Latest ArticlesDesigning highly efficient non-precious based electrocatalysts for oxygen reduction reaction (ORR) is of significance for the rapid development of metal-air batteries. Herein, a hydrothermal-pyrolysis method is employed to fabricate Fe, N co-doped porous carbon materials as effective ORR electrocatalyst through adopting graphitic carbon nitride (g-C3N4) as both the self-sacrificial templates and N sources. The g-C3N4 provides a high concentration of unsaturated pyridine-type N to coordinate with iron to form Fe-N active sites. Through adjusting the Fe doping amounts, it is proved that appropriate Fe doping content is conducive to the construction of abundant defects and active sites of Fe-N. The as-prepared catalyst exhibits superior electrocatalytic ORR performance in alkaline media with half-wave potential (E1/2 = 0.82 V) and onset potential (Eonset = 0.95 V), equivalent to the commercial Pt/C catalyst. Moreover, there is almost no activity loss after 10 k continuous cyclic voltammetry cycles and methanol tolerance, indicating the excellent durability and superior methanol tolerance. Remarkably, when assembled as the cathode in a Zn-air battery, the device displays a power density of 99 mW/cm2, an open-circuit potential of 1.48 V and long-term discharge-charge cycling stability, indicating the promising potential to substitute the Pt catalyst for practical application.
Carbon nanotube-based (CNT-based) interfacial evaporation material is one of the most potential materials for solar desalination. Here, we studied the evaporation rate of the CNT-based membranes with different hydrophilic and hydrophobic chemical modified surfaces using molecular dynamic simulations. We found that the hydrogen bonding density among water molecules at the interface is a key factor in enhancing the evaporation rate. For a hydrophilic CNT-based membrane, the strong interactions between the membrane outer surface and the water molecules can destroy the water-water hydrogen bonding interactions at the interface, resulting in the reduction of the hydrogen bonding density, leading to an enhancement effect in evaporation rate. We also found that there is an optimal thickness for evaporation membrane. These findings could provide some theoretical guidance for designing and exploring advanced CNT-based systems with more beneficial performance in water desalination.
Developing photocatalyst with high activity, superior stability and prominent selectivity for CO2 conversion is of great importance for the target of carbon neutralization. Herein, 3D dahlia-like NiAl-LDH/CdS heterosystem is developed through in-situ decoration of exfoliated CdS nanosheets on the scaffold of NiAl-LDH and the on-spot self-assembly. The formation of a hierarchical architecture collaborating with well-defined 2D/2D interfacial interaction is constructed by optimizing the ratio of CdS integrated in the formation of the heterojunction. The light-harvesting capacity of NiAl-LDH/CdS is improved by this unique scaffold, and the charge transfer between NiAl-LDH and CdS is effectively facilitated by virtue of the unique 2D/2D interface. As a result, the 3D hierarchical NiAl-LDH/CdS heterosystem presents 12.45µmol g−1 h−1 of CO production (3.3 and 1.6 folds of pristine NiAl-LDH and CdS) with 96% selectivity and superior stability. This 3D hierarchical design collaborating with 2D/2D interfacial interaction provides a new avenue to develop ideal catalysts for artificial photosynthesis.
In this study, novel iron-doped biochar (Fe-BC) was produced using a simple method, and it was used as an H2O2 activator for tetracycline (TC) degradation. Generally, iron loading can improve the separation performance and reactivity of biochar (BC). In the Fe-BC/H2O2 system, 92% of the TC was removed within 30 min with the apparent rate constant (kobs) of 0.155 min−1, which was 23.85 times that in the case of the BC/H2O2 system (0.0065 min−1). The effects of the H2O2 and Fe-BC dosage, initial pH, and TC concentration on the TC removal were investigated. The radical quenching and electron paramagnetic resonance (EPR) measurements demonstrated that the removal of TC using the Fe-BC/H2O2 process involved both radical (•OH and O2−•) and non-radical pathways (1O2 and electron transfer). In addition, the performance of the catalyst was also affected by the persistent free radicals (PFRs) and defective sites on the catalyst. Moreover, the degradation pathways of TC were proposed according to the intermediate products detected by LC-MS and the ecotoxicity of intermediates was evaluated. Finally, the Fe-BC/H2O2 showed high resistance to inorganic anions and natural organic matter in aquatic environments. Overall, Fe-BC is expected to be an economic and highly efficient heterogeneous Fenton catalyst for removing the organic contaminants in wastewater.
The development of green and convenient methods for C–S bond formation has received significant attention because C–S bond widely occurs in many important pharmaceutical and biological compounds. Recently, visible-light photoredox catalysis has been established as an efficient and general tool for the construction of C–C and C-heteroatom bonds. In this review, we have focused on the research on recent advances in C–S bond formation via visible-light photoredox catalysis, and the growing opportunities they present to the construction of complex chemical scaffolds for applications encompassing bioactive molecules synthesis, synthetic methodology development, and sulfur-containing drugs. We hope that this review will provide chemists with a synthetic tool that will open the door to further development of organsulfur chemistry
Metal-organic frameworks (MOFs) show great potential for various applications, but many of them suffer from the drawbacks of hydrolysis propensity and poor processability. Herein, we employ polymers of intrinsic microporosity (PIMs) with hydrophobic pores to decorate MOFs toward substantially improved water stability and shapeability. Through simple PIM-1 decoration, the sub-5 nm polymer layers can be uniformly deposited on MOF surfaces with almost no deterioration in porosity. Owing to the existence of superhydrophobic coating and the obstruction of water entrance into MOFs, the PIM-1 coated CuBTC exhibits impressive water resistance and excellent pore preservation ability after exposure in water, even in acidic and alkaline solutions. Moreover, polymer decoration improves the processability of MOFs, while various MOF/PIM-1 bulk wafers and oil-water separators can be obtained straightforwardly.
Bio-based epoxy thermoset prepared from renewable biomass raw materials can alleviate fossil energy crisis and reduce environmental pollution, which satisfies the needs of sustainable social development. In this study, a bio-based epoxy thermoset precursor (MGOL-EP) was synthesized from a naturally occurring magnolol through a facile and efficient one-step process. And the fully bio-based epoxy thermoset (MGOL-EP-SC) was obtained by self-curing without adding any other hardener. MGOL-EP-SC revealed an extremely high glass-transition temperature (Tg) of 265 ℃ and char yield of 53.2% (in N2), which were at the highest level among the fully bio-based epoxy thermosets reported so far. In addition, when the MGOL-EP was cured with 4, 4′-methylenedianiline (DDM), Tg of the MGOL-EP/DDM was decreased by 61 ℃ and the other comprehensive performance had also been decreased, which was due to a reduction in biphenyl structure content and cross-linking density by adding the external curing agents. Moreover, the MGOL-EP-SC presented certain killing rate (48.4%) to Staphylococcus aureus. These findings provide a new design strategy for engineering high-performance and functional epoxy thermoset with high biomass content.
Owing to the diversity of structure and potential applications in the field of electrics, sensors, and light-emitting diodes, lead halide perovskites have attracted great attention in recent years. Especially those lead halide perovskites with non-centrosymmetric crystal structures usually exhibit nonlinear optical (NLO) characteristics, which may endow them photoelectricity switching functionality. In this work, a lead-based hybrid organic-inorganic perovskite (HOIP) material, trimethyliodomethylammonium lead trichloride (TMIM·PbCl3), is obtained on the basis of tetramethylammonium lead chloride through halogen substitution on the cation part. It shows dual-phase-transition behavior around 345 and 358 K, which is significantly improved. TMIM·PbCl3 crystallizes in the chiral space group, P212121, and shows a well-defined second harmonic generation (SHG) response, and good switching endurance, which makes it an excellent candidate for SHG switching material. This work highlights the importance of halogen substitution for crystal engineering and may pave way for the further exploration of the optoelectronic devices.
Conductive hydrogels have attracted considerable attention owing to their potential for use as electronic skin and sensors. However, the loss of the inherent elasticity or conductivity in cold environments severely limits their working conditions. Generally, organic solvents or inorganic salts can be incorporated into hydrogels as cryoprotectants. However, their toxicity and/or corrosive nature as well as the significant water loss during the solvent exchange present serious difficulties. Herein, a liquid-like yet non-toxic polymer-polyethylene glycol (PEG) was attempted as one of the components of solvent for hydrogels. In the premixed PEG-water hybrid solvent, polyacrylamide (PAAm) was in situ polymerized, overcoming the inevitable water loss induced by the high osmotic pressure of the PEG solution and achieving tailored water capacity. Interestingly, the mechanical strength ("soft-to-rigid" transition) and anti-freezing properties of organohydrogels can be simultaneously tuned over a very wide range through adjusting PEG content. This was due to that with increasing PEG in solvent, the PAAm chains transformed from stretching to curling conformation, while PEG bonded with water molecules via hydrogen bonds, weakening the crystallization of water at subzero temperature. Additionally, a highly conductive Ti3C2Tx-MXene was further introduced into the organohydrogels, achieving a uniform distribution triggered by the attractive interaction between the rich functional groups of the nanofillers and the polymer chains. The nanocomposite hydrogels demonstrate high electrical conductivity and strain sensitivity, along with a wide working temperature window. Such a material can be used for monitoring human joint movement even at low temperature and has potential applications in wearable strain sensors.
Pharmaceutical salt formation is the most preferred and effective method to enhance the physicochemical properties of APIs. The aim of the study was to design and synthesize a series of new salts to improve the solubility of Imatinib (IM). Two stable salts with malonic acid (S1) and citric acid (S5), one metastable salt with fumaric acid (S2), two unstable salts with citric acid (S3, S4) were obtained for the first time. Single crystal and powder X-ray diffraction, Fourier transform infrared, differential scanning calorimetry, and thermogravimetric analysis were used to characterize the novel salts. The solubility and stability of the solid were also evaluated, and three salts (S1, S2, S5) had a more than 20 folds of solubility and a faster dissolution rate improved as compared to the pure drug in water and pH 6.8 buffer, respectively.
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