Effective Photocurrent Enhancement in Nanostructured CuO by Organic Dye Sensitization: Studies on Charge Transfer Kinetics

Mercurochrome-sensitized nanostructured CuO grown directly on Cu has been used as efficient photocathode in photoelectrochemical cell. The photocurrent density of the sensitized electrode is found to enhance from-1 mA/cm(2) (unsensitized) to -2.2 mA/cm(2) (dye sensitized for 24 h) at 0 V vs RHE under AM1.5G artificial solar illumination in aqueous 0.5 M Na2SO4 solution. The photoluminescence spectra demonstrated a strong absorption at 465 nm by the mercurochrome. Subsequent transfer of the photoexcited electrons to CuO conduction band enhances the photocurrent density. An incident photon-to-current conversion efficiency (IPCE) of 8% has been observed in the visible region. This is so far the highest reported value in p-type CuO based organic dye-sensitized photocathode. The dye sensitized CuO has thus the potential of photoreduction with higher Faradaic efficiency for various redox species due to additional carrier injection.