Surface-State-Regulated Product Distribution in Photothermal CO₂ Hydrogenation Over MXene-Based S-Scheme Catalyst

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Efficient carbon dioxide (CO2) conversion is vital for sustainable energy and environmental remediation.
• Developing advanced photocatalysts with enhanced carrier separation and photothermal synergy is crucial.
• Heterostructured materials offer tunable properties for catalytic applications.

Purpose of the Study:

• To design and synthesize a novel Ni/Ti3C2Clx MXene heterojunction for CO2 conversion.
• To investigate the charge transfer dynamics and photothermal effects in the heterojunction.
• To control the product distribution of CO2 hydrogenation to methane and methanol.

Main Methods:

• Synthesis of Ni/Ti3C2Clx MXene heterojunction using Lewis acid molten-salt etching.
• Characterization using in situ irradiated X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS).
• Ultrafast interfacial dynamics studied via femtosecond transient absorption spectroscopy (fs-TA).
• Density functional theory (DFT) calculations to understand reaction pathways.

Main Results:

• The Ni/Ti3C2Clx heterojunction exhibits an S-scheme charge transfer pathway for efficient carrier separation.
• Photothermal conditions coupled with the heterojunction enable regulated CO2 hydrogenation.
• Surface-state evolution, not just oxidation, modulates adsorption and reaction barriers.
• Moderately oxidized Ni-NiOx interfaces favor methanol formation, while extensive oxidation suppresses it.

Conclusions:

• The Ni/Ti3C2Clx MXene heterojunction is a promising material for photothermal CO2 conversion.
• Interface engineering in MXene-based heterojunctions is key for catalytic performance.
• Controlling surface states is pivotal for steering product selectivity in CO2 hydrogenation.