Microporous and Mesoporous Materials最新文献

A composite layer of homogeneously aligned liquid crystal (LC) doped with nano or mesoporous microparticles (NMPs) has been shown to act as normally opaque smart window (SW) in what is called NMP-LC mode. The porosity of the particle plays two important roles: (i) When the LC infiltrates the particle, it brings its refractive index to be closer to that of its LC surrounding at a certain orientation of the LC molecules and creates a large index mismatch at the orthogonal orientation; (ii) the LC infiltration brings the porous particle density to be closer to the surrounding LC, thus preventing precipitation and floating. Here we demonstrate that LC doped with cochleate cigar-shaped hollow particles and using DMOAP as an alignment layer acts as a normally transparent smart window. Under voltage, the best scenario that explains the polarization-independent scattering is to have the cochleate particles inclined at an angle to balance the dielectric with the elastic forces effectively. The emergence of the scattering mode results from the symbiotic interplay of two distinct phenomena – the NMP effect and the electro-hydrodynamic instability effect. The synergy between these two effects manifests in lower operating voltage and frequency requirements for the device, hence less energy consumption. The scattering increases between 30 °C and 50 °C, thus it acts as a self-adjustable window giving more shade as the outside temperature rises. The threshold voltage is found to decrease with temperature. The SW exhibits high transparency in the OFF state, and high haze in the ON state, and the durability test shows that the SW switches for at least 6 days without degradation of optical contrast.

Development of highly efficient and low-cost adsorbents for radioactive iodine vapor is significant but still challenged now. In this work, we reported a novel graphene aerogel (GA-Cu-ED) decorated by zero-valence copper and nitrogen active sites, prepared via a two-step route of hydrothermal reaction and freeze-drying processes. The combination of X-ray photoelectron spectroscopy (XPS) valence imaging and high-resolution transmission electron microscope (TEM) confirms the formation of Cu⁰ and its uniform distribution. Besides, the good elasticity and ultra-low density of this aerogel were proved. Adsorption experiments indicate that GA-Cu-ED has a high adsorption capacity of 3.76 g/g for gaseous iodine and short adsorption equilibrium time of 90 min. Even after three cycles, this aerogel still shows an almost unchanged adsorption capacity of 3.74 g/g. Meanwhile, this aerogel can be long-term stored under air atmosphere with only slight loss in adsorption performance. In addition, the captured iodine molecules can be tightly bound in this aerogel even after being exposed in air for three days. Mechanism analysis indicates the I-benzene conjugation, I–N charge transfer, and I₂–Cu⁰ chemisorption contribute together to the capture of gaseous iodine. Therefore, our work provides a highly efficient and reliable adsorbent for radioactive iodine vapor, which may be worthy in large-scale application in future.

Molybdenum (Mo) tends to form highly mobile, non-sorbing complex redox species, which complicates its immobilization and encapsulation in cement and glass matrices. This study explores the potential of incorporating Mo into an alternative green cementitious material known as geopolymer (GP). By employing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), morphological analysis, and nitrogen adsorption-desorption techniques, we obtained comprehensive insights into the chemical behavior of Mo and its impact on the morphology and structure of the GP matrix. XRD and TGA analysis demonstrated that increasing Mo content significantly enhances the crystallinity and thermal stability of the GP matrix, attributed to Mo field effects. High-resolution SEM, TEM, and EDS mapping revealed the structural encapsulation of Mo-rich cavities within the GP waste form. A decrease in leaching rates with higher Mo content, alongside reduced pore volume and pore size, underscores the material's chemical durability. Post-leaching characterizations confirmed that the GP retains excellent structural strength with minimal changes in mesoporosity and surface area. This resilience highlights the effectiveness of GPs in immobilizing non-sorbing species like MoO₃²⁻, making them ideal for long-term waste management.

The exploration of a suitable adsorbent for removal of toxic elements is a challenging task and in this context we have employed UiO-66 (Ce) based Metal Organic Frameworks (MOFs) synthesized by a room temperature method for the remediation of arsenic from aqueous solutions. The synthesized UiO-66 (Ce) and UiO-66 (Ce)-NH₂ MOFs were well characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), Thermogravimetry (TG), Brunauer–Emmett–Teller (B.E.T.), Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Octahedral morphology was observed for UiO-66 (Ce) whereas the morphology of UiO-66 (Ce)-NH₂ synthesized by this method was non-uniform. Bare MOF exhibited higher surface area and higher thermal stability in contrast to the amine functionalized MOF. We have studied the arsenic adsorption on both these MOFs in varying pH conditions. The adsorption isotherm studies revealed that bare MOF is much superior for adsorption of arsenic with adsorption capacity of ∼308 mg/g whereas the adsorption capacity of amine functionalized MOF was mere 70 mg/g. Adsorption kinetic studies demonstrated that MOFs follow Pseudo Second Order (PSO) model and elucidated that the adsorption process is predominantly chemisorption in nature. UiO-66 (Ce) could be successively used multiple times without much penalty in the adsorption capacity and the thermodynamics of adsorption suggested it to be spontaneous and favorable. Finally, an overview of the probable mechanism of adsorption is discussed by employing different experimental techniques like XRD, FT-IR and XPS.

Ordered mesoporous carbon CMK-1 was prepared via carbonization at a relatively low temperature (the first step) followed by partial graphitization (the second step of carbonization at higher temperature) inside the ordered mesopores of cobalt-loaded mesoporous silica MCM-48 using polyacrylonitrile (PAN) as a carbon/nitrogen source. This first step of the carbonization is called “infusibilization”, and the resultant material is denoted as PAN_inf. In an advanced temperature-programmed desorption analysis of the PAN_inf/MCM-48 composite, the temperature of the observed HCN signal indicated that carbonization was reduced from 550 to 450 °C by a Co catalyst. The amount of typical N₂ formation associated with the selective removal of pyridinic N species, resulting in the graphitic surface formation, also increased at a relatively high temperature (approximately 1000 °C) with the aid of the Co catalyst. The CMK-1 prepared through cobalt-catalyzed carbonization exhibited a higher electric double-layer capacitance with an Et₄N⁺BF₄^–/propylene carbonate electrolyte, and higher electrical conductivity than CMK-1 prepared without a catalyst. This also implied the progress of graphitization within the carbonaceous wall. These results suggest that the edge planes of the graphitic domains in CMK-1 are predominantly exposed on the surfaces of the carbonaceous walls, resulting in an increase in the number of adsorptive sites for the electrolyte during capacitance measurements.

Metal species supported on zeolites have proven efficient synergistic mechanisms against microorganisms, reducing the overall toxicity. Likewise, the deposition of metals by ultrasound is a method that has drawn attention due to its efficiency, low cost, and environmental friendliness. Hence, the antimicrobial properties of Zinc (Zn) species supported on LTA zeolite (NaA) via a sono-assisted method were explored in this study. Zeolite A modified with Zn species by ion exchange or sono-assisted precipitation of active Zn species (Zn(OH)₂, ZnO, and ZnO₂) was evaluated in a screening experiment by agar diffusion and micro broth assays. Finding that at a concentration of 30 mg/mL, drying the ZnO₂@NaA material activated a mechanism that inhibited the growth of E. faecalis by 100 % while eliminating the drying step, an inverse effect was produced, now inhibiting the growth of E. coli. This sample also presented promising properties as an antimycotic agent inhibiting the growth of C. albicans by 90 % at a concentration of 1 mg/mL. In addition, a viability analysis was performed on fibroblasts, demonstrating a potential toxicity reduction.

This ZnO₂@NaA material holds promise as an antibacterial and antifungal agent. Presenting a novel sono-assisted methodology for tuning the selectivity of inhibition mechanisms for peroxide-containing species in zeolites. This selected zinc-containing zeolitic material (ZnO₂@NaA) was then characterized by UV–Vis, FTIR, Raman spectroscopy SEM, XRD, and ζ-potential, evidencing the presence of ZnO₂ nanoparticles. This study opens perspectives for developing new antimicrobial Zn-containing zeolitic materials through a sono-assisted methodology for increasing selectivity in the inhibition mechanisms.

Electrocatalysis is essential for enhancing the energy conversion efficiency of zinc–air batteries. Nonetheless, the high cost and insufficient stability of electrocatalysts continue to hinder their commercial application. This study introduces a bifunctional composite electrocatalyst, NiCo–NG, consisting of Ni/Co bimetallic nanoparticles. The in situ integration of nanoscale graphene mitigates the agglomeration of Ni/Co metal atoms, resulting in a porous structure with a high specific surface area up to 244.6 m² g⁻¹. Notably, the NiCo–NG catalyst demonstrates enhanced conductivity, achieving an oxygen reduction reaction (ORR) half-wave potential of 0.793 V and a limiting current density of 7.64 mA cm⁻². This catalyst exhibits superior performance to commercial Pt/C electrodes, which exhibit a half-wave potential of 0.836 V and a limiting current density of 0.6 mA cm⁻². Moreover, the overpotential for the oxygen evolution reaction (OER) at a current density of 10 mA cm⁻² is only 306.3 mV. The introduction of Ni significantly augments the catalytic activity. Employing this dual-functional catalyst in rechargeable zinc–air batteries yields a maximum power density of 181.9 mW cm⁻² and a specific capacity of 804.2 mAh·g_Zn⁻¹. In addition, the fabricated battery demonstrates remarkable stability, enduring up to 3000 charge–discharge cycles. Ultimately, this research offers a novel electrocatalyst that could advance the commercialization of zinc–air batteries.

In this study, zeolite synthesized based on bentonite via the alkali fusion-hydrothermal method, and the effects of different synthesis parameters on the crystallinity and silicon-aluminum ratio of zeolite were investigated. The zeolite particles were modified by cationic surfactant and magnetized to prepare a MCTAB-BZ composite, which was then applied to the adsorption of diethyl phthalate (DEP) from aqueous solution. The effects of operating factors, including pH value, adsorption dosage, temperature, and adsorption time on the kinetic and isotherm adsorption behavior were studied. Highly crystalline ANA-zeolite can be prepared with the alkali content of 1:1, the aging time of 20 h, the aging water content of 1:15, and the crystallization time of 24 h. The results of the adsorption experiment show that the novel adsorbent-MCTAB-BZ composite shows the best adsorption capacity when the adsorption dosage is 6.25 g/L, temperature is 30 °C and adsorption time is 180 min at the original pH value of the aqueous solution. The adsorption results are presented well by the pseudo-second-order kinetic model and the Freundlich isotherm model.

In the face of an extensive literature on the use of zeolites for the removal of metals from water for environmental purposes, it is seldom considered that some metals are also essential nutrients for life and that zeolites could be profitably used to dose their release. Among these, Zn is a key micronutrient, and when its demand by crop is not fully balanced by adequate accessibility, fertilization must be provided using Zn salts that can be, however, easily leached and partly wasted in the environment.

In an attempt to solve this critical problem, a new controlled-release formulation of Zn using zeolite-containing geomaterials was designed, prepared, characterized, and tested by applying a sequential, multi-method approach. Different formulations were trialed, and the most effective included 30 wt% pumice by-product and 70 wt% clinoptilolite-rich zeolitized tuff, with about 20 mg/g of exchangeable Zn²⁺. The enrichment process reached equilibrium after about 8 h, a timing well-tuned with technology transfer. Desorption kinetic tests in a weekly acid environment revealed gradual Zn release, with about 4.28 wt% released after 6 h. When tested as a foliar fertilizer on Vitis vinifera, this formulation demonstrated superior resistance to leaching under simulated rainfall conditions compared to conventional ZnSO₄·6H₂O fertilizer, maintaining the initial level of Zn (130 mg/kg of dry leaves), while about 22 % of the Zn applied with ZnSO₄·6H₂O was loss. This outcome was plausibly due to mineral particle adhesion to leaf. Preliminary cost estimates suggest that the product designed here can be placed in the market with competitive sales prices.

In this study, an exploration of molecular interactions between CH₄, CO, CO₂, H₂O, N₂, NH₃, NO, NO₂, O₂, SO₂ gas molecules and B₁₂N₁₂(Zn) nanocage is conducted using advanced computational techniques, ωB97XD/Def2tzvp, unraveling fundamental behaviors. Employing global optimization methods and sophisticated tools like the bee colony algorithm in ABCluster software, the research offers insights into energy adsorption processes, confirming molecular stability through DFT calculations. The determination of electrophilicity index values through conceptual DFT analysis sheds light on relative reactivity levels and charge transfer phenomena, emphasizing that in some cases the nanocage's role as a potential electron acceptor. Natural bond analysis of charge transfer direction and valence shell orbital interactions enriches understanding, supported by comprehensive parameter compilation and critical point visualization. Further confirmation of interaction types and strengths through G(r)/V(r) ratios and ELF values enhances comprehension through quantum theory of atoms in molecule analysis. Ultimately, this study contributes significantly to computational chemistry, laying foundations for molecular design and engineering advancements. It sets the stage for future progress in materials science and catalysis, promising innovation in sustainable energy solutions and technological development.