Construction of Bi_2S_3/TiO_2/MoS_2 S-Scheme Heterostructure with a Switchable Charge Migration Pathway for Selective CO_2 Reduction

摘要

Switching between the redox potential of an appropriate semiconductor heterostructurecould show critical applications in selective CO_2 reduction. Designing asemiconductor photocatalyst with a wavelength-dependent response is an effectivestrategy for regulating the direction of electron flow and tuning the redox potential.Herein, the switching mechanism between two charge migration pathways andredox potentials in a Bi_2S_3/TiO_2/MoS_2 heterostructure by regulating the lightwavelength is achieved. In situ irradiated X-ray photoelectron spectroscopy (ISI-XPS),electron spin resonance (ESR), photoluminescence (PL), and experimental scavengeranalyses prove that the charge transport follows the S-scheme approach underUV–vis–NIR irradiation and the heterojunction approach under vis–NIR irradiation,confirming the switchable feature of the Bi_2S_3/TiO_2/MoS_2 heterostructure. Thisswitchable feature leads to the reduction of CO_2 molecules to CH_3OH and C_2H_5OHunder UV–vis–NIR irradiation, while CH_4 and CO are produced under Vis–NIRirradiation. Interestingly, the apparent quantum efficiency of the optimal compositeat λ = 600 nm is 4.23%. This research work presents an opportunity to developphotocatalysts with switchable charge transport and selective CO_2 reduction.