Plasmon-enhanced photoelectrochemical water splitting by InGaN/GaN nano-photoanodes

Abstract

It has been extensively focused on the development of photoelectrochemical (PEC) solar water splitting cells due to the urgent need for clean energy. In this study, InGaN/GaN multiple quantum wells (MQWs) nanorods (NRs) PEs are purposely designed with coupled plasmonic metal (Ag–Au core–shell nanowires) for high efficiency PEC water splitting, aiming for enhancing visible light absorption and carrier kinetic energy. By means of self-organized Nickel island patterning and ICP dry etching with proper depths, the photocurrent density of InGaN/GaN nano-photoanodes in NaCl solution can be significantly enhanced from 0.74 mA cm−2 to 1.4 mA cm−2 at 1.5 V versus RHE (reversible hydrogen electrode). Furthermore, by decorating plasmonic metal into the InGaN/GaN NR arrays, the PEC water splitting performance can reach a maximum photocurrent of 1.77 mA cm−2 at 1.5 versus RHE. Such improvement is mainly attributed to the synergistic effects of the visible light absorption of MQWs and the generation of surface plasmon resonance (SPR). The approach of plasmon-enhanced nanostructure with the III-nitride based nano-PEs will accelerate the developments of visible light photocatalysts for PEC solar cells.