Oxide Composites Research Articles

Influence of water vapor partial pressure on self-healing and oxidation of SiC-dispersed yttrium silicate composites

The self-healing and oxidation behavior of SiC-dispersed Y2Si2O7-Y2SiO5 composites were elucidated under various water vapor partial pressures PH2O. Samples were exposed in a furnace for self-healing experiments at 1100–1300°C and for high-temperature oxidation at 1200–1400°C, both for 1–24 h, under PH2O ranging from 2×104 to 5×104 Pa, while keeping PO2constant at 2×104 Pa. Water vapor promoted the self-healing effectiveness of the composites. A mechanism contributing to the closure of surface cracks was consistent with volume expansion derived from the oxidative conversion of SiC into SiO2 and the outward diffusion of yttrium cations. The formation of the internally oxidized zone signifies oxidation behavior, resulting from the inward diffusion of oxygen ions. Growth of the internally oxidized zone obeys the parabolic pattern. The influence of PH2O on the high-temperature oxidation of SiC/Y2Si2O7-Y2SiO5 is discussed in this study.

Excellent antibiotic degradation through PMS activation via bio derived Fe-Mn oxides with tunable defect concentration: Synergy between singlet oxygen oxidation and electron transfer

Regulating the defect sites and structural composition of metal-based metal catalysts is an effective strategy to improve the activity of activating PMS to degrade pollutants. Herein, bio derived Fe/Mn composite oxides (BFMO) rich in oxygen vacancy composed of crystalline manganese oxide coated with amorphous iron oxide was prepared through microbial mediation, and used for PMS activation in the degradation of tetracycline (TC). After 60 minutes reaction, the removal rate of TC achieved 92.4 %−98.8 % within wide pH range of 3–12. Besides, this system has outstanding anti-interference ability to common ions and humic acid (HA). The outstanding catalytic performance stemmed from the non-radical pathway for producing singlet oxygen (1O2) and electron transfer, facilitated by defect-rich polyvalent Mn and amorphous Fe species. Polyvalent Mn species accelerate the electron transfer process, and its surface defect structure further promotes the adsorption of pollutants on the surface of the materials. The redox cycle of Fe3+/Fe2+ was accelerate via electron-rich groups. This study explored the synergy triggered by microbe-mediated defect sites and structure-dependent, providing a design strategy for environmental remediation of PMS activated by Fe/Mn based bimetallic catalysts with strong resistance to environmental interference.

Construction of Magnetically Retrievable g-C3N4/CeO2-Fe3O4-Reduced Graphene Oxide Composites With Enhanced Visible-Light Photocatalytic Activity And Antibacterial Properties

Construction of Magnetically Retrievable g-C3N4/CeO2-Fe3O4-Reduced Graphene Oxide Composites With Enhanced Visible-Light Photocatalytic Activity And Antibacterial Properties

CaO composite improves the conversion efficiency of free radicals in the catalytic activation of permonsulfate by Cu-based oxides

The advanced oxidation technology based on persulfate has excellent performance in the efficient removal of refractory organic pollutants in water bodies, among which the heterogeneous catalytic activation system has been studied extensively due to its characteristics of convenient operation, low energy consumption, and no secondary pollution. Many studies have been focused on improving the overall oxidation efficiency of target substrates in heterogeneous catalytic oxidation systems. Herein, a series of bimetallic composite oxides (CaOMOx) (M = Cu, Fe, Ni, etc.) were prepared by combining inert metal oxides—CaO with various transition metal oxides, and were used for permonosulfate (PMS) activation. Among them, the introduction of CaO has the most obvious effect on the catalytic efficiency of CaOCuO/PMS system. Almost 100 % of benzothiazole (BTH) was degraded within 40 min at 0.3 g/L PMS and 0.15 g/L CaOCuO. The mechanism study showed that the introduction of CaO significantly increased the content of oxygen vacancies (OVs) on CaOCuO, and thus promoted the formation of surface hydroxyl groups to strengthen the adsorption capacity for PMS. In addition, the introduction of CaO enhanced the reducibility of Cu species and thus promoted the transformation of Cu2+ to Cu+, ensured the continuous and rapid generation of SO4•-, thereby promoting the improvement of oxidation efficiency. Our study provides a novel strategy for improving the conversion efficiency of free radical in heterogeneous persulfate catalytic oxidation systems.

Characterization and evaluation of gold mill tailings as an additive in cement-stabilized products

Abstract Gold mill tailings (GMT) are waste from gold mill processing plants usually collected and stored in tailings storage facilities (TSF) and left for years in many abandoned mines in the world. GMT is in large amounts and contains high concentrations of chemicals and compounds that may harm human lives and the ecosystem if not well-maintained. A characterization study is conducted on GMT from a small-scale mill processing plant in Agusan del Sur, Philippines, and its potential utilization as an additive to sand and cement in making cement-stabilized products is also evaluated. The elemental and oxide composition, the presence of free and total cyanide, and particle size analysis were determined. Different proportions of gold mill tailings, cement, and sand were prepared and tested for compressive strength and water absorption. The results showed that the GMT contained some potentially valuable elements like tin, zinc, and europium. GMT also contains potentially hazardous elements like lead (663ppm), arsenic (157ppm), and mercury (17ppm). The free cyanide in the effluent is also found at 1.9 ppm. These elements and compounds are potentially hazardous in case of tailings seepage or overflow to groundwater and neighboring agricultural lands. The evaluation of cement-stabilized samples shows that the GMT from the study area can be utilized as an additive to cement and sand in the production of cement-stabilized products however it must be properly treated and handled to ensure the safety of workers. The TCLP result showed that the product is non-toxic and non-reactive. The construction and proper maintenance of a TSF for small-scale gold milling plants in the study area is recommended to prevent environmental, health, and safety risks.

Efficient visible-light-driven photocatalytic degradation of indoor formaldehyde using an indium-based MOF/graphene oxide composite

Formaldehyde (HCHO) severely degrades indoor air quality, and conventional remediation methods are often inadequate for addressing low concentrations of HCHO indoors. In this study, we synthesized a MIL-68(In)-NH2/graphene oxide (GO) composite using a solvothermal method, aimed specifically at enhancing the photocatalytic degradation of HCHO under visible light. Our results show that the integration of GO enhances visible light absorption and facilitates efficient electron transport, significantly improving photocatalytic performance. The MIL-68(In)-NH2/GO composite achieves a 77 % degradation rate of HCHO, significantly outperforming MIL-68(In)-NH2 (51 %) and GO (22 %) alone. This enhanced activity is attributed to the effective separation of electron-hole pairs and synergistic interactions within the composite. We proposed an enhanced photocatalytic mechanism for the MIL-68(In)-NH2/GO system, identifying h+ and •O2– as the principal active species. Moreover, the MIL-68(In)-NH2/GO composite shows excellent reusability and stability, making it a promising candidate for eco-friendly and efficient indoor air purification using metal–organic frameworks.

One step synthesis of carboxymethyl cellulose/graphene oxide composites for removal of copper ion from aqueous solution

Excessive heavy metal ions in the environment often have an impact on plant growth and human health. In this study, carboxymethyl cellulose/graphene oxide composites (CMC/GO) were prepared by a simple solution blending evaporation method to remove copper ions. The structure of CMC/GO was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Scanning electron microscope, Brunauer–Emmett–Teller and X-rayphotoelectron spectroscopy. The results showed that the maximum adsorption capacity of the adsorbent CMC/GO reached 26.05 mg/g, when the pH of the solution was 5, the initial concentration of copper ions was 80 mg/L, and the dosage of the adsorbent was 0.4 g. The adsorption of copper ions onto CMC/GO is validated by the pseudo-second-order kinetics model (R = 0.99949), and the adsorption isotherm data was fitted well with the Langmuir isotherm (R = 0.9990). Thermodynamic data showed that the adsorption process of copper ions by composite CMC/GO is a spontaneous endothermic reaction (ΔG < 0, ΔH > 0). Moreover, the adsorbent showed better recyclability and the adsorption efficiency can still reach 85.0 % after 5 adsorption-desorption cycles.

Synergy of reduced graphene oxide composites with cerium doped lanthanum ferrite for high frequency (12.4–18 GHz) electromagnetic shielding application

In this paper, electromagnetic shielding properties of reduced graphene oxide (RGO) composites with cerium-doped lanthanum ferrite, La0.9Ce0.1FeO3 (LCFO), are studied. The synthesis procedure adopted is incipient wetness impregnation with SBA-15 as a template for LCFO and modified Hummer's method for graphene oxide (GO). The composites are synthesized by in-situ reduction of GO in the presence of LCFO, which acts as a magnetic filler in the weight ratios 1:0, 1:1, 2:1, 3:1 and 1:2 of LCFO and GO. X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM) and nitrogen absorption/desorption isotherm are used to investigate the structural properties. Vector network analyzer (VNA) is used to ascertain the shielding and dielectric properties. The La0.9Ce0.1FeO3-reduced graphene oxide (LCFG31) composite shows appreciable electrical conductivity of 81.43 S/m and an effective BET surface area value of 23.93 m2g-1. It attenuates >99.99 % of electromagnetic waves, and a shielding effectiveness (SE) value of 41.82 dB at a thickness of 2.36 mm in the Ku frequency band (12.4–18 GHz) has been achieved. The heterogeneous interfaces in the composite structure result in orientational and space charge polarization. The inclusion of magnetic ferrite as filler in composite incurs eddy current loss and magnetic losses. All these factors collectively make the composite material a good choice for electromagnetic shielding which can be further used for commercial applications.

Tuning the morphology and surface structure of MnOx@GF through Ce for high-efficiency degradation of Rhodamine B by electro-Fenton

Widespread and ineffective dye treatment in aquatic environment leads to serious pollution problems, threatening ecology and human health. Herein, manganese cerium bimetallic oxide cathode material (MnCeOx@GF) was prepared by hydrothermal method combined with calcination, and the electrochemical Fenton degradation performance of a typical dye Rhodamine B (Rh B) was investigated. The results show that the degradation of Rh B by MnCeOx@GF can reach 96.5 % within 2 h in acidic environment and continue to perform effectively after 4 repeated experiments. Combined with SEM and electrochemical test results, it can be seen that the bimetallic composite oxides formed by manganese and cerium on the surface of the support can effectively enhance the catalytic activity of the material, the addition of cerium changes the morphology of manganese oxides and promotes the generation of multiple valence composite oxides of transition metals, and improves the degradation of Rh B. Based on the free radical masking experiments, hydroxyl radical (·OH) is the main active substance in the electro-Fenton degradation process. This work not only provides a way to design and manufacture cathode materials for in situ electrosynthesis of H2O2, but also provides an important reference for improving the reusability of cathodes for sustainable dye wastewater treatment.

Study on Cycle Performance and Rate Performance of Lithium Cobalt Oxide

Lithium cobalt oxide (LiCoO2 ) cathode material, with its high energy density and operating voltage, is currently a mainstream material for lithium-ion battery cathodes. &amp;nbsp;&amp;nbsp;However, &amp;nbsp;the &amp;nbsp;crystal &amp;nbsp;structure &amp;nbsp;collapse &amp;nbsp;and &amp;nbsp;lattice &amp;nbsp;oxygen &amp;nbsp;evolution under high-voltage conditions lead to rapid capacity decay, severely limiting its practical applications. &amp;nbsp;&amp;nbsp;This paper &amp;nbsp;analyzes the main factors affecting the cycle performance and rate performance of lithium cobalt oxide, considering the physic- ochemical properties of the particles, including elemental content and particle size, and provides a mathematical model linking these properties to electrochemical per- formance. &amp;nbsp;The study offers insights for the practical production of high-voltage lithium cobalt oxide materials. At the beginning, we embarked on investigating the correlation between the physicochemical attributes (encompassing elemental composition and particle size) of lithium cobalt oxide and its cycle performance. An Ordinary Least Squares (OLS) linear regression model was formulated, yielding a robust fit with an R-Squared value of 0.94. This model was subsequently optimized through the application of an XGBoost algorithm, achieving an R-Squared value nearing unity, signifying a remarkable enhancement in model accuracy. Visual analysis of the results pinpointed the primary determinants of cycle performance, arranged in descending order of significance: 'Cycle Index,' Mg content, particle size distribution (D10), Zn, and Al. Then, our attention shifted to examining the link between the aforementioned physicochemical characteristics and the rate performance of lithium cobalt oxide. The Jarque-Bera and Shapiro-Wilk tests confirmed the normality of the data, fulfilling the prerequisites for hypothesis testing. An OLS linear regression model was developed, demonstrating a strong goodness-of-fit with an R-Squared value exceeding 0.8. This model was further honed with an XGBoost model, which achieved an R-Squared score approaching 1, indicating a substantial refinement in model precision. The visualization of model outcomes illuminated the key factors influencing rate performance, ranked in descending order of importance: particle size distribution (D50), Al, Mn, Zn, Mg, Ni, and Fe. Lastly, we devised an optimal strategy that encompasses the incorporation of strategic doping elements, the utilization of high-temperature sol-gel methods to bolster cycle performance, and coating modifications aimed at enhancing rate performance. This holistic approach fosters the structural stability of lithium cobalt oxide crystals, fortifying their high-potential cycle capabilities, and concurrently elevating their rate performance.

An ultra-durable ZIT glass-ceramic composite for immobilization of radioactive mixed lanthanide oxides

Zinc Titanate (ZIT) glass-ceramic composite is a potential candidate waste form for immobilizing radioactive lanthanide oxides due to its relatively high lanthanide embedding capacity and low reaction temperature. However, the composition of lanthanide oxides after electrolytic refining is very complex and the immobilization mechanism of lanthanide oxides by ZIT composite is not clear. Herein, we prepared ZIT-PrEu glass-ceramic waste forms by a solid-phase sintering method at 1200 °C for 4 h using mixed lanthanide oxides of Pr6O11 and Eu2O3 simulated as radioactive waste. The XRD and SEM results show that different mixed lanthanide oxide ratios have very little effect on the composition and microstructure of ZIT-PrEu waste forms with different waste embedding rates. With the increase of waste embedding rate, the density of the ZIT-PrEu glass-ceramic waste forms with different mixed lanthanide oxide ratios first increases and then decreases. When the embedding rate increases to 25 wt.%, the density of ZIT-PrEu waste forms with different mixed lanthanide oxide ratios reaches a maximum. The ZIT-PrEu glass-ceramic waste forms embedded with 25 wt.% waste exhibit excellent chemical durability, and the leaching rates of Pr ion and Eu ion are only 10-6 - 10-7 g·m-2·d-1 after 28 days at 90 °C. Moreover, the phase evolution of the ZIT composites immobilizing lanthanide oxides at different temperatures is revealed by XRD and FT-IR measurements. The lanthanides (Ln) are mainly present in the form of LnPO4 monazite phases.

Enhancing microbial fuel cell performance with free-standing three-dimensional N-doped porous carbon anodes

Microbial fuel cells (MFCs) utilize microorganisms as catalysts to transform the chemical energy to electrical power. However, the practical application of MFCs is currently impeded by low power output, which is caused by insufficient microbial colonization on the anode, slow extracellular electron transfer at the microbe-anode interface, and low oxygen reduction reaction catalytic efficiency at the cathode. Herein, a three-dimensional (3D) hierarchical porous anode of Carbonization-CTS-MF/rGOtempreture (CCMF/rGOT) by pyrolyzing crosslinked composite of melamine formaldehyde resin (MF), chitosan (CTS) and graphene oxide (GO). The macroporous anode provides a biocompatible surface for exoelectrogens and 3D electron transfer pathways. In addition, an appropriate balance of graphitic-N and pyrrolic-N content optimizes both conductivity and the number of active sites, thereby synergistically enhancing extracellular electron transfer (EET) efficiency. Therefore, the power density of CCMF/rGO1000 anode is 11.28 W/m3, which surpasses the CCMF1000 anode without 3D reduced graphene oxide (rGO) conductive network (10.04 W/m3), and traditional carbon cloth anode (4.36 W/m3). Moreover, the anode runs stably for more than 200 days with a maximum operating voltage of 0.69 V, which achieves chemical oxygen demand (COD) removal rate of 95.4 %. This work provides a promising strategy to prepare a free-standing 3D anode with enriched exoelectrogens and enhanced EET to improve the MFCs performance.

Integrating recognition peptide into a nanozyme to mimic uricase binding pocket as a multifunctional nanoplatform for highly selective uric acid recognition, sensing and degrading

Nanozyme based colorimetric sensor for physiological biomarkers detection is becoming an increasingly influential technology in diagnosis, but the selective discrimination of biomarkers using single nanozyme without natural enzyme is greatly challenging. Here, a colorimetric detection platform for biomarker is successfully constructed by integrating recognition peptide (RGPT) into a nanozyme to mimic the binding pocket in natural enzyme. Firstly, RGPT-ultrafine palladium nanoparticles (PdNPs)@reduced graphene oxide (rGO) composite was facilely prepared using an arginine-rich RGPT. RGPT-PdNP@rGO composite displays outstanding laccase-like activity with Km being 0.075 mM at significantly low dosage used, which is one magnitude lower than that of natural enzyme. RGPT-PdNP@rGO nanozyme based one-step sensor can selectively detect uric acid (UA) with a comprehensive linear range from 0.2 to 110 μM and a limit of detection of 120 nM. Moreover, RGPT-PdNP@rGO composite displays an outstanding activity for UA oxidation with Km being 0.024 mM, revealing the nanozyme exhibits a similar affinity towards UA as natural uricase due to the cooperation of the three components. Compared with our previous work, these extremely improved UA recognition, sensing and degrading performances not only support the role of RGPT in enhancing with the recognition ability of the composite nanozyme for targeted UA, but also reveal the recognition role of RGPT is associated closely with inorganic components in the composite. This work provides more definitive and comprehensive information about multifunctional nanozymes for precise biomarker recognition by introducing recognition peptide, which is highly significant for applications beyond mimic-enzyme catalyst, including theranostic, sensing, and energy fields.

Microstructural evolution and 1500 °C oxidation resistance of Mo(Al,Si)2 fabricated via an innovative two-step SHS-SPS technique

An innovative two-step approach of self-propagating high-temperature synthesis (SHS) and spark plasma sintering (SPS) was developed to rapidly fabricate MoSi2 and Mo(Al,Si)2 ceramics for high-temperature anti-oxidation applications. The SHS process predominantly promoted the synthesis of high-purity and high-yield MoSi2 and Mo(Si,Al)2 phases in the alloyed powders. Subsequently, dense and crack-free MoSi2 and Mo(Al,Si)2 ceramics were produced using SPS. 1500 °C oxidation tests of the ceramics (100 h) revealed the formation of a protective SiO2 oxide layer on the surface of MoSi2 ceramics, while an Al-Si-O composite glassy oxide layer formed on Mo(Si,Al)2 ceramics., which exhibited better thermal stability and lower oxygen permeability compared to the single SiO2 oxide layer. However, an excessive Al content (>0.05 at.%) compromised the oxidation resistance due to the emergence of a Si-depleted Mo5(Si,Al)3 layer with inferior oxidation resistance, which was caused by the high-temperature diffusion of Si. Therefore, via this novel two-step SHS-SPS technique compact and crack-free Mo(Si,Al)2 ceramics can be rapidly synthesized at high temperatures. When trace amount of Al was added (0.05 at.%), Mo(Si0.95,Al0.05)2 showed optimum high-temperature oxidation resistance.

Wet-chemical preparation and physicochemical characterization of nanostructured Zn-Bi2O3/CeO2 composite: A visible-light-driven catalyst for the annihilation of pharmaceutical pollutant

A modified co-precipitation technique assisted with cetyltrimethylammonium bromide (CTAB) surfactant was used to synthesize a nanostructured and zinc-doped mixed metal oxide (Zn-Bi2O3/CeO2) composite. Using X-ray diffraction (XRD), the synthesized nanocomposite was studied in terms of its crystal structure, grain size, percentage crystallinity, and percentage porosity. Energy dispersive X-ray elemental analysis (EDX) was used to ascertain the chemical composition, SEM to confirm the creation of nanostructure material, and Fourier transform infrared spectroscopy (FTIR) to extract the existing functional groups. Investigation of light harvesting properties (UV/Vis) and thermogravimetric analysis (TGA) reveals that the doped composite exhibits a band gap driven by visible light and remarkable thermal stability at high temperatures. The pH value at which a material's net charge is zero, known as pHpzc, is 7.93 for the doped mixed metal oxide composite. The Zn-Bi2O3/CeO2 nanocomposite effectively eliminates 98.4 percent of the quinolone antibiotic (levofloxacin) via a mechanism that integrates sorption and photocatalytic degradation induced by visible light. To determine the optimal circumstances for the efficient operation of a photocatalyst, we experimented with different time intervals, beginning drug concentrations, catalyst dosages, operating temperatures, and pH levels. Reusability tests and post-activity FTIR analysis were used to investigate the long-term usability and structural stability of the newly developed doped composite photocatalyst. The scavenging tests revealed a potential photocatalytic mechanism to explain the annihilation of the levofloxacin drug on the synthesized catalyst. The physicochemical and photocatalytic evaluations recommend that the assembled integrated material has excellent potential for mineralizing medicinal products in pharmaceutical wastes.

Efficient ethidium bromide removal using sodium alginate/graphene oxide composite beads: Insights into adsorption mechanisms and performance

This study explores the efficacy of sodium alginate/graphene oxide (SA/GO) composite beads for ethidium bromide (EtBr) removal from aqueous solutions. GO was synthesized and crosslinked with SA to design composite beads, which were evaluated under various physicochemical conditions. Characterization techniques, including FESEM, TGA, XRD, and FTIR, were employed to analyze the beads before and after EtBr adsorption. Results demonstrated rapid EtBr adsorption onto SA/GO, following the Freundlich isotherm model with a maximum adsorption capacity of 2.97mmol g−1 (1171.05 mg g−1). The influence of solution pH and the negligible role of Br− ions suggested that electrostatic interaction was the primary mechanism for EtBr adsorption on SA/GO. XRD and FTIR analyses revealed that EtBr adsorption also occurred in the interlayer space of SA/GO beads, with the ethidium cations (Et+) entering this space in a horizontal or oblique (≥45°) orientation. The accumulation of Et+ within the interlayer space was estimated to form 1–6 basic inclined layers. SA/GO beads demonstrated promising characteristics for EtBr pollutant treatment, including low environmental impact, cost-effectiveness, rapid adsorption kinetics, and high removal efficiency. This study provides valuable insights into the adsorption mechanisms and performance of SA/GO beads, highlighting their potential for future field applications in the environmental remediation of EtBr contamination.

Electrochemical sensing of gatifloxacin using Ag2S/RGO nanocomposite

As a widely-used fluoroquinolone antibiotics, 1-Cyclopropyl-6-fluoro-8-methoxy-7-(3-methyl-1-piperazinyl)-4-oxo-1,4-dihydro-3-quinolinecarboxylic acid (gatifloxacin, GAT) has aroused much concern recently and it is of great importance to realize the accurate and efficient detection. Herein, the silver sulfide/reduced graphene oxide composite (Ag2S/RGO) was synthesized with one-pot method and was coated on the glassy carbon electrode to develop an effective electrochemical sensor for GAT. After the optimization of the size of Ag2S, the pH of buffer solution, and the scanning rate, the Ag2S/RGO modified electrode exhibits good linear relationship to GAT within wide ranges of 0.2 µM − 20 µM and 20 µM − 250 µM with a detection limit of 0.0667 µM. Besides, the proposed sensor shows good selectivity to GAT versus multiple interferences, including organic compounds, ions, and other antibiotics. At last, the proposed sensor was successfully applied in the GAT analysis in various real samples (including shrimp, fish, and chicken) with satisfying recoveries of 91.8 % − 102.4 %. In general, the proposed Ag2S/RGO-based electrochemical sensor provides a novel strategy for the GAT analysis, which is of significance for the development of efficient analytical techniques for antibiotics.

Incorporation of Mg/Al metal oxide into ionic liquids for CO2 capture and conversion into cyclic carbonate under solvent-free conditions: Effect of coordination ability, recyclability, and catalytic study

The direct conversion of carbon dioxide (CO2) and propylene oxide (PO) into propylene carbonate (PC) offers a green way to utilize anthropogenic CO2. However, this reaction is limited by low conversion of PO and harsh reaction conditions. In this study, we solve this problem using ionic liquids (ILs)/metal oxide composites (ILs@MAO). The catalytic activity of MAO-500 (500 = annealing temperature) is poor evidenced by its low conversion of PO (24.94%). However, ILs@MAO-500 has a high conversion of PO (97.54%) under similar reaction conditions (2 h at 1.5 MPa CO2 pressure, 90 °C, and 0.85 g catalyst). The ILs consist of imidazolium cation with weak coordinated [NTf2]– anion leading to outward movement of anion resulting in the formation of “heterodinuclear complex”. This complex generates an amorphous-crystalline intermediate with balanced acid-base sites that activate PO and stabilize the catalytic intermediate. In large part, the high PO conversion is theorized to be primarily due to the abundant reactive sites in the ILs that are covalently immobilized on the MAO-500 carrier. Furthermore, even after multiple recycling, ILs@MAO-500 remains stable and exhibits high yield and selectivity. The proposed solvent-free catalytic system is mild, kinetically fast, and naturally safe for coupling CO2 and PO into PC synthesis.

Interface engineering-induced enhancements in sodium-ion batteries: A nexus of ZnS nanoparticles and reduced graphene oxide for augmented storage and conductivity

Due to the inherent sluggish kinetics and the pronounced volumetric expansion of zinc sulfide (ZnS), it has become a prevalent modification strategy to regulate its morphology and composite with graphene for using ZnS as anodes in sodium-ion batteries (SIBs). Nevertheless, the elucidation of mechanisms underpinning the electrochemical performance facilitated by graphene incorporation remains scant. To further describe the synergistic mechanism, the ultrafine ZnS nanoparticles anchored on reduced graphene oxide (rGO) were synthesized through a simple solvothermal method. Research shows that the ZSG (ZnS nanoparticles-reduced graphene oxide composite) electrode suggests superior rate capability, maintaining a reversible specific capacity of 228.6 mAh·g−1 upon returning from a high current density of 5 A·g−1. Furthermore, the nanoscale integration of ZnS particles with rGO synergistically mitigates the structural expansion of the ZSG electrode encountered during cycling, thereby decelerating the degradation of cyclic performance. Insights gleaned from first-principles calculations and comprehensive electrochemical evaluations reveal that the built-in electric field, engendered within the composite architecture, substantially augments charge transfer ability and mitigates the energy barriers impeding sodium ion (Na+) diffusion accordingly. Consequently, the methodology adopted for synthesis and the synergistic modification mechanism can proffer a reference for the design of advanced anode materials in SIBs.

Mechanism of selective uranium adsorption using polyvinyl alcohol /Cyphos IL-101 / reduced graphene oxide composites

A novel composite material for uranium extraction from seawater, APGO, was prepared by crosslinking reduced graphene oxide (rGO) loaded with trihexyl(tetradecyl)phosphonium chloride (Cyphos IL-101) with polyvinyl alcohol. The experimental results indicate that the surface of APGO contains functional groups, such as carboxyl, hydroxyl, and phosphate, that have adsorption properties for uranium. APGO exhibits excellent hydrophilicity and stability while preserving the intact two-dimensional network structure of rGO. The specific surface area of APGO was 9.23 m2/g with an average pore size of 27.50 nm. Furthermore, the optimal pH range for APGO to adsorb uranium is 6–8, making it more suitable for extracting uranium from seawater. Notably, the selective adsorption capacity of APGO for uranium is significantly enhanced compared to that of AGO, with a Kd value approximately 4.6 times higher than that of AGO. The theoretical adsorption capacity is 467mg/g at 318 K (pH = 6). The process of uranium adsorption by APGO is a spontaneous endothermic reaction. The adsorption performance of APGO is noteworthy because it exhibits only a 2 % decrease after five adsorption–desorption cycles. Furthermore, APGO demonstrates commendable recyclability. Overall, APGO demonstrates a remarkable affinity for uranium and promising potential for efficiently extracting uranium from seawater.