Photoelectrochemical Water Splitting

Overall water splitting to produce H2 and O2 over a semiconductor photocatalyst using solar energy is a promising process for the large-scale production of clean, recyclable H2. Numerous attempts have been made to develop photocatalysts that function under visible-light irradiation to efficiently utilize solar energy. For direct photoelectrochemical decomposition of water, several primary requirements of the semiconductor must be met: the semiconductor system must generate sufficient voltage to drive the electrolysis, the energetic of the semiconductor must overlap that of the hydrogen and oxygen redox reactions, the semiconductor system must be stable in aqueous electrolytes, and finally the charge transfer from the surface of the semiconductor must be fast enough not only to prevent corrosion but also reduce energy losses due to overvoltage. Comparing semiconductor properties it turned out, that the cubic polytype of silicon carbide (3C-SiC) ideally fits these requirements. However, due to the lack of suitable 3C-SiC almost nothing is reported so far on the photoelectrochemical behavior of SiC, which is not yet well understood.