Borophene as a Promising Material for Charge-Modulated Switchable CO2 Capture.

Ideal carbon dioxide (CO2) capture materials for practical applications should bind CO2 molecules neither too weakly to limit good loading kinetics nor too strongly to limit facile release. Although charge-modulated switchable CO2 capture has been proposed to be a controllable, highly selective, and reversible CO2 capture strategy, the development of a practical gas-adsorbent material remains a great challenge. In this study, by means of density functional theory (DFT) calculations, we have examined the possibility of conductive borophene nanosheets as promising sorbent materials for charge-modulated switchable CO2 capture. Our results reveal that the binding strength of CO2 molecules on negatively charged borophene can be significantly enhanced by injecting extra electrons into the adsorbent. At saturation CO2 capture coverage, the negatively charged borophene achieves CO2 capture capacities up to 6.73 × 1014 cm-2. In contrast to the other CO2 capture methods, the CO2 capture/release processes on negatively charged borophene are reversible with fast kinetics and can be easily controlled via switching on/off the charges carried by borophene nanosheets. Moreover, these negatively charged borophene nanosheets are highly selective for separating CO2 from mixtures with CH4, H2, and/or N2. This theoretical exploration will provide helpful guidance for identifying experimentally feasible, controllable, highly selective, and high-capacity CO2 capture materials with ideal thermodynamics and reversibility.