Regulating Exciton Dissociation and Photocatalytic CO 2 Reduction Over Single‐Atom Cu‐In 2 S 3 Nanosheets

Abstract Uncovering the excitation processes of photocatalysts and enhancing the dissociation of excitons into free photogenerated electrons and holes for photocatalytic CO 2 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 In 2 S 3 nanosheets (Cu‐In 2 S 3 ), which can enhance photocatalytic CO 2 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 CO 2 reduction of Cu‐In 2 S 3 nanosheets. The aforementioned strategy for enhancing the dissociation efficiency of excitons in photocatalysts will offer a highly efficient and promising approach for the photocatalytic CO 2 reduction and other photocatalytic applications.