Protecting Semiconductors for Artificial Photosynthesis
For far longer than humans have existed, plants and many microbes have been using photosynthesis to convert the energy of sunlight into something more useful. We would like to do the same and create systems that release hydrogen and oxygen from water, for use as fuel. Achieving this has proven very difficult, and one reason why has to do with semiconductors corroding in water, but researchers at Caltech have found a coating that may solve that problem.
Two semiconductors used fairly often for their light absorbing properties are silicon and gallium arsenide. These properties would make them ideal for artificial photosynthesis systems, except that they will both corrode in water, and ultimately become useless. For some time researchers have been looking for ways to protect them, and now the Caltech researchers have turned to leaky titanium dioxide (TiO2). Leaky oxides were first developed in the 1990s for potential use in computer chips, but they leaked too much charge to be useful. That leaking is exactly what the researchers are going for though. The researchers found that they could put a thin layer of TiO2 onto the semiconductors, without disrupting the light coming in or the electrons going out, while still blocking the water.
This is definitely promising research but is also very early research. The leaky TiO2 layer has not been tested enough to determine how it will behave over long periods of time. The relatively short-term tests though have demonstrated the material's great potential for this application though, by setting some new records in the field.