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.