New Means of Producing Porous Silicon
Silicon is a very useful material thanks to its semiconducting properties, but for some applications it has some issues. Or, more accurately, we have some issues getting it to work well for certain applications. One such application is using porous silicon to create hydrogen, but researchers at Penn State have found a solution.
Hydrogen is a very useful gas as it wants to react with a number of other elements and materials, and those reactions can release useable energy. The semiconducting properties of silicon make it well suited for generating hydrogen from water, but it will work best if the silicon is porous. Producing porous silicon is difficult and expensive though, as it requires etching away silicon, producing a lot of waste. The Penn researchers however have found a fairly quick and easy way to produce porous silicon from silicon tetrachloride, a relatively cheap silicon source. The key is to break the strong bonds between the silicon and chlorine atoms, which the researchers achieved with a sodium potassium alloy. This resulted in porous silicon with potassium chloride and sodium chloride in the pores, which could be removed with heat-treatment and water.
While porous silicon could have uses in sensors and other technologies, it can be used to produce hydrogen from water just with sunlight. When the light strikes the silicon, an electron can be excited, which causes the water to reduce and release hydrogen gas that can be captured and used as needed.
Source: Penn State