Regulating Exciton Dissociation and Photocatalytic CO₂ Reduction Over Single-Atom Cu-In₂S₃ Nanosheets

Uncovering the excitation processes of photocatalysts and enhancing the dissociation of excitons into free photogenerated electrons and holes for photocatalytic CO₂ reduction is imperative yet quite challenging. Herein, an efficient strategy of reducing the binding energy of excitons to boost exciton dissociation is reported by anchoring the low valence single-atom Cu sites in In₂S₃ nanosheets (Cu-In₂S₃), which can enhance photocatalytic CO₂ reduction activity. The investigations of photo-irradiated Kelvin probe force microscopy (KPFM), in situ irradiates X-ray photoelectron spectroscopy (XPS), and temperature-dependent photoluminescence (TD-PL) indicate that the doping of low valence single-atom Cu can efficiently drive the charge transfer and separation. Moreover, the studies of the dynamic behaviors of charge carriers by femtosecond time-resolved spectroscopy (fs-TAS) reveal that the doping of low valence Cu single-atom sites allows the promotion of exciton dissociation by reducing the binding energy of the exciton, resulting in an enhanced photocatalytic CO₂ reduction of Cu-In₂S₃ nanosheets. The aforementioned strategy for enhancing the dissociation efficiency of excitons in photocatalysts will offer a highly efficient and promising approach for the photocatalytic CO₂ reduction and other photocatalytic applications.