High-efficiency entangled hierarchical GaN nanowire-based photoanode for solar-driven water splitting

Abstract

In spite of significant endeavors aimed at augmenting the solar-to-hydrogen conversion efficiency of GaN-based photoanodes, further strides are imperative to unlock the full potential of GaN as a promising photoanode material. Within this article, we unveil the utilization of entangled hierarchical GaN nanowires (EHNWs) as high-performance photoanodes for efficient solar-driven water splitting, culminating in hydrogen generation. The strategy entails the passivation of GaN nanowires with ZnO overlayers, synergistically supported by an efficient co-catalyst endowed with visible-range light absorption capabilities. The results underscore the promising viability of this approach in the quest for sustainable hydrogen production through solar energy utilization. The growth of EHNWs-based nanostructures engenders an expanded active surface area, bolstering photocatalytic activity, and expediting proficient charge transportation. The amelioration of surface defects and the broadening of the photo absorption spectrum in the visible domain collectively confer a significant enhancement in photocurrent density, reaching up to 3 mA cm−2 which is ∼5 times higher as compared to bare EHNWs. Remarkably, the achieved solar-to-hydrogen conversion efficiency of 4.7 % stands amongst the upper echelons of reported values for GaN-based photoelectrodes cultivated via metal–organic chemical vapor deposition (MOCVD).