Abstract
Inspired by our recent success in designing CO2-phobic and CO2-philic domains on nano-MgO for effective CO2 adsorption, our ongoing efforts focus on incorporating dopants into pristine MgO to further enhance its CO2 adsorption capabilities. However, a clear set of guidelines for dopant selection and a holistic understanding of the underlying mechanisms is still lacking. In our investigation, we combined first-principles calculations with experimental approaches to explore the crystal and electronic structural changes in MgO doped with high-valence elements (Al, C, Si, and Ti) and their interactions with CO2. Our findings unveiled two distinct mechanisms for CO2 capture: Ti-driven catalytic CO2 decomposition and CO2 polarization induced by Al, C, and Si. Ti doping induced outward Ti atom displacement and structural distortion, facilitating CO2 dissociation, whereas C doping substantially bolstered the electron donation capacity and CO2 adsorption energy. Pristine and C-doped MgO engaged CO2 through surface O atoms, while Al-, Si-, and Ti-doped MgO predominantly relied on dopant-O atom interactions. Our comprehensive research, integrating computational modeling and experimental work supported by scanning electron microscopy and thermal gravimetric analysis, confirmed the superior CO2 adsorption capabilities of C-doped MgO. This yielded profound insights into the mechanisms and principles that govern dopant selection and design.