Polarity-dependent photoelectrochemical activity in ZnO nanostructures for solar water splitting

ZnO nanotubes and nanosheets with different morphologies, tailored by a simple chemical route without templates and capping agents, were successfully synthesized as a photoelectrode. From their XRD patterns, the relative intensities of (100) and (002) peaks from the nanorods and nanosheets vary with degree of polarity in the ZnO nanostructures. Photoelectrochemical measurements clearly revealed that the polar facets of nanosheets yielded conversion efficiency three times that of ZnO nanotubes with nonpolar-facets because of the high surface energy, spontaneous polarization and negative flat-band potential of a polar-orientated surface. (C) 2011 Elsevier B.V. All rights reserved.