Spin Crossover as an Efficient Strategy for Controllable Gas Molecule Capturing on Open Metal Sites in Ni-BTC and Cu-BTC

Abstract

The development of efficient sorbent materials for capturing harmful gases, in particular CO2, is one of the most important research topics due to climate change concerns. In this regard, metal–organic frameworks (MOFs) incorporating open metal sites (OMSs) have emerged as promising materials. In this article, we propose the spin crossover as an experimentally feasible strategy for controllable gas molecule capturing on the OMS-containing MOFs. To this end, we have selected the neutral and cationic forms of M2(BTC)4 with M = Ni and Cu as prototypes of the paddlewheel secondary building unit of HKUST-1 and DUT-8, respectively. The interplay between magnetic properties and the adsorption behaviors of M2(BTC)4 toward six small gas molecules (CH4, H2, N2, CO2, CO, and H2S) is investigated using first-principle calculations. It is found that the adsorption of gas molecules on the low spin (LS) state of copper and high spin (HS) state of nickel is thermodynamically more favored. Whereas the differences between the adsorption enthalpies on the LS and HS states for cupric systems are not significant, in the case of nickel centers, the differences can reach more than 150 kJ mol–1. Our results indicate that all gas molecules are strongly adsorbed at the HS state of nickel centers and change from being chemisorbed to being physisorbed at the LS state. Taking inspiration from these results, we introduce Ni2(BTC)4 paddlewheels as controllable CO2 capture materials via spin crossover at the Ni center. To our knowledge, this is the first study that suggests the spin transition as a promising approach for CO2 capture/release technology.

Synthesis of nanocellulose aerogels and Cu-BTC/nanocellulose aerogel composites for adsorption of organic dyes and heavy metal ions

“…In addition to combining the beneficial properties of organic and inorganic ingredients, they show unique properties that exceed expectations of a simple mixture of these parts 5 , 7 . Due to their specific characteristics including their record-breaking surface areas (more than 7000 m 2 /g) 8 , ultrahigh porosities 9 , low density 10 , high thermal stability 11 , and tunable pore structure 12 , MOFs have received specific attention for many applications such as gas separation and storage 13 , catalysis 14 , adsorption 15 , 16 , energy storage 17 , drug delivery 18 – 20 , chemical sensing 21 , 22 and so on 23 .…”

“…Cellulose is a promising polymer for the preparation of aerogel compounds due to its unique properties such as inexpensive 48 , renewable 49 , degradable 50 , abundant 51 , non-toxic 52 , and environmentally friendly 53 . In particular, nanocellulose materials show a specific promise for use in aerogel materials, since by reducing the size of cellulose fibers, completely uniform materials with advanced mechanical properties can be obtained 15 , 19 . Nanocellulose aerogels have a high surface area and low density compared to regenerated cellulose aerogels 54 .…”

Photo-induced reversible nitric oxide capture by Fe–M(CO2H)4 (M = Co, Ni, Cu) as a building block of mixed-metal BTC-based MOFs

“…Barth et al 57 Recently, we have shown that the modulation of magnetic properties through spin crossover is a promising approach for CO 2 capture/release technology in Ni-BTC MOFs. 59 Following that work, the current study explores the photo-induced reversible capture of NO molecules by focusing on MOFs incorporating Fe(II)-M (M = Co, Ni, Cu) nodes and carboxylate linkers (Fe-M(CO 2 H) 4 ) as the prototypes of paddle-wheel secondary building units of the synthesized FeM-BTC MOFs. [60][61][62] BTC-based MOFs have been selected for our study because they offer high capability for capturing gas molecules due to their robustness and large surface area.…”

Synthesis of Nanocellulose Aerogels and Cu-BTC/Nanocellulose Aerogel Composites for Adsorption of Organic Dyes and Heavy Metal Ions

“…In addition to combining the bene cial properties of organic and inorganic ingredients, they show unique properties that exceed expectations of a simple mixture of these parts [7], [5]. Due to their speci c characteristics including, their record-breaking surface areas (more than 7000 m 2 /g) [8], ultrahigh porosities [9], low density [10], high thermal stability [11], and tunable pore structure [12], MOFs have received speci c attention for many applications such as gas separation and storage [13], catalysis [14], adsorption [15], energy storage [16], drug delivery [17] [18] [19], chemical sensing and so on [20].…”

“…Cellulose is a promising polymer for the preparation of aerogel compounds due to its unique properties such as inexpensive [45], renewable [46], degradable [47], abundant [48], non-toxic [49], and environmentally friendly [50]. In particular, nanocellulose materials show a speci c promise for use in aerogel materials, since by reducing the size of cellulose bers, completely uniform materials with advanced mechanical properties can be obtained [15] [18]. Nanocellulose aerogels have a high surface area and low density compared to regenerated cellulose aerogels [51].…”