Enhanced Charge-Modulated Switchable CO2 Capture on Graphene-like BeN4 with Beryllium Vacancy

Beryllonitrene is a new type of Dirac semimetal two-dimensional (2D) material that has recently been fabricated and attracted significant attention with potential for carbon dioxide (CO2)-related applications. The unique symmetric geometry of this material offers different energetically favorable adsorption sites for CO2 uptake. Here, we report that single-vacancy beryllonitrene with a central hollow symmetric atomic ring can be served as a highly efficient CO2 capture adsorbent. Charge modulation response of single-vacancy beryllonitrene, occurring spontaneously once excess electrons are added or removed, is simulated using density functional theory (DFT). We employ the charge modulation strategy by adding extra electrons into the system, which manipulates the binding interactions to secure the chemisorption of CO2 molecules. Our results indicate a strong response of the single-vacancy beryllonitrene to the introduced electrons, improving the adsorption energy by −0.9888 eV. This reversible process is synergistically applied with biaxial tensile strain to enhance the gas separation performance. We demonstrate that strained single-vacancy beryllonitrene is cohesively structured and can smoothly adjust the adsorption interaction strength under different charge states. This study brings theoretical insights into the potential influence of controlled defect engineering of beryllonitrene accompanied by charge modulation and strain to boost the CO2 adsorption performance.