Journal of The Chinese Chemical Society最新文献

A d¹⁰ Cu(I) two-dimensional (2D) metal–organic framework (MOF) with chemical formulas, {[Cd(L)(tcm)(H₂O)]⋅2H₂O}_n (1) (L = 1,3,5-tris(4-pyridylethynyl)benzene; tcm⁻¹ = tricyanomethanide) was synthesized and structurally characterized by single crystal X-ray diffraction method. In 1, the coordination geometry of Cu(I) ion is distorted tetrahedral coordinated to four N atoms from three L and one tcm⁻ ligands. A 2D puckered honeycomb-like layer is formed via the bridges of Cu(I) ions and L ligands with tris-monodentate coordination mode. Two 2D layers are mutually interpenetrated via the π–π stacking interaction between benzene ring of L ligand and pyridyl ring of neighboring L ligand to form a two-fold interpenetrated 2D net and then arranged orderly to construct its 3D supramolecular network. Thermal stability and in-situ temperature-dependent structural variations of 1 are performed by TG analysis associated with temperature-dependent PXRD measurement. The water vapor ad-/de-sorption isotherm and CO₂ adsorption isotherm of 1 are measured and discussed.

Using chemical activation techniques at dissimilar carbonization temperatures, activated carbon adsorbents were produced from Palmyra palm fruit biomass in this work. X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, laser Raman spectroscopy, scanning electron microscopy, CHNS-elemental analysis, and N₂ adsorption studies were among the characterization techniques used to assess the characteristics of the carbon adsorbents. The carbon adsorbents from Palmyra palm fruit were used to absorb CO₂ in a temperature range of 25–70°C. The findings of the characterization showed that these carbons have a large surface area and microporosity. The temperature of carbonization and the activating agent had an impact on the surface characteristics. The samples with the highest adsorption capacity, 4.70 mmol/g at 25°C, were the activated carbons made by treating them with KOH and then carbonizing them at 750°C. The physicochemical properties of the adsorbents provided an explanation for their high adsorption capacity. The adsorbents showed simple desorption and maintained constant activity during ten cycles of recycling.

The development of Cu-SSZ-13 represents a significant breakthrough in the field of NO_x removal from mobile exhaust, demonstrating excellent selective catalytic reduction (SCR) activity across a broad temperature range (200–500°C). However, the limited reactivity of Cu-SSZ-13 at temperatures below 200°C poses a challenge for the removal of NO_x emitted during vehicle cold starts. To stimulate new efforts to enhance low-temperature SCR performance, this review provides a fundamental understanding of the nature of Cu-SSZ-13 in catalyzing the SCR reaction. The structures, coordination environments, and oxidation states of Cu²⁺ during the SCR reaction, as well as the redox cycle pathway of Cu²⁺ ions and the characteristics of the rate-determining step, were discussed. Based on these insights, several strategies for improving the low-temperature activity of Cu-SSZ-13 are proposed. Finally, the review offers a perspective on the future of low-temperature SCR of NO_x over Cu-SSZ-13.

Focus of the figure: Spray pyrolysis being as a low-cost synthesis technique to prepare CuMnO₂ thin films that deliver the enhanced performance of the photoelectrocatalytic water splitting reaction. More details about this figure will be discussed by Dr. Ming-Hsi Chiang and his co-workers on pages 1203-1210 in this issue.

The sustainable and ecofriendly synthesis of transition metal oxide-based nanomaterials has always been a matter of concern. In this study, a bioinspired synthesis route was adopted to synthesize ZrO₂-Zr₃Er₄O₁₂-based mixed nanomaterial using leaf extract of medicinal plant Amaranthus viridis as reducing and stabilizing agent in replacement of the obnoxious chemicals which are a great threat to the sustainable environment. The synthesized material revealed the spherical shaped morphology through scanning electron microscopy, whereas crystal size of 15.7 nm was observed through Xray-diffraction, and band gap value of 2.7 eV was acquired using Tauc plot. Newly synthesized ZrO₂-Zr₃Er₄O₁₂ nanocomposite was then investigated for its role as electrocatalyst in a generation of energy through the hydrogen evolution reaction and oxygen evolution reaction. The ZrO₂-Zr₃Er₄O₁₂-based electrocatalyst showed better potential for hydrogen evolution reaction measurements with the overpotential value of 242 mV. Furthermore, the notable capacitance value of 495.6 F/g was obtained through cyclic voltammetry for energy storage studies. The cyclic stability was also analyzed using linear sweep voltammetry and results showed promising stability for 2000 cycles. Consequently, the green and economical synthesis route as well as promising electrochemical behavior of ZrO₂-Zr₃Er₄O₁₂-based electrode make it feasible choice for large scale application.

In order to study the catalytic activity of beta cyclodextrin-encapsulated zinc oxide (ZnO) nanoparticles in microbial oil synthesis, rice-washed waste water (RWW) was used as the fermentation medium and streptomyces fradiae as the microbe. The introduction of zinc oxide nanoparticles during fermentation had an impact on output and growth. The biomass percentage was 1.5 times greater and the fatty acid profile was better than in the control samples. The analysis of the induction period (IP) revealed that samples containing zinc oxide nanoparticles had maximum oxidation stability for up to 120 days of storage, along with a considerable reduction in autoxidation. The cetane number and calorific value, however, increased with the addition of ZnO nanoparticles. A new study discovered that the use of ZnO nanoparticles encapsulated in β-CD led to much increased production (63.5 g/L) of microbial oil than the control sample (42.5 g/L). Therefore, it is anticipated that these nanoparticles would find utility in energy-related applications.

Electronic and thermoelectric properties of the full-Heusler materials Co₂CrGe, Co₂FeGe, and Co₂NiGa are studied, using first-principles full potential linearized augmented plane waves method. To treat the exchange correlation, Generalized Gradient Approximation parameterized by PBE-sol with the inclusion of spin polarization is used. The frequency fluctuation order is continual at 300 K after heating to 3 ps with very small distraction in the atomic structure conforming the structure stability of the studied structures. Also inclusion of spin-orbit coupling effect on density of states undermines significant change in peaks specially d-states in the materials and caused a degeneracy. Band structure analysis clarified that states crossing the Fermi level have the importance for enhancing the thermoelectric properties of the materials. The topology of the states indicates a gap at the bulk level, which is the unique character of the heavy elements in the materials Co₂CrGe, Co₂FeGe, and Co₂NiGa. Thermoelectric properties are calculated for a temperature of 300 K using semi-classical Boltzmann's theory implemented in BoltzTraP code. In these calculations, it is found that these materials favor electron doping with having maximum values of ZT in the n-type region.

In the current research, the rare earth-doped magnesium aluminate (MgAl₂O₄:Eu³⁺) spinels were produced by the combustion synthesis method. The employment of thermodynamic calculations revealed that the combustion approach is a proper way to synthesize MgAl₂O₄:Eu³⁺ material by urea fuel, although this procedure was fulfilled at 500°C, the final temperature will be around 2030°C. The x-ray and FT-IR spectra confirmed the successful formation of spinels, while it was shown that the calcination procedure results in a significant increase of crystallinity. On the other hand, it was interestingly seen that the addition of large amounts of Eu³⁺dopant (10 wt%) suppresses the crystallinity. The MAUD calculations interestingly revealed that the increase of Eu³⁺ dopant from 1 to 10 wt% leads to the increase of MgO and Al₂O₃ impurities. The related microstructural evaluations revealed that the particle size of the synthesized powders is mostly less than 40 nm which shows the superiority of combustion synthesis over other commercial methods. Also, the broadening of XRD peaks confirmed the formation of nano-sized powder. The photoluminescence (PL) characterizations showed that doping of MgAl₂O₄ with 7 wt% Eu³⁺ brings the most intensive emission properties at the wavelengths of 592 and 617 nm.