Direct Water Splitting Under Visible Light with a Nanostructured Photoanode and GaInP2 Photocathode

Abstract

Thin films of hematite nanorod and GaInP2 were used for direct water splitting under visible light. In open circuit conditions, the potential of hematite shifted cathodically and that of GaInP2 anodically, which generated an open circuit voltage between the two electrodes. In short circuit condition, the combination of the two photoelectrodes can split water under visible light illumination, though with a very low current of µA/cm2 level even at 1 W/cm2 light. By means of chopped light, we found that hematite nanorod has a low photocurrent, which is responsible for the low short circuit current of the 2-electrode combination. The low photoresponse of hematite nanorods is due to the recombination of photo- generated charges, low holes mobility, and short diffusion length.