Conversion Of 4-nitrophenol Research Articles

Green synthesis of reduced graphene oxide-AgAu bimetallic nanocomposite: Catalytic performance

In this study, we prepared lichen reduced-graphene oxide (LrGO)-bimetallic nanoparticle nanocomposites (LrGO-AgAu) by applying a green, facile and one pot approach. LrGO-AgAu was synthesized via simultaneous reduction of graphene oxide (GO), AgNO3 and HAuCl4 with Cetraria Islandica (L.) Ach. extract. Characterization of the prepared nanocomposites were carried out by transmission electron microscopy (TEM), scanning electron microscopy (SEM), ultraviolet-visible (UV-Vis) spectroscopy, X-Ray Diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The synthesized LrGO-AgAu bimetallic nanoparticle nanocomposites were used for catalytic conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with NaBH4. The effect of nanocomposite composition on catalytic activity was examined. It is obtained that AgAu bimetallic nanoparticles with small particle sizes were decorated LrGO nanosheets homogenously and superior catalytic performance was achieved for the decomposition of 4-NP. The results showed that catalytic reduction reaction of 4-NP to 4-AP with noble metallic NPs nanocatalysts obtained by lichen extract is a facile and low-cost approach for removal.

Lyotropic liquid crystal directed synthesis of anisotropic copper microparticles and their application in catalysis

A simple, room-temperature approach for the synthesis of stable microparticles of copper in a lyotropic liquid crystal (LLC) template is described. The LLC phase having a hexagonal ordering is prepared using a mixture of non-ionic surfactant triton-X 100 and water in the ratio of 40:60 wt%. A controlled growth of copper particles is achieved in this medium by reducing cupric chloride using hydrazine hydrate under basic condition without the aid of any external stabilizing agent. Monodisperse, platelet-like copper microparticles (size ∼0.25 μm) are formed in this synthesis, which are well-dispersed in the lyotropic phase without aggregation. Besides, the copper particles are found to be stable for several months in the liquid crystalline medium. The LLC medium directed the growth of anisotropic microparticles and also acted as a stabilising agent. These micro platelets of copper are found to exhibit significant catalytic and electrocatalytic activity for the sodium borohydride mediated conversion of 4-nitrophenol to 4-aminophenol and for the reduction of hydrogen peroxide respectively.

Stable and efficient graphitic carbon nitride nanosheet–supported ZnS composite catalysts toward competent catalytic performance for the reduction of 4-nitrophenol using NaBH4

The development of efficient heterogeneous catalysts for degrading organic pollutants or converting them into harmless and even useful products is of vital significance for environmental remediation. Herein, we reported the simple synthesis of highly active and stable graphitic carbon nitride (g-C3N4) nanosheet–supported ZnS composites (g-C3N4/ZnS) and demonstrated its excellent performances as a catalyst for the reductive conversion of 4-nitrophenol (4-NP). The prepared g-C3N4/ZnS composites were characterized by a collection of analytical techniques. The catalytic activity exhibited by the g-C3N4/ZnS composite was 4.1 and 1.9 times higher than that of g-C3N4 and ZnS, respectively. The remarkably increased catalytic performance of the g-C3N4/ZnS composite was mainly attributed to the synergistic effect of the junction or interface formed between g-C3N4 and ZnS, resulting in enhanced catalytic activity. Notably, the synthesized g-C3N4/ZnS composite was found to exhibit an outstanding catalytic activity and excellent recyclability for five cycles in the reduction of 4-NP using NaBH4 without considerable loss of catalytic activity, demonstrating its long-term stability. This work shows significant progress for low-cost fabrication of the g-C3N4/ZnS composite with excellent catalytic activity.

Preparation and catalytic performance of polymer gold nanocomposites

The development of efficient heterogeneous catalysts for reductive conversion of 4-nitrophenol (4-NP) is of vital significance for environmental remediation, dyestuff industry, pharmaceutical industry. We reported that Au@D201, a polymer gold nanocomposite of gold nanoparticles loaded on D201 resin, was prepared using macroporous styrenic ion exchange resin D201 as carrier, chloroauric acid as gold source and sodium borohydride as reducing agent. The average diameter of gold nanoparticles in Au@D201 composites is 5 nm, which has excellent catalytic properties for the reduction of 4-nitrophenol. The Au@D201 was characterized by ultraviolet–visible spectroscopy, X-ray diffraction, mercury injection instrument, transmission electron microscopy and X-ray photoelectron spectroscopy (XPS). The results reveal that some of the gold nanoparticles were loaded on the surface of the resin, and most of the gold nanoparticles were in the resin pores. A strong chemical interaction, between the gold nanoparticles and the resin, is similar to the cross-linking action of the macromolecules. The gold nanoparticles provide a new cross-linking point for the resin, increasing the degree of cross-linking of the resin and causing some degree of resin ordering to occur. XPS shows that the electron density of the outer layer of the gold atom increases, indicating that there are some conjugated interactions between the resin and gold atoms. Conjugated interactions and the gold quantum size effect are the main reasons for improving the catalytic effect of the composite material. When the gold nano-loading amount is 0.1%, it still has an excellent catalytic effect on the reduction reaction of 4-nitrophenol.

Gold Nanoparticles Stabilized by 1,2,3-Triazolyl Dendronized Polymers as Highly Efficient Nanoreactors for the Reduction of 4-Nitrophenol

Dendronized polymer (DP)-encapsulated gold nanoparticles (AuNPs) are well prepared and characterized, and their catalytic performance is also evaluated. First, the nanoreactors self-assembled from water-soluble 1,2,3-triazolyl DP 1 are employed as templates to generate DP-encapsulated AuNPs. The resulting AuNPs are characterized through UV–visible spectroscopy and high-resolution transmission electron microscopy. The catalytic activity of DP-encapsulated AuNPs was estimated by the conversion of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in water and an extremely catalytic activity is found for the reduction reaction with remarkable TONs up to 2000 and TOFs up to 7350 h− 1. This catalytic performance is comparable to these micellar AuNPs encapsulated by the known analogues including the trz-containing triethylene glycol (TEG) and polyethylene glycol (PEG) dendrimers, which may be because that DPs 1 has the similar behavior in solution as the dendrimer analogues.

Synergistic effect of bimetallic Cu:Ni nanoparticles for the efficient catalytic conversion of 4-nitrophenol

A non-noble metal-based bimetallic Cu–Ni system for the conversion of 4-nitrophenol and effective recyclability by magnetic retrieval of the catalyst.

Green and facile synthesis of Rh/GO nanocomposites for high catalytic performance

We report a facile and green route to prepare ligand-free ultrafine rhodium (Rh) nanoparticles decorated on graphene oxide (GO) nanosheets. The ultrafine Rh nanoparticles with average size 1.8 ± 0.4 nm were synthesized by pulsed laser ablation in liquid. The Rh nanoparticles could be uniformly supported on the surface of GO through the electrostatic interaction. The reduction of 4-nitrophenol in presence of NaBH4 was performed as a model reaction to evaluate the catalytic properties of Rh/GO nanocomposites. The Rh/GO nanocomposites showed remarkable high catalytic activities with rapid and complete conversion of 4-nitrophenol to 4-aminophenol. The kinetic constant rate of the Rh/GO nanocomposites was 7.62 × 10−3 s−1, which is 27 times higher than commercial Rh/C catalyst, revealing the high catalytic activity in catalytic hydrogenation. The Rh/GO nanocomposites showed good stability and high catalytic activity due to the small size Rh nanoparticles, uniformly dispersed on GO nanosheets. This work may provide a green and alternative method to prepare ligand-free supported ultrafine noble metal heterogeneous catalysis.

3D and Plasmonic Nanoparticle Decorated Catalytic System via Bio-inspired Polydopamine Coating: Cigar Filter Case Study

Despite the significant progress, the well-controlled deposition of nanoparticles onto the support materials having 3-D nano-morphologies for the catalytic applications is still facing challenges such as the limited accessibility of reacting molecules to catalyst surface, uncontrolled aggregation of nanoparticles, high cost and highly complicated fabrication procedures. In this study, to overcome these challenges, a simple yet versatile alternative platform is proposed to control the gold nanoparticle (AuNP) size, surface coverage and morphology onto the 3-D cigar filter surface via bio-inspired polydopamine (PDOP) coating. The effect of gold deposition time on AuNPs characteristics and their catalytic activity in the model reaction were investigated in detail. It is found that both AuNPs properties and catalytic activity can be controlled by changing deposition time. The deposition of AuNPs via functional groups of PDOP such as amine, catechol, and imine provided total conversion of 4-nitrophenol to 4-aminophenol within an hour.

Gold nanoparticles supported by amino groups on the surface of magnetite microspheres for the catalytic reduction of 4-nitrophenol

Fe3O4/P(GMA-DVB)/PAMAM/Au microspheres are fabricated to research the catalytic performances to 4-nitrophenol. In the preparation process, Fe3O4 microspheres act as magnetic cores, PAMAM dendrimers growing up on the surface of P(GMA-DVB) polymer work as carriers, and Au nanoparticles serve as catalytic materials. The stability of the prepared microspheres is evaluated by successively catalytic experiments to measure the conversion of 4-nitrophenol, and catalytic efficiency can still maintain up to 78.7% after ten cycles. Moreover, the effects of major factors including the concentration of the prepared microspheres and the temperature of reaction system on the conversion of 4-nitrophenol are also investigated in detail. The manuscript reveals that 4-nitrophenol can be almost converted to 4-aminophenol within 7 min at 45 °C in the case of using 1.0 g/L Fe3O4/P(GMA-DVB)/PAMAM/Au microspheres. Such excellent catalytic properties are ascribed to the optimum structure of the prepared microspheres, which favors the sufficient contact between Au nanoparticles and 4-nitrophenol. The results and strategies exhibited here provide insight into the preparation of sophisticated structures of catalysts to treat wastewater.

Synthesis and Properties of the Self-Assembly of Gold-Copper Nanoparticles into Nanoribbons.

We report the efficient wet-chemical production of self-assembled gold-copper bimetallic nanoparticles (diameter of ∼2 nm) into two-dimensional flexible ribbonlike nanostructures. The direct observation of a layered arrangement of particles into nanoribbons was provided through high-resolution transmission electron microscopy and electron tomography. These nanoribbons showed photoluminesce and efficient photocatalytic activity for the conversion of 4-nitrophenol. The thermal stability of the nanoribbons was also measured by in situ heat treatment in the electron microscope, confirming that the self-assembled gold-copper nanoribbons efficiently supported up to 350 °C. The final morphology of the nanoparticles and their ability to self-assemble into flexible nanoribbons were dependent on concentration and the ratio of precursors. Therefore, these experimental factors were discussed. Remarkably, the presence of copper was found to be critical to triggering the self-assembly of nanoparticles into ordered layered structures. These results for the synthesis and stability of self-assemblies of metallic nanoparticles present a potential extension of the method to producing materials with catalytic applications.

Coordination polymer derived Ni based composite material with N-doped mesoporous carbon as matrix for pollutants removal

To obtain a magnetic composite material for water treatment, a Ni based composite material with nitrogen doped mesoporous carbon as matrix (Ni@NC) has been synthesized with coordination polymer as precursor. In Ni@NC, Ni nanoparticle with the size about 3–5 nm dispersed evenly in nitrogen doped mesoporous carbon matrix. Ni@NC exhibits striking catalytic activity in reductive conversion of 4-nitrophenol to 4-aminophenol with the existence of sodium borohydride (NaBH4). The conversion efficiency reaches almost 100% in 160 s with the amount of Ni@NC as low as 5 mg. After eight successive cycles of reductions, the efficiency still retains above 99%. For a catalyst, chemical content plays an important role in its performance. Here, the influence of nitrogen species on 4-nitrophenol reductive property is discussed in detail, which illustrates pyrrolic N and quaternary N both play significant roles during catalytic reduction process. In addition, Ni@NC also possesses excellent activity in catalytic reduction of organic dyes, such as Rhodamine B (RhB), methyl orange (MO) and methylene blue (MB). Due to its large surface area and suitable pore size, Ni@NC also possesses adsorption removal property towards tetracycline and Cr2O72−. Magnetic measurement reveals ferromagnetic character of Ni@NC, which facilitates its magnetic separation from the treated samples. All these merits make Ni@NC a promising multifunctional environmental material in waste water treatment.

Oxygen vacancy rich tungsten oxide with nitrogen doped mesoporous carbon as matrix for overall water splitting and 4-nitrophenol reductive removal

A nitrogen doped mesoporous carbon matrix supported oxygen vacancies rich tungsten oxide composite material, WO3-x@NC (1 > x > 0), has been fabricated successfully with chitosan and H3PW12O40 as precursors through calcination. In this composite material, WO3-x particles with the size about 10–15 nm disperse evenly in nitrogen doped mesoporous carbon matrix. WO3-x@NC presents low overpotentials (η10) of 61 and 306 mV to reach a current density of 10 mA/cm2 for HER and OER in 1.0 M KOH, respectively. With WO3-x@NC as both cathode and anode at the same time, an electrolyzer, WO3-x@NC//WO3-x@NC was constructed for overall water splitting, which only needs a cell voltage of 1.60 V to achieve a current of 10 mA/cm2. During this process, WO3-x@NC//WO3-x@NC exhibits remarkable stability in 48 h. Moreover, besides HER and OER, WO3-x@NC also shows striking catalytic activity for reductive conversion of 4-nitrophenol to 4-aminophenol. Oxygen vacancies from WO3-x and good electron transportation property of nitrogen doped carbon matrix play important roles in overall water electrocatalytic splitting and 4-nitrophenol reductive removal. We expect WO3-x@NC will find its way as a new resource for hydrogen energy as well as a promising material in 4-nitrophenol removal from water.

Effective catalytic reduction of aromatic nitrocompounds using mineral beyerite, CaBi2O2(CO3)2

The synthesis of the mineral beyerite (CaBi2O2(CO3)2) by a single step hydrothermal approach is highly beneficial to demonstrate its multifunctional nature. The present work, deals with the application of CaBi2O2(CO3)2 as a heterogeneous catalyst. The formation of bulk polycrystalline beyerite via hydrothermal method at 140 °C led to the formation of single phase thin rectangular plates as evidenced from PXRD, SEM and TEM characterizations. These rectangular plates of beyerite with sharp edges show excellent reduction catalytic activities of aromatic nitro compounds in the presence of NaBH4. For example, pseudo first order reaction rate constant for the conversion of 4-nitrophenol to 4-aminophenol using beyerite as catalyst is found to be 2.5 × 10−1 min−1. The catalyst is environmental friendly, devoid of expensive noble metals and can be recycled upto five successive catalytic cycles with maximum conversion efficiency. TEM images of the catalyst after reduction reactions showed the possible presence and involvement of metallic bismuth (Bi°). The usage of CaBi2O2(CO3)2 can also be expanded, for the reduction of other (2-nitrophenol, 3-nitrophenol, 2, 4-dinitrophenol) nitro compounds, and also for the reduction of aqueous solutions containing Cr(VI), methyl orange (MO) and Rhodamine-6G (Rh 6G). The demonstration of the mineral beyerite as a reduction catalyst offers new possibilities to develop novel solid state materials for various catalytic applications.

WO3-x based composite material with chitosan derived nitrogen doped mesoporous carbon as matrix for oxygen vacancy induced organic pollutants catalytic reduction and IR driven H2 production

A nitrogen doped mesoporous carbon matrix supported tungsten oxide composite material, WO3-x@NC, (1 >x > 0), was fabricated successfully with chitosan and polyoxometalates as precursors through calcination. In this composite material, tungsten oxide particles with the size about 5–8 nm disperse evenly in the framework of nitrogen doped mesoporous carbon matrix. WO3-x@NC exhibits striking catalytic activity for reductive conversion of 4-nitrophenol to 4-aminophenol with the existence of sodium borohydride (NaBH4). The conversion efficiency reaches almost 100% in 2.5 min with a small amount of WO3-x@NC as catalyst. After 5 successive cycles of reactions, this value still retains above 92%. Besides 4-nitrophenol, WO3-x@NC also possesses excellent activity in catalytic removal of organic dyes, such as Rhodamine B (RhB) and methyl orange (MO). Oxygen vacancies from WO2 and good conductivity of nitrogen doped carbon matrix play important roles in the removal of these organic pollutants. WO3-x@NC also possesses outstanding IR light driven photocatalytic H2 evolution activity. Furthermore, the influence of calcination temperature on catalysis is studied and an ideal condition to obtain catalyst with high activity has been obtained. We expect that WO3-x@NC will find its way as a promising material in water purification as well as a new resource for hydrogen energy.

Convenient synthesis of Mn-doped Zn (O,S) nanoparticle photocatalyst for 4-nitrophenol reduction

The conversion of 4-nitrophenol as a toxic and waste pollutant to 4-aminophenol as a non-toxic and useful compound by photocatalytic reduction is highly important. In this work, the solid-solution concept by doping was involved to synthesis earth-abundant and green material of Mn-doped Zn(O,S). Zn(O,S) with different Mn doping contents was easily synthesized at low temperature 90°C for 4-NP reduction without using the reducing agent of NaBH4. The Mn-doped Zn(O,S) catalyst exhibited the enhancements in optical and electrochemical properties compared to un-doped Zn(O,S).It was found that 10% Mn-doped Zn(O,S) had the best properties and it could totally reduce 4-NP after 2h photoreactions under low UV illumination. The hydrogen ion was proposed to involve the 4-NP reduction to 4-AP, which is hydrogen ion and electron replaced the oxygen in amino (NO2) group of 4-NP to form the nitro (NH2) group. We alsoproposed the incorporation of Mn in Zn site in the Zn(O,S) host lattice could make the oxygen surface bonding weak for easily forming the oxygen vacancy. The more oxygen vacancy for more hydrogen ion would be generated to consume for 4-NP reduction.

Towards single crystalline, highly monodisperse and catalytically active gold nanoparticles capped with probiotic Lactobacillus plantarum derived lipase

Owing to the eco-friendly nature of biomolecules, there lies a huge interest in exploring them as capping agents for nanoparticles to achieve stability and biocompatibility. Lipase extracted from the probiotic Lactobacillus plantarum is utilized for the first time to study its efficacy in capping gold nanoparticles (GNPs) in the room temperature synthesis using HAuCl4. The synthesized lipase-capped GNPs are characterized using UV–visible spectroscopy, FT-IR, HR-TEM, DLS and zeta potential measurements. Importantly, selected area electron diffraction (SAED) studies with HR-TEM have revealed the effect of lipase capping in tuning the polycrystallinity of the GNPs. The lipase-capped GNPs are explored for their catalytic efficiency towards an environmentally and industrially important conversion of 4-nitrophenol to 4-aminophenol. Exploiting the amine functional groups in the protein, the recoverability and reusability of the GNPs have been demonstrated through immobilization over amine-functionalized Fe3O4 nanoparticles.

Ag Nanoparticle/Nanofibrillated Cellulose Composite as an Effective and Green Catalyst for Reduction of 4-Nitrophenol

In this work, silver nanoparticles (Ag NPs) prepared through in situ green and facile synthesis by using nanofibrillated cellulose (NFC) hydrogel as support, stabilizer and reducing agent by two different methods. Their catalytic abilities were examined for conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The structure of as-synthesized composites with different AgNO3 concentrations were characterized by ultraviolet–visible spectroscopy, field emission scanning electron microscopy, transmission electron microscopy; energy dispersive spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Results show that all nanocomposites demonstrated excellent catalytic activity. Among them, Ag@NFC-2 sample, with spherical and well-dispersed Ag NPs along the nanofiber, produced by the second method having 0.25 M AgNO3 concentration presented outstanding catalytic efficiency.

Oxygen vacancy rich Cu2O based composite material with nitrogen doped carbon as matrix for photocatalytic H2 production and organic pollutant removal.

A nitrogen doped carbon matrix supported Cu2O composite material (Cu/Cu2O@NC) was fabricated successfully with a coordination polymer as precursor through calcination. In this composite material, Cu2O particles with a size of about 6-10 nm were dispersed evenly in the nitrogen doped carbon matrix. After calcination, some coordinated nitrogen atoms were doped in the lattice of Cu2O and replace oxygen atoms, thus generating a large number of oxygen vacancies. In Cu/Cu2O@NC, the existence of oxygen vacancies has been confirmed by electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS). Under visible light irradiation, Cu/Cu2O@NC exhibits excellent H2 production with the rate of 379.6 μmol h-1 g-1. Its photocatalytic activity affects organic dyes, such as Rhodamine B (RhB) and methyl orange (MO). In addition to photocatalysis, Cu/Cu2O@NC also exhibits striking catalytic activity in reductive conversion of 4-nitrophenol to 4-aminophenol with in presence of sodium borohydride (NaBH4). The conversion efficiency reaches almost 100% in 250 s with the quantity of Cu/Cu2O@NC as low as 5 mg. The outstanding H2 production and organic pollutants removal are attributed to the oxygen vacancy. We expect that Cu/Cu2O@NC will find its way as a new resource for hydrogen energy as well as a promising material in water purification.

Fabrication of reduced graphene oxide decorated with gold and nickel for the catalytic reduction of 4-nitrophenol

Reduced graphene oxide (Ni/rGO) decorated by metallic Ni nanoparticles (NPs) was firstly fabricated through in situ thermal decomposition and subsequent reduction in 5% H2/N2 gas at 600 °C, and then Au NPs were loaded on the surface of the as-prepared Ni/rGO. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM) were used to characterize the Ni-decorated rGO and Ni/rGO@Au nanocomposites. The results show that both Ni and Au NPs are highly dispersed on rGO, and Ni/rGO@Au possesses excellent activity toward the conversion of 4-nitrophenol into 4-aminophenol in the presence of NaBH4, showing almost four orders of magnitude higher activity parameter κ (9.7 × 10−2 s−1mg−1) than Ni/rGO (1.1 × 10−5 s−1mg−1), though Ni/rGO has a better performance in the catalytic conversion of 4-NP. In the meantime, the Ni/rGO@Au can be easily recycled by an external magnetic field and the conversion of 4-nitrophenol at the 8th cycle is still close to 95%.

Bio-fabrication of catalytic platinum nanoparticles and their in vitro efficacy against lungs cancer cells line (A549)

Platinum based drugs are considered as effective agents against various types of carcinoma; however, the severe toxicity associated with the chemically prepared platinum complexes limit their practical applications. Similarly, water pollution caused by various organic moieties is another serious health problem worldwide. Hence, an intense need exists to develop new, effective and biocompatible materials with catalytic and biomedical applications. In the present contribution, we prepared platinum nanoparticles (PtNPs) by a green route using phytochemicals as a source of reducing and stabilizing agents. Well dispersed and crystalline PtNPs of spherical shapes were prepared and characterized. The bio-fabricated PtNPs were used as catalyst and anticancer agents. Catalytic performance of the PtNPs showed that 84% of the methylene blue can be reduced in 32min under visible light irradiation (K=0.078min−1). Similarly the catalytic conversion of 4-nitrophenol to 4-aminophenol was achieved in <20min (K=0.124min−1). The in vitro anticancer study revealed that biogenic PtNPs are the efficient nano-agents possessing strong anticancer activity against the lungs cancer cells line (A549). Interestingly, the as prepared PtNPs were well tolerated by normal human cells, and therefore, could be effective and biocompatible agents in the treatment of different cancer cells.