Solution-growth and optoelectronic properties of ZnO:Cl@ZnS core-shell nanowires with tunable shell thickness

Arrays of vertically aligned ZnO:Cl@ZnS core-shell nanowires (NWs) were grown by a facile low-cost, high-yield and seed-free two-step process. These NWs were used to demonstrate the potential of 3D electrodes based on core-shell heterostructures to enhance charge carrier separation and transfer. With this goal in mind, the photocurrent density of ZnO:Cl@ZnS NWs was characterized as a function of the shell thickness. Although no significant variations in the absorption and photoluminescence spectra were found with the presence of the shell, the photocurrent measured from the core-shell NWs was highly enhanced with respect to bare ZnO:Cl NWs. These photocurrent variations are associated with the control of the band bending in the core-shell NW surface, which modifies the efficiency of charge carrier transfer between the NW and the electrolyte. (C) 2012 Elsevier B.V. All rights reserved.