Enhanced photoelectrochemical water-splitting effect with a bent ZnO nanorod photoanode decorated with Ag nanoparticles

Zinc oxide (ZnO) nanorods coated with silver (Ag) film on a polyethylene terephthalate (PET) flexible substrate were used as the photoanode for water splitting. The hybrid nanostructures were prepared via low-temperature hydrothermal growth and electron beam evaporation. The effects of plasmonic enhanced absorption, surface recombination inhibition and improved charge transport are investigated by varying the Ag thickness. Light trapping and absorption enhancement are further studied by optimizing the curvature of the PET substrates. The maximum short circuit current density (J _SC, 0.616mAcm ²) and the photoelectron conversion efficiency (PCE, 0.81%) are achieved with an optimized Ag film thickness of 10nm and substrate bending radius of 6.0mm. The maximum J _SC and PCE are seven times and ten times, respectively, higher than those of the bare ZnO nanorods on flexible substrates without bending. The overall PEC performance improvement is attributed to the plasmonic effects induced by Ag film and improved charge transport due to inhibition of ZnO surface charge recombination. Enhanced light trapping (harvesting) induced by bending the PET substrates further improved the overall efficiency.