Novel hydrostable Z-scheme Ag/CsPbBr3/Bi2WO6 photocatalyst for effective degradation of Rhodamine B in aqueous solution

In this study, a hydrostable Z-scheme Ag/CsPbBr₃/Bi₂WO₆ photocatalyst was designed and fabricated for the degradation of Rhodamine B (RhB). The structural instability of CsPbX₃ perovskites in water is one of the main obstacles that restrict their practical application in photocatalytic wastewater treatment. The photocatalyst was prepared in three steps: passivation of CsPbBr₃ nanocrystals (NCs) with 3-mercaptopropionic acid (MPA), construction of a heterojunction between MPA-passivated CsPbBr₃ NCs and Bi₂WO₆ ultrathin nanosheets, and doping Ag nanoparticles as charge mediators in the heterojunction. The as-obtained 5%Ag/20%CsPbBr₃/Bi₂WO₆ exhibits good stability and excellent photocatalytic activity. The degradation rate is 93.9% in 120 min, which is 4.41 times than that of Bi₂WO₆.     

Structural characterization,thermal stability,and solvent de-/ad-sorption behavior of two d10 M(II) (M = Cd and Zn) coordination polymers constructed by 1,3,5-tris(4-pyridylsulfanyl-methyl)-2,4,6-trimethyl-benzene (L1)

Two d¹⁰ M(II) (M = Cd and Zn) coordination polymers (CPs) with chemical formulas, {[Cd(L¹)(NCS)₂(H₂O)]⋅C₂H₅OH}_n (1) , and {[Zn(L¹)(NCS)₂]⋅C₂H₅OH⋅0.5H₂O}_n (2) (L¹ = 1,3,5-tris(4-pyridylsulfanylmethyl)-2,4,6-trimethylbenzene) were synthesized and structurally characterized by single-crystal x-ray diffraction method. In compound 1 , the coordination environment of Cd(II) ion is distorted octahedral bonded to three nitrogen donors from three L¹ ligands located in a facial-position, two nitrogen donors from NCS⁻ and one water molecule. The L¹ acts as a bridge ligand with tris-monodentate coordination mode in a cis-cis-cis structural conformation, connecting the Cd(II) to form a two-dimensional (2D) zigzag-like layered metal-organic frameworks. Adjacent 2D layers are then arranged orderly in an ABAB manner to complete its three-dimensional (3D) supramolecular architecture. In compound 2 , the coordination environment of Zn(II) ion is distorted tetrahedral bonded to two nitrogen donors from two L¹ ligands and two nitrogen donors from two NCS⁻ ligands. The L¹ acts as a bridge ligand with bis-monodentate coordination mode in a cis-cis-cis structural conformation, connecting the Zn(II) ions to form a one-dimensional (1D) zigzag-like polymeric chain. Adjacent chains are arranged orderly in an alternate ABAB manner to generate a 2D framework and then further arranged in an AAA manner to complete its 3D supramolecular architecture. The structural characterization as well as thermal-stability and solvents de-/ad-sorption behavior of 1 and 2 are studied and discussed in details.     

Structure determination and magnetic studies of triazole chelated Co(II) coordination polymers

Two cobalt(II) halide complexes with 1,2,4-triazole as a ligand were synthesized. Their structures were determined by extended x-ray absorption fine structure (EXAFS) and powder x-ray diffraction (XRD). Both complexes [Co(Htrz)Cl₂]_n ( 1 ) and {[Co(Htrz)₂(trz)]BF₄}_n ( 2 ) form one-dimensional polymeric chain and the distances of Co⋯Co are 3.3521(2) Å and 3.8629(2) Å, respectively. The Htrz and Cl⁻ are bridging ligands to connect two Co(II) ions in 1 , and the local environment of Co site is in a distorted octahedron with {CoN₂Cl₄} core. In complex 2 , two Htrz and one trz are bridging ligands to connect two Co(II) ions, and the local geometry of Co is in a pseudo octahedron with {CoN₆} core. The analysis of Co L_II,III-edge XAS indicates that the Co(II) of both complexes are at high spin state with t_2g⁵e_g² configuration and the crystal field strength (10Dq) is about 1.2 eV. The broken-symmetry DFT calculations indicate that antiferromagnetic coupling state of Co⋯Co is the most stable state in both complexes; and the coupling constants of 1 and 2 are −0.32 cm⁻¹ and −3.70 cm⁻¹, respectively. Based on the distances of Co⋯Co and coupling constants, such antiferromagnetic interaction is achieved through triazole ligands.     

One-pot synthesis of CuO/TiO2 nanocomposites for improved photocatalytic hydrogenation of 4-nitrophenol to 4-aminophenol under direct sunlight

The excellent photocatalytic hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with NaBH₄ in the aqueous medium is still a big challenge. Herein, we report a facile one-pot evaporation-induced self-assembly (EISA) method to synthesize a series of CuO/TiO₂ nanocomposites. The as-synthesized CuO/TiO₂ photocatalysts exhibit remarkable catalytic activity under direct sunlight in selective hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) due to the synergistic interaction of guest copper nanoparticles with host titanium dioxide (TiO₂) species. Especially, 5 wt% CuO/TiO₂ nanocomposite revealed superior reaction rate constant (k) value (0.306 min⁻¹) when compared to 3 wt% CuO/TiO₂ (0.192 min⁻¹) and 7 wt% CuO/TiO₂ (0.240 min⁻¹). Moreover, several characterization techniques (XRD, TEM, N₂ adsorption–desorption isotherm, DRS, and XPS) were executed to deeply investigate the effect of copper content on the bulk and interfacial properties of the catalysts. The characterization results proved that the superior photocatalytic hydrogenation over 5 wt% CuO/TiO₂ catalyst can be ascribed to moderate CuO loading as well as even dispersion of CuO species on the surface of active TiO₂ host, which can largely improve the light absorption ability within visible light region. Besides, the 5 wt% CuO/TiO₂ catalyst exhibits remarkable recyclability and durability, retaining its superior activity (above 95%) up to several repeating cycles, proving its practical applicability for hydrogenation reactions at domestic and industrial levels.     

A novel lipid droplets-targeting fluorescent probe based on dicyanisophorone and carbazole for Cu2+ and its application

A novel fluorescent probe, LCH , based on dicyanisophorone and carbazole, was prepared for the visual detection of Cu²⁺. The probe LCH could recognize Cu²⁺ by fluorescence quenching in EtOH/H₂O (1/4, v/v) solution, which could be easily identified under the 365 nm UV lamp, and the detection limit was as low as 0.785 μM. The recognition mechanism of probe LCH with Cu²⁺ was determined by combining ¹H NMR titration, MS, and theoretical calculations. Practical application experiments showed that probe LCH could be used to detect Cu²⁺ in the test strip experiments. Cell imaging experiments showed that the probe LCH owned good cell permeability and could be applied to the imaging of Cu²⁺ in HepG2 cells. In addition, fluorescence colocalization experiments showed that LCH could target lipid droplets. These results indicate that the probe LCH will have a good application prospect in environmental detection and clinical medicine.     

Hierarchical Integration of Organic Core/Shell Microwires for Advanced Photonics

The combination of multiple components or structures into integrated micro/nanostructures for practical application has been pursued for many years. Herein, a series of hierarchical organic microwires with branch, core/shell (C/S), and branch C/S structures are successfully constructed based on organic charge transfer (CT) cocrystals with structural similarity and physicochemical tunability. By regulating the intermolecular CT interaction, single microwires and branch microstructures can be integrated into the C/S and branch C/S structures, respectively. Significantly, the integrated branch C/S microwires, with multicolor waveguide behavior and branch structure multichannel waveguide output characteristics, can function as an optical logic gate with multiple encoding features. This work provides useful insights for creating completely new types of organic microstructures for integrated optoelectronics.     

Liquid Fluxional Ga Single Atom Catalysts for Efficient Electrochemical CO2 Reduction

Precise design and tuning of the micro-atomic structure of single atom catalysts (SACs) can help efficiently adapt complex catalytic systems. Herein, we inventively found that when the active center of the main group element gallium (Ga) is downsized to the atomic level, whose characteristic has significant differences from conventional bulk and rigid Ga catalysts. The Ga SACs with a P, S atomic coordination environment display specific flow properties, showing CO products with FE of ≈92 % at −0.3 V vs. RHE in electrochemical CO₂ reduction (CO₂RR). Theoretical simulations demonstrate that the adaptive dynamic transition of Ga optimizes the adsorption energy of the *COOH intermediate and renews the active sites in time, leading to excellent CO₂RR selectivity and stability. This liquid single atom catalysts system with dynamic interfaces lays the foundation for future exploration of synthesis and catalysis.     

Pd0-Catalyzed Asymmetric Carbonitratation Reaction Featuring an H-Bonding-Driven Alkyl−PdII−ONO2 Reductive Elimination

Reductive elimination of alkyl−Pd^II−O is a synthetically useful yet underdeveloped elementary reaction. Here we report that the combination of an H-bonding donor [PyH][BF₄] and AgNO₃ additive under toluene/H₂O biphasic system can enable such elementary step to form alkyl nitrate. This results in the Pd⁰-catalyzed asymmetric carbonitratations of (Z)-1-iodo-1,6-dienes with (R)-BINAP as the chiral ligand, affording alkyl nitrates up to 96 % ee. Mechanistic studies disclose that the reaction consists of oxidative addition of Pd⁰ catalyst to vinyl iodide, anion ligand exchange between I⁻ and NO₃⁻, alkene insertion and S_N2-type alkyl−Pd^II−ONO₂ reductive elimination. Evidences suggest that H-bonding interaction of PyH⋅⋅⋅ONO₂ can facilitate dissociation of O₂NO⁻ ligand from the alkyl−Pd^II−ONO₂ species, thus enabling the challenging alkyl−Pd^II−ONO₂ reductive elimination to be feasible.     

Reversible Switching CuII/CuI Single Sites Catalyze High-rate and Selective CO2 Photoreduction

Herein, we first design a model of reversible redox-switching metal–organic framework single-unit-cell sheets, where the abundant metal single sites benefit for highly selective CO₂ reduction, while the reversible redox-switching metal sites can effectively activate CO₂ molecules. Taking the synthetic Cu-MOF single-unit-cell sheets as an example, synchrotron-radiation quasi in situ X-ray photoelectron spectra unravel the reversible switching Cu^II/Cu^I single sites initially accept photoexcited electrons and then donate them to CO₂ molecules, which favors the rate-liming activation into CO₂^δ−, verified by in situ FTIR spectra and Gibbs free energy calculations. As an outcome, Cu-MOF single-unit-cell sheets achieve near 100 % selectivity for CO₂ photoreduction to CO with a high rate of 860 μmol g⁻¹ h⁻¹ without any sacrifice reagent or photosensitizer, where both the activity and selectivity outperform previously reported photocatalysts evaluated under similar conditions.     

High Power- and Energy-Density Supercapacitors through the Chlorine Respiration Mechanism

Supercapacitor represents an important electrical energy storage technology with high-power performance and superior cyclability. However, currently commercialized supercapacitors still suffer limited energy densities. Here we report an unprecedentedly respiring supercapacitor with chlorine gas iteratively re-inspires in porous carbon materials, that improves the energy density by orders of magnitude. Both electrochemical results and theoretical calculations show that porous carbon with pore size around 3 nm delivers the best chlorine evolution and adsorption performance. The respiring supercapacitor with multi-wall carbon nanotube as the cathode and NaTi₂(PO₄)₃ as the anode can store specific energy of 33 Wh kg⁻¹ with negligible capacity loss over 30 000 cycles. The energy density can be further improved to 53 Wh kg⁻¹ by replacing NaTi₂(PO₄)₃ with zinc anode. Furthermore, thanks to the extraordinary reaction kinetics of chlorine gas, this respiring supercapacitor performs an extremely high-power density of 50 000 W kg⁻¹.