Photocatalytic Degradation of Tetracycline Hydrochloride Based on the Structure-Property Exploration of BiOCl.

The correlation between structure and properties in the photodegradation reaction of bismuth oxychloride (BiOCl) was explored in this work. Three BiOCl samples with different sizes, morphological structures, and defects were prepared through a hydrothermal method with experimental manipulation. Their structural properties were comprehensively characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron spin resonance, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, and photoluminescence. Taking the photodegradation of tetracycline hydrochloride (TC-HCl) as the probe reaction, we found that high activity could be achieved by decreasing their crystal size and thickness, introducing proper defects in the structure, and assembling the nanosheets to get microball structure. Combined with radical-scavenge experiments and electron spin resonance (ESR) spin-trap spectra, we conclude that ̇O2- was the dominant reactive oxygen species for the degradation reaction. The degradation detailed pathway of TC-HCl was further analyzed using liquid chromatography-mass spectrometry. This work explores the structure-property correlation of BiOCl and provides strategies for the rational design of active photocatalysts for water remediation.

Facile solvent-free radical polymerization to prepare itaconate-functionalized hydrochar for efficient sorption of methylene blue and Pb(II).

An itaconate-functionalized hydrochar (IFHC) was prepared from one-step solvent-free radical copolymerization of bamboo hydrochar, itaconic acid, ammonium persulphate and sodium hydroxide in solvent-free environment, and was employed to absorb methylene blue (MB) and Pb(II) from wastewater. Characterizations show IFHC has rich carboxylate and tends to adsorb cationic contaminants. The largest adsorbed quantities of MB and Pb(II) by IFHC are up to 1036 and 291.8 mg·g-1 at 298 K respectively as per the Langmuir isotherm. Sorption of MB and Pb(II) onto IFHC can be expressed well by Langmuir isotherm and pseudo-2nd-order kinetics equations. The high sorption performance depends on the rich carboxylate, which can adsorb MB/Pb(II) through an electrostatic interaction/inner-surface complexation mechanism. The sorptive capacity of regenerated IFHC decreased below 10% after 5 desorption-resorption cycles. Thus, the solvent-free free radical copolymerization is an environmentally-friendly strategy to synthesize novel efficient sorbents that can clean cationic contaminants from wastewater.

Activation of ZrO2-WO3 solid acid catalysts in a Friedel-Crafts reaction through post-hydrothermal treatment.

ZrO2-WO3 mixed oxide plays an essential role in the chemical and petroleum industries. So far, very little work has paid attention to the activation of the low activity of ZrO2-WO3 catalysts. In this work, poorly reactive ZrO2-WO3 was prepared as a model catalyst by a sol-gel method and it was accompanied by post-hydrothermal treatment with various solutions. The catalytic results in the Friedel-Crafts reaction of anisole and benzyl alcohol showed that the post-hydrothermal treatment with ethylenediamine or ammonium hydroxide solutions dramatically improved the activity of ZrO2-WO3, while the hydrothermal treatments with water or ammonia chloride solution resulted in poorer activity and selectivity. The former treatments were found to induce a huge transformation of the ZrO2 crystal from monoclinic to tetragonal as well as a significant increase in acidic WO x clusters that anchored onto ZrO2. The generation of the WO x clusters was responsible for the activation of ZrO2-WO3.

Correction: The fabrication of hollow ZrO2 nanoreactors encapsulating Au-Fe2O3 dumbbell nanoparticles for CO oxidation.

Correction for 'The fabrication of hollow ZrO2 nanoreactors encapsulating Au-Fe2O3 dumbbell nanoparticles for CO oxidation' by Fan Yang et al., Nanoscale, 2021, 13, 6856-6862, DOI: 10.1039/D1NR00173F.

Enhanced removal of Cr(VI) by cation functionalized bamboo hydrochar.

Chemical modification on hydrochars can significantly improve their ability of removing heavy metal ions from wastewater, but so far no research has focused on the chemical modification through free radical reaction. In this work, a cation functionalized hydrochar (CFHC) bearing - N+H2R was synthesized by grafting-polymerization of glycidyl methacrylate (GMA) onto bamboo hydrochar under initiation by benzoyl peroxide, followed by the amination with the introduced epoxy group and diethylenetriamine and a subsequent hydrochloric acid treatment. The resulted CFHC exhibited a superior removal capacity of 424.09 mg·g-1 for Cr(VI), and the highest sorption occurred at pH of 2. Combining a series of characterizations and tests, it was concluded that the sorption conformed to the pseudo-second-order and Freundlich equations, indicating a multilayer chemisorption process that mainly driven by electrostatic reaction, reduction, and surface complexation. This research proved that a free radical polymerization treatment could effectively transform hydrochars into super adsorbents for wastewater treatment.

Hollow and mesoporous aluminosilica-encapsulated Pt-CoOx for the selective hydrogenation of substituted nitroaromatics.

Hollow and mesoporous aluminosilica nanoreactors (HMANs) with Pt-CoOx cores (∼4.7 nm) and hollow aluminosilica shells (∼50 nm) were designed by a selective etching method. The Pt-CoOx@HMANs demonstrate a greatly enhanced activity and selectivity for the hydrogenation of various substituted nitroaromatics compared to Pt@HMANs and Pt-CoOx@SiO2.

The fabrication of hollow ZrO2 nanoreactors encapsulating Au-Fe2O3 dumbbell nanoparticles for CO oxidation.

Nanosized Au catalysts suffer from serious sintering problems during synthesis or catalytic reactions at high temperatures. In this work, we integrate dumbbell-shaped Au-Fe3O4 heterostructures into hollow ZrO2 nanocages to make Au-Fe2O3@ZrO2 yolk-shell nanoreactors with high activity as well as ultra-high sintering resistance for high-temperature CO oxidation. The synthesis starts with the fabrication of a (Au-Fe3O4)@SiO2@ZrO2 core-shell nanostructure with a Au-Fe3O4 dumbbell nanoparticle (DB) core and SiO2/ZrO2 double shells, followed by calcination and the selective removal of the inner SiO2 shell with alkaline solution to obtain Au-Fe2O3@ZrO2 nanoreactors. The retained ZrO2 hollow (outer) shells protect the Au NPs from aggregation at temperatures up to 900 °C and show excellent long-term stability. Compared to Au@ZrO2 yolk-shell nanoreactors, Au-Fe2O3@ZrO2 shows improved activity in CO oxidation due to the active Au-Fe2O3 interface. This strategy can be extended to other yolk-shell nanoreactors with various nanocomposites and for different catalytic reactions.

Highly Efficient Ir-CoOx Hybrid Nanostructures for the Selective Hydrogenation of Furfural to Furfuryl Alcohol.

Decoration of noble metals with transition-metal oxides has been intensively studied for heterogeneous catalysis. However, controllable syntheses of metal-metal oxide heterostructures are difficult, and elucidation of such interfaces is still challenging. In this work, supported IrCo alloy nanoparticles are transformed into supported Ir-CoOx close-contact nanostructures by in situ calcination and following selective reduction. Relative to Ir/Al2O3, Ir-CoOx/Al2O3 shows greatly enhanced activities for the hydrogenation of furfural derivatives to the corresponding furfuryl alcohol derivatives with more than 99% selectivity and demonstrates significantly improved activities and selectivity for hydrogenations of α,ß-unsaturated aldehydes to α,ß-unsaturated alcohols. The modification of Ir surfaces with CoOx prevents Ir nanoparticles from growing, achieving high thermal and catalytic stabilities. Theoretic calculation suggests that the better catalytic performance of Ir-CoOx/Al2O3 is ascribed to the Ir-CoOx interaction, which promotes the absorption of furfural as well as desorption of furfuryl alcohol, resulting in enhanced catalytic activities.

Fabrication of Ir-CoOx@mesoporous SiO2 Nanoreactors for Selective Hydrogenation of Substituted Nitroaromatics.

Nanosized Ir catalysts suffer from serious side reactions and poor stability during hydrogenation of substituted nitroaromatics to produce aromatic amines. In this work, core-shell nanostructures with sub-4 nm Ir-CoOx hybrid cores and mesoporous SiO2 shells were designed and prepared to overcome these problems. The Ir-CoOx hybrid cores were converted from IrCo alloy nanoparticles (NPs) inside SiO2 through in situ calcination and reduction pretreatments. The SiO2 mesoporous shells in Ir-CoOx@SiO2 nanoreactors prevented the agglomeration/sintering of IrCo NPs, while allowing the free reactants and products (big molecules). The synergy between Ir and CoOx species improved H2 adsorption, thus affecting the reaction rate as well as the selectivity to aromatic amines. As a result, the obtained Ir-CoOx@SiO2 nanocatalyst showed tremendous improvement in catalytic activity, selectivity, and stability.

Non-noble metal-nitride based electrocatalysts for high-performance alkaline seawater electrolysis.

Seawater is one of the most abundant natural resources on our planet. Electrolysis of seawater is not only a promising approach to produce clean hydrogen energy, but also of great significance to seawater desalination. The implementation of seawater electrolysis requires robust and efficient electrocatalysts that can sustain seawater splitting without chloride corrosion, especially for the anode. Here we report a three-dimensional core-shell metal-nitride catalyst consisting of NiFeN nanoparticles uniformly decorated on NiMoN nanorods supported on Ni foam, which serves as an eminently active and durable oxygen evolution reaction catalyst for alkaline seawater electrolysis. Combined with an efficient hydrogen evolution reaction catalyst of NiMoN nanorods, we have achieved the industrially required current densities of 500 and 1000 mA cm-2 at record low voltages of 1.608 and 1.709 V, respectively, for overall alkaline seawater splitting at 60 °C. This discovery significantly advances the development of seawater electrolysis for large-scale hydrogen production.

Direct Z-Scheme charge transfer in heterostructured MoO3/g-C3N4 photocatalysts and the generation of active radicals in photocatalytic dye degradations.

Photocatalytic degradation is an attractive strategy to purify waste water contaminated by macromolecular organics. Compared with the single-component photocatalysts, heterostructures of different semiconductors have been widely used to improve the photocatalytic performance. In this work, we fabricate a hetero-structured photocatalyst consisting of two-dimensional graphitic carbon nitride (g-C3N4) nanosheets and commercial MoO3 microparticles through a simple mixing and annealing process. The photocatalytic performance was evaluated in various dye degradation reactions, especially Rhodamine (RhB) degradation. The MoO3/g-C3N4 composite shown a significant improvement compared with individual MoO3 or g-C3N4 as well as their physical mixture. By applying electron spin resonance (ESR) spin-trap spectra, radical scavenge experiments and electrochemical analysis, we find that a direct Z-scheme charge transfer between MoO3 and g-C3N4 not only causes an accumulation of electrons in g-C3N4 and holes in MoO3, but also boosts the formation of superoxide radical and hydroxyl radical. The superoxide radical and hole dominate the photocatalytic degradation, while the hydroxyl radical plays a negligible role and its production can be suppressed by lowering the pH value.

NO oxidation catalysis on copper doped hexagonal phase LaCoO3: a combined experimental and theoretical study.

Cobalt-based perovskite catalysts showed excellent performance towards NO-NO2 oxidation. We systematically investigated the influence of different levels of Cu-doping on the catalytic performance of hexagonal phase LaCoO3 (LaCo1-xCuxO3 (x = 0.1, 0.2, 0.3)) for NO oxidation. The catalytic activities of the oxide catalysts followed the sequence: LaCo0.9Cu0.1O3 > LaCoO3 > LaCo0.8Cu0.2O3 > LaCo0.7Cu0.3O3 where the highest NO conversion for LaCo0.9Cu0.1O3 was 82% at 310 °C. The relevant structural characterizations were conducted by XRD, BET, FTIR and TEM. The interaction between Co and Cu promoted the conversion of NO to NO2. Upon increasing the Cu doping content, a decrease of the performance resulted from the generation of isolated CuO on the surface of the oxides, confirmed using H2-TPR and XPS. Combined with first-principle calculations, we explored the reaction mechanism of NO oxidation on the surface and found that Cu doping would facilitate the reaction by decreasing the energy of oxygen vacancy formation and the NO2 desorption barrier from Co- or Cu-nitrite.

A soft-templated method to synthesize sintering-resistant Au-mesoporous-silica core-shell nanocatalysts with sub-5 nm single-cores.

Nano-gold (sub-5 nm)@mesoporous-silica (m-SiO2) core-shell nanospheres with controlled size and core number were prepared via a soft-templated method. The single-core Au@m-SiO2 particles showed great sintering-resistance at 750 °C and kept high catalytic activity for CO oxidation after the treatment.

Cholesterol synthesis in mice is suppressed but lipofuscin formation is not affected by long-term feeding of n-3 fatty acid-enriched oils compared with lard and n-6 fatty acid-enriched oils.

Hypocholesterolemic activity of dietary polyunsaturated fatty acids is observed after relatively short-term but not long-term feedings, and their long-term feedings are suspected to accelerate aging through tissue accumulation of lipid peroxides and age pigments (lipofuscin). To define the long-term effects of fats and oils in more detail, female mice were fed a conventional basal diet supplemented with lard (Lar), high-linoleic (n-6) safflower oil (Saf), rapeseed oil (Rap), high-alpha-linolenic (n-3) perilla oil (Per), or a mixture of ethyl docosahexaenoate and soybean oil (DHA/Soy) from 17 weeks to 71 weeks of age. The DHA/Soy and Per groups had decreased serum cholesterol levels compared with the Lar and Saf groups, but the difference between the Lar and Saf groups was not significant. The 3-hydroxy-3-methyglutary-CoA (HMG-CoA) reductase activity in the liver was also significantly lower in the Per and DHA/Soy groups. However, no significant difference in lipofuscin contents in the brain and liver was observed among the 5 dietary groups, despite significant differences in peroxidizability indices of the dietary and/or tissue lipids. These results indicate that n-3 fatty acid-rich oils are hypocholesterolemic by suppressing hepatic HMG-CoA reductase activity compared with animal fats and high-linoleic (n-6) oil, but tissue lipofuscin contents are not affected by a long-term feeding of fats and oils with different degree of unsaturation in mice.