Water is in great abundance. Unfortunately, water doesn’t burn, and so it’s difficult to use as a direct source of energy. What some people may not realize is that water is a molecule; it’s made up of smaller, more elementary units. Specifically, one molecule of water contains two atoms of hydrogen (H) and one molecule of water (O) arranged in the following way: H-O-H. This is the derivation of the common abbreviation for water, H2O. Since hydrogen is extremely flammable and can be used to power not only rockets but also hydrogen fuel cells, which produce useful electricity, it would seem that our energy problems are solved. We can use hydrogen for energy, water has hydrogen in it, and we have water.
The problem (as chemists have long known) is that water is reluctant to split into its component parts. You can run electricity through a vat of water and generate bubbles of hydrogen and oxygen gas (a process called electrolysis) but the cost of the electricity going in is greater than the energy produced by the hydrogen coming out. In other words, the process is not efficient. However, a recent result published in the prestigious journal Nature Chemistry by researchers from UC Davis just might prove to be the answer to this problem.
The chemists report that they were studying a form of manganese, a type of ore called Birnessite. When they used this material in the water electrolysis process, they found that the ore acted as a catalyst. Catalysts lower the activation energy required for a chemical reaction. When a catalyst is present, the reaction proceeds faster and with a lessened input energy requirement. The splitting of the water molecule became easier, when the manganese was also present in the experimental setup.
The reasoning behind this observation is that manganese can be present in a variety of oxidation states, meaning it can “hold onto” or “release” extra electrons on an “as needed” basis. This allows the manganese catalyst to act as an electron shuttle. As electricity is put into the water, the catalyst helps the water to become oxidized, which forms oxygen gas, protons, and electrons. The manganese stabilizes this process by soaking up some of the electrons and holding them in a stable form. Then, the manganese gives up the electrons (going into a different oxidation state) so that the protons and electrons can recombine to form hydrogen gas. This hydrogen can be siphoned off separately from the oxygen gas formed in the process. The result is a more efficient method of producing hydrogen gas (a fuel) from water.
The production of hydrogen from water has been known for a long time. This newly described catalyst is a step in the right direction, in that we are getting closer to the point of “break even” – when more energy is produced than consumed. The resulting energy production will be clean and non-polluting. What an exciting time that will be!
The source of this article can be found at:
Rosalie K. Hocking, Robin Brimblecombe, Lan-Yun Chang, Archana Singh, Mun Hon Cheah, Chris Glover, William H. Casey, Leone Spiccia. Water-oxidation catalysis by manganese in a geochemical-like cycle. Nature Chemistry, 2011.