Exploring the Role of III‐V Semiconductor‐Based Nanowire Composition and Geometry on Photoelectrochemical Reactions

Over the past two decades, nanoscale structures such as nanowires (NWs) based on III‐V semiconductors have emerged as versatile device components in electronic and photonic applications. In particular, for photoelectrochemical applications, the high surface‐to‐volume ratio of NWs is expected to significantly enhance surface reaction kinetics, mainly by providing more active sites conducive to light‐driven processes. However, few studies have investigated these advantages for III‐V NWs. A particular challenge lies in the stability of such structures compared to more easily fabricated planar surfaces. In order to investigate the beneficial effects of GaAs‐based NW structures for solar water splitting on current density, electrode stability in electrolyte, and bubble detachment, linear sweep voltammetry and scanning electron microscopy are performed before and after 2 h of operation using chronoamperometric measurements. The results show that NW absorber structures exhibit a significantly lower onset potential compared to bare substrates. The durability of NWs appears to be strongly influenced by NW geometry and defect density, both of which increase susceptibility to corrosion. Nitrogen‐based passivation layers have been observed to significantly increase the longevity of NWs. These results provide valuable insights into the durability of NW‐based devices, with particular relevance for their application in solar energy conversion technologies.