Journal of Saudi Chemical Society最新文献

An exceptional method of incorporating Sn ions into Zinc Oxide (ZnO) using a tandem system of Pulsed Laser Deposition (PLD) and Radio-Frequency Magnetron Sputtering (RFMS) to synthesize and functionalize ZnO nanostructures is demonstrated in this study for gas-sensing application. The RFMS power was varied up to 50 W to sputter a pure Sn metal target, while simultaneously or successively growing ZnO nanostructures on a templated MgO < 0001 > substrate and on an Au-plated Al₂O₃ gas sensor, via PLD process at the substrate temperature of 700 °C in 100–500 millitorr oxygen/argon gas background. The morphologies of the grown Sn-ZnO nanostructures were characterized by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and X-ray Diffraction (XRD), and while their chemical/oxidation states and optical properties were analyzed by X-ray photospectroscopy (XPS) and photoluminescence (PL), respectively. For simultaneous deposition, the resulting (0002)-dominated 2D grain-like ZnO nanostructures were influenced by the interaction of the dynamic PLD plasma with static RFMS plasma at different powers. For successive growth, at 50 W-RF power, a remarkable increase in the sensor response to 50-ppm carbon monoxide (CO) gas was observed at 250 °C, which could be attributed to the creation of more adsorption sites in the Sn-ZnO depletion region caused by the replacement of some Zn sites with Sn ions in the ZnO matrix. This study, therefore, exhibits the viability of this hybrid system to design, synthesize, and functionalize Sn-ZnO nanomaterials, either by simultaneous/successive deposition, for gas-sensing applications.

Antibiotic contamination is a global environmental problem. The emerging contaminant norfloxacin (NOR) may increase the risk of drug resistance and thereby harm human health. The practical application of metal–organic framework crystals is usually limited by their powder form and difficulty in recovery. In this study, a magnetic Co-MPS-800 composite was prepared from carbonization with ZIF-67@pine sawdust, and significantly raised the NOR removing ability from wastewater. The changes in functional group composition, elemental contents, morphology, thermal stability and adsorption mechanism of the magnetic Co-MPS-800 composite were interpreted using FT-IR, XRD, SEM, BET, TGA and XPS. The Co-MPS-800 has an isoelectric point of 9.15 and a large specific surface area (174.58 m²·g⁻¹). The impacts of pH, contact time, temperature and dosage on the performance of Co-MPS-800 were also studied. The adsorption capacity over NOR reached 221.98 mg·g⁻¹ at 303 K, pH=6.0. The NOR adsorption is best suited a pseudo-2nd-order kinetic model and the Freundlich isotherm. Co-MPS-800 also had excellent reusability, and the removal rate reached 82.94 % after four repeated uses. Therefore, the magnetic Co-MPS-800 composite is effective in removing NOR from aqueous solutions. Altogether, this functional MOF-derived porous carbon may serve as a promising pollutant biosorbent, and its preparation strategy may provide insights for future studies.

Sulfamethoxazole (SMX) is an extensively applied antibacterial drug, and it is also a pollutant that poses a serious threat to human and ecosystem health. In this research, a 3D hierarchical hollow ball-flower structure catalyst (CoAl-LDHs@CoS_x-rGO) was tailored for the first time to efficiently degrade SMX via visible light coupling PMS activation. A series of characterizations confirm that the target catalyst is successfully prepared and the optimized 0.1CoAl-LDHs@CoS_x-rGO sample possesses superior specific surface area of 306.0 m²/g, and significantly higher photocurrent response and lower electrochemical impedance. More importantly, 0.5 g/L of the sample can degrade 98.59 % of SMX within 50 min via visible light coupling PMS activation, and after 7 degradation cycles, the degradation rate only decreased by 8.49 %. A series of parameters that affect degradation rate have been optimized in detail. Capture experiments and ESR indicate that e⁻, •OH and SO₄^•− make major contributions to degradation, and visible light coupling PMS activation generates stronger signals than alone visible-light or PMS system. LC-MS, TEST toxicity assessment and theoretical calculation were conducted to elucidate degradation route and intermediate toxicity. The research provides a new approach to design catalysts with highly exposed activity sites for efficiently removing SMX from environmental water.

The Cr/Al₂O₃ catalyst, a prevalent system in commercial applications, plays a significant role in propane dehydrogenation (PDH). Notable improvements in this catalyst’s efficiency are essential for its continued use. In order to examine the effect of alkaline earth metals on the catalyst performances in the propane dehydrogenation reaction, a series of Cr/η-Al₂O₃ were synthesized by the impregnation method. The synthesized catalysts were designated as Cr-T/η-Al₂O₃, where T represents Ca, Mg, Sr, and Ba. The supports and the catalysts were studied using the following techniques: XRD, N₂ adsorption–desorption, temperature-programmed desorption and reduction, UV–Vis and Raman spectroscopy, and XPS analyses. The findings reveal that the Cr-Ba/η-Al₂O₃ catalyst exhibits better catalytic performance, with significantly higher propane conversion and propylene selectivity (with initial values of 66 % and 86.2 %, respectively) compared to other catalysts. The enhanced performance is attributed to the increased dispersion of Cr species, stabilization of Cr⁶⁺ species, and reducing the total amount of acid sites and strong acid sites, which are crucial for maintaining active sites and minimizing coke deposition. The Ba-modified catalyst also demonstrated excellent stability, with a lower deactivation rate (Ba(0.201 h⁻¹) < Sr(0.213 h⁻¹) < Ca(0.270 h⁻¹) < Mg(0.310 h⁻¹) < parent(0.338 h⁻¹)) and robust regenerative capacity over multiple cycles.

Sulfonated poly (ether ether ketone) (SPEEK) ion exchange membranes for VRFB are promising alternatives to Nafion, but require improved mechanical and chemical stability for long-term operation. Here, we have fabricated composite membranes using SPEEK as proton conductive medium and TiO₂ nanopapers as reinforcing framework to improve the mechanical and chemical stabilities of SPEEK membranes. The SPEEK/TiO₂ nanopaper composite membranes exhibited almost twice the tensile strength and only one-third the vanadium ion permeability compared to pristine SPEEK (DS=60 %). Due to the excellent cell performance such as high EE, slow capacity degradation and long-term lifetime, these high durable composite membranes could be found their potential use as ion exchange membranes for commercial VRFBs.