Recyclable and superior selective CO2 adsorption of C4B32 and Ca@C4B32: a new category of perfect cubic heteroborospherenes

Abstract

The capture and separation of CO₂ have attracted significant interest as a strategy to control the global emission of greenhouse gases. From the perspective of environmental protection, it is crucial to explore high-performance adsorbents that can efficiently capture CO₂. Herein, we report a density functional theory study on the viability of the heteroborospherene C₄B₃₂ for the first time. C_2v C₄B₃₂ was revealed to be a perfect cubic heteroborospherene with the HOMO–LUMO gap of 3.47 eV at the PBE0 level. Then, we evaluated the potential application of C₄B₃₂ in the capture and separation of CO₂. Our results indicate that the cubic-like C₄B₃₂ can efficiently capture CO₂ with a −1.34 eV adsorption energy via chemisorption at the most acidic and basic sites of the cage. The strong interaction between CO₂ and C₄B₃₂ could be supported by an effective charge transfer and orbital overlap. C₄B₃₂ also displayed high selectivity for the separation of CO₂ from NH₃, N₂, CH₄, CO, and H₂ mixtures. Furthermore, it was feasible to tune the CO₂-capture ability of C₄B₃₂ by metal-doping, which regulated the Lewis acidity/basicity of the C₄B₃₂ surface. In particular, Ca-doping could significantly enhance the CO₂-capture ability of C₄B₃₂. Our results show that as a highly symmetrical and stable heteroborospherene, C₄B₃₂ can be used as a building block for the design and synthesis of novel nanomaterials for the capture and separation of CO₂.