Fabrication of ZnO nanostructures using Al doped ZnO (AZO) templates for application in photoelectrochemical water splitting

ZnO nanostructured thin films have been fabricated by continuous spray pyrolysis (CoSP) technique using different seed layers and implemented as photoanodes for photoelectrochemical (PEC) water splitting. Effects of Al loading (0.02–0.2 wt%) in the ZnO seed and the voltage applied during the spray on morphological, structural, optical and photoelectrochemical properties of ZnO nanostructures have been studied. In the ZnO films grown on Al doped ZnO(AZO) seed with lower Al wt%, a red shift in the band gap has been observed along with increased (0 0 2) orientation in the XRD pattern. A blue shift in band gap is observed with AZO seed having higher Al wt% which can be attributed to the Burstein-Moss effect. The decrease in the band gap with stronger (0 0 2) orientation becomes more prominent on applying the voltage. Linear sweep voltammetry measurements carried out on the ZnO films grown on AZO seed and with applied voltage show a significant increase in photocurrent under illumination as compared to that for unmodified ZnO thin films. The significantly improved photoresponse of ZnO nanostructured thin films using a simple and cost effective fabrication method can find applications for water splitting under light leading to hydrogen generation and other related products.