Journal of Solid State Chemistry最新文献

The photosensitive building blocks of photochromic MOFs are mostly 4,4′-bipyridine. However, the linear structure and kind of 4,4′-bipyridine derivatives limit the development of its properties and applications. Therefore, a “Y"-shaped 2,4,6-tri (4-pyridyl)-1,3,5-triazine derivative ([H₃p-Batpt]Cl₃, TPT) with high conjugation, bare nitrogen and oxygen sites that was selected as a novel photosensitive ligand to replace the traditional 4,4′-bipyridine ligand for photochromic MOFs. Then, [H₃p-Batpt]Cl₃ was combined with Eu^III and terephthalic acid (H₂TPA) to construct a multifunctional Eu-MOF [Eu₂ (p-Batpt) (TPA)₃(H₂O)]n (1). 1 possess degradation of tetracycline (TC), photochromic and photoluminescence properties. The colored 1 (1P) after irradiation with UV–vis light (300 W, Xe-lamp) is difficult to fade due to donor-acceptor (D-A) π-π and radical-π interactions. In addition, 1 is used in photocatalysis because it is an excellent N-type semiconductor. The TC degradation rate of 1 can reach 67.42 % under visible light and be recycled six times. Interestingly, the TC degradation rate of 1P was 6.78 % higher than that of 1. Electrochemical tests show that 1P has higher charge separation efficiency and a smaller band gap. The free radicals capture and ESR experiments of 1 revealed that holes (h⁺) played a leading role in the photocatalytic degradation of TC. This research expands the application of photochromic MOFs and provides a reference for removing organic pollutants.

Two new isostructural lanthanide(III)−metal organic frameworks (Ln-MOFs), namely [Ln₂(FDA)₃(TMS)₂(H₂O)₂]·H₂O (Ln = Eu 1 and Tb 2, H₂FDA = 2,5-furandicarboxylic acid, TMS = tetramethylene sulfone), have been synthesized and characterized. Single-crystal X-ray diffraction analysis reveals that both Ln-MOFs exhibit three-dimensional structures crystallizing in the monoclinic C2/c space group. Luminescent sensing studies indicate that 1 and 2 possess commendable capabilities for detecting Fe³⁺ and Cr³⁺, with low detection limits of 20.00 nM and 43.41 nM for 1 and 66.10 nM and 0.37 μM for 2, respectively. Furthermore, the investigation into the mechanism revealed the quenching of Fe³⁺ can be ascribed to the dual effects of inner filter effect (IFE) and the static quenching. Conversely, the dynamic quenching mechanism has played a predominant role during the sensing process of Cr³⁺.

The solvent-free method fabrication of zeolites represents an eco-friendly approach, which a highly attractive field of scientific research. A novel method for synthesis of micron-sized silicalite-1 zeolite under fluoride-free and solvent-free conditions has been developed. Characterization of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunner-Emmett-Teller (BET) surface area were used to analyze the properties and structure of the silicalite-1 zeolite. The effects of mineralizers, organic structuring direct agents, catalyst, and crystallization time on the synthesized silicalite-1 zeolite are investigated. Silicalite-1 zeolite has microporous and mesoporous structures with a BET surface area of 350.4 m²/g. The synthesis mechanism of micron-sized silicalite-1 zeolite has been proposed, revealing that the intermediate sodium silicate dry gel is crucial for the formation of zeolite.

In this work, bismuth tungstate (Bi₂WO₆) films enriched with oxygen vacancies were fabricated via the hydrogen treatment with an excellent catalytic activity. The photocurrent density of Bi₂WO₆ H-15 is 0.18 mA/cm² at 1.23 V (vs. RHE), which is 11.25 times higher than that of pure Bi₂WO₆. The introduction of oxygen vacancy not only increases the charge concentration, facilitates the charge transport, promotes the water absorption ability, but also extends the light absorption of Bi₂WO₆. The density of states (DOS) calculated by the density functional theory (DFT) showed that a new defect level was formed and increased DOS at the valance band maximum (VBM). This work manifests the effective use of oxygen vacancies in regulating carriers transport, which is of great significance for the PEC oxygen evolution reaction.

Heavy metal and dye pollution pose a serious threat to human health and ecology, and there is an urgent need to develop novel adsorbent materials for wastewater treatment. In this study, a novel functionalized zirconium-based MOF UiO-66-Gd was prepared by a post-synthetic modification strategy and used for the simultaneous removal of Pb²⁺, Cu²⁺ and methylene blue (MB) from wastewater. UiO-66-Gd retained the crystalline structure and morphological features before modification. The specific surface area reached 574.94 m²/g, which can provide abundant active sites for adsorption. The effects of several factors on the adsorptive performance of UiO-66-Gd were investigated by batch adsorption experiments. The adsorption of Pb²⁺ by UiO-66-Gd reached the adsorption equilibrium in only 5 min. The theoretical maximum adsorption capacities for Pb²⁺, Cu²⁺ and MB were 833.33, 354.61 and 564.91 mg/g, respectively. In addition, UiO-66-Gd has excellent anti-interference and regeneration properties with potential for practical applications. Competition adsorption experiments showed that UiO-66-Gd had the greatest affinity for Pb²⁺. The adsorption of UiO-66-Gd on Pb²⁺ and Cu²⁺ was mainly through electrostatic interactions and chelation, and on MB mainly through electrostatic interactions, π-π interactions and hydrogen bonding. Overall, UiO-66-Gd has great potential for application in the removal of Pb²⁺, Cu²⁺ and MB.

The proton conductivity (σ) of the highly stable metal-organic frameworks (MOFs) built by carboxylic acid ligand and aluminum metal has not been fully investigated. Herein, a three-dimensional aluminum-based MOF, [(AlOH)₂TCPP]_n (namely Al-TCPP) with exceptional structural stability was solvothermally synthesized using an organic multifunctional bridging ligand, meso-tetra(4-carboxyphenyl)porphine (H₄TCPP) with a large stiff ring structure and Al(NO₃)₃⋅9H₂O as raw materials. The dependency of σ on temperature and relative humidity (RH) was surveyed using the AC impedance test after the MOF's thermal, water, and chemical stabilities, as well as nitrogen and H₂O vapor adsorptions, were all characterized. Experimental results demonstrated that this highly stable MOF with a high specific surface area exhibited impressive proton conductivity, with an optimal σ of 3.2 × 10⁻⁴ S/cm under 100 °C/98 % RH. Furthermore, the proton-conducting mechanism inside the framework was highlighted using computed activation energy and structural analysis. This study provides new inspiration for designing and searching for high-performance proton-conductive materials.

In this work, an ultraviolet light-driven YPrO₃ photocatalyst was successfully synthesized via the sol-gel method, utilizing yttrium nitrate hexahydrate (Y(NO₃)₃·6H₂O) and praseodymium nitrate hexahydrate (Pr(NO₃)₃·6H₂O) as the yttrium and praseodymium sources, respectively, with oxalic acid dihydrate (H₂C₂O₄·2H₂O) serving as an auxiliary solvent. In addition, the prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy(XPS), thermogravimetric and differential scanning calorimetry (TG-DSC), ultraviolet visible diffuse reflectance spectroscopy (UV VisDRS), and an electrochemical workstation. Also, the photocatalytic activity of YPrO₃ samples was explored by using methyl orange (MO) solutionas a model pollutant to simulate wastewater under varying synthesis temperatures and illumination durations. The material with the highest degradation efficiency was subjected to cycling and recovery experiments to assess its stability. Furthermore, the photocatalytic mechanism of YPrO₃ was investigated. Experimental results revealed that pure YPrO₃ samples could be effectively synthesized at calcination temperatures ranging from 850 °C to 1000 °C, with the sample prepared at 900 °C exhibiting the optimal photocatalytic activity. This sample possessed an average grain size of 4–5 μm. Under UV light irradiation for 90min, the YPrO₃ sampleprepared at 900°Cachieved approximately 80 % degradation of methyl orange at an initial concentration of 5 mg/L. After five consecutive cycles, the degradation rate remained as high as 70.39 %, with no change in the crystal structure, indicating excellent stability. The photocatalytic mechanism of YPrO₃ was found to involve the synergetic effect of superoxide radicals and photogenerated holes in degrading pollutants. In conclusion, YPrO₃could be a promising photocatalyst with excellent performance, holding broad application prospects.

In this work, we propose a computational and experimental approach to systematically select pyridine-based ionic liquids (IL) and examine their impact on the pore structure of CH₄/N₂ adsorption materials. Our objective is to design novel MIL-53(Al)@IL composites, with MIL-53(Al) as the parent metal organic framework (MOF), for efficient CH₄/N₂ separation. The optimal addition of pyridine-based ionic liquids resulted in the MIL-53(Al)@BH-3 (N-butylpyridinium hydrogen sulfate abbreviated as BH-3) composite, which features an ultramicropore structure and a large specific surface area of 1204 cm² g⁻¹. The MIL-53(Al)@BH-3 composite achieved a high CH₄ capacity of 28.21 cm³(STP) g⁻¹ and a selectivity of 7.7 at 298K and 1 bar in pure-component equilibrium adsorption. In breakthrough experiments, CH₄ breakthrough occurred significantly later than N₂ (approximately 2 min). Therefore, the strategy of manufacturing porous MIL-53(Al)@BH-3 composites effectively enhances the overall adsorption performance for CH₄/N₂ separation.

The present study investigates the structure stability, electronic structures, and optical properties of Zintl compounds CsZn4P₃ and CsZn₄As₃ by first-principles calculations. An assessment of the phonon dispersion curves and elastic constants indicate both dynamic and mechanical stability for the both compounds. By employing the HSE06 hybrid functional, both compounds display direct bandgap with widths of 0.93 eV for CsZn₄P₃ and 0.66 eV for CsZn₄As₃. Furthermore, an analysis of the dielectric constant, refractive index, extinction coefficient, and energy loss as functions of photon energy is conducted to study the optical properties. Based on the semi-classical Boltzmann transport theory and the Slack's equation, a large Seebeck coefficient and minimum lattice thermal conductivity are obtained for CsZn₄As₃, which result in a figure of merit value of 0.79 at 700 K. These findings underscore the potential of CsZn₄As₃ as a promising candidate for future research and development in the realm of thermoelectric materials.