Augmenting Ultrafast Hot Electron Injection from Localized Surface Plasmon Resonance via an AlGaN/GaN Interlayer for Ta 3 N 5 -Based Efficient Water Splitting

In typical metal–semiconductor architectures, metal nanoparticles under irradiation could induce localized surface plasmon resonance (LSPR) and generate hot electrons via an electronic effect to inject into the semiconductor within femtoseconds, thereby influencing separation and transport of photogenerated carriers. While recent research has extensively explored the impact of plasmon effects on catalytic performance and selectivity, strategies to minimize energy losses during ultrafast hot carrier injection and thereby enhance catalytic efficiency still remain scarcely investigated. Herein, we introduce an AlGaN/GaN interlayer that substantially enhances hot electron injection efficiency from Au nanorods (AuNRs), achieving an ABPE of 3.45% and one of the lowest onset potentials (0.236 VRHE at 0.2 mA·cm–2); this enhancement of ultrafast injection dynamics was also captured using femtosecond transient absorption spectroscopy. Furthermore, finite-difference time-domain (FDTD) simulation and wavelength-resolved photoelectrochemical measurements quantitatively deconvoluted the enhanced hot electron injection, revealing an approximately 300% increase in photocurrent density following AlGaN/GaN insertion. Meanwhile, density functional theory (DFT) calculations showed a high lattice match of 99.22% between GaN-Al and Ta3N5, corroborating the possibility for enhancing electron transfer efficiency. This work provides critical insights into enhancing hot electron injection efficiency in LSPR-mediated systems and may inspire further innovative applications of plasmon in catalysis.