Application of Bimetallic Hydroxide/Graphene Composites in Wastewater Treatment.

The increasing discharge of antibiotic wastewater leads to increasing water pollution. Most of these antibiotic wastewaters are persistent, strongly carcinogenic, easy to bioaccumulate, and have other similar characteristics, seriously jeopardizing human health and the ecological environment. As a commonly used wastewater treatment technology, non-homogeneous electro-Fenton technology avoids the hazards of H2O2 storage and transportation as well as the loss of desorption and reabsorption. It also facilitates electron transfer on the electrodes and the reduction of Fe3+ on the catalysts, thereby reducing sludge production. However, the low selectivity and poor activity of electro-synthesized H2O2, along with the low concentration of its products, combined with the insufficient activity of electrically activated H2O2, results in a low ∙OH yield. To address the above problems, composites of layered bimetallic hydroxides and carbon materials were designed and prepared in this paper to enhance the performance of electro-synthesized H2O2 and non-homogeneous electro-Fenton by changing the composite mode of the materials. Three composites, NiFe layered double hydroxides (LDHs)/reduced graphene oxide (rGO), NiMn LDHs/rGO, and NiMnFe LDHs/rGO, were constructed by the electrostatic self-assembly of exfoliated LDHs with few-layer graphene. The LDHs/rGO was loaded on carbon mats to construct the electro-Fenton cathode materials, and the non-homogeneous electro-Fenton oxidative degradation of organic pollutants was realized by the in situ electrocatalytic reduction of O2 to ∙OH. Meanwhile, the effects of solution pH, applied voltage, and initial concentration on the performance of non-homogeneous electro-Fenton were investigated with ceftazidime as the target pollutant, which proved that the cathode materials have an excellent electro-Fenton degradation effect.

Multi-level Reactive Oxygen Species Amplifier to Enhance Photo-/Chemo-Dynamic/Ca2+ Overload Synergistic Therapy.

Reactive oxygen species (ROS)-involved photodynamic therapy (PDT) and chemodynamic therapy (CDT) hold great promise for tumor treatment. However, hypoxia, insufficient H2O2, and overexpressed glutathione (GSH) in the tumor microenvironment (TME) hinder ROS generation significantly. Herein, we reported CaO2@Cu-TCPP/CUR with O2/H2O2/Ca2+ self-supply and GSH depletion for enhanced PDT/CDT and Ca2+ overload synergistic therapy. CaO2 nanospheres were first prepared and used as templates for guiding the coordination between the carboxyl of tetra-(4-carboxyphenyl)porphine (TCPP) and Cu2+ ions as hollow CaO2@Cu-TCPP, which facilitated GSH-activated TCPP-based PDT and Cu+-mediated CDT. The hollow structure was then loaded with curcumin (CUR) to form CaO2@Cu-TCPP/CUR composites. Cu-TCPP prevented degradation of CaO2, while Cu2+ ions reacted with GSH to deplete GSH, produce Cu+ ions, and release TCPP, CaO2, and CUR. CaO2 reacted with H2O to generate O2, H2O2, and Ca2+ to achieve O2/H2O2/Ca2+ self-supply for TCPP-based PDT, Cu+-mediated CDT, and CUR-enhanced Ca2+ overload therapy. Thus, this multilevel ROS amplifier enhances synergistic therapy with fewer side effects and drug resistance.

Modification Strategies for Development of 2D Material-Based Electrocatalysts for Alcohol Oxidation Reaction.

2D materials, such as graphene, MXenes (metal carbides and nitrides), graphdiyne (GDY), layered double hydroxides, and black phosphorus, are widely used as electrocatalyst supports for alcohol oxidation reactions (AORs) owing to their large surface area and unique 2D charge transport channels. Furthermore, the development of highly efficient electrocatalysts for AORs via tuning the structure of 2D support materials has recently become a hot area. This article provides a critical review on modification strategies to develop 2D material-based electrocatalysts for AOR. First, the principles and influencing factors of electrocatalytic oxidation of alcohols (such as methanol and ethanol) are introduced. Second, surface molecular functionalization, heteroatom doping, and composite hybridization are deeply discussed as the modification strategies to improve 2D material catalyst supports for AORs. Finally, the challenges and perspectives of 2D material-based electrocatalysts for AORs are outlined. This review will promote further efforts in the development of electrocatalysts for AORs.

Revealing the enhanced photoelectrochemical water oxidation activity of Fe-based metal-organic polymer-modified BiVO4 photoanode.

Metal-organic polymers (MOPs) can enhance the photoelectrochemical (PEC) water oxidation performance of BiVO4 photoanodes, but their PEC mechanisms have yet to be comprehended. In this work, we constructed an active and stable composite photoelectrode by overlaying a uniform MOP on the BiVO4 surface using Fe2+ as the metal ions and 2,5-dihydroxyterephthalic acid (DHTA) as ligand. Such modification on the BiVO4 surface yielded a core-shell structure that could effectively enhance the PEC water oxidation activity of the BiVO4 photoanode. Our intensity-modulated photocurrent spectroscopy analysis revealed that the MOP overlayer could concurrently reduce the surface charge recombination rate constant (ksr) and enhance the charge transfer rate constant (ktr), thus accelerating water oxidation activity. These phenomena can be ascribed to the passivation of the surface that inhibits the recombination of the charge carrier and the MOP catalytic layer that improves the hole transfer. Our rate law analysis also demonstrated that the MOP coverage shifted the reaction order of the BiVO4 photoanode from the third-order to the first-order, resulting in a more favorable rate-determining step where only one hole accumulation is required to overcome water oxidation. This work provides new insights into the reaction mechanism of MOP-modified semiconductor photoanodes.

B, N Co-Doping Sequence: An Efficient Electronic Modulation of the Pd/MXene Interface with Enhanced Electrocatalytic Properties for Ethanol Electrooxidation.

Improving the electrocatalytic properties by regulating the surface electronic structure of supported metals has always been a hot issue in electrocatalysis. Herein, two novel catalysts Pd/B-N-Ti3C2 and Pd/N-B-Ti3C2 are used as the models to explore the effect of the B and N co-doping sequence on the surface electronic structure of metals, together with the electrocatalytic properties of ethanol oxidation reaction. The two catalysts exhibit obviously stratified morphology, and the Pd nanoparticles having the same amount are both uniformly distributed on the surface. However, the electron binding energy of Ti and Pd elements of Pd/B-N-Ti3C2 is smaller than that of Pd/N-B-Ti3C2. By exploring the electrocatalytic properties for EOR, it can be seen that all the electrochemical surface area, maximum peak current density, and antitoxicity of the Pd/B-N-Ti3C2 catalyst are much better than its counterpart. Such different properties of the catalysts can be attributed to the various doping species of B and N introduced by the doping sequence, which significantly affect the surface electronic structure and size distribution of supported metal Pd. Density functional theory calculations demonstrate that different B-doped species can offer sites for the H atom from CH3CH2OH of dehydrogenation in Pd/B-N-Ti3C2, thereby facilitating the progress of the EOR to a favorable pathway. This work provides a new insight into synthesizing the high-performance anode materials for ethanol fuel cells by regulating the supported metal catalyst with multielement doping.

Recent Progress in Near-Infrared Organic Electroluminescent Materials.

Near-infrared (NIR) refers to the section of the spectrum from 650 to 2500 nm. NIR luminescent materials are widely employed in organic light-emitting diodes (OLEDs), fiber optic communication, sensing, biological detection, and medical imaging. This paper reviews organic NIR electroluminescent materials, including organic NIR electrofluorescent materials and organic NIR electrophosphorescent materials that have been investigated in the past 6 years. Small-molecule, polymer NIR fluorescent materials and platinum(II) and iridium(III) complex NIR phosphorescent materials are described, and the limitations of the development of NIR luminescent materials and future prospects are discussed.

Three types of noncovalent interactions studied between pyrazine and XF.

Three types noncovalent interactions (type I, II and III) between pyrazine (C4H4N2) and XF (X = F, Cl, Br, and I) have been discovered at the MP2/aug-cc-pVTZ level. TypeI is σ-hole interaction between the positive site on the halogen X of XF and the negative site on one of the pyrazine nitrogens. Type II is counterintuitive σ-hole interaction driven by polarization between the positive site on the halogen X of XF and a portion of the pyrazine ring. Type III is an interaction between the lateral regions of the halogen X of XF and the position of the pyrazine ring. Through comparing the calculated interaction energy, we can know that the type II and type III interactions are weaker than the corresponding type I interactions, and type III interactions are weaker than the corresponding type II interactions in C4H4N2-XF complexes. SAPT analysis shows that the electrostatic energy are the major source of the attraction for the type I (σ-hole) interactions while the type III interactions are mainly dispersion energy. For the type II (counterintuitive σ-hole) interactions in C4H4N2-XF (X = F and Cl) complexes, electrostatic energy are the major source of the attraction, while in C4H4N2-XF (X = Br and I) complexes, the electrostatic term, induction and dispersion play equally important role in the total attractive interaction. NBO analysis, AIM theory, and conceptual DFT are also being utilized.

Theoretical and conceptual DFT study of pnicogen- and halogen-bonded complexes of PH2X---BrCl.

The pnicogen and halogen bonding interactions in the PH2X---BrCl(X = H, F, OH, OCH3 and CH3) complexes have been studied at the MP2/aug-cc-pVTZ level. Analysis of interaction energies shows that the pnicogen-bonded structures are less stable than the corresponding halogen-bonded structures. The pnicogen and halogen bonds were also studied by conceptual DFT reactivity indices. Noncovalent interaction (NCI) and SAPT analysis reveals that the dispersion interactions dominate the pnicogen-bonded complexes of PH2X---BrCl in nature, while the halogen-bonded complexes are dominantly electrostatic energy. Graphical abstract It is found that the local softness s+ or s-on the basic center P of PH2X is related to the interaction energies (ΔECP) of halogen- or pnicogen-bonded complexes.

Luminescent properties of CdTe quantum dots synthesized using 3-mercaptopropionic acid reduction of tellurium dioxide directly.

A facile one-step synthesis of CdTe quantum dots (QDs) in aqueous solution by atmospheric microwave reactor has been developed using 3-mercaptopropionic acid reduction of TeO2 directly. The obtained CdTe QDs were characterized by ultraviolet-visible spectroscopy, fluorescent spectroscopy, X-ray powder diffraction, multifunctional imaging electron spectrometer (XPS), and high-resolution transmission electron microscopy. Green- to red-emitting CdTe QDs with a maximum photoluminescence quantum yield of 56.68% were obtained.

N'-[(E)-2-Hydroxy-benzyl-idene]-5-methyl-isoxazole-4-carbohydrazide monohydrate.

In the structure of the title compound, C(12)H(11)N(3)O(3)·H(2)O, the dihedral angle formed by the benzene and isoxazole rings is 2.03 (8)°. The mol-ecular conformation is stabilized by an intra-molecular O-H⋯N hydrogen bond. In the crystal structure, mol-ecules are linked into a three-dimesional network by inter-molecular N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds, and by π-π stacking inter-actions involving adjacent benzene and isoxazole rings [centroid-centroid separation = 3.663 (2) Å].

(E)-N'-Benzyl-idene-5-methyl-isoxazole-4-carbohydrazide.

The mol-ecule of the title compound, C(12)H(11)N(3)O(2), is approximately planar with an r.m.s. deviation of 0.0814 Šfrom the plane through all the non-H atoms. The dihedral angle formed by the benzene and isoxazole rings is 6.88 (16)°. The mol-ecular conformation is stabilized by an intra-molecular C-H⋯N hydrogen bond, forming an S(6) ring, and the mol-ecule displays an E configuration with respect to the C=N double bond. In the crystal structure, inter-molecular N-H⋯O hydrogen bonds form centrosymmetric dimers which are further linked by weak C-H⋯N inter-actions augmented by very weak C-H⋯π contacts, forming layers parallel to (120).

5-Methyl-N'-(3-nitrobenzylidene)isoxazole-4-carbohydrazide.

The mol-ecule of the title compound, C(12)H(10)N(4)O(4), displays an E configuration about the C=N bond. The dihedral angle between the benzene and isoxazole rings is 1.36 (5)° and the mol-ecular conformation is stabilized by the an intra-molecular C-H⋯N hydrogen bond. In the crystal structure, centrosymmetrically related mol-ecules are connected by pairs of N-H⋯O hydrogen bonds into dimers, which are further linked into a three-dimensional network by inter-molecular C-H⋯O hydrogen bonds and by π⋯π stacking inter-actions involving adjacent benzene and isoxazole rings, with a centroid-centroid separation of 3.861 (3) Å.