Light Harvesting and Carrier Dynamics Mediated by Plasmon and Topological Surface State in Bi 2 Se 3 /Cu 2‐x S/CdS for Full‐Spectrum Photocatalysis

ABSTRACT Doped semiconductor and topological insulator (TI) have been used to enhance photocatalytic energy conversion due to their unique plasmonic resonance and topological surface states (TSS). However, simultaneously leveraging both plasmon and TSS to improve photocatalysis and uncovering the underlying carriers’ dynamics mechanism remain a challenge. Herein, a TI‐plasmon‐semiconductor heterostructure was constructed for full‐spectrum photocatalytic hydrogen generation, driven by the strong interplay between plasmon and TSS as well as multi‐channel charge separation. This heterostructure was synthesized by growing Cu 2‐x S on Bi 2 Se 3 nanowires, followed by the deposition of CdS nanoparticles. A series of measurements reveals strong light harvesting ranging from ultraviolet to near‐infrared (NIR) region and multi‐interfacial hot‐carrier transfer mediated by the intense plasmon–TSS interaction within the TI–plasmon–semiconductor heterostructure. Under visible and NIR light irradiation, the Bi 2 Se 3 /Cu 2‐x S/CdS heterostructure achieves a high photocatalytic hydrogen generation rate, 91.3 times that of CdS. Moreover, it exhibits excellent NIR‐driven photocatalytic performance, owing to its efficient NIR light response caused by the co‐excitation of TSS and plasmon. This work provides fundamental insights into carrier dynamics in heterostructures based on TI and plasmonic materials, and offers inspiration for designing materials for solar energy conversion.