Controllable Synthesis of Vapor-Liquid-Solid Grown GaN Nanowires for Photoelectrochemical Water Splitting Applications

Vapor-liquid-solid (VLS) grown single crystalline GaN nanowire (NW) arrays of controllable aspect ratio and density were employed as the working photoanode for photoelectrochemical water splitting (PEC-WS) applications. The NW density of GaN NWs was controlled by tuning the different VLS growth parameters, while the aspect ratio was depending on the growth time. We observed a significant increase of the photocurrent with denser GaN NWs due to the enhanced light trapping effects; however, the PEC-WS process stability was degraded with time. Further increase of the photocurrent by about 34% at 1 Volt and a better time-dependent PEC-WS stability were achieved by increasing the aspect ratio of the GaN NWs due to the enhanced surface-to-volume ratio of the photoanode. The applied bias photon-to-current efficiency of the GaN NWs revealed a great shift of the optimal potential to lower values with enhanced NW lengths, indicating an interesting modification in the photoanode performance with increasing the aspect ratio of the GaN NWs. (C) The Author(s) 2015. Published by ECS. All rights reserved.