Highly Surface-Active Ca(OH)₂Monolayer as a CO₂Capture Material

Abstract

Greenhouse gas emissions originating from fossil fuel combustion contribute significantly to global warming, and therefore the design of novel materials that efficiently capture CO can play a crucial role in solving this challenge. Here, we show that reducing the dimensionality of bulk crystalline portlandite results in a stable monolayer material, named portlandene, that is highly effective at capturing CO. On the basis of theoretical analysis comprised of ab initio quantum mechanical calculations and force-field molecular dynamics simulations, we show that this single-layer phase is robust and maintains its stability even at high temperatures. The chemical activity of portlandene is seen to further increase upon defect engineering of its surface using vacancy sites. Defect-containing portlandene is capable of separating CO and CO from a syngas (CO/CO/H) stream, yet is inert to water vapor. This selective behavior and the associated mechanisms have been elucidated by examining the electronic structure, local charge distribution, and bonding orbitals of portlandene. Additionally, unlike conventional CO capturing technologies, the regeneration process of portlandene does not require high temperature heat treatment because it can release the captured CO by application of a mild external electric field, making portlandene an ideal CO capturing material for both pre- and postcombustion processes.

Lithium silicate nanosheets with excellent capture capacity and kinetics with unprecedented stability for high-temperature CO2 capture

“…For CO 2 capture, in general, two protocols can be used, post-combustion and pre-combustion. [2][3][4] Low-temperature sorbents (based on amines, silica, zeolites, carbon, and MOFs) are mainly used for postcombustion CO 2 capture from ue gas at low temperatures (25 to 75 C), while high-temperature sorbents are specically developed for pre-combustion capture between 500 and 700 C. [2][3][4] "Pre-combustion capture" is one of the most challenging but best ways to tackle climate change as CO 2 is captured during the process at high temperatures with ideally zero release into the environment. [5][6][7] Pre-combustion capture is potentially less expensive than post-combustion capture, as CO 2 gets captured as soon as it is produced during the process without releasing it into the environment.…”

Two-dimensional pnictogens: A review of recent progresses and future research directions

“…On the theoretical front, these efforts led to the prediction of 2D allotropes of group-IV elements, group IV, III-V, and II-VI compounds, [7][8][9][10][11][12][13][14][15] silicon dioxides, 16 transition metal dioxides 17,18 and dichalcogenides, 17,[19][20][21][22] monochalcogenides, [23][24][25] and alkali-earth metal hydroxides. 26,27 It was shown that these 2D materials display diverse electronic, optical, and magnetic properties for a wide range of technological applications, such as optoelectronics, spintronics, catalysts, chemical and biological sensors, supercapacitors, solar cells, nanotribology, [28][29][30] hydrogen production, and lithium or sodium ion batteries. 31,32 Very recently, the synthesis of ultrathin, 2D black phosphorus, through exfoliation from its layered bulk counterparts, has brought the suspended 2D monolayers and multilayers of group-VA elements [33][34][35] into the focus of current research.…”

Carbonation Reaction Mechanisms of Portlandite Predicted from Enhanced Ab Initio Molecular Dynamics Simulations

“…The spontaneous reaction is ascribed to the defects in the local coordination environment of the two surfaces as the reactivity of atoms surrounding a vacant site is reported to increase due to their reduced coordination state. [72]. The carbonation reaction occurs through a concerted C-O bond formation with the surface oxygen atoms (sp3 hybridization of the C atom) and a proton transfer to form an H 2 O molecule.…”