Synthetic Architecture of MgO/C Nanocomposite from Hierarchical-Structured Coordination Polymer toward Enhanced CO2 Capture

Designing of 3D Architecture Flower-like Mn-Promoted MgO and Its Application for CO2 Adsorption and CO2-Assisted Aerobic Oxidation of Alkylbenzenes

Sustainable chemistry research prioritizes reducing atmospheric carbon dioxide, and one logical solution is to develop adsorbents suitable for carbon capture and utilization. In this work, a new family of three-dimensional (3D) flower-like Mn-promoted MgO was synthesized by the coprecipitation method and used as an adsorbent for CO₂ capture and a catalyst for CO₂ utilization. The scanning electron microscopy (SEM) analysis of the samples shows a 3D architecture composed of thin nanosheets. The X-ray diffraction (XRD) analysis confirms the presence of the MgO with a cubic structure, while X-ray photoelectron spectroscopy (XPS) reveals the existence of Mn particles as a combination of Mn³⁺ and Mn⁴⁺ ions on MgO. N₂ adsorption-desorption experiments highlight the beneficial contribution of Mn particles to surface area enhancement and reveal the existence of mesopores. Furthermore, the designed 3D Mn-doped MgO as an adsorbent demonstrates its capability to improve the ability of MgO to adsorb CO₂ (from 0.28 mmol/g for pure MgO to 0.74 mmol/g) in ambient conditions and it is regenerable up to 9 cycles with a slight variation after the third cycle. Moreover, Mn-doped MgO shows good catalyst activity for the oxidation of ethylbenzene derivatives to carbonyl compounds in the presence of CO₂ and O₂. Mn-15/MgO shows excellent catalytic behavior with a conversion of 97.4 and 100% selectivity. Also, it is regenerable with an insignificant decrease in conversion (∼11.63%) after seven cycles, while the selectivity of acetophenone remains stable. The analyses of the recycled sample suggest that the chemical compositions of Mn and Mg influence the catalytic activity of those Mn-promoted MgO materials. The role of CO₂ gas in the aerobic oxidation of ethylbenzene to acetophenone has also been proved. Finally, the control experiments and EPR studies reveal that the reaction takes place through the formation of radicals.

Emerging trends in direct air capture of CO2: a review of technology options targeting net-zero emissions

The increasing concentration of carbon dioxide (CO2) in the atmosphere has compelled researchers and policymakers to seek urgent solutions to address the current global climate change challenges. In order to keep the global mean temperature at approximately 1.5 °C above the preindustrial era, the world needs increased deployment of negative emission technologies. Among all the negative emissions technologies reported, direct air capture (DAC) is positioned to deliver the needed CO2 removal in the atmosphere. DAC technology is independent of the emissions origin, and the capture machine can be located close to the storage or utilization sites or in a location where renewable energy is abundant or where the price of energy is low-cost. Notwithstanding these inherent qualities, DAC technology still has a few drawbacks that need to be addressed before the technology can be widely deployed. As a result, this review focuses on emerging trends in direct air capture (DAC) of CO2, the main drivers of DAC systems, and the required development for commercialization. The main findings point to undeniable facts that DAC's overall system energy requirement is high, and it is the main bottleneck in DAC commercialization.

Unraveling the interactions of reductants and reaction path over Cu-ZSM-5 for model coal-gas-SCR via a transient reaction study

Cu-ZSM-5 was selected as a candidate catalyst to explore the interaction between coal gas components and elucidate the reaction mechanism in the coal-gas-SCR process.

General approach to construct hierarchical-structured porous Co–Ni bimetallic oxides for efficient oxygen evolution

A novel, general and controllable approach was developed to produce a series of hierarchical-structured porous Co–Ni bimetallic oxides via topochemical transformation of bimetallic coordination polymers for boosted oxygen evolution catalysis.

Construction of a hierarchical-structured MgO-carbon nanocomposite from a metal–organic complex for efficient CO2 capture and organic pollutant removal

A hierarchical-structured porous MgO/C nanocomposite derived from a metal–organic complex performs as a remarkable adsorbent for CO₂ adsorption and organic pollutant removal.

Lennard-Jones Intermolecular Potentials for the Description of 6-Membered Aromatic Heterocycles Interacting with the Isoelectronic CO2 and CS2

We have generated Lennard-Jones potentials for the interaction between CX₂ (X = O, S) and 11 nitrogen-doped benzene derivatives in different orientations at the M06-2X/def2-tzvpp level as tools to parametrize accurate force fields and to better understand the interaction of these greenhouse gases with heterocyclic building blocks used in the design of capture and detection systems. We find that the most favorable interactions are found between the carbon in CO₂ and the main heterocycle in the ring in a parallel orientation, whereas the preferred interaction mode of CS₂ is established between sulfur and the π density of the aromatic ring. The fact that the preferences for interaction sites and orientations of CO₂ and CS₂ are most of the times opposite helps in terms of ensuring the selectivity of these systems in front of these two isoelectronic compounds. The existence of very good linear correlations ( R² values very close to one) between the number of nitrogen atoms in the heterocyclic ring and the depth of the interaction potential wells opens the door to the use of these results in generating coarse-grained potentials or models with predictive power for use in the design of larger systems.

Optimization of the structural characteristics of CaO and its effective stabilization yield high-capacity CO2 sorbents

Calcium looping, a CO₂ capture technique, may offer a mid-term if not near-term solution to mitigate climate change, triggered by the yet increasing anthropogenic CO₂ emissions. A key requirement for the economic operation of calcium looping is the availability of highly effective CaO-based CO₂ sorbents. Here we report a facile synthesis route that yields hollow, MgO-stabilized, CaO microspheres featuring highly porous multishelled morphologies. As a thermal stabilizer, MgO minimized the sintering-induced decay of the sorbents’ CO₂ capacity and ensured a stable CO₂ uptake over multiple operation cycles. Detailed electron microscopy-based analyses confirm a compositional homogeneity which is identified, together with the characteristics of its porous structure, as an essential feature to yield a high-performance sorbent. After 30 cycles of repeated CO₂ capture and sorbent regeneration, the best performing material requires as little as 11 wt.% MgO for structural stabilization and exceeds the CO₂ uptake of the limestone-derived reference material by ~500%.

The economic operation of a carbon dioxide capture technique of calcium looping necessitates highly effective CaO-based CO₂ sorbents. Here, the authors report a facile one-pot synthesis approach to yield highly effective, MgO-stabilized, CaO-based CO₂ sorbents featuring highly porous multishelled morphologies.

Design and Synthesis of a Biocompatible 1D Coordination Polymer as Anti-Breast Cancer Drug Carrier, 5-Fu: In Vitro and in Vivo Studies

Designable coordination polymers with suitable chemical diversities and biocompatible structures have been proposed as a promising class of vehicles for drug delivery systems. Here, we hydrothermally synthesized a novel one-dimensional (1D) coordination polymer, [Zn(H₂O)₆K₂(H₂BTC)₂(H₂O)₄](H₂BTC)₂·2H₂O, where H₃BTC = benzene-1,3,5-tricarboxylic acid (trimesic acid), cp.1. As the hydrogen bonds stabilized 1D chains in three dimensions, the cp.1 could be a good candidate for delivering small-molecule chemotherapeutics such as 5-fluorouracil (5-Fu). The synthesized cp.1 showed a remarkable 5-Fu loading of 66% with encapsulation efficiency of 98% and almost complete release process. The 5-Fu-loaded cp.1 displayed a time-dependent cytotoxicity effect against breast cancer cell lines MCF-7 and 4T1. The cellular uptake of cp.1 particles was investigated via confocal laser scanning microscopy using fluorescein isothiocyanate and LysoTracker Red staining. Furthermore, the in vivo antitumor impact of 5-Fu-loaded cp.1 was studied on 4T1 breast cancer BALB/c mice model. The intratumor treatment of 5-Fu-loaded cp.1 demonstrated beneficial antitumor efficacy by postponing tumor growth. These results suggest that the 5-Fu-loaded cp.1 microparticles with a great locoregional delivery can be efficient anticancer drug carriers for further clinical treatments.

Hierarchical Porous Magnesium Oxide (Hr-MgO) Microspheres for Adsorption of an Organophosphate Pesticide: Kinetics, Isotherm, Thermodynamics, and DFT Studies

In this study, hierarchical porous magnesium oxide (Hr-MgO) microspheres have been fabricated from a hydromagnesite precursor via a facile precipitation method followed by calcination. The Hr-MgO microspheres consist of several nanosheet building blocks that generate a flowerlike architecture. Chlorpyrifos (CPF), a persistent organic pollutant, has been chosen as a model organophosphate pesticide to determine the adsorptive capacities of the fabricated Hr-MgO. The equilibrium adsorption data fits well with the Langmuir isotherm model, showing a maximum adsorption capacity of 3974 mg g^-1, which is the highest value to date. Both kinetic as well as thermodynamic parameters reveal the spontaneous, exothermic, and pseudo-second-order nature of the adsorption process due to chemisorption between the pesticide and the adsorbent. Density functional theory studies suggest the importance of hydroxylation on the MgO surface for the successful destructive adsorption, which takes place via the cleavage of S═P and Cl-C bonds resulting in the fragmentation of CPF, which is in good agreement with Fourier transform infrared and mass spectrometric studies. The present study shows the potential use of hierarchically structured porous MgO microspheres as an efficient adsorbent for the removal of CPF pollutant.

Hierarchical Nanocomposite by the Integration of Reduced Graphene Oxide and Amorphous Carbon with Ultrafine MgO Nanocrystallites for Enhanced CO2 Capture

Exploring efficient and low-cost solid sorbents is essential for carbon capture and storage. Herein, a novel class of high-performance CO₂ adsorbent (rGO@MgO/C) is engineered based on the controllable integration of reduced graphene oxide (rGO), amorphous carbon, and MgO nanocrystallites. The optimized rGO@MgO/C nanocomposite exhibits remarkable CO₂ capture capacity (up to 31.5 wt % at 27 °C, 1 bar CO₂, and 22.5 wt % under the simulated flue gas), fast sorption rate, and strong process durability. The enhanced capture capability of CO₂ is the best among all of the MgO-based sorbents reported so far. The high performance of rGO@MgO/C nanocomposite can be ascribed to the hierarchical architecture and special physicochemical features, including the sheet-on-sheet sandwich-like structure, ultrathin nanosheets with abundant nanopores, large surface area, and highly dispersed ultrafine MgO nanocrystallites (ca. 3 nm in size), together with the rGO sheets and in situ generated amorphous carbon that serve as a dual carbon support and protectant system with which to prevent MgO nanocrystallites from agglomeration. In addition, the CO₂-uptake capacity at intermediate temperature (e.g., 350 °C) can be further improved threefold through alkali metal salt promotion treatment. This work provides a facile and effective strategy with which to engineer advanced graphene-based functional nanocomposites with rationally designed compositions and architectures for potential applications in the field of gas storage and separation.