Regulation of visible-light-driven photocatalytic degradation of Rhodamine B on BiOBr via zeta potential

Synthesis, structural characterization, DFT and molecular dynamics simulations of dinuclear (μ-hydroxo)-bridged triethanolamine copper(II) complexes: efficient candidates towards visible light-mediated photo-Fenton degradation of organic dyes

Multinuclear (di/tri) copper(II) complexes bridged through hydroxyl groups are very interesting coordination complexes owing to their potential applications in various fields. In this work, three novel dinuclear (μ-hydroxo)-bridged copper(II) complexes in the crystal form, namely, [Cu2(3,5-DIFLB)2(H2tea)2](H2O) (1), [Cu2(4-ClB)2(H2tea)2](H2O) (2), and [Cu2(4-ETHB)2(H2tea)2](H2O)2 (3) (where DIFLB = difluorobenzoate, CLB = chlorobenzoate, ETHB = ethoxybenzoate, and H3tea = triethanolamine), were isolated at room temperature using methanol and water in a 4 : 1 v/v ratio as a solvent. Furthermore, all three complexes (1-3) were characterised using spectroscopic (UV-vis, DRS, and FT-IR), electrochemical (CV) and single-crystal X-ray diffraction techniques. Structural insights gained by packing analysis revealed the role of steric constraints of substituents and various non-covalent interactions in lattice stabilization, which were indeed supported by theoretical and molecular electrostatic potential illustrations. Hirshfeld surface analysis provided quantitative verification about various non-covalent interactions (interatomic contacts) involved in the packing of molecules. Interestingly, as a potential application, complexes 1-3 all exhibited remarkable visible light-mediated photo-Fenton degradation of approximately 98% for 50 ppm concentration of organic dyes (fuchsin basic (FB) and methyl orange (MO)) in 90 minutes with the optimized conditions of 1 mg mL-1 of dye solution. In all the cases, dye degradation by these materials was ascribed to the symbiotic relations among the molecular structures of complexes 1-3, which were endowed with various electron-withdrawing and electron-releasing substituents and ionic strength, with respect to the structure, shape and interacting patterns of dye molecules. The adsorption mechanism indicates that various weak interactions between the donor and acceptor groups of complexes and dyes, such as electrostatic, hydrogen bonding, and direct coordination to metal sites, play a crucial role, which is confirmed by molecular dynamics (MD) simulations. Theoretical studies by DFT-based descriptors, molecular electrostatic potentials, and band gaps provided deep insights into various electronic and reactivity parameters. For subsequent processes of dye degradation, complexes 1-3 were stable and recoverable. The successful integration of experimental and theoretical approaches sheds light on copper-based dinuclear stable coordination complexes, showcasing a significant step towards the development of novel heterogeneous photo-Fenton catalysts.

An efficient electrochemical degradation of toxic pollutants in wastewater using BiOBr/BiVO4 hierarchical structured electrode material

The electrochemical degradation of alizarin red dye was studied using bismuth oxyhalide attached to bismuth vanadate nanocomposite synthesized via a simple solvothermal method. The electrochemical degradation of alizarin red dye was treated at current densities of 3 and 5 mA cm-1 for 30 min under different supporting electrolyte mediums (NaCl and KCl). Also, the electrochemical degradation of BiOBr/BiVO4 electrode shows higher degradation percentages of 97 and 99 for NaCl and KCl electrolyte solutions, which are higher degradation percentages than pure BiVO4 electrode (88 and 91 for NaCl and KCl). Also, the BiOBr/BiVO4 electrode shows 100% COD reduction during the 30th min of alizarin red dye using both NaCl and KCl electrolyte solutions. This may indicate that the prepared BiOBr/BiVO4 electrode shows an efficient electrode material for the degradation of textile dyes.

A direct dual Z-scheme 3DOM SnS2-ZnS/ZrO2 composite with excellent photocatalytic degradation and hydrogen production performance

A novel direct dual Z-scheme 3DOM (three-dimensional ordered macropores) SnS₂-ZnS/ZrO₂ composite was prepared by the template method combined with the in situ sulfur replacement technology. The composition, structure, morphology, and surface physicochemical properties of the composites were well characterized. The results indicate that it possesses a uniform and periodical macroporous structure, a large surface area (121.1 m² g^-1), broad visible light absorption, and high separation ability of photoinduced electron/hole pairs. 3DOM SnS₂-ZnS/ZrO₂ composite removed 96.8% of methyl orange within 210 min of simulated sunlight irradiation. Moreover, photocatalytic hydrogen production achieved the rate of 928.1 μmol g^-1, which was 66.3 times as high as that of the commercial P25 after 8 h simulated sunlight irradiation. The enhanced photocatalytic performance mainly attributed to the direct dual Z-scheme system, which improves the charge separation efficiency and optimizes the charge transfer pathway. The charge transfer mechanism over the 3DOM SnS₂-ZnS/ZrO₂ is discussed in detail based on the results of radical trapping experiments. Our work paves a new way to design 3DOM materials with direct dual Z-scheme structure.