Activity For Reduction Of P-nitrophenol Research Articles

Efficient photocatalytic reduction of p-nitrophenol under visible light irradiation based on Ag NPs loaded brown 2D g-C3N4 / g-C3N4 QDs nanocomposite

Recently, low-cost graphitic carbon nitride (g-C3N4) revealed high photocatalytic activities and provided solutions to environmental pollution. In this study, we synthesized brown mesoporous 2D g-C3N4 by calcination dicyandiamide with pluronic P123. This is followed by loading of Ag NPs on the prepared 2D g-C3N4 by photodeposition process. After that, a ternary composite 2% Ag/ 2D g-C3N4 / g-C3N4 QDs heterojunction photocatalyst has been successfully prepared. The prepared nanomaterials were comprehensively characterized by various analysis techniques such as XRD, UV–Vis., BET, XPS, SEM, TEM. This new system exhibited a large surface area with porous structure and a wide absorption of visible light. The results verified that Ag NPs decoration enhanced the charge separation of photo-generated carriers of g-C3N4 2D and g-C3N4 QDs, promote significant enhancement in the photocatalytic activity for reduction of p-nitrophenol with a rate constant (k) value of 0.49729 / min in 6 min. This rate is about two-fold higher than that observed for pure g-C3N4 2D and g-C3N4 QDs as well as shows an improvement compared to 2% Ag/ g-C3N4 2D and g-C3N4 2D/ g-C3N4 QDs. The results open the door to design highly efficient 2D/0D nanocomposite photocatalysts for a wide variety of environmental applications.

A novel approach for the synthesis of nanostructured Ag3PO4 from phosphate rock: high catalytic and antibacterial activities

BackgroundSilver orthophosphate (Ag3PO4) has received enormous attention over the past few years for its higher visible light photocatalytic performance as well as for various organic pollutants degradation in aqueous media. Therefore, considerable efforts have been made to the synthesis of Ag3PO4 with high catalytic efficiency, long lifetime, and using low-cost inorganic precursors.ResultsThis article describes our efforts to develop a novel approach to synthesize of nanostructured silver phosphate (Ag3PO4) using phosphate rock as alternative and natural source of PO43− precursor ions. The catalytic experimental studies showed that the nanostructured Ag3PO4 exhibited excellent catalytic activity for reduction of p-nitrophenol in the presence of NaBH4 at room temperature. Furthermore, the antibacterial studies revealed that the obtained Ag3PO4 possess significant effect against E. Coli and S. Aureus bacteria.ConclusionThe obtained results make the nanostructured Ag3PO4 prepared from natural phosphate as a highly promising candidate to be used as efficient catalyst and antibacterial agent.Graphic

Palladium nanoparticles decorated on ZSM-5 derived micro-/mesostructures (MMZ) for nitrophenol reduction and MB degradation in water

Palladium-based catalysts are promising for catalytic reduction in catalysis. The dispersion state of palladium nanoparticles (Pd NPs) impacts the catalytic performance, while the development of catalysts with highly dispersed Pd NPs is a major challenge. Herein, we developed ZSM-5 derived micro-/mesoporous silica MMZ to regulate Pd NPs size and dispersion. MMZ was synthesized by combined dissolution of ZSM-5 under basic condition and re-assembly of Al-or Si-containing species of ZSM-5 by cetyltrimethylammonium bromide (CTAB) instead of expensive carbon nanofiber reported earlier. The Pd precursor is introduced into MMZ by ultrasound assisted incipient wetness impregnation (U-IWI) strategy. Up to 1.0 wt% Pd was highly dispersed per g of MMZ without showing any X-ray diffraction lines (denoted as 1.0 Pd/MMZ), while obvious diffraction lines were noticed in the counterpart synthesized from ZSM-5 (denoted as 1.0 Pd/ZSM-5). Further calculation shows the size of Pd NPs in 1.0 Pd/MMZ is 3.5 nm, which is smaller than that in 1.0 Pd/ZSM-5. Our results also demonstrated that well-dispersed and smaller size Pd NPs corresponds to superior catalytic activity in reduction of p-nitrophenol (P-NP) and methylene blue (MB). The typical catalyst 1.0 Pd/MMZ exhibited complete reduction of P-NP and MB in water within 3 min. It is superior to 1.0 Pd/ZSM-5 catalyst with the same Pd content as well as to several reported catalysts. Furthermore, 1.0 Pd/MMZ not only keeps high catalytic activity for 6 consecutive cycles, but also exhibit long-term stability in hydrogenation reaction.

Fabrication of gold nanoparticles within hierarchically ZSM-5-based micro-/mesostructures (MMZ) with enhanced stability for catalytic reduction of p-nitrophenol and methylene blue

Gold nanoparticles (Au NPs) have received great attention in diverse catalytic reactions due to their excellent activity. However, the activity is severely relying on dispersion and size of Au NPs. Therefore, regulation of Au NPs for degradation of organic pollutants in water is of vital significance for environmental remediation. Herein, we developed microporous/mesoporous silica, MMZ, using ZSM-5 (SiO2/Al2O3 = 28) as structural constructing precursor and cetyltrimethylamoniumbromide (CTAB) as template via sequential dissolution-self-assembly strategy. The Au precursor is introduced into MMZ and ZSM-5 by ultrasound assisted impregnation and subsequent reduced for Au0 formation. The obtained materials were characterized by XRD, TEM, XPS, SEM, UV-DRS, N2 adsorption and TG/DTG techniques. XRD and TEM study revealed that up to1.0 wt% of Au can be well dispersed with smaller size of 2.8 nm in the material from MMZ (denoted as 1.0Au/MMZ), while serious aggregation and formation of large Au NPs occurs over ZSM-5 with the same Au loading (denoted as 1.0Au/ZSM-5). Catalytic studies also demonstrated that Au/MMZ has much higher catalytic activity for reduction of p-nitrophenol (P-NP) and methylene blue (MB) to p-aminophenol (P-AP) and leuco methylene blue compared with Au/ZSM-5 analogue and other reported Au-based catalysts previously. Moreover, Au/MMZ has good reusability and showed no change in its original catalytic performance till 7th cycles in reduction of P-NP and MB, which is attributed to stable structure and well dispersion of Au NPs over MMZ. Therefore, compared with other Au based catalysts used for catalytic reaction, this Au/MMZ is cheap and promising for industrial applications.

Preparation of Graphene-Co/Ni/Fe₃O₄ Nanocomposites and Their Electrocatalytic Activity for Reduction of p-Nitrophenol.

Graphene-based nanocomposites of graphene-Co, graphene-Ni, and graphene-Fe₃O₄ were synthesized via improved chemical-carbothermal reduction using graphite and nitrates as starting materials. The Co, Ni, and Fe₃O₄ nanoparticles are uniformly loaded on the surfaces of graphene nanosheets without serious folds and conglomeration. The average dimensions of the Co, Ni, and Fe₃O₄ nanoparticles attached to graphene are approximately 50, 60, and 5 nm, respectively. Subsequently, three novel types of graphene-Co/Ni/Fe₃O₄ nanocomposite-modified glassy carbon electrodes (GCEs) were fabricated, and their electrocatalytic activity for reduction of p-nitrophenol was investigated by cyclic voltammetry in phosphate buffer solution. Results show that the current values increase as the scanning rate is increased from 70 mV·s-1 to 100 mV·s-1 and that the electrochemical reactions on the surface of the graphene-Co/Ni/Fe₃O₄-modified GCEs are diffusion controlled. Compared with the bare GCE, the graphene-Co/Ni/Fe₃O₄ nanocomposite-modified GCEs display considerably higher reduction peak current, which proves that the graphene-Co/Ni/Fe₃O₄ nanocomposites possess favorable electrocatalytic ability for reduction of p-nitrophenol.

Facile assembly of Ag nanoparticles on H2SrTa2O7 nanosheets with improved catalytic property

As a typical noble nanomaterial, silver (Ag) nanoparticles have been widely used as a catalyst, but their performance is somewhat limited by self-aggregation. In this study, H2SrTa2O7 nanosheet-supported ultrafine Ag nanoparticles (Ag/H2SrTa2O7) were successfully synthesized, and the aggregation of Ag nanoparticles was effectively prevented. The Ag/H2SrTa2O7 catalyst exhibited excellent activity in p-nitrophenol reduction and was successfully recycled 10 times without a substantial decrease in its catalytic activity. This superior catalytic activity could be ascribed to the large surface area of H2SrTa2O7 nanosheets and the effective dispersion of Ag nanoparticles on the perovskite nanosheets. This work is important for the simple and green preparation of Ag catalysts with excellent catalytic performance on nontoxic perovskite nanosheets.

Preparation of Pt, Pd and Cu nano single and bimetallic systems-supported NaY zeolite and test their activity in p-nitrophenol reduction and as anticancer agents

The quest of new materials with higher catalytic activity and new biological applications does not end. Single and bimetallic nanoparticles (NPs)-supported NaY zeolite were prepared using NaBH4 as reducing agent. Platinum, copper and palladium NPs were prepared as single nanometals-supported NaY. Copper (inexpensive transition metal) was used as a common metal to prepare nano-bimetallic systems, namely, PtCuY and PdCuY. The samples were investigated by ICP, XRD, FTIR, TEM and the surface texture parameters were measured as well at 77 K. TEM images proved the formation of Pt, Cu and Pd metals nanoparticles on NaY support with particle size of 14, 41 and 50 nm, respectively. However, after using copper as a common metal, the size decreased to 6 and 25 nm in PtCuY and PdCuY, respectively.The activity of the prepared nanomaterials towards the reduction of p-nitrophenol (PNP) by NaBH4 was in the order of CuY > PdY > PtY. Copper increased the activity of Pt and Pd towards the reduction of PNP with 5 and 14 times in case of PdCuY and PtCuY, respectively. The antitumor activity of the prepared systems will be investigated against hepatocarcinoma. Copper nanoparticles showed the highest inhibiting activity (lowering IC50) as single system, moreover, it promoted the inhibiting activity of PtCuY rather than PtPdY.

REDUCTION OF p-NITROPHENOL TO p-AMINOPHENOL BY USING NiO CATALYSTS: A COMPARATIVE STUDY

Different nickel oxide catalysts have been prepared by simple precipitation method using different nickel precursors and using surfactant sodium dodecyl sulfate (SDS) or without surfactant. The prepared catalysts have been characterized by using XRD and FT-IR. The particle sizes have been calculated by using the Scherrer equation. The nickel oxide catalyst prepared by using nickel acetate as precursor and surfactant SDS has shown less particle size as compared to other catalysts prepared by using other precursors. Also, nickel oxide catalyst prepared using nickel acetate precursor and surfactant SDS has shown higher catalytic activity for reduction of p-nitrophenol (PNP) to p-aminophenol (PAP) using sodium borohydride (NaBH 4 ). Also, for the said reaction effect of concentration of p-nitrophenol on catalytic efficiency has been studied.

A facile construction of Au nanoparticles stabilized by thermo-responsive polymer-tethered carbon dots for enhanced catalytic performance

Carbon dots (CDs), the youngest member in the carbon nanomaterial family, have drawn considerable attention due to their interesting optical, physicochemical and electronic properties as well as broad promising applications. Here, we developed a facile and effective strategy for the preparation of Au nanoparticles stabilized by thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) functionalized carbon dots (Au@CD@P) under the gentle water media. The as-designed dopamine(DA)-terminated PNIPAM can be easily anchored to CDs via mussel-inspired chemistry route. Both CD@P and CDs could well stabilize the Au nanoparticles with interesting assembled structure. The as-prepared Au@CD and Au@CD@P nanohybrids with good dispersibility and stability exhibited the intriguing catalytic activity for reduction of p-nitrophenol (p-NP). Especially, Au@CD@P as catalyst also played a switching role in regulating the catalytic rate by temperature. In addition, Au@CD@P exhibited excellent recyclability which may have potential in green chemical industry for developing high-activity catalysts and easy production methods.

Synthesis of Au/NiO hollow micro-spheres and their adsorption and electrocatalytic properties for p-nitrophenol

The precursors of NiO and Au/NiO hollow spheres with different Au contents were prepared via a solvothermal method, and the final samples were obtained by calcining each precursor at 350 °C for 3 h. The as-synthesized samples were characterized by XRD, XPS, TEM, FE-SEM and BET, respectively. The absorption performances of NiO and Au/NiO hollow spheres for p-nitrophenol were studied. The results indicate that Au/NiO hollow spheres display higher adsorption property than pure NiO, furthermore, Au/NiO sample with 3 % Au shows the highest adsorption performance. The adsorption reagent concentration on the adsorption performance was investigated by using Au/NiO with 3 % Au. The electrocatalytic properties of the final samples modified on a glassy carbon electrode for p-nitrophenol reduction in a basic solution were investigated. The results revealed that the Au/NiO hollow spheres displayed enhanced electrocatalytic activity for p-nitrophenol reduction than NiO, and the electrocatalytic activity of the Au/NiO hollow spheres increases with increasing Au content.

Effect of NaBH4 on properties of nanoscale zero-valent iron and its catalytic activity for reduction of p-nitrophenol

The reduction of p-nitrophenol (p-NP) to p-aminophenol (p-AP) by nanoscale zero-valent iron (NZVI)/NaBH4 system in an oxygen environment was studied by means of liquid chromatography, spectroscopy (vibration and X-ray photoelectron), solid analyses (transmission electron microscopy and X-ray diffraction) and density functional theory (DFT) calculations. Addition of NaBH4 into NZVI suspension showed the disintegration of NZVI (60–100nm), resulting in the formation of much smaller particles (15–40nm) due to the chemical etching of outermost surfaces (i.e., magnetite). Interestingly, complete reduction of p-NP and high conversion efficiency of p-AP (>98%) were observed in NZVI/NaBH4 system even after four recycling which is quite comparable with widely used noble metallic catalysts. Surface analysis confirmed that NaBH4 can prevent the oxidation of NZVI surface, leading to the continuous reduction of p-NP in oxygen environments. Experimental results and DFT calculations suggested that not only the formation of smaller NZVI but also thermodynamic preferences for reduction of p-NP on outermost surfaces of NZVI (i.e., magnetite) may significantly affect the reduction process of p-NP in NZVI/NaBH4 system. These novel findings can promote the development of new NZVI technologies which can be used for wastewater reductive treatment in oxygen environments.

Facile deposition of gold nanoparticles on C60 microcrystals with unique shapes

Gold nanoparticles were densely deposited on the surface of C60 microcrystals having a variety of unique shapes. C60 microcrystals were prepared by a conventional liquid–liquid reprecipitation method. The shapes of C60 microcrystals, such as bipyramid, belt, disc, and rod, were achieved by carefully adjusting the solvent species in the liquid–liquid reprecipitation process. Gold nanoparticles were directly deposited on C60 microcrystals without adding any conventional reducing agent but only heating HAuCl4 in C60 microcrystals ethanol dispersion containing CS2. Scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, powder X-ray diffraction, absorption spectroscopy, and X-ray photoelectron spectroscopy studies were conducted to characterize the gold–C60 heterostructure. The gold–C60 heterostructure showed charge transfer behaviour where gold was an electron donor and C60 was an electron acceptor. C60 microcrystals-supported gold nanoparticles also showed catalytic activity in reduction of p-nitrophenol at room temperature. A facile reduction mechanism was suggested for gold deposition on the surface of C60 microcrystals.

Synthesis of Spinel-Structure CuFe2O4 Nanoparticles and Their Effective Electrocatalysis Properties

A series of CuFe2O4 nanoparticles was synthesized with the assistance of organic amines or inorganic bases via a hydrothermal method. The prepared samples were confirmed as a spinel-type structure by x-ray diffraction. The shapes of the samples were detected by transmission electron microscope (TEM), which confirmed that all the synthesized samples were nanoparticles. The electrocatalytic properties of the samples modified on a glassy carbon electrode were investigated for the reduction of p-nitrophenol, potassium chromate (K2CrO4), and sodium nitrite (NaNO2) in basic solution using the cyclic voltammetry method. The results showed that all the samples showed enhanced catalytic activity for the reduction of p-nitrophenol, K2CrO4, and NaNO2. Among the samples, CuFe2O4 prepared with cyclohexylamine (S-2) showed the highest catalytic activity for p-nitrophenol reduction, whereas CuFe2O4 prepared with NaOH and PVP (S-4) showed the highest activity for both K2CrO4 and NaNO2 reduction in basic solution.

Conducting polymer hydrogel reactor for synthesizing Au nanoparticles and its use in the reduction of p-nitrophenol

We describe a novel approach of synthesizing Au nanoparticles (NPs) using a conducting poly(3,4-ethylenedioxythiophene)/poly(acrylic acid) (PEDOT/PAA) hydrogel reactor. The resulted composite hydrogel (Au/PEDOT/PAA) displays enhanced strength due to the formation of Au NPs (30–100 nm in diameter) within the hydrogel. Also, it exhibits excellent catalytic activity for the reduction of p-nitrophenol (p-NP). By adjusting the concentration of HAuCl4 during the preparation, the content of Au NPs can be facilely modulated. The present findings may shed some light on designing and preparing new composites containing noble metal NPs. We describe a novel approach of synthesizing Au nanoparticles (NPs) by using a conducting poly(3,4-ethylenedioxythiophene)/poly (acrylic acid) (PEDOT/PAA) hydrogel reactor. Those Au NPs display excellent catalytic activity for reduction of p-nitrophenol.

One-Pot Green Synthesis of Ni Nanoparticles and Study of Its Catalytic Activity in the Hydrothermal Reduction of p-Nitrophenol

One-pot synthesis of Ni nanoparticles was carried by solution reduction process successfully in aqueous media by using hydrazine hydrate as a reducing agent. Greener stabilizing agent starch is used as a stabilizer, which also acts as a particle protector toward oxidation. The morphologies of the synthesized Ni nanoparticles were characterized by TEM and XRD. The prepared Ni nanoparticles were used as a catalyst in the reduction of p-nitrophenol to p-aminophenol under hydrothermal condition in the presence of sodium borohydrate as a source of hydrogen. The conversion was excellent (97%), as confirmed by LCMS. This also confirmed by the UV-visible spectrum study of the reaction mixture. The Ni nanoparticles were recycled at least five times without much loss in the catalytic activity.