ZnO-TiO2 core-shell nanowires decorated with Au nanoparticles for plasmon-enhanced photoelectrochemical water splitting

Abstract

The present work reports the development of Au-nanoparticle decorated ZnO-TiO2 core-shell nanowires on the Si-wafer. The developed Au-nanoparticle decorated ZnO-TiO2 core-shell nanowires exhibit a unique structure with uniform sensitization of Au-nanoparticles with the diameter in the range of 5–9 nm on the ZnO-TiO2 core-shell heterostructure. This unique structure of Au-nanoparticle decorated ZnO-TiO2 core-shell nanowires demonstrates an enhanced photocurrent density of 1.63 mAcm−2 upon illumination by visible light unveiling high photoelectrochemical water splitting activity. This photocurrent density is higher than the pristine ZnO nanowires (0.51 mAcm−2) and ZnO-TiO2 core-shell nanowires (1.23 mAcm−2). Furthermore, photoelectrochemical water splitting efficiency of Au-nanoparticle decorated ZnO-TiO2 core-shell nanowires was found to be 0.70%, which is higher than the ZnO nanowires (0.22%) and ZnO-TiO2 core-shell nanowires (0.53%) at the same applied potential of +0.8 VRHE. The improved photocurrent density and efficiency is due to the enhanced absorbance in the visible region owing to the surface plasmon resonance effect of Au-nanoparticle, effective withdrawal of hot electron from the Au-nanoparticle at the interface of metal/semiconductor due to Schottky barrier as well as excellent charge-separation and transportation originating from the core-shell nanowires.