"A very promising route to making a carbon-containing fuel is to hydrogenate carbon dioxide (or carbon monoxide) using solar-produced hydrogen," said Fujita, who leads the artificial photosynthesis group in the Brookhaven Chemistry Department.
But with platinum as the main ingredient in the most effective water-splitting catalysts, the process is currently too costly to be economically viable.
Comsewogue High School students Shweta and Shilpa Iyer entered the lab as the search for a cost-effective replacement was on.
The Brookhaven team had already identified some promising leads with experiments demonstrating the potential effectiveness of low-cost molybdenum paired with carbon, as well as the use of nitrogen to confer some resistance to the corrosive, acidic environment required in proton exchange membrane water electrolysis cells. But these two approaches had not yet been tried together.
The students set out to identify plentiful and inexpensive sources of carbon and nitrogen, and test ways to combine them with a molybdenum salt.
"The students became excited about using familiar materials from their everyday lives to meet a real-world energy challenge," Chen recounted. The team tested a wide variety of sources of biomassleaves, stems, flowers, seeds, and legumeswith particular interest in those with high protein content because the amino acids that make up proteins are a rich source of nitrogen. High-protein soybeans turned out to be the best.
To make the catalyst the team ground the soybeans into a powder, mixed the powder with ammonium molybdate in water, then dried and heated the samples in the presence of inert argon gas. "A subsequent high temperature treatment (carburization) induced a reaction between molybdenum and the carbon and nitrogen components of the soybeans to produce molybdenum carbides and molybdenum nitrides,
|Contact: Karen McNulty Walsh|
DOE/Brookhaven National Laboratory