nitrates were combined in staggered ratios and reacted in an oven to form MMO films, which were then compared for their performance as oxygen evolving catalysts in basic, acidic and pH neutral salt electrolyte solutions at certain voltages (1-10 V). It has been concluded that (1) highly basic or acidic electrolytes work best so far, with acidic electrolytes being the most consistently active, and (2) MMOs containing the elements yttrium, iron, and copper are the best oxygen evolving catalysts observed thus far. The quantitative part of this study is to analyze different MMOs for their capacity to produce a photocurrent given a low voltage (under 1 V). In a series of experiments, MMOs (as described before) were compared for their performance at inducing a photocurrent, mostly in basic or pH neutral salt electrolyte. The electrochemical test cell was hooked up to an LED system, which was connected to a computer; a computer software called "Solar Materials Discovery (SMD)" was used to collect the data (current produced upon exposure to light, given a certain specific voltage) for each MMO combination. It has been concluded that MMO combinations containing iron and copper (especially 1:1 iron:copper) worked the best; combinations containing nickel, cobalt, and zinc have also worked well.