Transition-Metal-Doped SiP₂ Monolayer for Effective CO₂ Capture: A Density Functional Theory Study

Two-dimensional materials have exhibited great potential in mitigating climate change through sensing and capturing carbon dioxide. The interaction of CO₂ on orthorhombic silicon diphosphide remains unexplored in spite of its interesting properties such as high carrier mobility, piezoelectricity, and mechanical stability. Here, using density functional theory, the adsorption of CO₂ on pristine and Ti-, V-, and Cr-doped monolayer SiP₂ is investigated. Doped systems exhibited significantly stronger adsorption (-0.268 to -0.396 eV) than pristine SiP₂ (-0.017 to -0.031 eV) and have the possibility of synthesis with low defect formation energies. Our results on adsorption energy, band structure, partial density of states, and charge transfer conclude that titanium- and vanadium-doped SiP₂ monolayers would be promising materials for CO₂ capture and removal.