Fabrication of GaN truncated nanocone array using a pre-deposited metallic nano-hemispheres template for efficient solar water splitting

The GaN truncated nanocone is an excellent candidate for better photoelectrochemical efficiency than other GaN nanostructures. Here the highly ordered GaN truncated nanocone array was fabricated using a pre-deposited metallic nano-hemispheres template on a wafer scale. The highly ordered profiles of pre-deposited metallic nano-hemispheres template were defined by anodic aluminum oxide (AAO) masks through electron beam evaporation. The formation mechanism for the profiles of nano-hemispheres and GaN truncated nanocones were investigated. The results elucidate that proper selection of AAO parameters enables controllability of desired profiles and depth of Cr nano-hemispheres template, further controllability of desired profiles and depth of the GaN truncated nanocones. The optical and photoelectrochemical characterizations show the substantial improvements in ultraviolet light absorption and photoelectrochemical efficiency with photocurrent density by 300% times with respect to planar counterpart. The presented synthetic strategy will pave the way towards low-cost and mass production of GaN truncated nanocone photoelectrode for efficient photocatalysis.