Seed-Assisted Synthesis of Ni(OH)₂ Nanosheets on InGaN Films as Photoelectrodes toward Solar-Driven Water Splitting

In this study, we conducted photoelectrochemical (PEC) water-splitting reactions using indium gallium nitride (InGaN) as photoelectrodes to extend light absorption from ultraviolet to visible wavelengths. However, the bare InGaN films experience significant photocorrosion due to numerous defects resulting from the substantial lattice mismatches between GaN and InGaN. While Ni(OH)₂ nanosheets, prepared through a hydrothermal method and decorated on the InGaN photoelectrodes, show promise in mitigating photocorrosion, incomplete coverage of Ni(OH)₂ on the InGaN photoelectrodes leads to corrosion in the uncovered areas. To enhance the coverage of Ni(OH)₂ nanosheets on InGaN-based photoelectrodes, we synthesized Ni(OH)₂ nanosheets using a NiO nanofilm as the seed layer. Experimental results demonstrate that photoelectrodes made of the Ni(OH)₂/NiO/InGaN composite films exhibit superior PEC performance compared to that of NiO-free InGaN photoelectrodes. Additionally, after stability tests, no significant photocorrosion was observed on the Ni(OH)₂-coated InGaN surface with the NiO seed layer while achieving higher photocurrents and increased hydrogen production rates. The Ni(OH)₂/NiO/InGaN photoelectrodes exhibit approximately 30% enhancement in photocurrents compared to the bare InGaN films.