Inorganic molecule (O2, NO) adsorption on nitrogen- and phosphorus-doped MoS2 monolayer using first principle calculations

We performed a systematic study of the adsorption behaviors of O₂ and NO gas molecules on pristine MoS₂, N-doped, and P-doped MoS₂ monolayers via first principle calculations. Our adsorption energy calculations and charge analysis showed that the interactions between the NO and O₂ molecules and P–MoS₂ system are stronger than that of pristine and N–MoS₂. The spin of the absorbed molecule couples differently depending on the type of gas molecule adsorbed on the P- and N-substituted MoS₂ monolayer. Meanwhile, the adsorption of O₂ molecules leaves N- and P–MoS₂ a magnetic semiconductor, whereas the adsorption of an NO molecule turns this system into a nonmagnetic semiconductor, which may provide some helpful information for designing new N- and P-substituted MoS₂-based nanoelectronic devices. Therefore, P- and N–MoS₂ can be used to distinguish O₂ and NO gases using magnetic properties, and P–MoS₂-based gas sensors are predicted to be more sensitive to detect NO molecules rather than pristine and N–MoS₂ systems.

We performed a systematic study of the adsorption behaviors of O₂ and NO gas molecules on pristine MoS₂, N-doped, and P-doped MoS₂ monolayers via first principle calculations.     

The synergistic effect of oxygen-containing functional groups on CO2 adsorption by the glucose–potassium citrate-derived activated carbon

A high surface area activated carbon prepared by an innovative approach using glucose as a carbon source and neutral potassium citrate (PC) as an activator was compared with the porous carbon from glucose using corrosive potassium hydroxide (KOH) as an activator. The PC method showed two notable advantages over KOH activation. The PC method not only significantly increased the yield of the activated carbon, particularly at high carbonization temperatures without sacrificing porosity, but also enhanced the oxygen content in the activated carbon. After investigating CO₂ adsorption on these activated carbons, a remarkable uptake of 3.57 mmol g⁻¹ at 25 °C at 1 bar was observed by the glucose–PC-derived carbon sample, which possessed the highest oxygen content. In addition, the glucose–PC-derived carbon samples exhibited higher CO₂/N₂ selectivity than the glucose–KOH derived samples. Coupled with the density functional theory (DFT) analysis that focused on the binding energy calculation, the doped oxygen-containing functional groups, such as carboxyl and hydroxyl groups, could effectively enhance the adsorption of CO₂.

A high surface area activated carbon which was prepared by an innovative approach using glucose as a carbon source and neutral potassium citrate as an activator was compared with the porous carbon using corrosive potassium hydroxide as activator.     

Fabrication of dopamine modified polylactide-poly(ethylene glycol) scaffolds with adjustable properties

Bio-based polymers have been widely used to be as scaffolds for repairing the bone defects. However, the polymer scaffolds are generally lack of bioactivity and cell recognition site. Seeking effective ways to improve the bioactivity and interaction between materials and tissue or cells is clinically important for long-term performance of bone repair materials. In this work, polylactide-b-poly(ethylene glycol)-b-polylactide (PLA-PEG-PLA, PLEL) tri-block copolymers were firstly synthesized by ring-opening polymerization of lactide using PEG with various molecular weights. Inspired by excellent adhesion of dopamine (DA), a facile and effective method was developed to fabricate polydopamine (PDA) and polydopamine/nano-hydroxyapatite (PDA/n-HA) modified PLEL scaffolds by deposition of PDA and PDA/n-HA coating. The surface structure, degradation rates and mineralization of the modified PLEL scaffolds were investigated, and obviously improved after immobilization of PDA and PDA/n-HA coatings. Moreover, the biocompatible results showed a significant increase in cells viability and adhesion. Therefore, the surface modification with PDA and PDA/n-HA could not only adjust the properties of scaffolds, but also reinforce the interfacial adhesion between the PLEL and cells.     

上颌乳前牙根管形态及根部牙本质力学性能的测定

目的 测量上颌乳前牙根管锥度、直径及根部牙本质的弹性模量和硬度,为用于上颌乳前牙的可吸收根管桩的制作提供参考。方法 选择全身麻醉下进行上颌乳前牙根管治疗的患儿,采用硅橡胶制取上颌乳前牙根管印模,扫描印模后测量根管的锥度和直径。收集10颗离体上颌乳前牙,测量根部牙本质的弹性模量和硬度。结果 本研究共收集了74颗上颌乳前牙的根管模型,其中乳中切牙28颗,乳侧切牙35颗,乳尖牙11颗。乳中切牙、乳侧切牙、乳尖牙的平均锥度依次为0.106、0.185、0.098,釉牙骨质界下方5 mm处平均直径依次为1.267、0.860、1.429 mm。10颗离体上颌乳前牙根部的牙本质弹性模量范围为19.919~25.017 GPa,硬度范围为0.867~1.082 GPa。结论 制作乳牙根管桩时,乳中切牙及乳尖牙根管桩建议取锥度为0.1,尖端直径为1.2、1.4 mm;乳侧切牙根管桩建议取锥度为0.2,尖端直径为0.8 mm;桩的弹性模量范围为20~25 GPa,硬度范围为0.87~1.08 GPa较为适宜。     

Efficient electrocatalytic reduction of carbon dioxide by metal-doped β12-borophene monolayers

Electrochemical reduction of CO₂ to value-added chemicals and fuels shows great promise in contributing to reducing the energy crisis and environment problems. This progress has been slowed by a lack of stable, efficient and selective catalysts. In this paper, density functional theory (DFT) was used to study the catalytic performance of the first transition metal series anchored TM–B_β12 monolayers as catalysts for electrochemical reduction of CO₂. The results show that the TM–B_β12 monolayer structure has excellent catalytic stability and electrocatalytic selectivity. The primary reduction product of Sc–B_β12 is CO and the overpotential is 0.45 V. The primary reduction product of the remaining metals (Ti–Zn) is CH₄, where Fe–B_β12 has the minimum overpotential of 0.45 V. Therefore, these new catalytic materials are exciting. Furthermore, the underlying reaction mechanisms of CO₂ reduction via the TM–B_β12 monolayers have been revealed. This work will shed insights on both experimental and theoretical studies of electroreduction of CO₂.

These new TM–B_β12 monolayers will display excellent catalytic performance for electroreduction of CO₂. Primary reduction product of Sc is CO (overpotential 0.45 V). Primary product Ti–Zn is CH₄, and Fe–B_β12 has 0.45 V overpotential.     

Morphology-controlled synthesis of CoMoO4 nanoarchitectures anchored on carbon cloth for high-efficiency oxygen oxidation reaction

Novel CoMoO₄ nanoarrays with different morphologies are anchored on a carbon cloth via a simple hydrothermal method by adjusting the Co/Mo atom ratio. The in situ growth and tight immobilization of the CoMoO₄ nanocomposite on the carbon cloth can facilitate the electrolyte infiltration and electrons transfer rate at the contact interface. Therefore, the free-standing electrode of CoMoO₄/carbon cloth with interconnected nanosheets shows superior electrocatalytic activity, and the overpotential of 286 mV is obtained at 15 mA cm⁻² in alkaline solution. Moreover, the catalyst also exhibits a small Tafel slope of 67 mV dec⁻¹ as well as good stability. The relationship between the active material morphology, contact interface and the electrocatalytic performance is also discussed. As the carbon cloth is commercially available, this simple but effective structural controlling method demonstrates a new large-scale practical electrode fabrication technique for high performance OER electrodes and large-scale water splitting.

Novel CoMoO₄ nanoarrays with different morphologies are anchored on a carbon cloth via a simple hydrothermal method by adjusting the Co/Mo atom ratio.     

Molecular dynamics simulation of four typical surfactants in aqueous solution

The thermodynamic values of the four surfactants, anionic surfactants, nonionic surfactants, zwitterion surfactants and gemini surfactants, were calculated by molecular dynamics simulation. The calculated results of thermodynamic parameters showed that the four surfactant can form micelles spontaneously. The mainly force for micellization process is entropy-driven, and as the temperature increases, the entropy-driven contribution is gradually reduced. There are linear enthalpy–entropy compensation phenomena for the four surfactants. Among the studied four surfactants, the gemini surfactant is the easiest to form micelles and has good stability, the zwitterion surfactant is the second, and the anionic surfactant is the least stable.

The thermodynamic values of the four surfactants, anionic surfactants, nonionic surfactants, zwitterion surfactants and gemini surfactants, were calculated by molecular dynamics simulation.     

Performance evaluation of interfacial polymerisation-fabricated aquaporin-based biomimetic membranes in forward osmosis

Aquaporins play a promising role in the fabrication of high-performance biomimetic membranes. Interfacial polymerisation is a promising strategy for synthesizing aquaporin-based membranes. In this study, robust and high-performance aquaporin-based biomimetic membranes were successfully fabricated by interfacial polymerisation, and the membrane separation performance and interfacial polymerisation method were systematically evaluated. The effects of modification methods on the performance of aquaporins-based biomimetic membranes, including sodium hypochlorite and thermal post-treatment, protein-to-lipid ratio, liposome concentration and the addition arrangement of aquaporins were also investigated. Morphological observation suggested that the introduced proteoliposomes were completely embedded in the polyamide layer and that their spherical shape was preserved. Sodium hypochlorite post-treatment and thermal treatment were beneficial in improving the water flux and salt rejection of the resultant membrane without sacrificing the aquaporin activity. The biomimetic membranes had a high water flux and salt rejection, which were almost twice that of the control membranes, after aquaporin-based proteoliposomes were incorporated with an appropriated protein-to-lipid ratio and liposome concentration. The addition arrangement of aquaporins during the interfacial polymerisation procedure significantly influence the obtained membrane''s structure. Lastly, this article introduces valuable and systematic research on interfacial polymerisation fabricated aquaporin-based biomimetic membranes with outstanding separation performance.

Aquaporins play a promising role in the fabrication of high-performance biomimetic membranes.     

A high-sensitive room temperature gas sensor based on cobalt phthalocyanines and reduced graphene oxide nanohybrids for the ppb-levels of ammonia detection

Highly sensitive gas sensing materials are of great importance for environmental pollution monitoring. In this study, four nanohybrid materials containing different phenoxyl substituents of cobalt phthalocyanines (tetra-β-carboxylphenoxylphthalocyanine cobalt (cpoPcCo), tetra-β-(4-carboxy-3-methoxyphenoxy)phthalocyanine cobalt (cmpoPcCo), tetra-β-phenoxylphthalocyanine cobalt (poPcCo), and tetra-β-(3-methoxyphenoxy)phthalocyanine cobalt (mpoPcCo)) and reduced graphene oxide (rGO) (RPcCo/rGO) were synthesized via non-covalent interactions as a high performance gas sensing materials for the ppb-level detection of ammonia (NH₃). Various characterization techniques, including FT-IR, Raman, UV-vis, TGA, XPS and SEM, were used to confirm the structure, element information and morphology of the as-synthesized materials. The obtained materials were used in interdigital electrodes to fabricate the sensing device, and the gas sensing performance was investigated at room temperature. The obtained sensors exhibited excellent sensitivity, selectivity, good reproducibility and perfect response–concentration linearity towards NH₃, which are mainly ascribed to the synergetic effects of RPcCo and rGO due to the specific surface area structure for NH₃ diffusion, the abundant active sites to adsorb NH₃, and excellent conductivity for efficient electron transport, particularly the effect of RPcCo. For example, the cpoPcCo/rGO-based sensor showed a higher and faster response for low concentration of NH₃ (∼2.5 and 45 s for 100 ppb of NH₃), a ppb level detection and superior stability over 60 days. Besides, the effect of different phenoxyl substituents of cobalt phthalocyanines on the sensing performance and the sensing mechanism for the sensitivity enhancement were discussed and confirmed by the first-principles density functional theory calculations and electrochemical impedance spectroscopy (EIS).

Highly sensitive gas sensing materials are of great importance for environmental pollution monitoring.     

Catalytic developments in the epoxidation of vegetable oils and the analysis methods of epoxidized products

Functionalization of vegetable oils (VOs) including edible, non-edible, and waste cooking oil (WCOs) to epoxides (EVOs) is receiving great attention by many researchers from academia and industry because they are renewable, versatile, sustainable, non-toxic, and eco-friendly, and they can partially or totally replace harmful phthalate plasticizers. The epoxidation of VOs on an industrial scale has already been developed by the homogeneous catalytic system using peracids. Due to the drawbacks of this method, other systems including acidic ion exchange resins, polyoxometalates, and enzymes are becoming alternative catalysts for the epoxidation reaction. We have reviewed all these catalytic systems including their benefits and drawbacks, reaction mechanisms, intensification of each system in different ways as well as the physicochemical properties of VOs and EVOs and new findings in recent years. Finally, the current methods including titrimetric methods as well as ATR-FTIR and ¹H NMR for determination of conversion, epoxidation, and selectivity of epoxidized vegetable oils (EVOs) are also briefly described.

Epoxidation of vegetable oils by different means to improve their functional properties and to replace the harmful phthalate plasticizers along with their analysis are shown.