Ultrathin Conductor Enabling Efficient IR Light CO₂ Reduction

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Converting carbon dioxide and water into hydrocarbons and oxygen using low-energy infrared (IR) light is a significant scientific challenge.
• Existing photocatalytic systems often struggle with efficient light harvesting and charge separation under IR irradiation.

Purpose of the Study:

• To design and fabricate an ultrathin conductor system capable of harvesting IR light and facilitating concurrent CO2 and water transformation.
• To investigate the photocatalytic performance of ultrathin copper sulfide (CuS) atomic layers for CO2 reduction and water oxidation.

Main Methods:

• Fabrication of ultrathin CuS layers.
• Characterization using temperature-dependent resistivities, valence-band spectroscopy, synchrotron-radiation photoelectron spectroscopy, and UV-Vis-NIR spectroscopy.
• Theoretical calculations to affirm metallic nature and understand electronic band structure.
• Evaluation of photocatalytic performance under IR light irradiation.

Main Results:

• Ultrathin CuS layers exhibit metallic properties with a partially occupied band enabling IR light harvesting and suitable band-edge positions.
• A novel cooperative intraband-interband transition under IR irradiation facilitates simultaneous CO2 reduction and water oxidation.
• CuS atomic layers achieved nearly 100% selective CO production at a rate of 14.5 μmol g⁻¹ h⁻¹ with excellent stability over 96 hours.

Conclusions:

• Ultrathin metallic CuS atomic layers are effective IR-light-driven photocatalysts for CO2 and water conversion.
• The unique electronic structure and ultrathin configuration are key to enhanced photocatalytic activity and charge dynamics.
• Conducting metal sulfides and nitrides show potential as IR-light-responsive photocatalysts for sustainable energy applications.