Effect of the Support Nanostructure (Nanofibers and Nanotubes) on the Photoelectrochemical Performance of TiO2-CdO@CdS Semiconducting Architectures

Nanofibers and nanotubes of TiO2 were decorated with CdO@CdS type core@shell particles, via a facile route consisting of cadmium electrodeposition on previously formed TiO2 nanostructures, its thermal oxidation to obtain CdO and later surface sulfidation by ion-exchange in Na2S aqueous solution. The diffraction patterns (XRD) of the resulting hetero-nanostructures confirm the formation of the cubic CdO and CdS phases, whereas their Photoelectron spectra (XPS) indicate the sole presence of CdS on the surface. Interestingly, tested as photoanodes in a home-made photoelectrochemical (PEC) cell, they exhibit better performances, toward water oxidation and hydrogen generation than pristine TiO2 nanostructures. These improvements are attributed to a higher visible light absorbance and a convenient band alignment between TiO2-CdO and CdO-CdS. Moreover, although TiO2 nanofibers present a higher surface area to be coupled with CdO@CdS, TiO2 nanotubes coupled with CdO@CdS achieved the maximum photoresponse at -0.25 V vs SCE, under 1 sun illumination. It indicates that this nanostructure, because of its ability for directional electron transport, is the most suitable matrix to build efficient TiO2-CdO@CdS photoanodes for PEC use. (C) 2017 The Electrochemical Society. All rights reserved.