2D/3D Assemblies of Amine-Functionalized Graphene Silica (Templated) Aerogel for Enhanced CO2 Sorption

Suppression Strategies for Si Anode Volume Expansion in Li-Ion Batteries Based on Structure Design and Modification: A Review

Silicon anodes have received increasing attention due to their exceptionally high theoretical capacity in lithium-ion batteries (LIBs). However, the defect of anode volume expansion caused by solid-electrolyte interphase (SEI) crushing limits the cycle life seriously. To overcome the obstacle, one must understand the mechanism behind anode volume expansion prior to exploring the suppression strategies. In this review, the recent advances in Si-based anode modification and structural design are categorized comprehensively, the scaled-up framework structures are deeply discussed, and the impacts of various composite structures on cycling performance and Coulombic efficiency are emphasized, particularly the synergistic effects of carbon/MXene assembled with silicon. Some reliable strategies for anode volume expansion restriction have been proposed. The porous structure of monocrystalline silicon spheres reconstructed by alloy sintering can restrain volume expansion effectively due to the reshaped uniform internal stress field. The inner-stress offset induced by Si anode expansion and two-dimensional material layer collapse can provide a perfect inhibition effect on SEI fragmentation when monocrystalline silicon spheres are assembled with graphene or MXene. Moreover, how special nanoshape structures provide anode stability after long cycles are summarized. This current review will be beneficial to facilitate the exploration of strategies for suppression of Si-based anode volume expansion and to pave an avenue for extensive application of Si-based LIBs in the future.

Melamine Network as a Solution for Significant Enhancement of the Mechanical, Adsorptive, and Surface Properties in a Novel Carbon Nanomaterial-Silica Aerogel Composite

Silica aerogels exhibit exceptional characteristics such as mesoporosity, light weight, high surface area, and pore volume. Nevertheless, their utilization in industrial settings remains constrained due to their brittleness, moisture sensitivity, and costly synthesis procedure. Several studies have proved that adding nanofillers, such as carbon nanotubes (CNT) or graphene nanoplatelets (GNP), can improve the mechanical strength of the aerogels. The incorporation of nanofillers is often accompanied by agglomeration and pore blockage, which, in turn, deteriorates the surface area, pore volume, and low density. Including flexible melamine foam (MF) as a scaffold for the silica aerogel and nanofiller composite can prevent the restacking of the nanofillers through π-π interaction, hence maintaining the incredible properties of aerogels and improving their mechanical properties. CNT, GNP, and the polymeric silica precursor, polyvinyltrimethoxysilane (PVTMS), were added to a MF, at varying concentrations, to fabricate the MF-aerogel nanocomposites. Surfactant and sonication were utilized to ensure a homogeneous dispersion of the nanofillers in the system. The presence of MF prevented the agglomeration of nanofillers, resulting in lower density and relatively higher surface properties (SBET up to 929 m2·g-1 and pore volume up to 4.34 cc·g-1). Moreover, the MF-supported samples could endure 80% strain without breakage and showed an outstanding compressive strength of up to ∼20 MPa. These aerogel nanocomposites also demonstrated an excellent volatile organic compound (∼2680 mg·g-1) and cationic dye adsorption (∼10 mg·g-1).

Tuning Dimensionality of Benzimidazole Aggregates by Using Tetraoctylammonium Bromide: Enhanced Electrochemiluminescence Studies

Exploring the depolymerization strategy of liposoluble luminophores in the aqueous phase is vital for the development of electrochemiluminescence (ECL). In this work, tetraoctylammonium bromide (TOAB) with four long hydrophobic chains and short hydrophilic ends is used as a template to limit the aggregation of benzimidazole (BIM). By adjusting the loading of BIM on the hydrophobic chains of TOAB, a two-dimensional lamellar BIM/TOAB is formed, the ECL intensity of which is 6.4 times higher than that of the aggregated BIM (H₂O₂ as the coreactant). In terms of ECL spectroscopies, cyclic voltammetry , ECL transients, and the adjustment of the scanning potential range, the ECL mechanism is thoroughly studied. This work provides a new way to depolymerize organic luminophores and reveals a possible pathway in the annihilation ECL mechanism.

Thermal Swing Reduction-Oxidation of Me(Ba, Ca, or Mg)SrCoCu Perovskites for Oxygen Separation from Air

The climate change impact associated with greenhouse gas emissions is a major global concern. This work investigates perovskite compounds for oxygen separation from air to supply oxygen to oxyfuel energy systems to abate these significant environmental impacts. The perovskites studied were Me0.5Sr0.5Co0.8Cu0.2O3−δ (MeSCC) where the A-site substitution was carried out by four different cations (Me = Ca, Mg, Sr, or Ba). SEM analysis showed the formation of small particle (<1 µm) aggregates with varying morphological features. XRD analysis confirmed that all compounds were perovskites with a hexagonal phase. Under reduction and oxidation reactions (redox), Ba and Ca substitutions resulted in the highest and lowest oxygen release, respectively. In terms of real application for oxygen separation from air, Ba substitution as BaSCC proved to be preferable due to short temperature cycles for the uptake and release of oxygen of 134 °C, contrary to Ca substitution with long and undesirable temperature cycles of 237 °C. As a result, a small air separation unit of 0.66 m3, containing 1000 kg of BaSCC, can produce 18.5 ton y−1 of pure oxygen by using a conservative heating rate of 1 °C min−1. By increasing the heating rate by a further 1 °C min−1, the oxygen production almost doubled by 16.7 ton y−1. These results strongly suggest the major advantages of short thermal cycles as novel designs for air separation. BaSCC was stable under 22 thermal cycles, and coupled with oxygen production, demonstrates the potential of this technology for oxyfuel energy systems to reduce the emission of greenhouse gases.

Carbon Dioxide Capture through Physical and Chemical Adsorption Using Porous Carbon Materials: A Review

Due to rapid industrialization and urban development across the globe, the emission of carbon dioxide (CO2) has been significantly increased, resulting in adverse effects on the climate and ecosystems. In this regard, carbon capture and storage (CCS) is considered to be a promising technology in reducing atmospheric CO2 concentration. Among the CO2 capture technologies, adsorption has grabbed significant attention owing to its advantageous characteristics discovered in recent years. Porous carbon-based materials have emerged as one of the most versatile CO2 adsorbents. Numerous research activities have been conducted by synthesizing carbon-based adsorbents using different precursors to investigate their performances towards CCS. Additionally, amine-functionalized carbon-based adsorbents have exhibited remarkable potential for selective capturing of CO2 in the presence of other gases and humidity conditions. The present review describes the CO2 emission sources, health, and environmental impacts of CO2 towards the human beings, options for CCS, and different CO2 separation technologies. Apart from the above, different synthesis routes of carbon-based adsorbents using various precursors have been elucidated. The CO2 adsorption selectivity, capacity, and reusability of the current and applied carbon materials have also been summarized. Furthermore, the critical factors controlling the adsorption performance (e.g., the effect of textural and functional properties) are comprehensively discussed. Finally, the current challenges and future research directions have also been summarized.

Two-dimensional material-based functional aerogels for treating hazards in the environment: synthesis, functional tailoring, applications, and sustainability analysis

Environmental pollution is a global problem that endangers human health and ecological balance. As a new type of functional material, two-dimensional material (2DM)-based aerogel is one of the most promising candidates for pollutant detection and environmental remediation. The porous, network-like, interconnected three-dimensional (3D) structure of 2DM-based aerogels can not only preserve the characteristics of the original 2DMs, but also bring many distinct physical and chemical properties to offer abundant active sites for adsorbing and combining pollutants, thereby facilitating highly efficient monitoring and treatment of hazardous pollutants. In this review, the synthesis methods of 2DM aerogels and their broad environmental applications, including various sensors, adsorbents, and photocatalysts for the detection and treatment of pollutants, are summarized and discussed. In addition, the sustainability of 2DM aerogels compared to other water purification materials, such as activated carbon, 2DMs, and other aerogels are analyzed by the Sustainability Footprint method. According to the characteristics of different 2DMs, special focuses and perspectives are given on the adsorption properties of graphene, MXene, and boron nitride aerogels, as well as the sensing and photocatalytic properties of transition metal dichalcogenide/oxide and carbon nitride aerogels. This comprehensive work introduces the synthesis, modification, and functional tailoring strategies of different 2DM aerogels, as well as their unique characteristics of adsorption, photocatalysis, and recovery, which will be useful for the readers in various fields of materials science, nanotechnology, environmental science, bioanalysis, and others.

Bio-mass derived functionalized graphene aerogel: a sustainable approach for the removal of multiple organic dyes and their mixtures

Herein, fabrication of a functionalized graphene aerogel (f-GA) from a biomass (pear fruit)-derived graphene aerogel (GA) is described. f-GA is showing better adsorption capacity towards CV, MB and RhB dyes than GA and activated charcoal.

Fullerene-intercalated graphene nanocontainers for gas storage and sustained release

Molecular dynamics simulations are performed to investigate the storage capacity and sustained release of nitrogen (N₂) in the graphene-based nanocontainers. Sandwiched graphene-fullerene composites (SGFC) composed of two parallel graphene sheets and intercalated fullerenes are constructed. The simulation results show that the mass density of N₂ at the first layer is extremely high, due to the strong adsorption ability of graphene sheets. And N₂ molecules at this adsorbed layer are thermodynamically stable. Furthermore, we analyze the storage efficiency of SGFC. In general, the gravimetric and volumetric capacities decrease with the increasing number of intercalated fullerenes. On the contrary, the stability of SGFC is enhanced by more intercalated fullerenes. We therefore make a compromise and propose that 1 fullerene per 5 nm² graphene to build a SGFC, which is much effective to storage N₂. We also verify the reversibility that N₂ can sustainably release from the SGFC. Our results may provide insights into the design of graphene-based nanocomposites for gas storage and sustained release with excellent structural stability and high storage capacity. Graphical abstract.