CdS nanoparticles sensitized large-scale patterned ZnO nanowire arrays for enhanced solar water splitting

CdS nanoparticle-sensitized patterned ZnO nanowire arrays (NWAs) were designed and synthesized through two-beam laser interference lithography (2BLIL), hydrothermal synthesis, and successive ion layer adsorption and reaction (SILAR) method. The absorption spectroscopies and two-dimensional finite difference time domain (FDTD) simulations carried out on the patterned ZnO NWAs/CdS samples demonstrate a significant enhancement of light absorption in the visible region compared to the non-patterned ones. The patterned ZnO NWAs/CdS photoanodes have a maximum solar-to-hydrogen conversion efficiency of 0.67 % at -0.4 V vs. Ag/AgCl, which is about 22 times that of the non-patterned ZnO NWA samples and about 3 times that of the CdS film samples. Such enhancement is attributed to that the patterned ZnO NWAs with ordered nanostructures have increased light-harvesting ability due to the light scattering effect, and the ZnO/CdS type II band alignment accelerates separation of photogenerated electron-hole pairs. The results suggest that the narrow band gap semiconductor-sensitized ZnO NWAs with highly ordered nanostructures have promising applications in solar energy conversion devices.