A New Way to Make Watet Fuels Hope for Green Tech

Scientists have found a radical new way of making water that could substantially lower costs for green technology. The University of Illinois researchers have unlocked the trick to making water from unlikely starting materials, such as alcohols. They are expecting their discovery to lead to better catalysts and less expensive fuel cells.

"We found that unconventional metal hydrides can be used for a chemical process called oxygen reduction, which is an essential part of the process of making water," said Zachariah Heiden, a doctoral student and lead author of a paper accepted for publication in the Journal of the American Chemical Society.

A water molecule is composed of two hydrogen atoms and one oxygen atom. However, you can't simply take two hydrogen atoms and stick them onto an oxygen atom. The actual reaction to make water is a bit more complicated: 2H2 + O2 = 2H2O + Energy.

Basically, the equation says: To produce two molecules of water (H2O), two molecules of diatomic hydrogen (H2) must be combined with one molecule of diatomic oxygen (O2) and that energy will be released in the process.

"This reaction (2H2 + O2 = 2H2O + Energy) has been known for two centuries, but until now no one has made it work in a homogeneous solution," said Thomas Rauchfuss, a U. of I. professor of chemistry and the paper's corresponding author.

The well-known reaction also describes what happens inside a hydrogen fuel cell where the diatomic hydrogen gas enters one side of the cell, diatomic oxygen gas enters the other side. The hydrogen molecules lose their electrons and become positively charged through a process called oxidation, while the oxygen molecules gain four electrons and become negatively charged through a process called reduction. The negatively charged oxygen ions combine with positively charged hydrogen ions to form water and release electrical energy.

"Most compounds react with either hydrogen or oxygen, but this catalyst reacts with both," Heiden said. "It reacts with hydrogen to form a hydride, and then reacts with oxygen to make water; and it does this in a homogeneous, non-aqueous solvent."

They are hopeful that these new catalysts will lead to eventual development of more efficient hydrogen fuel cells, substantially lowering their cost.

Posted by Rebecca Sato: This post was adapted from materials issued by University of Illinois at Urbana-Champaign.

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Links:
http://uiuc.edu
http://www.sciencedaily.com/releases/2007/10/071031125457.htm