Construction of Bi₂S₃/TiO₂/MoS₂ S‐Scheme Heterostructure with a Switchable Charge Migration Pathway for Selective CO₂ Reduction

Abstract

Switching between the redox potential of an appropriate semiconductor heterostructure could show critical applications in selective CO2 reduction. Designing a semiconductor photocatalyst with a wavelength‐dependent response is an effective strategy for regulating the direction of electron flow and tuning the redox potential. Herein, the switching mechanism between two charge migration pathways and redox potentials in a Bi2S3/TiO2/MoS2 heterostructure by regulating the light wavelength is achieved. In situ irradiated X‐ray photoelectron spectroscopy (ISI‐XPS), electron spin resonance (ESR), photoluminescence (PL), and experimental scavenger analyses prove that the charge transport follows the S‐scheme approach under UV–vis–NIR irradiation and the heterojunction approach under vis–NIR irradiation, confirming the switchable feature of the Bi2S3/TiO2/MoS2 heterostructure. This switchable feature leads to the reduction of CO2 molecules to CH3OH and C2H5OH under UV–vis–NIR irradiation, while CH4 and CO are produced under Vis–NIR irradiation. Interestingly, the apparent quantum efficiency of the optimal composite at λ = 600 nm is 4.23%. This research work presents an opportunity to develop photocatalysts with switchable charge transport and selective CO2 reduction.

Rational design of a 2D TiO2–MoO3 step-scheme heterostructure for boosted photocatalytic overall water splitting

“…As reported previously, the absolute electronegativity (x) values of the TiO 2 and MoO 3 photocatalysts were 5.81 and 6.4 eV, respectively. 56,58 From the above results, the band gap values of the synthesized TiO 2 and MoO 3 photocatalysts were found to be 3.1 and 2.82 eV, respectively. Hence, from eqn (3) and ( 4), the E CB and E VB values were calculated and found to be (À0.24 and 0.49 eV) and (2.86 and 3.31 eV) for the synthesized TiO 2 and MoO 3 photocatalysts, respectively.…”

“…The results are consistent with other studies. 56,58 Based on the optical study, the band gap values of TiO 2 and TO-MO-30 were found to be 3.1 and 2.9 eV, respectively, indicating that the visible light absorption of TiO 2 is significantly enhanced. The formation of the heterostructure would be the reason for the enhancement.…”

Surface defect-engineered CeO2−x by ultrasound treatment for superior photocatalytic H2 production and water treatment

“…The generated ˙OH was detected by using DMPO as a radical trapping substance in an aqueous solution. 8…”

“…5 Consequently, the efficiency of charge kinetics operations is greatly reduced, and the photocatalytic activity is significantly decreased. Several techniques have been studied to enhance the photocatalytic efficiency of semiconductor nanostructures like defect engineering, doping of metals or non-metals, construction of heterojunctions, metal loading, etc., [6][7][8] Engineering defects in semiconductor photocatalysts is an efficient method to control and change the regional coordination of active sites in semiconductor photocatalysts. 9 For altering the bandgap energies in nanostructures and improving photoexcited electron transport, defect engineering offers great potential.…”

“…Several techniques have been studied to enhance the photocatalytic efficiency of semiconductor nanostructures like defect engineering, doping of metals or non-metals, construction of heterojunctions, metal loading, etc. , 6–8…”