Enhancing CO₂ Adsorption on MgO: Insights into Dopant Selection and Mechanistic Pathways

Area of Science:

• Materials Science
• Chemical Engineering
• Computational Chemistry

Background:

• Effective carbon dioxide (CO2) adsorption is crucial for climate change mitigation.
• Previous work demonstrated CO2-philic and CO2-phobic domains on nano-magnesium oxide (MgO).
• Guidelines for dopant selection and understanding CO2 adsorption mechanisms in MgO are lacking.

Purpose of the Study:

• To investigate the effects of doping pristine MgO with high-valence elements (Al, C, Si, Ti) on CO2 adsorption.
• To elucidate the mechanisms of CO2 interaction with doped MgO.
• To establish principles for dopant selection and material design for enhanced CO2 capture.

Main Methods:

• Combined first-principles calculations with experimental approaches.
• Investigated crystal and electronic structural changes in doped MgO.
• Utilized scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA) for experimental validation.

Main Results:

• Identified two CO2 capture mechanisms: Ti-driven catalytic CO2 decomposition and CO2 polarization by Al, C, and Si.
• Ti doping induced structural distortion facilitating CO2 dissociation.
• Carbon (C) doping significantly enhanced electron donation capacity and CO2 adsorption energy, with C-doped MgO showing superior performance.

Conclusions:

• Doping MgO with high-valence elements offers distinct mechanisms for CO2 capture.
• Carbon-doped MgO exhibits superior CO2 adsorption capabilities due to enhanced electron donation and adsorption energy.
• The study provides fundamental insights into dopant selection and design principles for advanced CO2 adsorbents.