Project description:Ce-doped ZnO (ZnO:Ce) nanorods have been prepared through a solvothermal method and the effects of Ce-doping on the structural, optical and electronic properties of ZnO rods were studied. ZnO:Ce rods were characterized by XRD, SEM, TEM, XPS, BET, DRS and Raman spectroscopy. 5% Ce-doped ZnO rods with an average length of 130 nm and a diameter of 23 nm exhibit the highest photocatalytic activity for the degradation of the Orange II dye under solar light irradiation. The high photocatalytic activity is ascribed to the substantially enhanced light absorption in the visible region, to the high surface area of ZnO:Ce rods and to the effective electron-hole pair separation originating from Ce doping. The influence of various experimental parameters like the pH, the presence of salts and of organic compounds was investigated and no marked detrimental effect on the photocatalytic activity was observed. Finally, recyclability experiments demonstrate that ZnO:Ce rods are a stable solar-light photocatalyst.
Project description:For several decades, the iron-based Fenton-like catalysis has been believed to be mediated by hydroxyl radicals or high-valent iron-oxo species, while only sporadic evidence supported the generation of singlet oxygen (1O2) in the Haber-Weiss cycle. Herein, we report an unprecedented singlet oxygen mediated Fenton-like process catalyzed by ∼2-nm Fe2O3 nanoparticles distributed inside multiwalled carbon nanotubes with inner diameter of ∼7 nm. Unlike the traditional Fenton-like processes, this delicately designed system was shown to selectively oxidize the organic dyes that could be adsorbed with oxidation rates linearly proportional to the adsorption affinity. It also exhibited remarkably higher degradation activity (22.5 times faster) toward a model pollutant methylene blue than its nonconfined analog. Strikingly, the unforeseen stability at pH value up to 9.0 greatly expands the use of Fenton-like catalysts in alkaline conditions. This work represents a fundamental breakthrough toward the design and understanding of the Fenton-like system under nanoconfinement, might cause implications in other fields, especially in biological systems.
Project description:Photo-Fenton is a promising photocatalytic technology that utilizes sunlight. Herein, an Fe-free 3%-CuO/Sr0.76Ce0.16WO4 photocatalyst was synthesized to apply simulated wastewater degradation via a photo-Fenton process under simulated sunlight. The photodegradation efficiency of RhB solution over the 3%-CuO/Sr0.76Ce0.16WO4 photocatalyst is 93.2% in the first 3 h; its photocatalytic efficiency remains at 91.6% even after three cycle experiments. The kinetic constant of the 3%-CuO/Sr0.76Ce0.16WO4 photocatalyst is 0.0127 min-1, which is 2.8-fold that of an intrinsic Sr0.76Ce0.16WO4 sample. The experiment of radical quenching revealed that the photogenerated electrons and holes are transferred to CuO to form hydroxyl radicals. Besides, the photocatalyst was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), diffused reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS) measurements. It has some reference significance for the design of iron-free photocatalysts.
Project description:In this work, a photo-electro Fenton catalytic nanoplatform based on concave octopus-like PtCu nanoframes was fabricated for organic dyestuff degradation. The electrochemical oxidation reaction was performed to generate hydrogen peroxide (H2O2) on the interface of PtCu nanoframes via a promising electro-Fenton process for on-demand aqueous remediation.
Project description:It is an urgent challenge to develop low-cost and high-performance catalysts for the oxygen evolution reaction (OER). We synthesized nanoparticulate electrocatalysts consisting of cobalt-doped goethite-type iron oxyhydroxide (α-FeOOH) with controlled Co/Fe ratios [Co x Fe1-x OOH (x ≤ 0.20)] based on our own wet process. A Co0.20Fe0.80OOH-coated glassy carbon electrode generated a current density (j) of 10 mA cm-2 at an overpotential (η) as small as 383 mV (1.61 V vs the reversible hydrogen electrode) in an alkaline electrolyte, with a small Tafel slope of 40 mV dec-1 and excellent durability, whereas pure α-FeOOH required η = 580 mV to reach the same current density. This can be ascribed to the effect of Co doping, which resulted in an increase in electrochemically active surface area and a decrease in charge-transfer resistance. The content of cobalt, a scarce resource, in the catalyst is much smaller than those in most of the other Fe-based catalysts reported so far. Thus, this study will provide a new strategy of designing cost-effective and high-performance catalysts for the OER in alkaline solution.
Project description:The study of nonenzymatic template-directed RNA copying is the experimental basis for the search for chemistry and reaction conditions consistent with prebiotic RNA replication. The most effective model systems for RNA copying have to date required a high concentration of Mg2+. Recently, Fe2+, which was abundant on the prebiotic anoxic Earth, was shown to promote the folding of RNA in a manner similar to the case of Mg2+, as a result of the two cations having similar interactions with phosphate groups. These observations raise the question of whether Fe2+ could have promoted RNA copying on the prebiotic Earth. Here, we demonstrate that Fe2+ is a better catalyst and promotes faster nonenzymatic RNA primer extension and ligation than Mg2+ when using 2-methylimidazole activated nucleotides in slightly acidic to neutral pH solutions. Thus, it appears likely that Fe2+ could have facilitated RNA replication and evolution in concert with other metal cations on the prebiotic Earth.
Project description:Heterogeneous photo-Fenton systems offer efficient solutions for the treatment of wastewaters in the textile industry. This study investigated the fabrication and structural characterization of novel peculiar-shaped CuIIO, FeIII2O3, and FeIIO nanoparticles (NPs) compared to the properties of the iron(II)-doped copper ferrite CuII0.4FeII0.6FeIII2O4. The photocatalytic efficiencies of these NPs and the composite of the simple oxides (CuIIO/FeIIO/FeIII2O3) regarding the degradation of methylene blue (MB) and rhodamine B (RhB) as model dyes were also determined. The catalysts were synthesized via simple co-precipitation and calcination technique. X-ray diffractometry (XRD), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS) were utilized for structural characterization. The structure of CuIIO was bead-like connected into threads, FeIII2O3 was rod-like, while FeIIO pallet-like, with average crystallite sizes of 18.9, 36.9, and 37.1 nm, respectively. The highest degradation efficiency was achieved by CuIIO for RhB and by CuII0.4FeII0.6FeIII2O4 for MB. The CuIIO/FeIIO/FeIII2O3 composite proved to be the second-best catalyst in both cases, with excellent reusability. Hence, these NPs can be successfully applied as heterogeneous photo-Fenton catalysts for the removal of hazardous pollutants. Moreover, the simple metal oxides and the iron(II)-doped copper ferrite displayed a sufficient antibacterial activity against Gram-negative Vibrio fischeri.
Project description:Sunlight inactivation of Escherichia coli has previously been shown to accelerate in the presence of oxygen, exogenously added hydrogen peroxide, and bioavailable forms of exogenously added iron. In this study, mutants unable to effectively scavenge hydrogen peroxide or superoxide were found to be more sensitive to polychromatic simulated sunlight (without UVB wavelengths) than wild-type cells, while wild-type cells grown under low-iron conditions were less sensitive than cells grown in the presence of abundant iron. Furthermore, prior exposure to simulated sunlight was found to sensitize cells to subsequent hydrogen peroxide exposure in the dark, but this effect was attenuated for cells grown with low iron. Mutants deficient in recombination DNA repair were sensitized to simulated sunlight (without UVB wavelengths), but growth in the presence of iron chelators reduced the degree of sensitization conferred by this mutation. These findings support the hypothesis that hydrogen peroxide, superoxide, and intracellular iron all participate in the photoinactivation of E. coli and further suggest that the inactivation rate of enteric bacteria in the environment may be strongly dependent on iron availability and growth conditions.
Project description:We present a general strategy for the synthesis of stable 3-D metallosupramolecular tetragonal prisms in which multicomponent coordination-driven self-assembly allows for single supramolecular species to be formed. The appropriate stoichiometric combination of a tetraphenylethylene-based tetratopic donor (1), a linear dipyridine donor (2), and a 90 degrees platinum metal complex (3) affords tetragonal prisms (4) as single products. The compounds have been characterized by multinuclear NMR spectroscopy and electrospray ionization mass spectrometry. The size of the supramolecules was determined by pulsed-gradient spin-echo NMR and modeled with molecular force field simulation methods.