Latest ArticlesVisible-light heterogeneous photocatalyst with high activity and selectivity is crucial for the development of organic transformations, but remains a formidable challenge. Herein, a simple and effective strategy was developed to integrate tetrazine moiety, a visible light active unit, into robust metal-organic frameworks (2D MOF-1(M), M = Co, Mn, Zn, and 3D MOF-2(Co)). MOF-1 series are isomorphous 2D porous frameworks, and MOF-2(Co) displays 3D porous framework. Interestingly, benefiting from the oxidative active species of O2•−, these MOFs all exhibit obviously highly enhanced photocatalytic activities toward the straightforward condensation of o-aminothiophenol and aromatic aldehydes at room temperature in EtOH under visible-white-light irradiation. Notably, compared to 3D MOF, the 2D layered MOF-1(Co) exhibited more excellent catalytic activity with a wide range of substrates possessing preeminent tolerance of steric hindrance. Most impressively, MOF-1(Co) can be recycled at least five times without significant loss of catalytic activity or crystallinity, exhibiting excellent stability and reusability. This study sheds light on the wide-ranging prospects of visible light active 2D MOFs as green photocatalysts for the preparation of fine chemicals.
Finding improved therapeutic protocols against non-Hodgkin's lymphoma (NHL) remains an unmet clinical demand. Phototherapy is a promising alternative treatment for traditional clinical therapeutic methods, but the limited tissue penetration blocks the therapeutics. Inspired by the excellent physical and chemical properties of black phosphorus nanosheets (BPNSs), a fluorescence and thermal imaging guided photo-/sono-synergistic treatment platform BPNSs@PEG-SS-IR780/RGD is developed. This ingenious multifunctional theranostic platform not only exhibits outstanding photothermal conversion efficiency and highly efficient reactive oxygen species generation, but also has good biocompatibility, tumor-targeting and tumor microenvironment responsiveness. In addition, BPNSs@PEG-SS-IR780/RGD could actively target the tumor sites and generate excellent photothermal, photodynamic and sonodynamic therapeutic efficacy. Both in vitro and in vivo experiments indicate that BPNSs@PEG-SS-IR780/RGD can be a promising nanomaterial for NHL imaging and therapy. Taken together, this study not only expands the application field of black phosphorus materials, but also provides a possibility to design a new generation of NHL treatment regimens with clinical application potential.
Chemical upcycling of end-of-life poly(lactide) plastics to lactide, lactate ester and new poly(lactide) has been achieved by using magnesium bis[bis(trimethylsilyl)amide] [Mg(HMDS)2] as promoter. Mg(HMDS)2 showed high efficiency in L-lactide polymerization and poly(lactide) depolymerization. Mg(HMDS)2/Ph2CHOH catalytic system displayed high ring-opening selectivity and the characteristic of immortal polymerization. Taking advantage of transesterification, depolymerizations of end-of-life poly(lactide) plastics to lactate ester (polymer to value-added chemicals) and lactide (polymer to monomer) were achieved with high yields. Besides, a new "depolymerization-repolymerization" strategy was proposed to directly transform poly(lactide) into new poly(lactide). This work provides a theoretical basis for the design of polymerization and depolymerization catalysts and promotes the development of degradable polymers.
Activation of (bi)sulfite (S(Ⅳ)) by metal oxides is strongly limited by low electrons utilization. In this study, two carbon-supported cobalt ferrites spinels (CoFe2O4 QDs-GO and CoFe2O4 MOFs-CNTs) have been successfully synthesized by one-step solvothermal method. It was found that both catalysts could efficiently activate S(Ⅳ), with rapid reductive dechlorination and then oxidative degradation of a recalcitrant antibiotic chloramphenicol (CAP). Characterizations revealed that CoFe2O4 spinels were tightly coated on the carbon bases (GO and CNTs), with effectiveness of the internal transfer of electrons. O2˙− was identified for the reductive dechlorination of CAP, with simultaneously detection of both •OH and SO4˙− responsible for further oxidative degradation. The sulfur oxygen radical conversion reactions and molecular oxygen activation would occur together upon the carbon-based spinels. Spatial-separated interfacial reductive-oxidation of CAP would occur with dechlorination of CAP by O2˙− on the carbon bases, and oxidative degradation of intermediates by SO4˙−/•OH upon the CoFe2O4 catalysts.
Lignin and its derivatives hold great potential in developing high performance porous carbon materials for supercapacitors due to the versatile features of high carbon content, abundant multifunctional groups, low cost, and environmental benefits. Unfortunately, their derived porous carbon generally has the features of unfavorable microporous-dominated morphologies and low specific surface area (SSA) attributed from the highly-branched structure of lignin, which are hardly suitable for the supercapacitors with ionic liquid (IL) electrolyte, leading to poor energy density and rate capability. Herein, porous carbon materials with desirable mesoporous contributions from sodium lignosulphonate are designed via a facile template method. Such rich mesoporisity carbon materials not only possess with three-dimensional interconnected network, large SSA, as well as favorable pore size distribution for accelerated ion and electron mass transfer, but also feature low heteroatom content for high electrochemical stability. Consequently, the optimal electrode exhibits a high capacitance of 166 F/g at 0.5 A/g, superior rate performance (59 Wh/kg at 59 kW/kg), as well as impressive cycle life with good capacitance retention of 93.1% in EMIBF4 electrolytes. The present work opens a new avenue to design porous carbon materials with high mesopore properties from lignin for effective compatibility with IL electrolyte in high-performance supercapacitors.
To achieve smart and personalized medicine, the development of hydrogel dressings with sensing properties and biotherapeutic properties that can act as a sensor to monitor of human health in real-time while speeding up wound healing face great challenge. In the present study, a biocompatible dual-network composite hydrogel (DNCGel) sensor was obtained via a simple process. The dual network hydrogel is constructed by the interpenetration of a flexible network formed of poly(vinyl alcohol) (PVA) physical cross-linked by repeated freeze-thawing and a rigid network of iron-chelated xanthan gum (XG) impregnated with Fe3+ interpenetration. The pure PVA/XG hydrogels were chelated with ferric ions by immersion to improve the gel strength (compressive modulus and tensile modulus can reach up to 0.62 MPa and 0.079 MPa, respectively), conductivity (conductivity values ranging from 9 × 10-4 S/cm to 1 × 10-3 S/cm) and bacterial inhibition properties (up to 98.56%). Subsequently, the effects of the ratio of PVA and XG and the immersion time of Fe3+ on the hydrogels were investigated, and DNGel3 was given the most priority on a comprehensive consideration. It was demonstrated that the DNCGel exhibit good biocompatibility in vitro, effectively facilitate wound healing in vivo (up to 97.8% healing rate) under electrical stimulation, and monitors human movement in real time. This work provides a novel avenue to explore multifunctional intelligent hydrogels that hold great promise in biomedical fields such as smart wound dressings and flexible wearable sensors.
Simultaneous acquisition of fluorescence property and refractive index using a single surface plasmon coupled emission (SPCE) measurement has been achieved, thus achieving synchronicity in real time. The SPCE sensor was employed for monitoring the adsorption of volatile organic compounds (VOCs) by dye-encapsulated metal-organic frameworks (Dye@MOFs). Refractive index can reveal surface molecular adsorption and the fluorescence with information on refractive index can provide a comprehensive analysis of the adsorption events of VOCs on the interface. Meantime, the signal intensity can be amplified by combining the responses caused by changes in refractive index and the fluorescence property in parallel. This all-in-one method opens up a route to monitoring multiple processes simultaneously occurring on the interface.
Iron-chromium redox flow batteries (ICRFBs) possess advantages of high safety, long cycle time, and low-cost. Increasing Cr3+/Cr2+ reaction activity is suggested as one of the most promising strategies to improve the performance and prolong the lifetime of ICRFBs. To improve the slow reaction kinetics of the negative electrode, a type of defected carbon cloth with Bismuth (Bi) catalyst introduction is prepared by defect engineering method and electrochemical deposition, which provided defect sites and active sites to catalyze the redox couple's reaction of ICRFBs. Furthermore, this modified carbon cloth adsorbs Cr(Ⅲ) hydrate more easily, which has a more stable structure and can significantly improve the performance of ICRFBs. Both experimental analysis and theoretical calculation indicated that the modified electrode has excellent electrocatalytic ability, which can enhance the reaction rate of Cr3+/Cr2+, improve capacity retention and stabilize cycling performance. The capacity degradation rate of an ICRFB single cell with the modified electrodes is just 0.23% per cycle at a current density of 140 mA/cm2. Additionally, the energy efficiency (EE) remains around 83%, which is 8.45% higher than that of the pristine electrode assembled battery under 60 cycles. This work supplies a simple method to obtain a high-performance electrode material for ICRFBs and makes it a practical solution to promote ICFRBs large-scale commercialization process.
Catalyzed by cerium ammonium nitrate (CAN), the oxidative cracking reaction of alkenes occurred to produce carbonyls in good yields under mild conditions. The reaction employed molecular oxygen (O2) as the safe and clean oxidant. The catalyst dosage was reduced to as low as 0.5 mol%, while no additive was required. Thus, it may afford a generally green synthetic approach for introducing oxygen into organic molecules as well as the biomass degradation and the resource recycling from the C=C bond-containing waste polymers. X-ray photoelectron spectroscopy (XPS) analysis and control experiments demonstrated that the process proceeded via a single electron transfer (SET) reaction-initiated free radical reaction mechanism. In the process, both Ce and NO3− acted as the oxygen carrier to promote the oxidation reaction. The application of the abundantly existed nitrate in CAN was found to be the key for reducing the catalyst loading.
It is established that monitoring blood glucose on a daily basis is one of the most effective solutions to prevent and treat diabetes. Consequently, developing a glucose sensing platform with outstanding sensing performance occupies an indispensable position for the early diagnosis and risk assessment of diabetes. Recently, biosensor has been deemed as a promising apparatus to acquire the signals for glucose monitoring based on 2D materials. However, it is unsatisfied to deploy some materials widely as a result of some inherent defects. Carbon nanotubes have comparatively high toxicity. MoS2 with unfavourable biocompatibility are still arduously implemented on being functionalized. Fortunately, MXene, a brand-new and rapidly developing two-dimensional material, exhibits marvellous application potential in the domain of biosensing. Therefore, it has exerted tremendous attention from diverse scientific fields owning to its remarkable properties, such as excellent hydrophilicity, metal-like conductivity, abundant surface functional groups, unique layered structure, large specific surface area and remarkable biocompatibility. This review mainly focuses on the main synthetic route of MXenes, as well as the recent advancements of biosensors involving MXenes as an electrode modifier for glucose detection. In addition, the promising prospects and challenges of glucose sensing technology based on MXenes are also discussed.
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