Reaction Mechanism of Hydrogen Generation and Nitrogen Fixation at Carbon Nitride/Double Perovskite Heterojunctions

Photocatalytically active heterojunctions based on metal halide perovskites (MHPs) are drawing significant interest for their chameleon ability to foster several redox reactions. The lack of mechanistic insights into their performance, however, limits the ability of engineering novel and optimized materials. Herein, a report is made on a composite system including a double perovskite, Cs2AgBiCl6/g-C3N4, used in parallel for solar-driven hydrogen generation and nitrogen reduction, quantified by a rigorous analytical approach. The composite efficiently promotes the two reactions, but its activity strongly depends on the perovskite/carbon nitride relative amounts. Through advanced spectroscopic investigation and density function theory (DFT) modeling the H2 and NH3 production reaction mechanisms are studied, finding perovskite halide vacancies as the primary reactive sites for hydrogen generation together with a positive contribution of low loaded g-C3N4 in reducing carrier recombination. For nitrogen reduction, instead, the active sites are g-C3N4 nitrogen vacancies, and the heterojunction best performs at low perovskites loadings where the composites maximize light absorption and reduce carrier losses. It is believed that these insights are important add-ons toward universal exploitation of MHPs in contemporary photocatalysis

Characterization by Potentiometric Procedures of the Stability Constants of the Binary and Ternary Complexes of Cu(II) and Duloxetine Drug with Amino Acids

Potentiometric titration method has been used to define stoichiometries and stability constants of ternary complexes of Cu(II) with duloxetine (D) and some selected amino acids (L). The protonation constants of the ligands and the stability constants of the binary and ternary complexes of Cu(II) with the ligands were calculated from the potentiometric data using the HYPERQUAD program. The formation constants of the complexes formed in aqueous solutions and their concentration distributions as a function of pH were evaluated at 25°C and ionic strength 0.10 mol·L−1 NaNO3. Respective stabilities of ternary complexes have been determined compared with the corresponding binary complexes in terms of Δlog  K and %R.S. values. A novel binary and ternary duloxetine (D) drug with glycine and its Cu(II) complexes has been synthesized and characterized by several spectroscopic methods. Electronic spectra and magnetic susceptibility measurements reveal square planar geometry for both complexes. The elemental analyses and mass spectral data have justified the [Cu(D)(Gly)] and [Cu(D)Cl(H2O)] composition of complexes, where D = duloxetine and Gly = glycine. The EPR spectra of Cu(II) complexes support the mononuclear structures. Thermal properties and decomposition kinetics of Cu(II) complexes are investigated

Facile fabrication of CuScS2/CoO as an efficient electrocatalyst for oxygen evolution reaction and water treatment process

Producción CientíficaA major issue is the production of green and sustainable energy while the development of an effective, affordable, readily available with a higher rate of oxygen and hydrogen evolution reactions is need of the time. Here in present work, we fabricated CuScS2, CoO, and CuScS2/CoO to replace the extremely expensive Pt/C and IrO2 that are employed as the benchmark materials for water electrolysis. We have also investigated their electrochemical performance in an alkaline environment for the oxygen evolution reaction (OER). The CuScS2/CoO nanocomposite is more effective electrode material than CuScS2 and CoO. The composite material shows smaller overpotential (179 mV) and reduced Tafel slope (46 mV dec−1) value than individual materials to attain a current density of 10 mA cm−2. The better efficiency of the composite material is due to well-distinct good shape with greater BET surface area, and relatively small resistance to charge transfer. Furthermore, the CuScS2/CoO exhibits remarkable electrocatalytic as well as photocatalytic performance in comparison to CuScS2 and CoO. This research provides a valuable guide for developing an OER electrocatalyst in an alkaline medium and shows better electrochemical as well as photocatalytic performance of CuScS2/CoO nanomaterials.This work was funded by the Researchers Supporting Project Number (RSP2023R243) King Saud University, Riyadh, Saudi Arabi

Ti₃C₂-MXene/NiO Nanocomposites-Decorated CsPbI₃ Perovskite Active Materials under UV-Light Irradiation for the Enhancement of Crystal-Violet Dye Photodegradation

Ti3C2-MXene material, known for its strong electronic conductivity and optical properties, has emerged as a promising alternative to noble metals as a cocatalyst for the development of efficient photocatalysts used in environmental cleanup. In this study, we investigated the photodegradation of crystal-violet (CV) dye when exposed to UV light using a newly developed photocatalyst known as Ti3C2-MXene/NiO nanocomposite-decorated CsPbI3 perovskite, which was synthesized through a hydrothermal method. Our research investigation into the structural, morphological, and optical characteristics of the Ti3C2-MXene/NiO/CsPbI3 composite using techniques such as FTIR, XRD, TEM, SEM–EDS mapping, XPS, UV–Vis, and PL spectroscopy. The photocatalytic efficacy of the Ti3C2-MXene/NiO/CsPbI3 composite was assessed by evaluating its ability to degrade CV dye in an aqueous solution under UV-light irradiation. Remarkably, the Ti3C2-MXene/NiO/CsPbI3 composite displayed a significant improvement in both the degradation rate and stability of CV dye when compared to the Ti3C2-MXene/NiO nanocomposite and CsPbI3 perovskite materials. Furthermore, the UV–visible absorption spectrum of the Ti3C2-MXene/NiO/CsPbI3 composite demonstrated a reduced band gap of 2.41 eV, which is lower than that of Ti3C2-MXene/NiO (3.10 eV) and Ti3C2-MXene (1.60 eV). In practical terms, the Ti3C2-MXene/NiO/CsPbI3 composite achieved an impressive 92.8% degradation of CV dye within 90 min of UV light exposure. We also confirmed the significant role of photogenerated holes and radicals in the CV dye removal process through radical scavenger trapping experiments. Based on our findings, we proposed a plausible photocatalytic mechanism for the Ti3C2-MXene/NiO/CsPbI3 composite. This research may open up new avenues for the development of cost-effective and high-performance MXene-based perovskite photocatalysts, utilizing abundant and sustainable materials for environmental remediation

Green Synthesis of Silver Nanoparticles Using Thespesia populnea Bark Extract for Efficient Removal of Methylene Blue (MB) Degradation via Photocatalysis with Antimicrobial Activity and for Anticancer Activity

The green synthesis method was used to effectively fabricate Ag-NPs by using Thespesia populnea bark extract. The structural, morphological, elemental composition, and optical properties of as-synthesized Ag-NPs were characterized by powder X-ray diffraction (P-XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), transmission electron microscopy (TEM), and UV-Vis spectroscopy. Their photocatalytic efficiency as a photocatalyst was examined by degradation of methylene blue (MB) dye under direct sunlight irradiation. After 120 minutes of sunlight irradiation, Ag-NPs show photocatalytic degradation efficiency (DE percent) of 92%. The hydroxyl and superoxide radicals were found to be responsible for biodegradation. To the best of our acquaintance, this is the first research to use Ag-NPs as a photocatalyst for the efficient degradation of MB dye and its antimicrobial activity by using Thespesia populnea bark extract. The cytotoxic viability against SK-MEL cell line with a median inhibitory concentration (IC50) of 45 μL/mg proved its potent anticancer property. Based on the findings, the study revealed the significance of as-synthesized green Ag-NPs over other physically/chemically prepared Ag-NPs

Halide-driven formation of lead halide perovskites: insight from ab initio molecular dynamics simulations

Controlling the crystallization mechanism of metal halide perovskites is of utmost importance to grow defect-less perovskite layers for efficient solar cells and optoelectronic devices. Despite its relevance, there is a lack of microscopic understanding of the nucleation and crystallization processes during the formation of the perovskite phase from its precursors. To unveil the electronic and atomistic features of this process we carry out ab initio molecular dynamics simulations on a model system which consists of a stoichiometric layered lead iodide (PbI2)·methylammonium iodide (MAI) structure, characteristic of intermediate phases observed in sequential deposition methods. Our results show clear evidence of halide-driven chemistry: MAI iodine ions attack lead ions in the PbI2 layers and cause a nucleophilic substitution of Pb–I bonds with a subsequent breaking of the PbI2 layer. Undercoordinated [PbIn]2−n complexes are initially formed which create the 3D perovskite framework mediated by additional nucleophilic attacks. The relatively fast rearrangement of [PbIn]2−n complexes followed by motion of MA cations limits the perovskite growth. Our results provide insight into the key steps of the perovskite formation on a microscopic scale, providing hitherto inaccessible details on the factors limiting the perovskite growth and on the effect of different halides on the kinetics of crystal formation

Controlled Synthesis of Europium-Doped SnS Quantum Dots for Ultra-Fast Degradation of Selective Industrial Dyes

Herein, SnS and Eu-doped SnS QDs have been synthesized by a facile chemical co-precipitation method for efficient photocatalytic degradation of organic dye molecules. The structural, morphological, and optical properties of QDs were investigated by various physiochemical characterization techniques. The photocatalytic degradation of methylene blue (MB) and crystal violet (CV) dyes have been studied under visible light irradiation under direct sunlight using a spectrophotometer. Enhanced photodegradation efficiency of 87% and 94% were attained for SnS and Eu (4%)-doped SnS, respectively. For CV dye, the pure SnS showed only 70.7% however the Eu (4%)-doped SnS achieved 99% efficiency. The rate constant value of the doped SnS was found to be much higher than that of pure SnS for both dyes. The obtained results from various characterization studies provided the reason for the enhancement of the photocatalytic activity of Eu-doped SnS QDs due to the presence of Eu3+ in the SnS lattice, and also smaller crystallite size with high surface area and its morphological features. Moreover, the Eu3+ plays an essential role in reducing the band gap, hampering recombination, and the generation of free radicals, thus the QDs promoted attractive degradation activity and high stability

Controlled Synthesis of Europium-Doped SnS Quantum Dots for Ultra-Fast Degradation of Selective Industrial Dyes

Herein, SnS and Eu-doped SnS QDs have been synthesized by a facile chemical co-precipitation method for efficient photocatalytic degradation of organic dye molecules. The structural, morphological, and optical properties of QDs were investigated by various physiochemical characterization techniques. The photocatalytic degradation of methylene blue (MB) and crystal violet (CV) dyes have been studied under visible light irradiation under direct sunlight using a spectrophotometer. Enhanced photodegradation efficiency of 87% and 94% were attained for SnS and Eu (4%)-doped SnS, respectively. For CV dye, the pure SnS showed only 70.7% however the Eu (4%)-doped SnS achieved 99% efficiency. The rate constant value of the doped SnS was found to be much higher than that of pure SnS for both dyes. The obtained results from various characterization studies provided the reason for the enhancement of the photocatalytic activity of Eu-doped SnS QDs due to the presence of Eu3+ in the SnS lattice, and also smaller crystallite size with high surface area and its morphological features. Moreover, the Eu3+ plays an essential role in reducing the band gap, hampering recombination, and the generation of free radicals, thus the QDs promoted attractive degradation activity and high stability

Synthesis, DNA Binding, and Molecular Docking Studies of Dimethylaminobenzaldehyde-Based Bioactive Schiff Bases

A new series of p-dimethylaminobenzaldehyde derivatives were tested for therapeutic potential by exploring their properties through characterization. The derivatives were synthesized by 1 : 1 condensation reaction of p-dimethylaminobenzaldehyde and substituted amines. The synthesized compounds 1–8 were characterized by different characterization techniques including IR, mass, 1H NMR, and 13C NMR spectroscopy, elemental analysis, and mass spectrometry. Furthermore, binding of these Schiff bases to Ct-DNA was examined by absorption spectroscopy, fluorescence quenching, circular dichroic, viscosity measurement, molecular docking, and molecular dynamics simulation methods. Schiff bases were tested for antimicrobial activity against bacterial species Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus by the disc diffusion method. The pharmacological treatment of Schiff bases showed that 1–8 have promising potential against tested bacterial strains. The molecular docking study of the target compounds was also carried out against B-DNA dodecamer d(CGCGAATTCGCG)2, and it has been found that 1–8 can bind to Ct-DNA via an intercalative mode. DPPH free radical and hydrogen peroxide scavenging assays were employed to assess the antioxidant potential of synthesized Schiff bases

Microporous nickel phosphonate derived heteroatom doped nickel oxide and nickel phosphide: Efficient electrocatalysts for oxygen evolution reaction

Designing low-cost and highly efficient electrocatalysts based on widely abundant elements is highly desirable for future green energy production. Transition metal oxides and phosphides have recently been demonstrated to be promising and cost-effective electrocatalysts due to their distinct surface properties and good conductivity. Herein, we have synthesized a new microporous organic-inorganic hybrid nickel phosphonate (NiPPA) material under hydrothermal reaction condition without the use of structure directing agent. The microporous NiPPA material can be converted to N, P-codoped nickel oxide (NP/NiO) and N, O-codoped nickel phosphide (NO/NiP) following pyrolysis under air and nitrogen atmospheres, respectively. These high surface area materials are subsequently explored as electrocatalysts towards oxygen evolution reaction (OER) in alkaline media. Among the three catalysts, NP/NiO exhibits the highest electrocatalytic activity for OER with an overpotential of 332 mV to reach a current density of 10 mA cm and a low Tafel slope of 65.6 mV dec in 1.0 M KOH solution. Furthermore, the as-prepared NP/NiO catalyst displays an outstanding stability over a period of 15 h, suggesting the high durability of this catalyst for OER