Electrochemical water splitting to generate hydrogen energy fills a yawning gap in the intermittency issues for wind and sunlight power. Transition metal (TM) oxides have attracted significant interest in water oxidation due to their availability and excellent activity. Typically, the transitional metal oxyhydroxides species derived from these metal oxides are often acknowledged as the real catalytic species, due to the irreversible structural reconstruction. Hence, in order to innovatively design new catalyst, it is necessary to provide a comprehensive understanding for the origin of surface reconstruction. In this work, the most recent developments in the reconstruction of transition metal-based oxygen evolution reaction electrocatalysts were introduced, and various chemical driving forces behind the reconstruction mechanism were discussed. At the same time, specific strategies for modulating pre-catalysts to achieve controllable reconfiguration, such as metal substituting, increase of structural defect sites, were summarized. At last, the issues for the further understanding and optimization of transition metal oxides compositions based on structural reconstruction were provided.
In silico and in vitro biological evaluation of novel serial sulfonate derivatives on pancreatic lipase activity
The novel benzothiazole sulfonate hybrid derivatives containing azomethine group were synthesized and characterized using 1H NMR, 13C NMR, and HRMS analysis. The potential enzyme inhibition activities against pancreatic lipase of the novel benzothiazole sulfonate hybrid derivatives containing azomethine group were screened with in vitro and in silico methods. IC50 values of compounds 5b (23.89 µM), 5i (28.87 µM), and 5f (30.13±4.32) were found to be more effective pancreatic lipase inhibitors than orlistat (57.75 µM) in vitro studies. Also, the binding affinities of compounds 5b (-8.7 kcal/mol), 5i (-8.6 kcal/mol), and 5f (-8.9 kcal/mol) were found potential inhibitors for pancreatic lipase in silico studies. In addition, the absorption distribution, metabolism, and excretion properties (ADME), molecular properties, toxicity estimation, and bioactivity scores of the synthesized compounds were scanned. It was found to have the ability to cross the brain-blood barrier for compounds 5a, 5b, 5c, and 5d. All compounds were calculated to be taken orally as drugs, suitable for absorption in the intestinal tract and not carcinogenic, as well as very strongly bound to plasma proteins. Finally, compound 5f was observed to be the best inhibitor for pancreatic lipase according to in vitro and in silico studies.
CO2 Electroreduction to C2+ Products over Cu‐Pb Heterojunction Catalyst
The electrochemical CO2 reduction reaction (CO2RR) presents a promising approach for producing valuable chemicals and fuels, offering a dual benefit in terms of environmental preservation and the efficient utilization of carbon resources. In this work, we proposed a stepwise electrodeposition method to prepare Cu-Pb bimetallic heterojunction catalyst on polyaniline-modified carbon paper (PANI-CuPb-x), where x is the electrodeposition times(min). Among the studied catalysts, the electrode electrodeposited for 2 min (PANI-CuPb-2) exhibited a remarkable performance during the electrocatalysis CO2 to multicarbon (C2+) products process, achieving a Faraday efficiency (FE) of 81.46 % and a partial current density of 15.41 mA cm-2 at −1.2 V (vs. RHE) in an H-type cell. Detailed study demonstrated that introducing Pb could effectively improve the formation of COOH*inhibite hydrogen evolution reaction (HER). Furthermore, the heterojunction structure in the catalysts facilitated C-C coupling of the generated C1 intermediate species, which enhanced CO2 to C2+ reaction.
Catalytic activity of metal oxides supported on graphene oxide in oxidative desulfurization and denitrogenation
The proposed mechanism on the ODN and ODS.
In this work, the effect of different parameters on catalyst efficiency in the catalytic oxidative desulfurization (ODS) and denitrogenation (ODN) process is studied. A series of samples with different metal compounds, including Ni, Cu, Co, CoNi, CoCu, and CuNi on a reduced graphene oxide (GO) were prepared by an impregnation method. The synthesized samples were carefully characterized by Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) analysis, and X-ray powder diffraction (XRD) techniques. The potential of this methodology was illustrated by the oxidation of 84.11% carbazole (CBZ) and 88.36% dibenzothiophene (DBT) in model fuel containing 500 ppmw sulfur and nitrogen. The effect of DBT and CBZ initial concentration and oxidant type on the oxidation process was investigated. The initial concentration of 250 ppmw for DBT and 100 ppmw for CBZ showed more efficiency than other initial concentrations (1,000, 750, 500, 250 ppmw) for DBT and (500, 400, 250, 100 ppmw) for CBZ, and NaClO as an oxidant showed higher performance than H2O2, formic acid, and oxygen. The results indicated that the Co-Cu/rGO catalyst shows higher activity than other prepared catalysts in the oxidation of DBT and CBZ. Moreover, the catalyst could be regenerated three times with no discernible decrease in its catalytic activity. Lastly, the catalytic oxidation of CBZ and DBT was the proposed reaction mechanism.
A porphyrin‐based porous organic polymer containing flexible chains for efficient heterogeneous photocatalysis
A porphyrin-based porous organic polymer H2Pp-TAPM containing flexible chains has been synthesized successfully. The H2Pp-TAPM has demonstrated the ability to facilitate the transfer and separation of photogenerated electron–hole pairs and delivered superior activity in the selective aerobic oxidation of sulfides to sulfoxides.
Porphyrin-based porous organic polymers (Por-POPs) are attracting increasing attention because of their potential in visible light photocatalysis. The distinctive attributes of Por-POPs have been elucidated by investigating their response to specific reactions, such as the aerobic oxidation of sulfides. However, most researchers choose porphyrin molecules with relatively short peripheral substituent chains and strong stiffness to construct porphyrin-based materials, especially Por-POPS. Herein, we designed and prepared a flexible POP material H2Pp-TAPM by incorporating extra π-conjugated rigid units TAPM into a relatively flexible porphyrin monomer H2Pp through imine linkages. The POP synthesized in this study has demonstrated the ability to facilitate the transfer and dissociation of photogenerated electron–hole pairs, leading to the production of singlet oxygen 1O2 and superoxide radical anions O2˙−. These anions act as effective mediators for the selective aerobic oxidation of sulfides, resulting in the conversion of 99% and the selectivity more than 99%. Furthermore, the H2Pp-TAPM has excellent stability and recyclability, indicating its attractiveness as heterogeneous photocatalyst for the transformation of organic compounds. This makes it a promising candidate for visible-light-driven reactions.
Novel dinuclear Ni (II) Schiff base complexes induced noncovalent exchanges: Crystal structure investigation, electrochemical assessment, Hirshfeld surface analysis and SARS‐CoV‐2 docking study
In this work, novel Ni (II) complexes, namely, [Ni2(L)2(OAc)2(EtOH)2] (1a), [Ni2(L)2(OAc)2(H2O)2] (1b-1) and [Ni2(L)2(OAc)2(EtOH)2] (1b-2) as co-crystal were synthesized by the 1:1 condensation (https://www.sciencedirect.com/topics/chemistry/condensation) of Ni (CH3COO)2·4H2O and Schiff base ligand (H2L) (2-hydroxy-4-methoxybenzaldehyde and 2-amino-2-methylpropanol). The ligand based on Schiff base and fabricated complexes (1a) and (1b-1 and 1b-2) were successfully identified by CHN assessment, FT-IR, UV–Vis spectra, melting point and CV voltammogram. The electrochemical behavior investigation shows that the nickel complexes exhibited irreversible oxidation processes in methanol solution. Additionally, the crystal structures of complexes (1a) and (1b) have been recognized by single-crystal X-ray diffraction investigation. It turned out that the complexes (1b-1) and (1b-2) crystallize together, making a co-crystal 1b with an additional EtOH solvent molecule in the crystal structure. A detailed study of intermolecular exchanges was performed using attractive graphical analysis tools such as three-dimensional Hirshfeld surfaces analysis, two-dimensional fingerprint plots (FPs), and enrichment ratios (E), which make C-H … C, C-H … O hydrogen bond, C … O, H … H, and O … O short contacts on Hirshfeld surfaces with color code are observed. Moreover, an appraisement of the inhibitory trace against coronavirus (main protease SARS-CoV-2, PDB ID: 6Y2F) and molecular targets of human angiotensin-converting enzyme-2 (ACE-2) was performed by a molecular docking study in which two nickel complexes performed best for PDB protein ID: 6M0J and all three complexes for PDB protein ID: 6Y2F.
Cyclic Voltammetry as an Activation Method of TiO2 Nanotube Arrays for Improvement of Photoelectrochemical Water Splitting Performance
Photocatalysis: Cyclic voltammetry of TiO2 nanotube (TNT) arrays was used for activating photoelectrochemical water splitting performance. The highest photocurrent was obtained for Na2SO4-activated TNTs. EPR and luminescent analysis of defects shows that enhanced photoactivity correlates with higher luminescence quantum yield, lowest paramagnetic defect content and larger decay time of the luminescence.
Abstract
A facile and eco-friendly method for activating anodic TiO2 nanotubes (TNTs) by cyclic voltammetry (CV) is proposed, and photoelectrochemical properties of CV-activated TNTs are compared with those of non-activated TNTs and of TNTs activated by hydrogen-thermal reduction. EPR and luminescence studies show that the pristine samples demonstrate rather large content of paramagnetic and luminescing defects, while hydrogenation and CV-activation lead to the different type of rearrangement of defects. TNTs activated by CV-Na2SO4 demonstrate significantly improved photocurrent density (2.25 mA cm−2) in comparison with that of the hydrogen treated and pristine ones (0.93 mA cm−2 and 0.31 mA cm−2) under NUV-irradiation at 0.2 V (RHE). Enhanced photoactivity of Na2SO4-activated TNTs correlates with higher luminescence quantum yield, lowest paramagnetic defects content and larger decay time of the luminescence. Thus, a decrease in the content of defects is an important factor that reduces the non-radiative recombination of charge carriers. The activation-induced redistribution of surface and bulk defects in nanotubes explains the increased photoelectrochemical activity of TiO2-based anodes. Cyclic voltammetry has been proved to be a reliable method to increase the efficiency of TNTs in PEC water splitting.
Crystal Structure and Photocatalytic Properties of the CsV0.625Te1.375O6 Mixed‐Valence β‐Pyrochlore Compound
The complex mixed-valence tellurium and vanadium compound Cs(V3+ 0.0625V5+ 0.5625Te4+ 0.34375Te6+ 1.03125)O6 with a classical cubic β-pyrochlore structure has been prepared. As a result of features of its electron structure, the compound possesses photocatalytic activity under visible light irradiation with an apparent quantum efficiency (QE) ϕx=3.63 ⋅ 10−6 molecules/photons for methylene blue degradation (MB). The investigation of MB oxidation products shows a rather deep decomposition to simple aromatic and non-aromatic compounds.
Abstract
A new β-pyrochlore compound with complex composition of Cs(V3+ 0.0625V5+ 0.5625Te4+ 0.34375Te6+ 1.03125)O6 has been synthesized by a solid-state reaction and characterized by single-crystal X-ray diffraction and thermal analysis. The compound possesses the typical cubic symmetry with space group , however some of the oxygen atoms shift from the special position 48 f to the general crystallographic positions 32e, 96 g and 96 h. This shift is caused by complex B-site composition with mixed-valence vanadium and tellurium atoms, especially the presence of the large Te4+ ion. The locations of the valence band and conduction band edges were determined experimentally under vacuum conditions by X-ray photoelectron spectroscopy, UV-visible and impedance spectroscopy and evaluated theoretically for water solutions. The photocatalytic ability of the compound under visible light irradiation was determined using the methylene blue decomposition process as an example. The nature of the active radical species and possible dye degradation pathway were suggested according to experimental data.
Reversible Photobleaching of Silver Clusters in Silica‐Based Glass under Ultraviolet Irradiation
Luminescent silver clusters in silica-based glass show photobleaching under CW UV irradiation. Degradation of cluster luminescence is reversible and restores after the heat treatment below glass transition temperature. The proposed mechanism of photobleaching is photoionization of silver clusters.
Abstract
Inorganic glasses doped with luminescent silver clusters are promising materials for photonic applications as white light generation, optical data storage, and spectral conversion. This work reports the photostability study of luminescent silver clusters dispersed in silica-based glass under continuous ultraviolet irradiation. The photobleaching process model is proposed and the quantum yield of photobleaching is derived from the experimental data. The proposed mechanism of photobleaching is photoionization of silver clusters. Degradation of cluster luminescence is reversible and restores after the heat treatment, indicating the possibility to release trapped electrons and return the initial charge state of clusters. The effect of heat treatment temperature on the luminescence restoration is studied, the amount of restored luminescent clusters depends linearly on the heat treatment temperature.
Construction of a Ce‐UiO‐66/MCo2O4 Heterojunction for Photocatalytic Cr(VI) Detoxification Through a p‐n Junction Formation Mechanism
Let's collaborate! MCo2O4 (M=Mn, Zn, Fe) was synthesized and combined with Ce-UiO-66 to create a heterojunction structure for use as a photocatalyst for chromium(VI) reduction. The resulting Ce-UiO-66/MCo2O4 heterojunctions exhibited high Cr(VI) reduction under visible light irradiation and maintained high photoreduction efficiency even after four cycling tests, demonstrating excellent photocatalytic stability.
Abstract
Heterojunction engineering in catalyst structures is a promising approach to solve some restrictions in photocatalyst design, such as a narrow photoabsorption range and rapid recombination of photogenerated charge carriers. In this work, MCo2O4 (M=Mn, Zn, Fe) was synthesized using a template method. The porous MCo2O4 was composited by Ce-UiO-66 to form a heterojunction structure. The resultant material Ce-UiO-66/MCo2O4 had a hierarchically porous architecture and was used as a photocatalyst for Cr(VI) reduction. The coupling of Ce-UiO-66 and MCo2O4 resulted in a p-n junction mechanism for charge carrier transfer. The Ce-UiO-66/MCo2O4 heterojunctions exhibited high Cr(VI) reduction ability under visible light irradiation over 120 min. The highest Cr(VI) photoreduction rate of the heterojunction is 14 times that of Ce-UiO-66. The binary heterojunction maintains high photoreduction efficiency (100 %) of Cr(VI) after four cycling tests showing excellent photocatalytic stability.