Ultraviolet-Visible-near infrared induced photocatalytic H₂ evolution over S-scheme Cu_2-xSe/ZnSe heterojunction with...

Localized surface plasmon resonance (LSPR) effect plays a crucial role in the field of solar energy utilization. In this work, we successfully prepared a Cu_2-xSe/ZnSe S-scheme heterojunction with a broad-spectrum response using the hot-injection and low-temperature water bath method. Importantly, we demonstrated that the photothermal effect induced by the LSPR of nonstoichiometric Cu_2-xSe can significantly improve the slow kinetics of water splitting, resulting in an apparent activation energy reduction from 50.1 to 28.7 kJ·mol^-1. This improvement is responsible for achieving the highest photocatalytic H₂ evolution rate of 63.6 mmol·g^-1·h^-1 over 2.7 % Cu_2-xSe/ZnSe under the wavelength ranged from 200 to 2500 nm, which is 3.4 and 5.6 times higher than that of ZnSe and Cu_2-xSe, respectively. Furthermore, the composite exhibits a remarkable H₂ production rate of 0.108 mmol·g^-1·h^-1 under near-infrared spectroscopy (800<λ<2500 nm), while ZnSe shows limited capability in H₂ releasing. Additionally, Cu_2-xSe/ZnSe demonstrates distinct photocurrent response when λ > 800 nm. The enhanced performance in H₂ evolution can be attributed to the synergistic effect of LSPR-induced light absorption and S-scheme heterojunction, which not only expands the light absorption range to the near-infrared region but also facilitates hot electron injection, charge carrier separation and transfer, leading to a faster surface reaction kinetics. This study provides an effective approach for designing a broad-spectrum light responsive non-precious metal-based photothermal-assisted photocatalytic system.