The chain-walking of terminal alkenes (also called migration or isomerization reaction) is currently carried out in industry with unselective and relatively costly processes, to give mixtures of ...alkenes with significant amounts of oligomerized, branched and reduced by-products. Here, it is shown that part-per-million amounts of a variety of commercially available and in-house made ruthenium compounds, supported or not, transform into an extremely active catalyst for the regioselective migration of terminal alkenes to internal positions, with yields and selectivity up to >99% and without any solvent, ligand, additive or protecting atmosphere required, but only heating at temperatures >150 °C. The resulting internal alkene can be prepared in kilogram quantities, ready to be used in nine different organic reactions without any further treatment.
Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need ...of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cysteine-based metal–organic framework (MOF) was accomplished, to give a robust and crystalline solid catalyst fully characterized with the help of single-crystal X-ray diffraction (SCXRD). These results illustrate the advantages of metal speciation in ligand-free homogeneous organic reactions and the translation into solid catalysts for potential industrial implementation.
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•Bi2O3/Bi/ZnIn2S4 heterojunctions were designed and facilely fabricated.•Bi2O3/Bi/ZnIn2S4 is efficient for DNP, TC and Cr6+ ions degradation.•Bi2O3/Bi/ZnIn2S4 heterojunctions hydrogen ...rate production is 482.5 μmol·g−1·h−1.•Bi2O3/Bi/ZnIn2S4 is a novel Z-scheme photocatalytic system.
Construction of heterojunctions is conventionally regarded as the prevailing technique to enhance solar-driven photocatalytic water splitting and photodegradation of pollutants. Herein, we report a novel design of a ternary Bi2O3/Bi/ZnIn2S4 system, which was facilely synthesized to satisfy these stringent criteria for sunlight photocatalytic removal of organic and ionic pollutants and hydrogen evolution. Bi2O3/Bi/ZnIn2S4 could degrade 2,4-dinitrophenol (94.6%), tetracycline (96.5%), and Cr6+ (96.3%) effectively under visible light and give a hydrogen production rate of 482.5 μmol·g−1·h−1 under visible light. Based on first-principles calculations and electrochemical results, our system could be identified as a Z-scheme. Photocorrosion of the sulfide is prohibited while the catalytic capabilities are simultaneously benefited due to lowered bandgap in light harvesting, internal electric fields in charge separations, and surface plasmonic resonance enhanced electron boost.
Photocatalysis represents a promising technology that might alleviate the current environmental crisis. One of the most representative photocatalysts is graphitic carbon nitride (g-C3N4) due to its ...stability, cost-effectiveness, facile synthesis procedure, and absorption properties in visible light. Nevertheless, pristine g-C3N4 still exhibits low photoactivity due to the rapid recombination of photo-induced electron-hole (e−-h+) pairs. To solve this drawback, Z-scheme photocatalysts based on g-C3N4 are superior alternatives since these systems present the same band configuration but follow a different charge carrier recombination mechanism. To contextualize the topic, the main drawbacks of using g-C3N4 as a photocatalyst in environmental applications are mentioned in this review. Then, the basic concepts of the Z-scheme and the synthesis and characterization of the Z-scheme based on g-C3N4 are addressed to obtain novel systems with suitable photocatalytic activity in environmental applications (pollutant abatement, H2 production, and CO2 reduction). Focusing on the applications of the Z-scheme based on g-C3N4, the most representative examples of these systems are referred to, analyzed, and commented on in the main text. To conclude this review, an outlook of the future challenges and prospects of g-C3N4-based Z-scheme photocatalysts is addressed.
Finding reliable photocatalysts capable of driving reactions using only sunlight is more needed than ever. A variety of strategies to harvest sunlight and convert it into chemical energy have been ...successfully utilized such as synthesizing nanostructures, using metal nanoparticles, doping, and others. In this work, we discover a facile way to anchor CuS nanoplatelets on 2D MoS2 by the solvothermal method using ethylene glycol (EG) as both a reduction agent and an exfoliating agent of bulk MoS2. Using CuS as a co-catalysis on MoS2 with their huge surface areas, led to improved photocatalytic activity for three different applications including H2 evolution, CO2 reduction, and endosulfan degradation. Specifically, Cu–S@MoS2 3% nanocomposite produced 9.86 μmol g−1 h−1 of H2, 0.48 μmol g−1 h−1 of CO and full decomposition of endosulfan within 6 h. The Cu-loaded MoS2 nanocomposites were thoroughly characterized by spectroscopic (including synchrotron-based spectroscopy) and microscopic methods to understand the formation of Cu–S during the solvothermal process. Moreover, the role of the EG during the synthetic procedure was revealed experimentally and studied theoretically via DFT simulations.
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•A facile solvothermal method using ethylene glycol to anchor CuS nanoplatelets on 2D MoS2 has been demostrated.•Cu–S@MoS2 was for the first time used for improving H2 evolution, CO2 reduction, and endosulfan degradation.•Achieved notable results with Cu–S@MoS2, producing 9.86 μmol g−1 h−1 of H2, 0.48 μmol g−1 h−1 of CO, and full endosulfan decomposition with 6 h.•The role of ethylene glycol as a stabilizing and exfoliating agent during Cu–S@MoS2 synthesis was theoretically studied via DFT simulations.
Ionic liquids are
composed of an organic cation and a highly delocalized
perfluorinated anion, which remain tight to each other and neutral
across the extended liquid framework. Here we show that
n
...-alkanes in millimolar amounts enable a sufficient ion charge separation
to release the innate acidity of the ionic liquid and catalyze the
industrially relevant alkylation of phenol, after generating homogeneous,
self-stabilized, and surfactant-free microdroplets (1–5 μm).
This extremely mild and simple protocol circumvents any external additive
or potential ionic liquid degradation and can be extended to water,
which spontaneously generates microdroplets (
ca
.
3 μm) and catalyzes Brönsted rather than Lewis acid reactions.
These results open new avenues not only in the use of ionic liquids
as acid catalysts/solvents but also in the preparation of surfactant-free,
well-defined ionic liquid microemulsions.
Photocatalytic hydrogen evolution is a promising approach for direct solar-to-fuel conversion. Although significant research efforts have been put on the development of lead-free metal halide ...perovskites to reach excellent optoelectronic properties, their rational design for efficient heterojunction photocatalytic systems still poses challenges. Here, we report a new strategy to tailor the interface of hybrid tri(dimethylammonium) hexaiodobismuthate (DMA3BiI6) and amorphous molybdenum sulfide (a-MoSx) heterojunctions. Specifically, a-MoSx was prepared with abundant apical S2– or bridging S22– ligands to allow coupling with DMA3BiI6 via an interfacial Mo–S–Bi linkage. The as-obtained heterostructures were found to show an improved visible-light-driven photocatalytic hydrogen evolution in hydroiodic acid splitting under mild conditions reaching a superior hydrogen evolution rate of around 750 µmol g−1 h−1 and an apparent quantum efficiency (AQE) of 13.0 % at 420 nm. The high activity was kept after a long-term performance test for 3 days.
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•A new strategy to form a-MoSx/DMA3BiI6 heterojunction photocatalysts with interfacial Mo–S–Bi linkage is reported.•Apical S2– or bridging S22– ligands of a-MoSx allow formation of Mo–S–Bi linkage.•The visible light photocatalytic HER activity of a-MoSx/DMA3BiI6 is among the highest for bismuth halide perovskites.•The high activity was retained after 3 days test.
Lead-free perovskites have attracted considerable attention in photocatalytic hydrogen evolution due to their better moisture stability and lower toxicity than those of their lead-based analogues. ...However, their activity remains low and needs to be improved for practical applications. Properly engineered heterojunction photocatalysts can provide more active sites and stimulate efficient charge transfer. In this study, 1 T′/2 H−MoS2 nanoflowers were synthesized and coupled with tri(dimethylammonium) hexaiodobismuthate (DMA3BiI6) to form heterojunctions using a simple heating−cooling process. The synthesized 1 T′/2 H−MoS2/DMA3BiI6 composites exhibit excellent photocatalytic hydrogen evolution activity of hydroiodic acid splitting under visible-light irradiation with up to a rate of 241.5 µmol g⁻1 h⁻1 and apparent quantum efficiency of 11.2 % at 420 nm. Furthermore, a retained long-term performance stability after 3 days (12 cycles) of repeated hydrogen evolution reaction (HER) measurements was observed. Experimental and DFT studies indicate that the improved photocatalytic HER performance after the introduction of 1 T′/2 H−MoS2 on DMA3BiI6 is due to the efficient charge transfer and separation at the heterojunction interfaces in the composite. Accordingly, our work highlights a new potentially viable strategy to construct lead-free halide perovskite-based heterostructures for efficient photocatalytic HER.
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•1 T′/2 H−MoS2 was combined with DMA3BiI6 to construct heterojunction photocatalysts.•1 T′/2 H−MoS2/DMA3BiI6 photocatalyst shows enhanced HER activity and good stability.•The observed photocatalytic HER rate is the highest among all the reported hybrid Bi-halide perovskite systems.•Improved HER activity arises from efficient separation/transfer of photogenerated charge carriers.
Cu
TeO
(CTO) has been synthesized by hydrothermal synthesis applying different pH values without any template or a calcination step to control the crystalline phase and the morphology of ...nanoparticles. The physicochemical properties characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, N
adsorption, X-ray photoelectron spectroscopy, and diffuse reflectance ultraviolet-visible (DRUV-vis) spectroscopy techniques revealed that the pH values significantly influence the crystal growth. In acidic media (pH = 2), crystal growth has not been achieved. At pH = 4, the yield is low (10%), and the CTO presents irregular morphology. At pH = 6, the yield increases (up to 71%) obtaining an agglomeration of nanoparticles into spherical morphology. At basic conditions (pH = 8), the yield increases up to 90% and the morphology is the same as the sample obtained at pH = 6. At high basic conditions (pH = 10), the yield is similar (92%), although the morphology changes totally to dispersed nanoparticles. Importantly, the as-prepared CTO semiconductor presents photocatalytic activity for H
production using triethanolamine as a sacrificial agent under visible light illumination. The results also revealed that the nanoparticles agglomerated in a spherical morphology with larger surface area presented almost double activities in H
production compared to heterogeneously sized particles. These results highlight the suitable optoelectronic properties, including optical band gap, energy levels, and photoconductivity of CTO semiconductors for their use in photocatalytic H
production.
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