Nanoporous GaN Photoanode Decorated with Plasmonic Au Nanoparticles for Enhanced Solar Water Splitting

Photoelectrochemical (PEC) water splitting is a promising approach to generating eco‐friendly hydrogen energy from water. Despite long‐lasting efforts, the existing methods still suffer limitations in the design of photoelectrodes with optimal structures for efficient operation. Herein, a novel porous gallium nitride (PGaN) photoanode decorated with plasmonic Au nanoparticles (AuNPs) is fabricated. After microstructural optimization, this composite photoanode improves the water‐splitting efficiency from 0.036% to 0.30% and exhibits a 2.7 times improvement of the photocurrent density in comparison with the planar GaN photoanode. The significant improvement of the water‐splitting efficiency is attributed to the synergistic combination of the porous structure with the plasmonic AuNPs that greatly benefits electron–hole pairs generation, separation, and charge‐carrier transport. The photoanode is robust and easy to fabricate, and this work provides an idea for future exploration of durable and efficient GaN‐based photoelectrodes.