High capacity CO₂ capture by α-BeH₂ nanosheet through charge modulation: A first-principles study

Abstract

The increasing concern regarding elevated atmospheric CO₂ levels and their environmental impact is driving the development of advanced materials and technologies for efficient CO₂ capture and conversion. In this study, we focus on investigating the adsorption of CO₂ on beryllium hydride (α-BeH₂) nanosheets through charge modulation, using density functional theory calculations. There is minimal difference in adsorption energy between the 1e⁻ negatively charged surface and the neutral surface. Our findings indicate that the adsorption energy of CO₂ can be significantly enhanced by introducing three positively charged states. These results demonstrate that the +3e positively charged α-BeH₂ surface is an excellent sorbent for CO₂ capture, with an adsorption energy of −0.85 eV/CO₂. This indicates a transition from physisorption to chemisorption on these positively charged nanosheets. Focusing on the adsorption behavior, we discovered that introducing three positive charges into the α-BeH₂ nanosheet enables the uptake of eighteen CO₂ molecules. This achieves a CO₂ capture capacity of 74.18 wt% and an adsorption energy of −0.51eV/CO₂. These values are significantly higher than those observed with many other 2D substrates. Molecular dynamics (MD) simulations confirmed the thermal stability of the 18CO₂/BeH₂ complex at 300 K. Overall, our findings highlight α-BeH₂ monolayers with 3e positive charges as a promising substrate for highly efficient CO₂ capture.