Plasmonic copper nanoparticle aggregates for near-infrared light-driven hydrogen evolution

Abstract

The development of novel photosystems integrating broadband near-infrared (NIR) light harvesting with efficient charge separation remains a long-pursued objective in photocatalysis research. This work demonstrates that aggregated copper nanoparticles (Cu NPs), prepared via self-assembly, exhibit significantly broadened light absorption extending into the NIR region due to electronic coupling between neighboring Cu particles. Concurrently, the aggregation generates a substantial dipole moment, markedly enhancing charge carrier separation and transport efficiency. These synergistic effects—enhanced light harvesting and improved charge dynamics—enable the aggregated Cu NPs to achieve efficient photocatalytic hydrogen production under red/NIR light irradiation. The system yields apparent quantum yields (AQYs) of 0.82% at 610 nm and 0.191% at 850 nm. Crucially, the phenomenon of aggregation-induced red/NIR light photocatalysis was also confirmed in Ag nanoparticle aggregates, establishing its generality. These findings highlight aggregated Cu NPs as effective red/NIR absorbers for solar fuel production and establish aggregation as a novel avenue for manipulating the optical and electronic properties of plasmonic photocatalysts, opening new pathways for utilizing low-energy photons in photocatalysis.