2D/1D MoS₂ /TiO₂ Heterostructure Photocatalyst with a Switchable CO₂ Reduction Product

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Efficient charge carrier transfer is crucial for selective CO2 photoreduction using heterostructure photocatalysts.
• Understanding and controlling charge transfer pathways dictates the efficiency and selectivity of photocatalytic reactions.

Purpose of the Study:

• To investigate the regulation of charge transfer pathways and redox potentials in 2D MoS2/1D TiO2 heterostructures.
• To elucidate the switchable charge transfer mechanisms under different light wavelengths.
• To explore the selective photocatalytic CO2 reduction products based on light conditions.

Main Methods:

• Fabrication of 2D MoS2/1D TiO2 heterostructures.
• In situ measurements and experiments to analyze charge transfer mechanisms (S-scheme and heterojunction).
• Photocatalytic CO2 reduction experiments under simulated solar and visible light.
• 13CO2 isotope labeling and photoelectrochemical H2 generation measurements.
• Density functional theory (DFT) calculations for band structure analysis.

Main Results:

• Charge transfer pathway in MoS2/TiO2 heterostructures is switchable, following an S-scheme mechanism under simulated solar light and a heterojunction approach under visible light.
• Photocatalytic CO2 reduction product switches from CO to CH4 upon changing light irradiation from simulated sunlight to visible light.
• 13CO2 isotope labeling confirmed CO2 as the carbon source for both CH4 and CO.
• Photoelectrochemical H2 generation results corroborated the switchable properties of the heterostructure.
• DFT calculations accurately predicted the band structure and supported the proposed charge transfer pathways.

Conclusions:

• The MoS2/TiO2 heterostructure exhibits tunable charge transport and redox potential by varying light wavelength.
• This switchable property allows for selective photocatalytic CO2 reduction to different products (CO or CH4).
• The findings provide a pathway for developing advanced photocatalysts for selective artificial photosynthesis.