Latest ArticlesCatalytic transfer hydrogenation (CTH) of furfural (FF) to furfuryl alcohol (FFA) has received great interest in recent years. Herein, Cu-Cs bimetallic supported catalyst, CuCs(2)-MCM, was developed for the CTH of FF to FFA using formic as hydrogen donor. CuCs(2)-MCM achieved a 99.6% FFA yield at an optimized reaction conditions of 170 ℃, 1 h. Cu species in CuCs(2)-MCM had dual functions in catalytically decomposing formic acid to generate hydrogen and hydrogenating FF to FFA. The doping of Cs made the size of Cu particles smaller and improved the dispersion of the Cu active sites. Importantly, the Cs species played a favorable role in enhancing the hydrogenation activity as a promoter by adjusting the surface acidity of Cu species to an appropriate level. Correlation analysis showed that surface acidity is the primary factor to affect the catalytic activity of CuCs(2)-MCM.
Constructing 3D multifunctional conductive framework as stable sulfur cathode contributes to develop advanced lithium-sulfur (Li-S) batteries. Herein, a freestanding electrode with nickel foam framework and nitrogen doped porous carbon (PC) network is presented to encapsulate active sulfur for Li-S batteries. In such a mutually embedded architecture with high stability, the interconnected carbon network and nickel foam matrix can expedite ionic/electronic transport and sustain volume variations of sulfur. Furthermore, rationally designed porous structures provide sufficient internal space and large surface area for high active sulfur loading and polar polysulfides anchoring. Benefiting from the synergistic superiority, the Ni/PC-S cathode exhibits a high initial capacity of around 1200 mAh/g at 0.2 C, excellent rate performance, and high cycling stability with a low decay rate of 0.059% per cycle after 500 cycles. This work provides a useful strategy to exploit freestanding porous framework for diverse applications.
A multifunctional nanocomposite of AgNPs@GQDs is prepared by synergistic in-situ growth of silver nanoparticles (AgNPs) on the complex of tannic acid (TA) and graphene quantum dots (GQDs) for the construction of dual-mode biosensing platform and cancer theranostics. The nanocomposite exhibits a hydrogen peroxide (H2O2)-responsive degradation, in which Ag0 is oxidized to Ag+ along with the release of oxidized TA and GQDs. The degradation induces the decreased absorbance and enhanced fluorescence (FL) intensity due to the suppression of Förster resonance energy transfer (FRET) in AgNPs@GQDs, which is employed for colorimetric/fluorescence dual-mode sensing of H2O2. The intrinsic peroxidase-like activity of GQDs nanozyme can effectively catalyze the oxidation reaction, enhancing the detection sensitivity significantly. Based on the generation of H2O2 from the oxidation of glucose with the catalysis of glucose oxidase (GOx), this nanoprobe is versatilely used for the determination of glucose in human serum. Further, through combining the H2O2-responsive degradation of AgNPs@GQDs with high H2O2 level in cancer cells, the nanocomposites exhibit good performance in cancer cell recognition and therapy, in which the synergistic anticancer effect of Ag+ and oxidized TA contribute to effective cell death, and the liberated GQDs are used to monitor the therapeutic effect by cell imaging.
Radiotherapy is commonly used to treat advanced pancreatic cancers and can improve survival by 2 months in combination with gemcitabine. However, prognosis and survival improvement remain unsatisfactory, and effective therapies are urgently needed. Piperlongumine has been demonstrated to have therapeutic potentials against various cancers. In this study, we synthesized a series of piperlongumine derivatives and provided evidence that piperlongumine derivatives could be used as effective radiosensitizers in pancreatic cancer. Two compounds enhanced the radiosensitivity of Panc-1 and SW1990 cells. In a pancreatic bi-flank xenograft tumor model, they significantly inhibited tumor growth. Piperlongumine derivatives could induce reactive oxygen species (ROS) expression and regulate the Keap1-Nrf2 protective pathway with enhancement of radiation-induced DNA damage, G2/M-phase cell cycle arrest, and apoptosis. Collectively, our data offer a proof of concept for the use of piperlongumine derivatives as a novel class of radiosensitizers for the treatment of pancreatic cancer.
Selective separation of CO2/CH4 and C2H2/CH4 are promising for their high-purity industrial demand and scientific research on account of the similar molecular radius and physical properties. In this work, a unique 3D microporous MOF material [Cu(SiF6)(sdi)2] solvents (1, sdi = 1, 1'-sulfonyldiimidazole) was successfully constructed by cross-linking 1D coordination polymer chains. The dense functional active sites on the inner walls of the channel of 1a can provide strong binding affinities to CO2, C2H2, and thus effectively improve the gas separation performance of CO2/CH4 and C2H2/CH4.
Stable solid electrolyte interphase (SEI) has been well established to be critical for the reversible operation of Li (ion) batteries, yet our understanding of its mechanical properties currently remains incomplete. Here, we used an electrochemical quartz crystal microbalance combined with dissipation monitoring (EQCM-D) to investigate SEI formation. By quantitatively estimating in-situ, the change in mass, shear modulus, and viscosity of the SEI, we show that the SEI formation in propylene carbonate (PC)- and ethylene carbonate/diethyl carbonate (EC/DEC)-based electrolytes involves the growth of a rigid layer followed by a viscoelastic layer, whereas a distinct "one-layer" rigid model is applicable to the SEI formulated in tetraethylene glycol dimethyl ether (TEGDME)-based electrolyte. With the continuous formation of the SEI, its shear modulus decreases accompanied by an increase in viscosity. In TEGDME, the lightest/thinnest SEI (mass lower than in PC by a factor of nine) yet having the greatest stiffness (more than five times that in PC) is obtained. We attribute this behavior to differences in the chemical composition of the SEIs, which have been revealed by tracking the mass-change-per-mole-of-electron-transferred using EQCM-D and further confirmed by X-ray photoelectron spectroscopy.
Metallic zinc is attractive anode material of rechargeable aqueous Zn-based batteries due to its ambient stability, high volumetric capacity, and abundant reserves. Nonetheless, Zn anodes suffer from issues such as low coulombic efficiency (CE), large polarization and dendrite formation. Herein, uniform Zn electrodeposition is reported on carbon substrates by selective nitrogen doping. Combined experimental and theoretical investigations demonstrate that pyrrolic and pyridinic nitrogen doped in carbon play beneficial effect as zinc-philic sites to direct nucleation and growth of metallic Zn, while negligible effect is observed for graphite nitrogen in Zn plating. The carbon cloth with modified amount of doped pyrrolic and pyridinic nitrogen stabilizes Zn plating/stripping with 99.3% CE after 300 cycles and significantly increases the deliverable capacity at high depth of charge and discharge compared to undoped carbon substrate and Zn foil. This work provides a better understanding of heteroatom doping effect in design and preparation of stable 3D carbon-supported zinc anode.
Lithium sulfur batteries with high energy density are thought to be the most potential energy storage technology that can be commercialized. However, the shuttle effect of polysulfides deteriorates its electrochemical performance. Herein, a novel Co9S8 nanostructure derived from metal organic framework material (MOF) was explored by simple liquid phase reaction and heat vulcanization of 2-methylimidazole and Co(NO3)2·6H2O on the surface of the original PP separator. The Co9S8 nano-flower cluster array wall was vertically and closely arranged with the thickness of 200 nm, and the polysulfide can be adsorbed by its physical and chemical action to slow down the "shuttle effect". It is found that the cell with the modified separator can achieve an ideal discharge capacity of about 600 mAh/g at 1 C. The specific capacity is maintained at 500 mAh/g after 200 cycles, with only 0.11% of capacity decay per cycle. It provides a new way for the utilization of MOF material derivatives to modify the separator in order to improve the electrochemical performance of lithium-sulfur batteries.
Non-enzymatic electrochemical sensors for the determination of hydrogen peroxide (H2O2) have attracted more and more concerns. A series of nickel and cobalt double oxides (NixCoy-DO) with the different ratios of Ni/Co have been prepared by a polyol-mediated solvothermal method for H2O2 detection. The obtained products exhibit honeycomb-like open porous microtubes constituted with the low-dimensional nanostructured NixCoy-DO blocks after the calcination treatment. Compared with nickel oxides, the introduced Co ions in NixCoy-DO can induce the production of surficial oxygen vacancies, and further enhance the electrode surface activity. In particular, the NiCo-DO sample (with an atomic ratio of Ni/Co = 4:3) shows the richest surficial oxygen vacancies and presents the highest H2O2 detection activity among all the as-prepared samples, demonstrating an excellent sensitivity of 698.60 μA L mmol-1 cm-2 (0 ~ 0.4 mmol/L), low detection limit (0.28 μmol/L, S/N = 3), as well as long stability, high selectivity and good reproducibility. This work lends a new impetus to the potential application of double metal oxides for the next generation of non-enzymatic sensors.
Developing highly efficient nickel or iron based hydroxide electrocatalysts is primary essential but challenging for oxygen evolution reaction (OER) at ultra-high current densities. Herein, we developed a facile method to prepare nitrogen and iron doped nickel(Ⅱ) hydroxide nanosheets on self-supported conductive nickel foam (denoted as Fe, N-Ni(OH)2/NF) through ammonia hydrothermal and impregnation methods. Owing to the optimization of the electronic structure by nitrogen doping and the strong synergistic effect between Fe and Ni(OH)2, the three-dimensional (3D) Fe, N-Ni(OH)2/NF nanosheets delivered superior electrocatalytic OER performances in basic solution with low potentials of 1.57V and 1.59V under 500mA/cm2 and 1000mA/cm2 respectively and robust operation for 10 h with ignored activity decay, comparing well with the potentials of previously reported NiFe based electrocatalysts as well as the benchmark commercial Ir/C/NF. In-situ Raman spectroscopy revealed that the main active species were NiOOH during the OER process. The present results are expected to provide new insights into the study of OER process towards ultra-high current densities.
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