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Intercalated complexes of 1T′-MoS <sub/>2</sub> nanosheets with alkylated phenylenediamines as excellent catalysts for electrochemical hydrogen evolution
摘要： Two-dimensional layered MoS2 has recently been considered as an excellent catalyst for the water-splitting hydrogen evolution reaction (HER). Herein, we synthesize 1T0 phase MoS2 that was intercalated with a series of alkylated p-phenylenediamines (PDs). The substituted N atoms produced S vacancies, leading to a composition of MoS2-2xNx (x = 0.1). The more abundant methyl groups induce a larger charge transfer, resulting in excellent HER performance: for tetramethyl PD, the overpotential is 0.15 V at 10 mA cm-2 with a Tafel slope of 35 mV dec-1. The catalytic activity of the complexes depends on the concentration of the intercalated molecules, showing an optimum at a concentration of 8 mol%. First-principles calculations showed that the intercalated complexes (1T0 phase) having N atom–S vacancy (N–VS) pairs are stabilized by a large charge transfer from the PD molecules that is enhanced by the methyl groups (i.e., 0.40e–0.84e per molecule at 6.25 mol% intercalation). The charge transfer increases the density of states at and just above the Fermi level, thereby increasing the electron concentration at low cathodic bias. The active sites for the Volmer reaction are found to be N atoms in the proximal N–VS pairs. The activation barrier for the Heyrovsky reaction becomes higher at higher concentrations of the intercalants, suggesting that the experimental HER performance is also kinetically controlled.
关键词： catalysis,first-principles calculations,MoS2,hydrogen evolution reaction,intercalation
更新于2025-09-19 17:15:36
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Photochemistry and Photophysics - Fundamentals to Applications || Catalytic Degradation of Organic Dyes in Aqueous Medium
摘要： Water pollution by the textile industry is an emerging issue. Textile industry is the major industrial sector which contributes to water pollution. Textile industry releases a huge amount of unfixed dyes in wastewater effluents. About 20% of the dye production all over the world is discharged as waste in industrial effluents by textile industry. These dyes are highly stable and colored substances which disturb the aqueous ecosystem significantly. Therefore, there is a need for methods to remove organic dyes from textile industrial effluents. Photocatalysis and catalytic wet oxidation are best practices for degradation of dyes in wastewater. In photocatalysis, the dye molecules can be completely degraded into inorganic non-toxic compounds by irradiation of the dye solution under visible or ultra-violet light in the presence of semiconductor metal-oxide photocatalysts. In catalytic wet oxidation, various metal-based catalysts in supported or unsupported form can be used as heterogeneous catalysts for degradation of dyes in the presence of oxygen or hydrogen peroxide. These processes have several preferences like easy separation of the catalyst from reaction mixture and recycling of the catalyst.
关键词： degradation,Langmuir-Hinshelwood mechanism,dyes,catalysis
更新于2025-09-19 17:15:36
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A four-state fluorescent molecular switch
摘要： Cross-coupling reactions are among the most powerful C–C and C–X bond forming tools in organic chemistry. Traditionally, cross-coupling methods rely on the use of aryl halides or pseudohalides as electrophiles. In the past three years, decarbonylative cross-couplings of amides have emerged as an attractive method for the construction of a wide variety of carbon–carbon and carbon–heteroatom bonds, allowing for the synthetically-valuable functional group inter-conversion of the amide bond. These previously elusive reactions hinge upon selective activation of the N–C(O) acyl amide bond, followed by CO extrusion, in a formal double N–C/C–C bond activation, to generate a versatile aryl–metal intermediate as an attractive alternative to traditional cross-couplings of aryl halides and pseudohalides. In this perspective review, we present recent advances and key developments in the field of decarbonylative cross-coupling reactions of amides as well as discuss future challenges and potential applications for this exciting field.
关键词： amides,transition-metal catalysis,C–C bond formation,decarbonylative cross-coupling,C–X bond formation
更新于2025-09-19 17:15:36
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Photon catalysis of deuterium iodide photodissociation
摘要： A catalyst enhances a reaction pathway without itself being consumed or changed. Recently, there has been growing interest in the concept of "photon catalysis" in which nonresonant photons, which are neither absorbed nor scattered, promote reactions. The driving force behind this effect is the interaction between the strong electric field associated with a pulsed, focused laser and the polarizability of the reacting system. In this study, the effect of near-infrared, nonresonant radiation on the photodissociation of deuterium iodide is demonstrated. We use nanosecond pulses rather than time-resolved spectroscopy to investigate the average effect of the electric field on the branching ratio for forming D + I(2P3/2) and D + I(2P1/2). Changes in the measured D-atom speeds between field-free and strong-field conditions confirm substantial differences in dissociation dynamics. Both the magnitude and direction of change in the branching ratios are dependent upon the photodissociation wavelength. Experiments and theoretical calculations confirm that the mechanism for photon catalysis under these conditions is dynamic Stark shifting of potential energy surfaces rather than electric-field-induced alignment of reagent molecules.
关键词： deuterium iodide,dynamic Stark shifting,photon catalysis,photodissociation,nonresonant radiation,branching ratio
更新于2025-09-19 17:15:36
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Pt-TCO free Sn-Ag-Cu ternary alloy as cost effective counter electrode layer for dye sensitized solar cell
摘要： The performance of dye sensitized solar cell (DSSC) is largely dependent on efficient electron reclamation from outer circuit to reduce the oxidized redox shuttle (electrolyte). The current transparent conducting oxide (TCO) glass substrates and platinum (Pt) metal as essential components of counter electrodes though efficient are very expensive which restrict commercialization of this technology. Furthermore, the sluggish catalytic activity of indium tin oxide (ITO) or fluorine doped tin oxide (FTO) play no role in electron reclamation. In this study, commercially available cost effective tin-silver-copper (Sn-Ag-Cu) ternary composite past has been investigated as potential replacement for FTO coating and Pt catalyst to work in conjunction with counter electrode of dye sensitized solar cell. Scanning electron microscopy (SEM) has been utilized to examine the morphology of as received paste. Electrochemical analysis such as cyclic voltammetery (CV) and electron impedance spectroscopy (EIS) have been employed to investigate the catalytic activity and electron kinetics respectively. Finally, current-voltage characteristics have been investigated using IVT 2600 solar simulator. The Sn:Ag:Cu composite exhibited remarkable catalytic properties which in turn lead to impressive over all photo energy conversion efficiency. The measured conversion efficiency was 6.78% which is almost 86% equivalent to DSSCs containing Pt has catalyst on FTO.
关键词： composite,copper,DSSC,catalysis,counter electrode,silver
更新于2025-09-19 17:13:59
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Plasmon‐Enhanced InGaZnO Ultraviolet Photodetectors Tuned by Ferroelectric HfZrO
摘要： Allene (C3H4) gas is produced and separated on million-metric-ton scale per year during petroleum refining but is rarely employed in organic synthesis. Meanwhile, the addition of an allyl group (C3H5) to ketones is among the most common and prototypical reactions in synthetic chemistry. Herein, we report that the combination of allene gas with inexpensive and environmentally benign hydrosilanes, such as PMHS, can serve as a replacement for stoichiometric quantities of allylmetal reagents, which are required in most enantioselective ketone allylation reactions. This process is catalyzed by copper salts and commercially available ligands, operates without specialized equipment or pressurization, and tolerates a broad range of functional groups. Furthermore, the exceptional chemoselectivity of this catalyst system enables industrially relevant C3 hydrocarbon mixtures of allene with methylacetylene and propylene to be applied directly.
关键词： enantioselective allylation,allene,copper catalysis,hydrosilanes,petroleum cracking byproduct,ketones
更新于2025-09-19 17:13:59
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Semiconductor Quantum Dots as Components of Photoactive Supramolecular Architectures
摘要： Luminescent quantum dots (QDs) are colloidal semiconductor nanocrystals consisting of an inorganic core covered by a molecular layer of organic surfactants. Although QDs have been known for more than thirty years, they are still attracting the interest of researchers because of their unique size-tunable optical and electrical properties arising from quantum confinement. Moreover, the controlled decoration of the QD surface with suitable molecular species enables the rational design of inorganic-organic multicomponent architectures that can show a vast array of functionalities. This minireview highlights the recent progress in the use of surface-modified QDs – in particular, those based on cadmium chalcogenides – as supramolecular platforms for light-related applications such as optical sensing, triplet photosensitization, photocatalysis and phototherapy.
关键词： supramolecular chemistry,sensing,catalysis,triplet sensitization,quantum dots
更新于2025-09-19 17:13:59
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Monolayer porphyrin assembled SPSf/PES membrane reactor for degradation of dyes under visible light irradiation coupling with continuous filtrationa?°
摘要： Porphyrin-based catalytic oxidation of hydrocarbon bonds is considered to be the most representative biomimetic catalysis. To mimic the biomimetic catalytic oxidation of nature under illumination of visible light, a monolayer of meso-tetrakis (1-methylpyridinium-4-yl) porphyrin immobilized sulfonated polysulfone/ polyethersulfone blend membrane (TMPyP@SPSf/PES) was prepared via a facile electrostatic assembly method. The visible light response region of TMPyP was expanded after it was immobilized on the SPSf/PES membrane surface, which resulted in the increase of the photocatalytic performance, and the Rhodamine B (RhB) degradation was increased from 30.0% to 93.4%. A photocatalytic membrane reactor (PMR) equipped with TMPyP@SPSf/PES membrane was employed for RhB treatment under continuous flow filtration coupling with photocatalysis, and the optimized degradation was up to 98.3%. Moreover, the TMPyP@SPSf/PES membrane can be reused for photocatalytic degradation of RhB after regeneration in TMPyP solution. More importantly, the TMPyP@SPSf/PES membrane can also efficiently degrade other cationic and anionic dyes (such as degradation of methylene blue 99.1%, acid fuchsin 96.8%). Finally, the oxidation mechanism and degradation pathway of RhB were further investigated by electron spin resonance (ESR), ultra-performance liquid chromatography and high-definition mass spectrometry (UPLC–HDMS) and gas chromatography-Mass spectrometry (GC–MS). It was revealed that the photogenerated hole (h+), superoxide radical (?O2?), and singlet oxygen (1O2) controlled the oxidation process. The degradation of RhB includes N-de-ethylate, wrecked of chromophore structures and opening-ring of benzene.
关键词： Photocatalytic membrane reactor,Biomimetic catalysis,Dye wastewater,TMPyP@SPSf/PES membrane,Electrostatic assembly
更新于2025-09-19 17:13:59
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Robust synthesis of Au‐based multishell structures as plasmonic catalysts for selective hydrogenation of 4‐nitrostyrene
摘要： In this paper, we describe a robust self-template strategy for facile and large-scale synthesis of porous multishell Au with controllable shell number, sphere size and in-situ surface modification. The process involved the rapid reduction of novel Au-melamine colloidal templates with a great amount of NaBH4 in presence of poly(sodium-p-styrenesulfonate) (PSS). After soaking the templates in other metal salt solution, the obtained bimetallic templates could also be generally converted into bimetallic multishell structures by same reduction process. In the hydrogenation of 4-nitrostyrene using NH3BH3 as a reducing agent, the porous triple-shell Au with surface modification (S-PTSAu) exhibited excellent selectivity (97 %) for 4-aminostyrene in contrast with unmodified triple-shell Au. Furthermore, it also showed higher enhancement of catalytic activity under irradiation of visible light as compared to similar catalysts with less shell number. This work opens up a new route in designing and synthesizing Au-based multishell structures for various applications.
关键词： Selectivity,Plasmonic catalysis,Self-sacrificial templates,Multishell Au,Hydrogenation
更新于2025-09-19 17:13:59
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Robust synthesis of Au-based multishell structures as plasmonic catalysts for selective hydrogenation of 4-nitrostyrene
摘要： In this paper, we describe a robust self-template strategy for facile and large-scale synthesis of porous multishell Au with controllable shell number, sphere size and in-situ surface modification. The process involved the rapid reduction of novel Au-melamine colloidal templates with a great amount of NaBH4 in presence of poly(sodium-p-styrenesulfonate) (PSS). After soaking the templates in other metal salt solution, the obtained bimetallic templates could also be generally converted into bimetallic multishell structures by same reduction process. In the hydrogenation of 4-nitrostyrene using NH3BH3 as a reducing agent, the porous triple-shell Au with surface modification (S-PTSAu) exhibited excellent selectivity (97 %) for 4-aminostyrene in contrast with unmodified triple-shell Au. Furthermore, it also showed higher enhancement of catalytic activity under irradiation of visible light as compared to similar catalysts with less shell number. This work opens up a new route in designing and synthesizing Au-based multishell structures for various applications.
关键词： Selectivity,Plasmonic catalysis,Self-sacrificial templates,Multishell Au,Hydrogenation
更新于2025-09-19 17:13:59