Enhanced solar hydrogen generation of high density, high aspect ratio, coaxial InGaN/GaN multi-quantum well nanowires

Abstract

In an attempt to partially mimic the natural photosynthesis, a process that converts sunlight into chemical fuel, a novel InGaN/GaN multi-quantum well (MQW) nanowire heterostructures photoanode with superior surface-to-volume ratio was designed. The light harvesting medium in this nanoscale architecture is a thick MQW composed of six periods of epitaxial InGaN/GaN shells deposited coaxially on the semipolar sidewall facets of a thin GaN core nanowire. High aspect ratio and wide photoresponse extended to the visible spectrum were demonstrated from the detailed characterizations of the as-grown nanowires. The result revealed that this nanoscale photoanode can convert up to 8.6% of the illuminating light into photocurrent that can be utilized for the facile generation of hydrogen fuel with a 0.21% solar-to-hydrogen conversion efficiency, which is comparable to that of the natural photosynthesis.