Stable response to visible light of InGaN photoelectrodes

The photoelectrochemical properties of ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{N}∕\mathrm{Ga}\mathrm{N}$ $(0⩽x⩽0.20)$ epitaxial films on sapphire (0001) substrates have been investigated. The flatband potential of ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{N}$ is shifted to more positive voltages with increasing indium incorporation. In aqueous HBr solution, the turnover number of the ${\mathrm{In}}_{0.20}{\mathrm{Ga}}_{0.80}\mathrm{N}$ electrode reaches 847 after $4000\mathrm{s}$ illumination, which suggests that ${\mathrm{In}}_{0.20}{\mathrm{Ga}}_{0.80}\mathrm{N}$ has good photostability. Moreover, ${\mathrm{In}}_{0.20}{\mathrm{Ga}}_{0.80}\mathrm{N}$ shows highest visible-light response among ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{N}$ $(0⩽x⩽0.20)$ and the incident photon conversion efficiency is about 9% at $400–430\mathrm{nm}$ in the HBr solution.