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This study reports on one of the best heterogeneous catalysts for the dehydrogenation of dimethylamine–borane (DMAB). This new catalytic system consists of highly monodisperse Pd and Ru alloy nanoparticles supported by poly(N -vinyl-pyrrolidone) (PdRu@PVP). The prepared heterogeneous catalyst can be reproducibly formed using an ultrasonic reduction technique for DMAB dehydrogenation under mild conditions. For the characterization of PdRu@PVP nanomaterials, several spectroscopic and microscopic techniques were used. The prepared PdRu@PVP nanomaterials with an average particle size of 3.82 ± 1.10 nm provided an 808.03 h−1 turnover frequency (TOF) in the dehydrogenation of DMAB and yielded 100% of the cyclic product (Me 2 NBH 2) 2 under mild conditions. Furthermore, the activities of catalysts were investigated theoretically using DFT-B3LYP calculations. The theoretical results based on density functional theory were in favorable agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the properties of new X zeolite catalysts, whose anions are compensated by different methylammonium cations. The properties of these catalysts, with varying degrees of exchange, are compared with those of Y zeolites containing the same cations. For steric reasons, cation exchange was restricted to the faujasite supercavity, and the degree of ion exchange decreased with the radius of the organic cation. The basicity of the catalysts was analyzed using X-ray photoelectron spectroscopy (XPS) and the Knoevenagel condensation reaction, with good correlation obtained between the results of the two methods. The best catalytic activity was observed for the faujasite with the highest aluminum content (X zeolite), exchanged using the monomethylammonium cation. The better performance of this catalyst was attributed to its basicity, as well as the available micropore volume. [Copyright &y& Elsevier]

Herein, green and non-toxic bismuth sulphide@graphitic carbon nitride (Bi 2 S 3 @g-C 3 N 4) nanosheets (NCs) were firstly synthesized by ultrasonicated-assisted method and characterized with different tool. Bi 2 S 3 @g-C 3 N 4 NCs antimicrobial activity tested against three types of microbes. As well the heterostructured Bi 2 S 3 @g-C 3 N 4 NCs was investigated for removing dye and hexavalent chromium under visible light and showed high efficiency of photocatalytic oxidation/reduction higher than g-C 3 N 4 alone, attributing to lower recombination photogenerated electron-hole pairs. Bi 2 S 3 @ g-C 3 N 4 NCs showed high antimicrobial efficiencies against Staphylococcus aureus (S. aureus) as a Gram positive bacterium, Escherichia coli (E. Coli)as a Gram negative bacterium and Candida albicans (C. albicans) and that the disinfection rates are 99.97%, 99.98% and 99.92%, respectively. The core mechanism is that the bacterial membrane could be destroyed by reactive oxygen species. The Bi 2 S 3 @g-C 3 N 4 NCs is promising for environmental disinfection including water and public facilities disinfection and solar photocatalytic depollution. Turnover number (TON) and Turnover frequency (TOF) are used as concise assessment indicator for photocatalytic efficiency. [Display omitted] • Bi 2 S 3 @g-C 3 N 4 NCs were successfully synthesized by ultrasonicated-assisted method. • Bi 2 S 3 @g-C 3 N 4 nanosheets (NCs) exhibited enhanced photocatalytic removal of dyes and Cr (VI). • Bi 2 S 3 @g-C 3 N 4 NCs had a high antibacterial efficiency against different microbes. • The Bi 2 S 3 @g-C 3 N 4 NCs is promising for environmental materials for disinfection and purification. • TON and TOF are used as concise assessment indicator for photocatalysis processes. [ABSTRACT FROM AUTHOR]

Within the context of electron transfer during the catalytic water oxidation reaction, the Ir-based system is among the most active. The reaction, mimicking photosynthesis II, requires the use of an electron acceptor such the Ce4+ cation. This complex reaction, involving adsorbed water at the interface of the metal cation and Ce4+, has mostly been studied in homogenous systems. To address the ambiguity regarding the gradual transformation of a homogenous system into a heterogeneous one, we prepared and studied a heterogeneous catalyst system composed of IrO2, with a mean particle size ranging from about 5 Å to 10 Å, dispersed on a TiO2 anatase support, with the objective of probing into the different parameters of the reaction, as well as the compositional changes and rates. The system was stable for many of the runs that were conducted (five consecutive runs with 0.18 M of Ce4+ showed the same reaction rate with TON > 56,000) and, equally importantly, was stable without induction periods. Extraction of the reaction rates from the set of catalysts, with an attempt to normalize them with respect to Ir loading and, therefore, to obtain turnover frequencies (TOF), was conducted. While, within reasonable deviations, the TOF numbers extracted from TPR and XPS Ir4f were close, those extracted from the particle shape (HR-STEM) were considerably larger. The difference indicates that bulk Ir atoms contribute to the electron transfer reaction, which may indicate that the reaction rate is dominated by the reorganization energy between the redox couples involved. Therefore, the normalization of reaction rates with surface atoms may lead to an overestimation of the site activity. [ABSTRACT FROM AUTHOR]

Herein, green and non-toxic bismuth sulphide@graphitic carbon nitride (Bi 2 S 3 @g-C 3 N 4 ) nanosheets (NCs) were firstly synthesized by ultrasonicated-assisted method and characterized with different tool. Bi 2 S 3 @g-C 3 N 4 NCs antimicrobial activity tested against three types of microbes. As well the heterostructured Bi 2 S 3 @g-C 3 N 4 NCs was investigated for removing dye and hexavalent chromium under visible light and showed high efficiency of photocatalytic oxidation/reduction higher than g-C 3 N 4 alone, attributing to lower recombination photogenerated electron-hole pairs. Bi 2 S 3 @g-C 3 N 4 NCs showed high antimicrobial efficiencies against Staphylococcus aureus (S. aureus) as a Gram positive bacterium, Escherichia coli (E. Coli)as a Gram negative bacterium and Candida albicans (C. albicans) and that the disinfection rates are 99.97%, 99.98% and 99.92%, respectively. The core mechanism is that the bacterial membrane could be destroyed by reactive oxygen species. The Bi 2 S 3 @g-C 3 N 4 NCs is promising for environmental disinfection including water and public facilities disinfection and solar photocatalytic depollution. Turnover number (TON) and Turnover frequency (TOF) are used as concise assessment indicator for photocatalytic efficiency., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Metal-catalyzed alkyne [2+2+2] cycloadditions provide a variety of substantial aromatic compounds of interest in the chemical and pharmaceutical industries. Herein, the mechanistic aspects of the acetylene [2+2+2] cycloaddition mediated by bimetallic half-sandwich catalysts [Cr(CO)3IndRh] (Ind = (C9H7)−, indenyl anion) are investigated. A detailed exploration of the potential energy surfaces (PESs) was carried out to identify the intermediates and transition states, using a relativistic density functional theory (DFT) approach. For comparison, monometallic parent systems, i.e., CpRh (Cp = (C5H5)−, cyclopentadienyl anion) and IndRh, were included in the analysis. The active center is the rhodium nucleus, where the [2+2+2] cycloaddition occurs. The coordination of the Cr(CO)3 group, which may be in syn or anti conformation, affects the energetics of the catalytic cycle as well as the mechanism. The reaction and activation energies and the turnover frequency (TOF) of the catalytic cycles are rationalized, and, in agreement with the experimental findings, our computational analysis reveals that the presence of the second metal favors the catalysis. [ABSTRACT FROM AUTHOR]