Mm. Khader et al., PHOTOELECTROCHEMICAL DISSOCIATION OF WATER AT COPPER-DOPED P-GAAS ELECTRODES, International journal of hydrogen energy, 18(11), 1993, pp. 921-924
Citations number
14
Categorie Soggetti
Energy & Fuels","Environmental Sciences","Physics, Atomic, Molecular & Chemical
Cu-doped p-GaAs was used as a photocathode in a three-electrode electr
ochemical cell. It was illuminated with visible light in 0.05M H2SO4.
The onset potential of photocurrent and H2O decomposition was about 0.
6 V, cathodic with respect to the flat-band potential of p-GaAs (0.3 V
vs SCE). The photocurrent anomaly near the flat-band potential (V(fb)
) was attributed to the poor catalytic properties of p-GaAs towards H-
2 evolution. It was also attributed to the existence of a surface stat
e which can trap the photoexcited electrons from the conduction band.
The deposition of five monolayers of Pt over the GaAs surface shifted
the onset potential of photocurrent by 0.1 V towards the positive dire
ction. Upon illumination of p-GaAs, H-2 evolved over it and O2 evolved
over the Pt counter-electrode in a 2:1 ratio. Their evolution obeys z
ero-order kinetics. The photocurrent as well as the water decompositio
n changed linearly with light intensity.