Plasmonic Hot-Electron Transfer in Gold-Nanostar-Conjugated Poly(heptazine imide) Photocatalyst

Plasmonic metal-semiconductor hybrid systems have emerged as promising platforms for enhancing photocatalytic efficiency through hot-carrier generation and transfer, with applications in solar energy conversion and chemical synthesis. Here, we investigate ultrafast charge carrier dynamics in a polymeric carbon nitride photocatalyst hybridized with gold nanostars. Using pump-probe spectroscopy, efficient electron scavenging and strong interfacial electronic coupling between gold and a poly(heptazine imide) matrix was observed, manifesting in significant modifications in the hot-carrier relaxation dynamics. Hot-electron injection from gold to poly(heptazine imide) with an efficiency of approximately 40% (standard error 12%) was observed, one of the highest reported for metal-semiconductor systems. This enhanced efficiency is attributed to the nanostar morphology, whose sharp features promote momentum relaxation and facilitate interfacial charge transfer. The findings provide direct insight into excitation-dependent electron dynamic processes and highlight the strong potential of carbon nitride-based composites for plasmonically enhanced photocatalysis, offering guidance for the design and optimization of advanced photocatalytic systems.