Reduction Of Para-nitrophenol Research Articles

Catalytic reduction of para nitrophenol by green-fabricated silver nanoparticles (AgNPs) from Solanum lycopersicum L. leaf extracts

Green-fabricated silver nanoparticles (AgNPs) are widely used in applications spanning from healthcare to industries due to their unique physicochemical, optical and catalytic properties. With that being said, they have recently been gaining widespread attention from the scientific community for their role in environmental remediation (also known as nanoremediation). Green synthesized AgNPs have shown to be efficient catalysts in the degradation of organic pollutants with one such example being para nitrophenol (PNP). PNP is a toxic organic compound and contaminant released in industry wastewater streams into water bodies like rivers and oceans which may harm aquatic life and even humans. The present study aims to synthesize AgNPs from the leaves of five Sri Lankan varieties of Solanum lycopersicum L. (tomato) and assess their ability to catalyze the degradation of PNP while also investigating if they pose cytotoxicity towards aquatic organisms. Four out of five varieties formed AgNPs under the optimum heating condition 90°C 60min as characterized by UV-Vis spectrophotometry. When subjected to scanning electron microscopy (SEM) analysis, AgNPs appeared spherical with an average diameter of approximately 40nm. Their bandgap energy was 2.70eV, classing them as semiconductors. Phytochemical analysis on leaf extracts revealed the presence of several phytoconstituents such as flavonoids, phenols, tannins and alkaloids required for the formation of AgNPs via bio-reduction. Catalytic activity was tested by the ability of AgNPs to degrade para nitrophenol (PNP) in the presence of NaBH4 and findings demonstrate that AgNPs catalyzed the degradation of PNP in under 75mins along with the formation of para aminophenol (PAP). Cytotoxicity of 4mg/mL and 1mg/mL AgNPs was studied in Artemia salina and results revealed 0% mortality of A. salina following 24h of exposure to AgNPs. Solanum lycopersicum L. is hence considered a good source of eco-friendly, non-toxic and biocompatible AgNPs that can efficiently degrade para nitrophenol. Synthesizing these AgNPs in large commercial quantities can help enhance environmental remediation efforts and effective wastewater management.

Platinum nanoparticle-decorated reduced graphene oxide nanosheets: A recyclable and highly efficient catalyst towards the reduction of para-nitrophenol and methylene blue

The present study focuses on the design and development of Pt nanoparticle (PtNPs) decorated reduced graphene oxide (RGO) nanohybrid as an efficient heterogeneous catalyst towards the reduction of p-nitrophenol (p-NP) and methylene blue (MB). The citrate reduction of chloroplatinic acid in the presence of amino-propyl trimethoxy silane (APTMS) modified graphene oxide (GO) produced RGO/PtNPs nanohybrid comprised of uniform and high-density distribution of smaller-sized PtNPs. The APTMS provide efficient nucleation points via their amino groups and thereby play a vital role in regulating the size as well as the distribution of the anchored PtNPs in the present approach. The morphological and structural characterization of RGO/PtNPs nanohybrid was done by using X-ray powder diffraction, scanning and transmission electron microscopy, Fourier transform infrared and Raman spectroscopic techniques. The homogeneous and high-density dispersion of smaller-sized PtNPs endows superior catalytic activity to RGO/PtNPs nanohybrid. The nanohybrid exhibited outstanding catalytic performance enabling rapid reduction of both p-NP and MB at ambient conditions. The estimated rate constants for p-NP and MB reduction were 15.9 × 10−3, and 187 × 10−3 s−1 respectively, which outperform the rate constants of several previously reported metal-based GO/RGO nanocatalysts. The recycling tests showed that the nanohybrid maintained good catalytic stability even after the fifth recycle run. The RGO/PtNPs nanohybrid can be exploited for sustainable and efficient catalytic reduction of other environmental pollutants also. Further, the strategy followed in the present study to achieve homogenous and high-density distribution of Pt nanoparticles could be adopted for the anchoring of other metal/metal oxide/semiconductor nanoparticles.

Solid regulating the electron transfer of ZVAl by ball milling for enhanced para-nitrophenol reduction: Necessity of iron sources

Para-nitrophenol (PNP) exhibits high toxicity, carcinogenicity, accumulation capacity and the existence of an electron-absorbing nitro group makes it hard to oxidize but can be reduced easily. Zero-valent aluminum (ZVAl) is an excellent reductant, while its insulation film limits its electron transfer. The oxide film needs to be broken to release the electrons inside ZVAl, and the electron transfer rate after the electron release needs to be controlled to avoid the rapid reaction that leads to the loss of ZVAl activity. Therefore, Fe-ZVAlbm was synthesized by directly one-pot ball milling solid ZVAl, FeSO4·7H2O and Fe3O4 to promote the electron release and regulate the electron transfer. FeSO4·7H2O and Fe3O4 showed splendid synergy for effectively removing 95.6% of PNP unaffected by co-existing ions in a broad pH range (3–11). FeSO4·7H2O with crystal structure could effectively cut the pristine insulation oxide film of ZVAl in the milling process, thus promoting electrons inside the ZVAl release. The conductive Fe3O4 particles embedded onto the surface of ZVAl and the surface-bound Fe(II) contained in Fe3O4 could mediate electron transfer to PNP and regulate the electron transfer rate. The superior electron transfer capacity of Fe-ZVAlbm was presented by the smallest radius of the Nyquist curve. In conclusion, Fe-ZVAlbm is of considerable potential for efficiently reducing nitro-substituted organic compounds, with broader prospects for wastewater treatment.

Understanding the role of dominant crystal facets on heterogeneous catalytic activity of BiOBr nanomaterials: Boosting catalytic efficiency through Fe (III)/Fe(II) incorporation

Herein, we have synthesized three different types of BiOBr nanomaterials (nanosheets, nanoplates and nanoflowers) by simply varying the pH of the solvent medium. Results suggest that the nanosheets contain predominantly (001) plane as the major exposed crystal facets. On the other hand, nanoflowers possess mainly (110) plane as the major exposed facet. However, nanoplates show both (001) & (110) crystal facets predominantly. Detailed morphological and elemental studies have been carried out to investigate the variation of positively charged oxygen vacancies depending on the nature of the predominantly exposed crystal facets. Furthermore, the relative extent of oxygen vacancies was further correlated with the overall surface area and the porosity of the as synthesized nanomaterials. Finally, all these three different types of nanomaterials with varying predominantly exposed crystal facets have been utilized for the catalytic reduction of para-nitrophenol to para-aminophenol as a model system through mild reducing agent NaBH4. A probable mechanism has been proposed to explain the facet dependent catalytic activities of different BiOBr nanomaterials. Finally, Fe (III)/ Fe (II) ions were specifically incorporated in BiOBr nanomaterials. The incorporation of Fe (III)/Fe (II) ions has been further correlated with the detail structural, elemental and optoelectronic properties. Depending on the exposed crystal facets, a huge enhancement has been observed for overall catalytic efficiency upon incorporation of Fe (III)/ Fe (II) ions. A suitable mechanism has been proposed.

Hexabranched dendrimers encapsulated metallic copper nanoparticles and their catalytic evaluation for the conversion of para-nitrophenol to para-aminophenol

Two new hexanuclear copper (II) complexes, [Cu6(G2hexpyD)(DMF)24](TFA)12 and [Cu6(G2hexbzaD)(DMF)18](TFA)12, where G2hexpyD and G2hexbzaD are second-generation dendrimers (G = 2) and TFA is trifluoroacetate, have been synthesized. The prepared copper (II) complexes have been fully characterized. Furthermore, to prepare dendrimer encapsulated copper nanoparticles (G2dendrimer-CuNPs), metal ions were chemically reduced by NaBH4 in 2-methoxyethanol, which yielded zero-valent metal particles with a narrow size distribution. The catalytic reduction of para-nitrophenol to para-aminophenol by G2dendrimer-CuNPs was evaluated in the presence of NaBH4. The reduction reaction was completed in 3 min. The reaction progress was monitored by electronic absorption spectroscopy. The rate constant was calculated to be 0.0073 and 0.0079 s−1 for G2hexbzaD-CuNPs and G2hexpyD-CuNPs, respectively. The results revealed that G2dendrimer-CuNPs exhibit high catalytic performance in the conversion of para-nitrophenol to para-aminophenol. Easy separation, low price, high recyclability and great efficiency are the main advantages of G2dendrimer-CuNPs that make them as the suitable catalysts for the catalytic reduction of para-nitrophenol.

Quick catalytic responsive chitosan flakes@Ag/CuO nanocomposites in organic synthesis and environmental remediation

This report deals with polymeric microgel of chitosan flakes (CF) for catalytic applications of bimetallic Ag/CuO nanoparticles (NPs). Nanocomposites, based on fabricated chitosan flakes, act as nanocatalyst and are used for swift chemical reduction of methylene blue (MB), para-nitro phenol (PNP) and dimethyl amino-benzaldehyde (DMAB) in presence of sodium borohydride or UV light. In our present work N-hydroxyl methyl acrylamide, instead of the traditional divinylic cross linker, has been employed as monomer as well as cross linker for the synthesis of chitosan flakes. The fabricated chitosan flakes have been doped with Ag/CuO NPs to yield nanocomposites. Three grades of nanocomposites have been synthesized by varying the amounts of N-hydroxyl methyl acrylamide, to optimize the crosslinking and suitable network, to yield stabilized NPs. FT-IR, XRD, TGA, SEM, TEM, EDX, DLS and Ultraviolet-Visible (UV-Vis.) spectroscopic characterization techniques have been performed to establish the polymeric chitosan flakes and nanocomposites. When the nanocomposites are employed as catalysts, the percentages of reduction of MB, PNP and DMAB, using sodium borohydride (NaBH4) or presence of UV-light, are over 90%, with lesser reaction time. The catalytic reduction in case of NaBH4 exhibits pseudo first order kinetics and the corresponding rate constant (kapp) values have been determined.

Effectual visible light photocatalytic reduction of para-nitro phenol using reduced graphene oxide and ZnO composite

Removing wastewater pollutants using semiconducting-based heterogeneous photocatalysis is an advantageous technique because it provides strong redox power charge carriers under sunlight irradiation. In this study, we synthesized a composite of reduced graphene oxide (rGO) and zinc oxide nanorods (ZnO) called rGO@ZnO. We established the formation of type II heterojunction composites by employing various physicochemical characterization techniques. To evaluate the photocatalytic performance of the synthesized rGO@ZnO composite, we tested it for reducing a common wastewater pollutant, para-nitro phenol (PNP), to para-amino phenol (PAP) under both ultraviolet (UV) and visible light irradiances. The rGOx@ZnO (x = 0.5–7 wt%) samples, comprising various weights of rGO, were investigated as potential photocatalysts for the reduction of PNP to PAP under visible light irradiation. Among the samples, rGO5@ZnO exhibited remarkable photocatalytic activity, achieving a PNP reduction efficiency of approximately 98% within a short duration of four minutes. These results demonstrate an effective strategy and provide fundamental insights into removing high-value-added organic water pollutants.

Synergistic visible light plasmonic photocatalysis of bi-metallic Gold-Palladium nanoparticles supported on graphene

Visible light photocatalysis using plasmonic nanoparticles is gaining currency due to the possibility of using freely available sun light to generate high energy ‘hot’ electrons. However, effective strategies have to be developed for the generation and stabilization of hot electrons and hot holes. In this work, nanoparticles of a plasmonic metal (Au) were combined with a highly active catalyst (Pd) nanoparticles along with a conductive catalyst support (few layered graphene, FLG). Nanoparticles having very small size could be prepared with the help of swollen liquid crystals as soft templates. The templates allowed entrapment of FLG along with a metal salt and yielded the nanocomposites on exposure to hydrazine vapor. Reduction of para-nitrophenol (p-NP) in presence of excess amount of sodium borohydride was used as a model reaction. Synergistic enhancement in photocatalytic activities could be observed with the Au-Pd/FLG being the best catalyst when compared to the nanoparticles of Au, Pd, Au-Pd and their nanocomposites with FLG (Au/FLG and Pd/FLG). Normalized rate constant (9.77 s−1 mg−1) of the Au-Pd/FLG was quite high compared to most other Au and Pd based nanomaterials that are reported in the literature. The enhanced photocatalytic activity of the Au-Pd/FLG nanocomposite could be correlated with its enhanced visible light activity. Moreover, enhanced adsorption of the reactant molecules and better charge transfer of the nanocomposite are also reasons for the observed photocatalytic activities of the Au-Pd/FLG nanocomposite.

Convergent paired electrochemical synthesis of symmetric dispiro and spiropyrimidine derivatives based on reduction of para-nitrophenol

• Electrochemical study of para -nitrophenol. • Electrochemical synthesis of dispiro and spiropyrimidine derivatives. • Evaluation of antibacterial susceptibility of synthesized compounds. • Detailed mechanistic study of synthesized compounds. • Optimization of effective parameters on the yield of synthesized compounds. A green electrochemical method was developed for the synthesis of new types of spiro and dispiro pyrimidine derivatives. The electrochemical generation of reactive intermediates from para -nitrophenol ( PNP ) and their reactions with barbituric acids ( BA1-BA3 ) is a key step in the formation of target products ( P 1- P 3 ). Our data show that the reactivity of the nucleophile (barbituric acids) plays an important role in the type of product. Accordingly, when barbituric acid ( BA1 ) or thiobarbituric acid ( BA2 ) is used as a nucleophile, dispiro product ( P 1 or P 2 ) is formed in a convergent paired electrochemical reaction. However, when 1,3-dimethylbarbituric acid ( BA3 ) is used as a nucleophile, due to its higher reactivity than BA1 , the final product is an spiro compound that results from the reaction of BA3 with cathodically generated para -nitrosophenol. The highly symmetric dispiro and spiro compounds ( P 1- P 3 ) have been successfully synthesized in a water/ethanol mixture at the carbon electrode in an undivided cell using the constant current electrolysis method. Also, the antibacterial tests indicated that the products P 1- P 3 showed good antibacterial performance against gram-positive bacteria ( Bacillus cereus and Staphylococcus aureus ). In this work, we synthesized a number of new spiro and dispiro pyrimidine compounds ( P 1- P 3 ) using a convergent paired electrochemical method, by electrolysis of PNP in the presence of barbituric acids ( BA1-BA3 ), under mild and green conditions for the first time.

β-Ni(OH)2 supported over g-C3N4: A novel catalyst for para-nitrophenol reduction and supercapacitor electrode

β-Ni(OH)2 supported over g-C3N4 was synthesized by two simple approaches. Its catalytic activity in reducing hazardous para-nitrophenol (PNP) to the industrially important para-aminophenol (PAP) was studied in detail. The applicability of this material as a supercapacitor electrode was also studied. The material shows 100% conversion efficiency with a rate constant of 65.4410 × 10−3 s−1. The catalytic efficiency and the supercapacitor electrode behaviour of the material can be explained based on the structure of β-Ni(OH)2 nanoparticle and the synergy between β-Ni(OH)2 and g-C3N4.

Kinetic investigation of para-nitrophenol reduction with photodeposited platinum nanoparticles onto tunicate cellulose.

Photodeposition is a specific method for depositing metallic co-catalysts onto photocatalysts and was applied for immobilizing platinum nanoparticles onto cellulose, a photocatalytically inactive biopolymer. The obtained Pt@cellulose catalysts show narrow and well-dispersed nanoparticles with average sizes between 2 and 5 nm, whereby loading, size and distribution depend on the preparation conditions. The catalysts were investigated for the hydrogenation of para-nitrophenol via transfer hydrogenation using sodium borohydride as the hydrogen source, and the reaction rate constant was determined using the pseudo-first-order reaction rate law. The Pt@cellulose catalysts are catalytically active with rate constant values k from 0.09 × 10-3 to 0.43 × 10-3 min-1, which were higher than the rate constant of a commercial Pt@Al2O3 catalyst (k = 0.09 × 10-3 min-1). Additionally, the Pt@cellulose catalyst can be used for electrochemical hydrogenation of para-nitrophenol where the hydrogen is electrocatalytically formed. The electrochemical hydrogenation is faster compared to the transfer hydrogenation (k = 0.11 min-1).

Green-monodispersed Pd-nanoparticles for improved mitigation of pathogens and environmental pollutant

This research, for the first time, demonstrates the synthesis of a novel double chain amphiphilic metallosurfactant complex i.e., bisdecanoatopalladium (II) (complex 1) which provides a template to fabricate monodispersed palladium nanoparticles (Pd NPs). Complex 1 was characterized using CHN, Mass, NMR and FTIR techniques. Complex 1 formed inverted metallomicelles (IMMs) in various n-alcohols and DCM at very low critical aggregation concentration (CAC), (1.19–1.65 × 10−4 M) estimated using conductivity studies. IMMs-supported greener synthesis of Pd NPs suggests the localized and controlled reduction of metalloaggregates and arrested growth of Pd NPs confined in the cavity of IMMs. UV–vis, XRD, HRTEM and DLS techniques have provided a detailed insight into the structure, morphology and dispersibility of as-obtained Pd NPs. The uniform surfactant coating enables the synthesis of highly monodispersed and spherical Pd NPs in a very narrow size of 1–2 nm. This green approach eliminates the existing challenges of controlling size, shape, and dispersibility. The superiority of Pd NPs has been explored in terms of catalytic and biological applications. The Pd NPs are found to be extremely selective, efficient, and eco-friendly and recyclable catalysts for the reduction of para-nitrophenol (PNP) with an achievable rate constant as high as 1.018 min−1 with mere 2 mol% catalyst dose. Pd NPs also exhibit excellent binding ability with BSA protein exhibiting a high binding constant of 9.7 × 105 M−1. Besides, Pd NPs can be promoted as excellent therapeutic agents as they have shown noteworthy (i) antimicrobial activity against pathogenic microbes i.e., Bacillus cereus ITCC 240 (MIC 0.002 μg/mL), Klebsiella pneumoniae ITCC 138 (MIC 0.003 μg/mL) and Curvularia lunata ITCC 6257 (MIC 0.001 μg/mL) and (ii) anticancer activity against human liver cancer cells i.e., HepG2 (IC50 25 μg/mL). The outcomes of this research epitomize Pd NPs as a potential green nano-system having broader prospective in catalytic and biological applications.

Kinetics and Langmuir–Hinshelwood mechanism for the catalytic reduction of para-nitrophenol over Cu catalysts supported on chitin and chitosan biopolymers

Herein we report the performance of cheaper, more efficient and eco-friendlier chitin (CN) and chitosan (CS) biopolymers supported Cu nanoparticles (Cu NPs) catalysts (1.5 wt% Cu/CN) and (4.5 wt% Cu/CS) in the reaction model of para-nitrophenol (p-NP) reduction to para-aminophenol (p-AP) by NaBH4. The catalysts were synthetized with impregnation method and CN was extracted from local shrimp shells wastes, while CS was obtained by the deacetylation of CN. It was found that the activity of 1.5 wt% Cu/CN, with a lower Cu loading, is better than that of 4.5 wt% Cu/CS, which achieved 100% p-NP conversion to p-AP in short reaction times at all studied reaction temperatures. The activity of each catalyst was found to depend on the interaction modes of Cu NPs with the functional groups of CN and CS, which affects the textural parameters of the catalysts and the dispersion of Cu NPs, as revealed by various characterization techniques used. Kinetic of p-NP reduction was found to follows the pseudo-first order with respect to p-NP concentration. The apparent rate constants at T = 25 °C were calculated to be kapp = 0.854 min−1 and 0.350 min−1 for 1.5 wt% Cu/CN and 4.5 wt% Cu/CS catalysts, respectively, which increased with the reaction temperature. Kinetics data of p-NP reduction at T = 25 °C, obtained for various concentrations of reagents, were successfully modeled using the Langmuir–Hinshelwood mechanism. The related kinetic parameters such as the adsorption equilibrium constants K(p-NP), K( $${\text{BH}}_{4}^{ - }$$ BH 4 - ) and the surface rate constant, k, were calculated. The competitive adsorption between p-NP and $${\text{BH}}_{4}^{ - }$$ BH 4 - was shown to control the rate of p-NP reduction to p-AP.

Silicone Nanofilament Support Layers in an Open-Channel System for the Fast Reduction of Para-Nitrophenol.

Chemical vapor phase deposition was used to create hydrophobic nanostructured surfaces on glass slides. Subsequently, hydrophilic channels were created by sputtering a metal catalyst on the channels while masking the outside. The surface tension gradient between the hydrophilic surface in the channels and the outside hydrophobicity formed the open-channel system. The reduction of para-nitrophenol (PNP) was studied on these devices. When compared to nanostructure-free reference systems, the created nanostructures, namely, silicone nanofilaments (SNFs) and nano-bagels, had superior catalytic performance (73% and 66% conversion to 55% at 0.5 µL/s flow rate using 20 nm platinum) and wall integrity; therefore, they could be readily used multiple times. The created nanostructures were stable under the reaction conditions, as observed with scanning electron microscopy. Transition electron microscopy studies of platinum-modified SNFs revealed that the catalyst is present as nanoparticles ranging up to 13 nm in size. By changing the target in the sputter coating unit, molybdenum, gold, nickel and copper were evaluated for their catalytic efficiency. The relative order was platinum < gold = molybdenum < nickel < copper. The decomposition of sodium borohydride (NaBH4) by platinum as a concurrent reaction to the para-nitrophenol reduction terminates the reaction before completion, despite a large excess of reducing agent. Gold had the same catalytic rate as molybdenum, while nickel was two times and copper about four times faster than gold. In all cases, there was a clear improvement in catalysis of silicone nanofilaments compared to a flat reference system.

Catalytic reduction of nitrophenol and MB waste water using homogeneous Pt NPs confined in hierarchically porous silica

Pt-containing catalysts are considered promising for diverse catalytic reactions, and their activity strongly depends on the dispersion degree of Pt nanoparticles (Pt NPs). In this study, we report an ultrasound assisted impregnation (UAI) strategy to promote Pt NPs dispersion in the nanoconfined spaces of as-prepared ZSM-5 derived micro-/mesoporous silica (MMZ) occluded with template. The precursor of Pt is successfully inserted into the nanoconfined spaces inherent in as-prepared MMZ (between the silica walls and cetyltrimethylammonium bromide (CTAB) template). The Pt NPs formed in the confined spaces were of smaller size than those generated through traditional ZSM-5 without confined spaces. Further calculations based on transmission electron microscopy (TEM) images indicates that the size of 1 wt% Pt per gram of MMZ (denoted as 1 wt%Pt/MMZ) is 3.8 nm, which is lower than that in 1 wt%Pt/ZSM-5. Experimental results demonstrated that well dispersive Pt NPs in 1 wt%Pt/MMZ catalyst led to the complete reduction of para nitrophenol (P-NP) and methylene blue (MB) with reaction rate constant (K) of 0.321 and 0.512 min−1, respectively, which are obviously higher than those of 1 wt%Pt/ZSM-5 and other reported Pt-based catalysts. 1 wt%Pt/MMZ catalyst exhibited good stability and recyclability than 1 wt%Pt/ZSM-5, and hence can be deemed of potential value for practical applications of wastewater treatment on industrial level.

Laser synthesis of uncapped palladium nanocatalysts

We report the synthesis of uncapped ‘naked’ palladium nanoparticles (PdNPs) through the facile and green route of femtosecond laser reduction in liquid using two different precursors: potassium tetrachloropalladate (K2PdCl4) and palladium nitrate (Pd(NO3)2). Stabilization of the Pd precursor by lowering the pH enabled the synthesis of PdNPs in the sub-5 nm range. Laser synthesis using both precursors generated ultrasmall spherical NPs with average diameters of 1.2 nm and 3.1 nm for the nitrate and chloride precursors, respectively. An additional population of anisotropic large particles with nanopopcorn and nanoflower morphologies observed in electron microscopy images appears to result from the aggregation of the ultrasmall PdNPs. The PdNPs are efficient catalysts for Suzuki cross-coupling reactions and for the reduction of para-nitrophenol by sodium borohydride in water. The excellent catalytic activity of our laser-generated PdNPs is attributed to the ligand-free structure and small particle sizes generated through laser reduction in liquid.

Fabrication of a new heterostructure Au/Pt/SnO2: An excellent catalyst for fast reduction of para-nitrophenol and visible light assisted photodegradation of dyes

Described here is a typical strategy to prepare Pt/SnO2, Au/Pt/SnO2 heterostructures on transparent conducting oxide (TCO, fluorine doped tin oxide, SnO2: F, resistivity: 10–12 Ω2) substrates. Synthesized Au/Pt/SnO2 heterostructure triggers nitrophenol reduction and enhances dye degradation under visible radiation. Bi-metallic system (Au and Pt), layer of active metal oxide (SnO2) are introduced to speed up these applications. The reduction rate is fast and within 8 min it can reduce almost 100 % of para-nitrophenol. The decrease in band gap from 3.66 eV (for SnO2) to 3.28 eV (for Au/Pt/SnO2) ensures absorption of visible light which results enhanced photodegradation of Rhodamine B (RhB) and Congored (CR) dyes. Trapping experiments are performed by introducing scavengers to investigate the role of active species (OH, e−, h+, O2−) involved in dye degradation. The effects of other parameters like pH, catalyst dosage and dye concentration are precisely investigated.

A Facile Synthetic Approach for Cu(OH)2-Cu2O Heterostructure: A Stable Catalyst for Pollutant Degradation

In the present study, we report the development of morphologically different copper and Cu(OH)2-Cu2O nanostructures by a single step chemical reduction method using ascorbic acid as environmental friendly reducing agent. Morphology and crystallographic patterns of the synthesized samples were analyzed using X-ray diffraction and scanning electron microscopy. Determination of catalytic performance of both copper and Cu(OH)2-Cu2O nanostructure towards hydrogenation reduction of para nitrophenol and para nitroaniline using sodium borohydride as the reducing agent suggested that Cu(OH)2-Cu2O nanostructure is comparatively efficient in hydrogenating the nitro aromatic compounds. The improved hydrogenation capacity was suggested to be due to the formation of an in-situ composite of Cu2O-Cu during the time of reduction reaction. Analysis on the degradation capacity of developed samples for methyl orange degradation using sodium borohydride as the reducing agent indicated significantly high reduction rate for Cu(OH)2-Cu2O nanostructure with a rate constant value of 0. 819 min-1, which is higher than many of the previously reported values.

Synthesis of Air-Stable Cu Nanoparticles Using Laser Reduction in Liquid

We report the synthesis of air-stable Cu nanoparticles (NPs) using the bottom-up laser reduction in liquid method. Precursor solutions of copper acetlyacetonate in a mixture of methanol and isopropyl alcohol were irradiated with femtosecond laser pulses to produce Cu NPs. The Cu NPs were left at ambient conditions and analyzed at different ages up to seven days. TEM analysis indicates a broad size distribution of spherical NPs surrounded by a carbon matrix, with the majority of the NPs less than 10 nm and small numbers of large particles up to ∼100 nm in diameter. XRD collected over seven days confirmed the presence of fcc-Cu NPs, with some amorphous Cu2O, indicating the stability of the zero-valent Cu phase. Raman, FTIR, and XPS data for oxygen and carbon regions put together indicated the presence of a graphite oxide-like carbon matrix with oxygen functional groups that developed within the first 24 h after synthesis. The Cu NPs were highly active towards the model catalytic reaction of para-nitrophenol reduction in the presence of NaBH4.

Hollow 1D copper oxide nanostructures with enhanced activity for catalytic reduction and photocatalytic degradation of organic pollutants

Catalytic reduction and photocatalytic degradation are two important methods used for remediation of organic pollutants in waste water streams. Copper oxide is a fascinating material that can exhibit catalytic activity in both reactions. In this study we created various 1D copper oxide nanostructures using thermal oxidation of pre-synthesized copper nanowires. The process yield wire like, rod like and tubular wire like copper oxide nanostructures. The tubular morphology is formed by the classic Kirkendall effect. The BET surface area follows the order copper nanowire precursor > 400 °C annealed sample (tube structure) > 150 °C annealed sample (wire like structure)> 180 °C annealed sample (rod like structure). The efficiency of the synthesized materials in catalytic reduction reaction is tested using para nitrophenol reduction reaction. The visible light photocatalytic activity of the materials is tested using the degradation of methyl orange reaction. The synthesized materials show promising activity in both reactions. Interestingly, the copper oxide nanostructures outperform precursor copper nanowires, which possess the highest surface area, in both reactions. The sample calcined at 400 °C exhibits almost twice the catalytic activity than that of metallic copper in the hydride reduction reaction. The photocatalytic degradation rate exhibited by the same copper oxide nanostructure is 23 times higher than that of copper nanowires. The copper oxide nanostructure prepared in this study show catalytic activity almost an order of magnitude higher than copper oxide nanoparticles reported in literature. Catalytic cycling studies show that the synthesized materials show little reduction in property even after three cycles. The macroscopic wire like morphology, and high catalytic activity in reduction reaction and visible light photoactivity make the synthesized materials multipronged for applications like waste water remediation.