Abstract

We investigate photoelectrochemical water splitting by a spontaneously formed In-rich InGaN nanowall network, combining the material of choice with the advantages of surface texturing for light harvesting by light scattering. The current density for the InGaN-nanowalls-photoelectrode at zero voltage versus the Ag/AgCl reference electrode is 3.4 mA cm−2 with an incident-photon-to-current-conversion efficiency (IPCE) of 16% under 350 nm laser illumination with 0.075 W·cm−2 power density. In comparison, the current density for a planar InGaN-layer-photoelectrode is 2 mA cm−2 with IPCE of 9% at zero voltage versus the Ag/AgCl reference electrode. The H2 generation rates at zero externally applied voltage versus the Pt counter electrode per illuminated area are 2.8 and 1.61 μmol·h−1·cm−2 for the InGaN nanowalls and InGaN layer, respectively, revealing ∼57% enhancement for the nanowalls.