Surface passivation and protection of Pt loaded multicrystalline pn+ silicon photocathodes by atmospheric plasma oxidation for improved solar water splitting

In the traditional methods such as atomic layer deposition and sputtering, a thin metal oxide layer was usually deposited before the loading of catalysts to protect Si photoelectrodes from oxidation during solar water splitting, and this often results in the transfer of photogenerated carriers from Si to electrolyte more or less inhibited. We here use an atmospheric plasma oxidation method to improve this. A SiO2 protective layer, also an effective passivation layer of Si to increase the life time of carriers, is fabricated on Pt loaded multicrystalline pn(+)-Si photocathodes. Compared with the un-protected one, the energy conversion efficiency of the plasma-treated Pt/pn(+)-Si photocathode increases from 6.2% to 8.9% under 100 mW/cm(2) Xe lamp, and its stability improves from less than 1-22 h under continuous H-2 production. This research provides a conceptual strategy to ensure the direct contact among the Si/Pt/electrolyte and protect and passivate the other part of Si simultaneously. Published by AIP Publishing.