Bifunctional 3D-MOF-based nanoprobes for electrochemical sensing and nanozyme enhanced with peroxidase mimicking for colorimetric detection of acetaminophen

The outgrowth of the zeolitic imidazole framework (ZIF-67) with substantial benefits was significantly used in the present study. The attractive properties of ZIF-67 are envisioned to develop a dual-functional sensing platform as electrochemical and colorimetric for acetaminophen detection. Co-ZIF-67 was developed as a synthesis-controlled material via three different preparation techniques as ZIF-67-C, ZIF-67-A, and ZIF-67-H. ZIF-67-C prepared via simple co-precipitation strategy in room temperature acquired rhombic dodecahedral structure with increased electrocatalytic activity. ZIF-67-C nanozyme exhibits enzymatic activity with intrinsic peroxidase mimicking and higher electron affinity than ZIF-67-A and ZIF-67-H. The well-developed ZIF-67-C without further aggregation and a steadily build structure resulted in an enhanced response. While the higher chance of aggregation and irregular arrangements of ZIF-67-A and ZIF-67-H resulted in lower performance toward acetaminophen detection. Moreover, the absorption of 3, 3 ', 5, 5' – tetramethylbenzidine (TMB) molecules could lower the diffusion distance leading to improved peroxidase mimicking activity. Nanozyme ZIF-67-C effectively oxidizes TMB to TMBox product and with hydroxyl radicals (^?OH) generation from H₂O₂ decomposition. Michaelis-Menten and Lineweaver Burk's model was estimated. The LOD was 0.014 μM (electrochemical) and 0.034 μM (calorimetric). The real samples as river water and lake water show good recovery in both sensing modes. The high surface area, improved electrical conductivity, high porosity of the prepared ZIF-67-C sample is beneficial for dual sensing applications and determined to be used in several applications.     

Catalytic Conversion of SO2 Released from the Roasting Process of Copper Sulfides to SO3 by New Nanocatalysts of Vanadium(V) Oxide

Two new silica‐supported vanadium(V) oxide nanocatalysts were synthesized from vanadyl(IV ) sulfate and vanadyl(IV ) oxalate by the sol–gel method. The nanocatalysts were characterized by Fourier transform infrared spectroscopy, thermogravimetry, X‐ray diffraction, X‐ray fluorescence, and field‐emission scanning electron microscopy. The average diameter of the nanocatalysts was ~16 nm. The catalytic activity of both nanocatalysts was investigated in the oxidation of sulfur dioxide (SO₂ ) released from the roasting of copper sulfides to sulfur trioxide (SO₃ ), and the results were compared with those obtained from a commercial BASF (Baden Aniline and Soda Factory) catalyst. It is worth mentioning that our nanocatalysts show higher activity than the commercial catalyst for the oxidation of SO₂ to SO₃ under similar reaction conditions. The suggested electrocatalytic mechanism for the oxidation of SO₂ to SO₃ was confirmed by computational studies. Our calculations indicate that the terminal VO bond of V₂O₅ is likely the most active site for the adsorption and oxidation of SO₂ .     

One-pot synthesis of novel pyrido[2,3-d]pyrimidines using HAp-encapsulated-γ-Fe2O3 supported sulfonic acid nanocatalyst under solvent-free conditions

Novel pyrido[2,3-d]pyrimidine derivatives were synthesized through a one-pot three-component approach using HAp-encapsulated-γ-Fe2O3[γ-Fe2O3@HAp-SO3H]catalyzed condensation of 6-arnino-2-（methylthio or ethylthio）pyrimidin-4（3H）-one,Meldrum＇s acid and aryl aldehydes at 60 ℃ and under solvent-free conditions.In this protocol the use of nanocatalyst provided a green,useful and rapid method to generate the products in short reaction times and excellent yields（88%-94%）.     

An Expedient Synthesis of Novel Derivatives of Pyrido[2,3‐d]pyrimidines Using Magnetically Supported ZrO2 Nanocatalyst

An efficient synthesis of pyrido[2,3‐d]pyrimidine derivatives via one‐pot multicomponent reactions of 6‐amino‐2‐(alkylthio)pyrimidin‐4(3H)‐one, 3‐cyanoacetylindole and arylaldehydes using [Fe₃O₄@ZrO₂] as magnetically recyclable nanocatalyst is reported. This protocol furnished the desired products in good to excellent yields (70–93 %) and lower reaction times. The catalyst could be easily and efficiently separated from the final product solution by an external magnet and be reused in 5 consecutive runs without any significant activity decrease.     

One‐pot and Environmentally Friendly Synthesis of New Spiroindolones Using Functionalized Multiwall Carbon Nanotubes as Powerful Catalyst

Multiwall carbon nanotubes were functionalized and then used as powerful nanocatalyst for the one‐pot, three‐component synthesis of new spiroindolones. Functionalized multiwall carbon nanotubes (FMWCNTs) showed a good catalytic ability and recyclability in the current reaction. The present strategy offers some interesting advantages such as simplicity, high yields of products, and non‐toxic nature.     

Enhanced visible-light-driven photocatalytic performance for degradation of organic contaminants using PbWO4 nanostructure fabricated by a new,simple and green sonochemical approach

Water contamination has turned into a critical global concern that menaces the entire biosphere and has a notable effect on the lives of living beings and humans. As a proper and environmentally friendly solution, visible-light photocatalysis technology has been offered for water contamination removal. There is a strong interest in the design of the efficient catalytic materials that are photoactive with the aid of visible light. Herein, to fabricate a highly efficient photocatalyst for removal of organic pollution in water, a facile and swift sonochemical route employed for creation of the spindle shaped PbWO₄ nanostructure with the aid of an environmentally friendly capping agent (maltose) for the first time. To optimize the efficiency, dimension and structure of lead tungstate, various effective factors such as time, dose of precursors, power of ultrasound waves and kind of capping agents were altered. The attributes of PbWO₄ samples were examined with the aid of diverse identification techniques. The produced lead tungstate samples in role of visible-light photocatalyst were applied to remove organic pollution in water. The kinds of pollutants, dose and type of catalyst were examined as notable factors in the capability to eliminate contaminants. Very favorable catalytic yield and durability were demonstrated by spindle-shaped PbWO₄ nanostructure (produced at power of 60 W for 10 min and with usage of maltose). Usage of ultrasonic irradiation could bring to improvement of catalytic yield of PbWO₄ to 93%. Overall, the outcomes could introduce the spindle-shaped PbWO₄ nanostructure as an efficient substance for eliminating water contamination under visible light.     

Application of ZnO‐Al2O3 Nanocomposite as Nanocatalyst for Photodegradation of Acid Violet 5B

ZnO‐Al₂O₃ nanocomposite (ZANC) is used as nanocatalyst for photodegradation of acid violet 5B (AV5B) as an industrial dye. The experimental data shows that the degradation of AV5B is accelerated by ZANC and UV light. The effects of various parameters such as pH, hydrogen peroxide and ethanol are investigated on the photodegradation efficiency. Photocatalytic degradation rate of AV5B is increased by ethanol and hydrogen peroxide. Based on the kinetic studies, the rate constant of the photodegradation reaction is estimated 2.829 × 10^‐1 min^‐1.     

Catalytic wet air oxidation of phenol over ultrasound-assisted synthesized Ni/CeO2–ZrO2 nanocatalyst used in wastewater treatment

Non-noble metal Ni with different loadings was coated on precipitated CeO₂–ZrO₂ support by the sonochemistry method and examined for catalytic wet air oxidation of phenol. The structure of the nanocatalysts was determined by BET, FESEM, XRD, and FTIR analyses. The results showed non-uniform morphology of the nanocatalyst at lower Ni contents changed to homogenous morphology with spherical nano particles at higher Ni contents. While the size of NiO crystals remained constant with rising Ni content, the crystallinity of NiO significantly increased. If the crystallinity of NiO was 100% in 20% wt Ni/CeO₂–ZrO₂, the crystallinity of NiO in 5% wt Ni was found to be 41.13%. The average particle size in Ni(15%)/CeO₂–ZrO₂ was 77 nm in which 85.71% of particle diameters were less than 100 nm. Catalytic wet air oxidation of phenol with different Ni loadings indicated improvement of phenol destruction at higher amounts of active phase. Removal of phenol increased with increasing catalyst loading from 4 to 9.0 g/l but further increase to 10 g/l declined the catalyst reactivity.     

Applications of nano-catalyst in new era

In the era of nanoscience where all the devices and technologies are going to smaller and smaller in size with improved properties; catalysis is an important field of application. In this review article we are trying to summarize data reported in literature for application of nano sized catalyst in our daily life which are useful for human beings. Improvement in catalytic properties due size of catalyst reduced to nano scale is discussed here. Introductive points regarding nanoscience; their functional approaches; current research are also here.Main applications of nanocatalysts in water purification; fuel cell; energy storage; in composite solid rocket propellants; bio diesel production; in medicine; in dye; application of carbon nano tubes and several other point of application are discussed here in detail.