Photoelectrochernistry (PEC) of straight and isolated CU2S nanowires arrayed on a copper foil is studied. A cathodic photocurrent is observed, which increases with the increasing negative bias of the film electrode, conforming to the p-type semiconducting nature of CU2S. PEC studies on the core/sheath nanowires of Cu2S (Cu2S nanowires coated with other nanoparticles such as CdS, polypyrrole, and Au) have revealed distinctly different characteristics. Cu2S/CdS nanowires exhibit a slightly higher photocurrent response due to the charge transfer between the p-type Cu2S core and n-type CdS sheath, whereas the photocurrent response obtained for Cu2S/PPy nanowires is generally an order of magnitude smaller than that for pure Cu2S nanowires under the same bias voltage. For Cu2S/Au nanowires, however, Au nanoparticles can readily accept the photogenerated electrons from the conduction band of CU2S; this redirects the electron transfer pathway and results in the anodic photocurrent response. On the basis of these findings, different photocurrent generation mechanisms are proposed. (c) 2005 The Electrochemical Society. [DOI: 10. 1149/1.1859991] All rights reserved.