Stanford Team Devises Solar Powered Water Splitter (w/video)

I don't understand why they have to put the silicon electrodes in contact with oxygen.

Can't they just wire the silicon in the solar panel to copper wires and put them in contact with water and oxygen?

Something has to come in contact with the water and will inevitable be exposed to the oxygen. The choice of materials appears to be one for performance reasons:

The authors pointed out that their approach is general enough to work on other semiconductor substrates and to integrate other catalysts, allowing for fine-tuning of electrodes to maximize performance.

Wouldn't it be more correct if the title was "Stanford team devises a way to protect silicon from oxidation"... That is how the video started.

Is this the prototype of the cheap product that's been promised years ago (although it still uses platinum & titanium)?