Organic Inorganic Hybrid Catalyst Research Articles

Perspectives on the highly selective oxidation of copper-mediated C3N4-BiVO4 organic-inorganic hybrid catalysts and the efficient generation of reactive oxygen species

Singlet oxygen (1O2) is a kind of reactive oxygen species (ROS) with both oxidizability and selectivity. The construction of 1O2 is the key to improve the selectivity of various organic reactions. In this study, Cu/C3N4-BiVO4 (CCN-BVO) ternary system significantly improved the catalytic effect of selective oxidation of glycerol to prepare high value chemical dihydroxyacetone (DHA). At the same time, CCN-BVO also has a strong environmental catalytic effect, and the decomposition effect of liquid phase organic pollutants can reach more than 90 % within 2 h. The superior ROS production capacity of CCN-BVO, particularly its ability to produce 1O2, has been confirmed by electron spin resonance (ESR) and quenching experiments as the reason for its excellent catalytic effect. Electrochemical characterization and X-ray photoelectron spectroscopy (XPS) proved that Cu can be used as an intermediary to accelerate electron conduction, and can also effectively construct defects to improve oxygen absorption efficiency, thus effectively increasing ROS yield. This study also theoretically confirmed the reaction path of glycerol catalysis through DFT calculation, which provided a theoretical basis for the subsequent design of efficient catalytic materials.

Novel flexible aromatic Cu3 metal-organic π-cluster for electrocatalytic CO2 reduction reaction

Producing Cn products through electrocatalytic CO2 reduction reaction (CO2RR) is of great significance in addressing the global warming crisis. Organic-inorganic hybrid catalysts, characterized by precise and controllable active sites and metal-ligand synergistic interactions, can enhance the reaction activity and stability of Cu-based catalysts. Herein, based on density functional theory (DFT), a novel flexible aromatic Cu3 metal-organic π-cluster (Cu3-π cluster) was constructed, consisting of triple-atom active centers and pentalyne ligands. During the catalytic CO2RR process, the adsorption of H can promote the activation of CO2, this converts the competing hydrogen evolution reaction (HER) into promoting CO2RR. Enhanced aromaticity of its cluster core is credited with stabilizing the coadsorption of H and CO2 (H* + CO2*), consequently lowering the reaction free energy of the CO2 activation process. Research has shown that Cu3-π cluster have high catalytic activity for electrocatalytic CO2 generation of C2H4. Considering the solvation effect, the limit potential of this reaction is −0.60 V. Furthermore, the reaction free energies suggest that the Cu3-π cluster is more inclined to yield C2H4(g) products via COCO* coupling. Moreover, the high CO coverage at the triple-atom active centers not only makes it more challenging for this cluster to adsorb H, but also reduces the energy barrier of the COCO* coupling reaction.In the entire reaction pathway of C2H4(g), there exhibits dynamic self-adaptive behavior in the bond lengths and bond angles of the three Cu atoms in the cluster core, leading to fluctuations in aromaticity. The flexibility and aromaticity changes in this structure enable the Cu3-π cluster to better stabilize intermediates. This work provides theoretical guidance for the application of metal-organic π-clusters, accelerates the screening of catalysts for CO2RR, and provides powerful theoretical guidance for the structure-activity relationships between aromaticity and catalytic activity.

Decoration of Bi2MoO6 nanosheets with NH2-UiO-66 for boosting visible-light photocatalytic activities

Constructing heterostructured photocatalysts for organic contaminants elimination is promising in the area of environmental purification. For boosting the photocatalytic performance, modulating the heterojunction interface can enhance solar light utilization and facilitate the transporation of photoinduced charge carriers. In this research, octahedral NH2-UiO-66 nanoparticles with large surface area and wide light absorption range were prepared and further employed to in-situ construction of NH2-UiO-66/Bi2MoO6 nanocomposite. The optimized NH2-UiO-66/Bi2MoO6 nanocomposite displays enhanced photocatalytic activities in the elimination of rhodamine B (RhB) and tetracycline (TC). The corresponding degradation rate constant is about 4 and 1.76 times larger than that of individual Bi2MoO6. Combined with the photochemical and electrochemical results, it can be speculated that the higher photocatalytic performance is assigned to the accelerative photoinduced carrier transfer by the formation of well-contacted heterostructured interface. This study provides a theoretical basis for further developing organic–inorganic hybrid catalyst with significant improvement of photocatalytic properties in wastewater treatment.

The influence of hydrogen bonding on the structure of organic-inorganic hybrid catalysts and its application in the solvent-free epoxidation of α-olefins.

In this study, two types of catalysts were prepared by the combination of gemini quaternary ammonium salt with two distinct species of phosphotungstic acid. Catalysts prepared by the Wells-Dawson type of phosphotungstic acid and Keggin-type phosphotungstic acid both exhibited dual-phase catalytic behavior, demonstrating both heterogeneous and homogeneous catalytic activities. In comparison to the catalyst prepared by the Keggin-type phosphotungstic acid, due to the higher size of Wells-Dawson type of phosphotungstic acid, hydrogen bonding could not effectively affect the catalyst prepared by H6P2W18O62. Subsequently, the influential factors on the catalytic reaction were investigated. Through the utilization of techniques such as XPS, FT-IR, Raman spectra and other characterization methods, two distinct structure and reaction mechanisms for these catalysts were elucidated under the influence of hydrogen bonding.

Synthesis, characterization and application of nano-silica@[DPSSP][Cl]2 as a novel organic–inorganic hybrid catalyst for the rapid condensation of aldehyde, ammonium acetate and thiobarbituric acid

Synthesis, characterization and application of nano-silica@[DPSSP][Cl]2 as a novel organic–inorganic hybrid catalyst for the rapid condensation of aldehyde, ammonium acetate and thiobarbituric acid

Quaternary Ammonium Salt Anchored on CuO Flowers as Organic–Inorganic Hybrid Catalyst for Fixation of CO2 into Cyclic Carbonates

Quaternary Ammonium Salt Anchored on CuO Flowers as Organic–Inorganic Hybrid Catalyst for Fixation of CO2 into Cyclic Carbonates

A Molybdenum(VI) Complex of 5-(2-pyridyl-1-oxide)tetrazole: Synthesis, Structure, and Transformation into a MoO3-Based Hybrid Catalyst for the Epoxidation of Bio-Olefins

The discovery of heterogeneous catalysts synthesized in easy, sustainable ways for the valorization of olefins derived from renewable biomass is attractive from environmental, sustainability, and economic viewpoints. Here, an organic–inorganic hybrid catalyst formulated as [MoO3(Hpto)]·H2O (2), where Hpto = 5-(2-pyridyl-1-oxide)tetrazole, was prepared by a hydrolysis–condensation reaction of the complex [MoO2Cl2(Hpto)]∙THF (1). The characterization of 1 and 2 by FT-IR and Raman spectroscopies, as well as 13C solid-state NMR, suggests that the bidentate N,O-coordination of Hpto in 1 (forming a six-membered chelate ring, confirmed by X-ray crystallography) is maintained in 2, with the ligand coordinated to a molybdenum oxide substructure. Catalytic studies suggested that 2 is a rare case of a molybdenum oxide/organic hybrid that acts as a stable solid catalyst for olefin epoxidation with tert-butyl hydroperoxide. The catalyst was effective for converting biobased olefins, namely fatty acid methyl esters (methyl oleate, methyl linoleate, methyl linolenate, and methyl ricinoleate) and the terpene limonene, leading predominantly to the corresponding epoxide products with yields in the range of 85–100% after 24 h at 70 °C. The versatility of catalyst 2 was shown by its effectiveness for the oxidation of sulfides into sulfoxides and sulfones, at 35 °C (quantitative yield of sulfoxide plus sulfone, at 24 h; sulfone yields in the range of 77–86%). To the best of our knowledge, 2 is the first molybdenum catalyst reported for methyl linolenate epoxidation, and the first of the family [MoO3(L)x] studied for methyl ricinoleate epoxidation.

CeO2/Ni-MOF with Synergistic Function of Enrichment and Activation: Efficient Reduction of 4-Nitrophenol Pollutant to 4-Aminophenol.

The conversion of organic pollutants to value-added chemicals has been considered as a sustainable approach to solve environmental problems. However, it is still a challenge to construct a suitable heterogeneous catalyst that can synchronously achieve the enrichment and activation of organic pollutants (such as 4-nitrophenol, 4-NP). Here, an organic-inorganic hybrid catalyst (CeO2/Ni-MOF) was successfully fabricated for efficiently reducing 4-NP to 4-aminophenol (4-AP) with water as the hydrogen source. Based on the synergistic effect of Ni-MOF (adsorption action) and CeO2 (active sites), CeO2/Ni-MOF could achieve a reaction rate of 1.102 μmol min-1 mg-1 with an ultrahigh Faraday efficiency (FE) (99.9%) and conversion (97.6%). In addition, the catalytic mechanism of 4-NP reduction over CeO2/Ni-MOF was elaborated in depth. This work presents a new avenue for the effective reduction of pollutants and provides a new strategy for designing high-performance catalysts for rare-earth metals.

A Lindqvist type hexamolybdate [Mo6O19]-modified graphene oxide hybrid catalyst: Highly efficient for the synthesis of benzimidazoles

In this work, a novel organic–inorganic hybrid catalyst ([Mo6O18] @GO-NH2) was synthesized by covalent attachment of Lindqvist type polyoxometalate [(C4H9)4N]2[Mo6O19] on the surface of graphene oxide (GO). To provide the hybrid catalyst, graphene oxide was covalently modified with an aminosilane, followed by treatment with a polyoxometalate complex. The resulting catalyst was identified by different analytical techniques TG, SEM, XRD, BET, EDX, FT-IR, and N2 adsorption–desorption. [Mo6O18] @GO-NH2 was used as an efficient catalyst for the preparation of various benzimidazoles. The result showed high activity, recoverability, reusability, and durability of the designed catalyst under applied conditions.

Collagen-coated superparamagnetic iron oxide nanoparticles as a sustainable catalyst for spirooxindole synthesis

In this work, a novel magnetic organic–inorganic hybrid catalyst was fabricated by encapsulating magnetite@silica (Fe3O4@SiO2) nanoparticles with Isinglass protein collagen (IGPC) using epichlorohydrin (ECH) as a crosslinking agent. Characterization studies of the prepared particles were accomplished by various analytical techniques specifically, Fourier transform infrared (FTIR) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), and Brunauer−Emmett−Teller (BET) analysis. The XRD results showed a crystalline and amorphous phase which contribute to magnetite and isinglass respectively. Moreover, the formation of the core/shell structure had been confirmed by TEM images. The synthesized Fe3O4@SiO2/ECH/IG was applied as a bifunctional heterogeneous catalyst in the synthesis of spirooxindole derivatives through the multicomponent reaction of isatin, malononitrile, and C-H acids which demonstrated its excellent catalytic properties. The advantages of this green approach were low catalyst loading, short reaction time, stability, and recyclability for at least four runs.

A fascinating click strategy to novel 1,2,3-triazolium based organic-inorganic hybrids for highly accelerated preparation of tetrazolopyrimidines

Herein, click reaction is used for the preparation of novel organic-inorganic Brønsted acidic ionic solids (BAISs) as new catalysts for the efficient synthesis of tetrazolopyrimidines. A series of mono and disubstituted-1,2,3-triazoles were synthesized under click reaction condition. The prepared 1,2,3-triazoles underwent reaction with 1,4-butanesultone to provide novel solid 1,2,3-triazolium N- butyl sulfonate zwitterions. Then, the reaction of phosphotungstic acid with the obtained zwitterions led to the novel 1,2,3-triazolium-N-butyl sulfonic acid phosphotungstate as acidic ionic solids. The synthesized BAIS catalysts were fully characterized using FTIR, 1H and 13C NMR, XRD, elemental analysis (CHNS), TG and DSC techniques. The introduced novel hybrids were used as efficient catalysts for the synthesis of targeted methyl-7-aryl-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylate and 6,6-dimethyl-9-aryl-5,6,7,9-tetrahydrotetrazolo[5,1-b]quinazolin-8(4H)-one derivatives via multicomponent reaction of aromatic aldehydes, active methylene compounds and 5-aminotetrazole. Low amount of the prepared 1,2,3-triazolium-N-butyl sulfonic acids phosphotungstate catalysts (5–10 mmol%) gave desired products in short times (20–45 min) with excellent yields (87–93%). Novelty of the introduced catalysts, ease of recovery and reusability up to four repeated runs with no significant decrease in the yields are highlighted superiorities of the introduced organic-inorganic hybrid catalysts.

Efficient One-Pot Synthesis of 1,4-Dihydropyridine and Polyhydroquinoline Derivatives Using Sulfanilic Acid-Functionalized Boehmite Nano-Particles as an Organic-Inorganic Hybrid Catalyst

Boehmite nanoparticles (BNPs) with a wide surface area and a large number of surface hydroxyl groups were covalently functionalized by 3-chloropropyl trimethoxysilane to support sulfanilic acid. This is a hybrid catalyst was then characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy (FESEM), thermal gravimetric analysis, X-ray diffraction and energy-dispersive X-ray spectroscopy. Accordingly BNPs@Si(CH2)3@NHSO3H was used as an effective catalyst for the one-pot three-component Hantzsch condensation reaction of aryl aldehydes, ammonium acetate and ethylacetoacetate for synthesize polyhydroquinolines and 1,4-dihydropyridine derivatives. These reactions were carried out in ethanol solvent under reflux conditions. This way offered here is operationally easy, environmentally benign, straightforward work-up, short reaction time and has high yield. Further, the heterogeneous catalyst be recycle simply and reused.

Enhanced electrochemical performance and stability of Pt/Ni electrocatalyst supported on SiO2-PANI nanocomposite: A combined experimental and theoretical study

Polyaniline-Silica (PANI-SiO2) nanocomposite was developed as a support for enhancing the performance of Pt/Ni electrocatalyst in direct methanol fuel cells (DMFCs). Bimetallic Pt/Ni electrocatalyst was deposited on the in-situ prepared PANI-SiO2 nanocomposite via cyclic voltammetry (CV) method. The electro-oxidation of methanol was studied at room temperature using CV, linear sweep voltammetry (LSV), and chronoamperometry (ChA) tests. The Pt/Ni/SiO2-PANI electrocatalyst resulted in an onset potential of −0.54 V and an excellent peak current density of 144 mA/cm2 showing its outstanding catalytic activity. Moreover, the Pt/Ni/SiO2-PANI electronic structure was theoretically investigated via density functional theory (DFT) calculations. The DFT results confirmed that employing the PANI-SiO2 structure for bimetallic PtNi nanostructure could lead to increasing the reactivity of the resulting catalyst and decreasing the energy gap. This observation was well consistent with the experimental results. The experimental and theoretical data indicated that PANI-SiO2, as an organic-inorganic hybrid catalyst support, considerably improved the stability and CO poisoning tolerance of the resulting electrocatalyst, both of which are crucial for practical alkaline direct methanol fuel cell applications.

Porous Silica-Based Organic-Inorganic Hybrid Catalysts: A Review

Hybrid organic-inorganic catalysts have been extensively investigated by several research groups in the last decades, as they allow combining the structural robust-ness of inorganic solids with the versatility of organic chemistry. Within the field of hybrid catalysts, synthetic strategies based on silica are among the most exploitable, due to the convenience of sol-gel chemistry, to the array of silyl-derivative precursors that can be synthesized and to the number of post-synthetic functionalization strategies available, amongst others. This review proposes to highlight these advantages, firstly describing the most common synthetic tools and the chemistry behind sol-gel syntheses of hybrid catalysts, then presenting exemplificative studies involving mono- and multi-functional silica-based hybrid catalysts featuring different types of active sites (acid, base, redox). Materials obtained through different approaches are described and their properties, as well as their catalytic performances, are compared. The general scope of this review is to gather useful information for those approaching the synthesis of organic-inorganic hybrid materials, while providing an overview on the state-of-the art in the synthesis of such materials and highlighting their capacities.

Iron–Phosphonate Nanomaterial: As a Novel and Efficient Organic–Inorganic Hybrid Catalyst for Solvent-Free Synthesis of Tri-Substituted Imidazole Derivatives

In this study, organic–metal nanocatalyst was synthesized by reacting ferric(ΙΙ) chloride with organic phosphonate ligand. The particle size was controlled with the help of the surfactant. Nanoparticle structure was analyzed using Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), dispersive X-ray (EDX), Brunauer–Emmett–Teller (BET) isotherm and X-ray diffraction (XRD) spectra. Next, its catalytic activity was investigated in the synthesis of heterocyclic compounds (2,4,5-trisubstituted imidazoles derivatives). Under optimal conditions, the products were obtained with good efficiency and short time. Products identification were evaluated using physical data, FT-IR, 1H and 13CNMR analysis. The results show that the new method, namely the use of iron-phosphonate nanostructures, is effective for the synthesis of trisubstituted imidazole derivatives. This method has many advantages such as short reaction time, high yield, solvent free conditions, recyclability of the catalyst, and easy workup.

Pumice-modified cellulose fiber: An environmentally benign solid state hybrid catalytic system for the synthesis of 2,4,5-triarylimidazole derivatives

In this study, we developed an instrumental hybrid catalytic system comprising cellulose fiber and volcanic pumice powder, which was applied as a suitable organic–inorganic hybrid catalyst for the synthesis of 2,4,5-triarylimidazole derivatives. High reaction yields (97%) were obtained in short reaction times (20 min) using this catalytic system. In physical terms, the high porosity of pumice provides an extremely high active surface area for electronic interactions among the components. Moreover, the most distinctive properties of this catalytic system are high biodegradability, simple separation of the catalyst, and good reusability. The natural pumice can be recovered easily using an external magnet and reused with no significant decline in the catalytic activity. The structural characteristics of this efficient catalytic system were assessed using various analytical methods.

Two Schiff-base complexes of copper and zirconium oxide supported on mesoporous MCM-41 as an organic–inorganic hybrid catalysts in the chemo and homoselective oxidation of sulfides and synthesis of tetrazoles

A simple and efficient procedure was reported for the synthesis of tetrazole derivatives, the chemo and homoselective oxidation of sulfides to sulfoxides in the presence of two Schiff-base complexes of zirconium oxide and copper anchored on MCM-41 as mesoporous and organometallic catalysts under green conditions. All the products were obtained in excellent yields with high TOF values indicating the high activity of the synthesized catalysts. These catalysts were characterized by XRD, TGA, SEM, EDS, FT-IR, TEM, WDX, BET and AAS techniques and can be recycled for several times without significant loss in catalytic activity. The recovered catalysts were characterized by SEM, FT-IR and AAS analysis which shown an excellent agreement with fresh catalysts.

A novel organic–inorganic hybrid material: production, characterization and catalytic performance for the reaction of arylaldehydes, dimedone and 6-amino-1,3-dimethyluracil

A novel silica-based organic–inorganic hybrid catalyst was prepared, characterized and applied for the synthesis of pyrimido[4,5-b]quinolines.

Synthesis and non‐parametric evaluation studies on high performance of catalytic oxidation‐extraction desulfurization of gasoline using the novel TBAPW11Zn@TiO2@PAni nanocomposite

In this work, the new catalyst (assigned as TBAPW11Zn@TiO2@PAni) was successfully designed and synthesized on the basis of quaternary ammonium salt of zinc monosubstituted phosphotungstate [(n‐C4H9)4N][PW11ZnO39] (TBAPW11Zn), titanium dioxide (TiO2), and polyaniline (PAni). This study reports the catalytic oxidation‐extraction desulfurization (ECODS) of sulfur‐containing molecules from real and the simulated (Th, BT, and DBT) gasoline using new organic–inorganic hybrid catalyst (TBAPW11Zn@TiO2@PAni). The ECODS results were shown that the concentration of sulfur compounds (SCs) of real gasoline was lowered from 0.4992 to 0.0122 wt.% with 97% efficiency at 35 °C after 1 h. Furthermore, the synthesized heterogeneous nanocatalyst showed high stability and reusability after five times without significant loss of activity. The high performance of TBAPW11Zn@TiO2@PAni/H2O2/CH3CO2H system can be a promising route with a superb potential in the generation of ultra‐low‐sulfur gasoline. Also the Mann–Whitney U‐test results show that there is not a significant difference between the mean of sulfur percentage for DBT & BT, BT & Th and DBT & Th in the presence of the catalyst. Based on the Kruskal–Wallis test results, we can conclude that the temperature, time and amount of catalyst have a significant effect on ECODS efficiency of TBAPW11Zn@TiO2@PAni nanocomposite.

Magnetic dextrin nanobiomaterial: An organic-inorganic hybrid catalyst for the synthesis of biologically active polyhydroquinoline derivatives by asymmetric Hantzsch reaction.

Dextrin is a low molecular weight polysaccharide obtained from natural resources. Due to exceptional properties such as chemical structure, having extreme reactive functional groups, low cost, commercial availability, non-toxicity and biocompatibility, it can be introduced as a green organocatalyst. The fabrication of hybrid materials from natural polymers and synthetic inorganic materials constructs compounds with new features, abilities and applications. Therefore, magnetic dextrin nanobiocomposite was prepared using a simple chemical co-precipitation. Then, it was characterized by Fourier transform infrared (FT-IR) spectroscopy, energy-dispersive X-ray (EDX) analysis, vibrating sample magnetometer (VSM) curve, scanning electron microscopy (SEM) image, X-ray diffraction (XRD) pattern, thermogravimetric analysis (TGA) and inductively-coupled plasma atomic emission spectroscopy (ICP-AES) analysis. Subsequently, to evaluate the catalytic performance of the synthetic hybrid catalyst, it was tested for the synthesis of biologically active polyhydroquinoline derivatives by four-component condensation reactions of aromatic aldehyde, ethyl acetoacetate, dimedone, ammonium acetate in ethanol under refluxing conditions. Experimental observations indicated some advantages of the present method, such as the use of green and biopolymer-based catalyst, simple procedure, mild reaction conditions, short reaction times (15-45min), appropriate yield of products (70-95%) and catalyst reusability after five consecutive runs without considerable catalytic performance decrease.