Google Play icon

Core / shell photocatalyst with spatially separated cocatalysts for more efficient water splitting

Share
Posted September 18, 2013
Separate but together
Photocatalytic splitting of water uses sunlight to split water into hydrogen and oxygen. It is an environmentally friendly way to obtain hydrogen for fuel cells. In the journal Angewandte Chemie, Japanese researchers have now introduced a new method for the production of more effective photocatalysts. Their method uses tiny hollow spheres coated with different cocatalysts on the inside and the outside.

In a photocatalytic water splitting reaction, the catalyst, usually a semiconductor, captures photons. Electrons get excited and rise from the valence band to the conduction band. The electronic voids left behind in the valence band are regarded as positively charged “holes”. If the electrons and holes manage to migrate to the surface of the catalyst before the opposite charges recombine, they can be transferred to water molecules and used to reduce the water to make hydrogen or oxidize it to make oxygen.

New catalyst systems are constantly being researched and developed, but their efficiency has always been found to be lacking. Theoretically, catalysts based on tantalum nitride (Ta3N5) should be especially well-suited candidates for photocatalysis with visible light. However, two main problems have hindered their successful use in practice: First, on the surface of the catalyst, the resulting products, oxygen and hydrogen, immediately react to produce water. Second, the charge separation of the electrons and holes formed in the reaction doesn’t quite work correctly as they recombine too quickly.

 

Source: Phys.org

Featured news from related categories:

Technology Org App
Google Play icon
86,845 science & technology articles