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In this manuscript, we accomplished the engineering of poly(methacrylic acid) [p(MAA)] micron-sized microgel (MG) integrated with silver nanoparticles (AgNPs). The micron-sized p(MAA) MG particles were synthesized by inverse suspension polymerization, and fabrication of silver nanoparticles was carried out via chemical reduction of Ag(I) ions in the synthesized MG network. The synthesized p(MAA) MG and p(MAA)–AgNPs composite was subjected for compositional and morphological analysis with Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), spectroscopy, and thermal gravimetric analyzer (TGA). The p(MAA) MG particles were observed to be spherical in shape with diameters in the range of 60–95 µm and found thermally stable below 225 °C. The existence of Ag in the p(MAA) MG was approved by EDX analysis. The prepared p(MAA)–AgNPs composite exhibited promising catalytic performance in the reduction of four different nitro-aromatic compounds including 4-nitrophenol (4-NP), 2-nitrophenol (2-NP), 2-nitroaniline (2-NA), and 4-nitroaniline (4-NA) with maximum reduction rates of 0.4205, 1.1222, 0.5195, and 1.6424 min−1, respectively. The catalyst was recycled for five consecutive cycles by a cost and time-effective process of filtration with gradual decrease in the catalytic activity to 10%. Also, the prepared p(MAA)–AgNPs composite was found active against Gram-negative E. coli and Gram-positive S. aureus with corresponding inhibition zones of 7 mm and 9 mm, respectively. [ABSTRACT FROM AUTHOR]

In this work, via the method of wet impregnation and chemical reduction, low-cost and available bentonite modified by cetyltrimethylammonium bromide (CTAB) was utilized as support to synthesize a novel organobentonite-supported Pd composite catalyst used for the catalytic transfer hydrogenation (CTH) of polyunsaturated fatty acid methyl ester (FAME). According to the results of characterization analysis, the organic modifier of CTAB was intercalated into the interlayer of bentonite, and the active metal Pd was immobilized and uniformly dispersed in the prepared composite catalyst. The possible formation mechanism of composite catalyst was proposed. The synthesized composite catalyst presented higher hydrogenation activity and selectivity compared with the pure nano-Pd catalyst. Moreover, the excellent stability remained for the composite catalyst after five catalytic runs in FAMEs hydrogenation. Hence, bentonite, as an economical and promising feedstock, could be used to synthesize a high-efficient and stable supported Pd composite catalyst successfully for the CTH of FAME. Low-cost bentonite, used as raw material, was modified by cetyltrimethylammonium bromide (CTAB) through the cation exchange process, forming organobentonite (OB) with an increased interlayer spacing. The cations of CTAB might be absorbed into the interlayers and on the surface of bentonite. The Pd ions were introduced through the impregnation of precursor solution of Pd (H2PdCl4) and bound to the cations of CTAB via electrostatic interactions. After the chemical reduction process by using NaBH4, the anionic PdCl42− could be reduced to metal Pd, which was immobilized and dispersed in the interlayers and on the surface of organobentonite, and then a novel Pd/OB composite catalyst formed. According to the result of TEM measurement, Pd particles showed the spheroidal shapes and dispersed uniformly in the synthesized composite catalyst. [ABSTRACT FROM AUTHOR]

Silver-decorated reduced graphene oxide (Ag@rGO) nanocomposite was synthesized via a facile chemical reduction method, and its morphology, functional groups, structure, optical and electrical characteristics were investigated. Large distributions of spherical Ag nanoparticles with particle size ranging from 108 to 126 nm anchored into rGO sheets were observed. The energy dispersive X-ray confirms the presence of carbon, oxygen and silver elements in the Ag@rGO nanocomposite. Fourier-transform infrared spectrum exhibited stretching vibrations due to C=O, C–H2, C–O, C=C, O–H and Ag–O bonds in Ag@rGO nanocomposite. X-ray diffraction results of Ag@rGO nanocomposite confirm the formation of rGO and metallic Ag nanoparticles exhibiting FCC structure. The bandgap and ID/IG values of Ag@rGO nanocomposite were obtained as 2.76 and 1.49 eV respectively. Moreover, the study of electrochemical properties of Ag@rGO nanocomposite was carried out, where the maximum specific capacitance of 717.3 and 433.05 F g−1 was achieved at 5 mV s−1 scan rate and 1 A g−1 current density. Moreover, the impedance spectroscopy study exhibited the charge transfer resistance (RCT) value as 6.98 and 71.29 Ω from the Nyquist and Bode plots. I–V characteristics curve shows that the addition of Ag into rGO increases its electrical conductivity. Thus, the results of Ag@rGO nanocomposite can be suitable for supercapacitor application. [ABSTRACT FROM AUTHOR]

Designing an efficient ORR electrocatalyst with superior methanol tolerance is crucial to fabricate direct methanol fuel cells (DMFC). In this regard, herein, Pt islands at Pd on carbon nanoparticles (Pd100-xPtx/C) was synthesized by combining the chemical reduction and galvanic replacement method, where Ag was used as a sacrificial element. The galvanic replacement of Ag by Pt in Pd100-xPtx/C was revealed from the absorption spectra with the absence of Ag's surface plasmon resonance (SPR) peak. XRD patterns endorse the formation of Pt@Pd/C and nanoscale crystallites. The photographic images of TEM demonstrate the formation of Pt islands at Pd on carbon matrix. The XPS spectra corroborate the metallic state of Pt and Pd in Pt20@Pd80/C. The optimum composition of Pt20-decorated Pd80 on carbon shows enhanced oxygen reduction reaction (ORR) in an acidic media. Moreover, Pt20-decorated Pd80 on carbon electrocatalyst exhibits low activation energy of 27.6 KJ mol-1 and superior tolerance towards methanol oxidation even at higher concentrations (20 M), signposting it as a promising ORR electrocatalyst for DMFC. [ABSTRACT FROM AUTHOR]

For effective CO2 methanation, monometallic Co(10)/SiO2 and Ni(10)/SiO2 and bimetallic Ni(5)Co(5)/SiO2 and Ni(2)Co(8)/SiO2 nanocomposite (NC) catalysts, where numbers between brackets indicate the metal content (wt%), have been prepared with solvate-stimulated modification, thermal decomposition, and chemical reduction stages using nanosilica A-300 as a carrier. The catalysts were characterized using SEM–EDX, nitrogen physisorption, and X-ray powder diffraction. The samples before and after the reduction with hydrogen have a similar mesoporous texture. The bimetallic Ni–Co/SiO2 NC catalysts showed improved catalytic activity compared to Ni/SiO2. The formers are characterized by the smallest bimetallic crystallites of ca. 12 nm in size. Activity in the methanation of the Ni–Co/SiO2 NC catalysts depends on the cobalt content resulting in a prominent increase in CO2 conversion and methane yield at 250–350 °C. The SEM–EDX analysis showed unusual flower-like nanostructures and proved the random distribution of Ni/Co bimetallic aggregates in the nanosilica matrix at the nanoscale level. Both Ni(2)Co(8)/SiO2 and Ni(5)Co(5)/SiO2 exhibited high activity in the CO2 methanation with 81–88% CH4 yield at 450 °C. The results of thermo-programmed desorption mass spectroscopy revealed that the catalytic reaction is passed through the formation of O-containing intermediates bound to the active Ni–Co and nanosilica sites. [ABSTRACT FROM AUTHOR]

Gypsum plaster is used in linings, coatings, decorative elements, and sealing and is a component of drywall. However, it is susceptible to the development of mold and other microorganisms, especially in hot and humid environments with poor ventilation and sunshine. In order to provide antimicrobial activity to the gypsum, zinc oxide nanoparticles (ZnO-NPs) were added to its matrix. Two types of ZnO-NPs were synthesized, by simple precipitation of sulfate heptahydrate (ZnSO4.7H2O) by sodium hydroxide (NaOH) and with the use of lauryl sulfate, resulting in nanoparticles with a diameter ~ 40 nm. The antimicrobial activity was assessed by the microdilution technique for determination of minimum inhibitory concentration against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Aspergillus niger. SEM images and the count of CFU present in the Staphylococcus aureus biofilm in the specimens composed of reference gypsum and with 15% ZnO-NPs of both syntheses show the efficacy of ZnO-NPs in the gypsum matrix against biofilm (p < 0.05). The specimens with ZnO-NPs also did not allow the proliferation of Aspergillus niger. Therefore, this new material, by preventing the proliferation of these microorganisms, will benefit the health of its users as well as the environment, due to the reduction in the use of chemicals to clean it. Consequently, bringing economic and environmental benefits. [ABSTRACT FROM AUTHOR]

Palladium–bismuth oxoiodide nanocomposites of various molar ratios of Pd and BiOI have been synthesized by the facile solvothermal method following the chemical reduction technique. The as-synthesized particles have been characterized by X-ray diffraction, spectrophotometric and microscopic studies. All the electrodes made of different Pd–BiOI nanocomposites show improved catalytic performance with synergistic effects for the oxidation of methanol in comparison with the pure components, Pd and BiOI. The modified graphite electrode containing a thin layer of Pd–BiOI composite having 10 mol% of Pd, designated as PB10, has shown the best electrocatalytic performance in comparison with other electrodes for methanol oxidation. The current density using PB10 is increased by 5.4 times with respect to Pd which is further improved by 6.4 times in the presence of visible light for methanol oxidation reaction. The retention of peak current at the 200th cycle of voltammetric operation is found to be 99.5% indicating significant stability of the electrodes. The study essentially suggests PB10 can be used as an efficient anode catalyst for oxidation of methanol in alkali. [ABSTRACT FROM AUTHOR]

This paper examines processes for the preparation of metallic iridium nanoparticles under hydrothermal conditions. The reduction of aqueous potassium hexachloroiridate(IV) solutions with sodium tetrahydridoborate in acidic and alkaline media at temperatures from 130 to 180°C has been shown to take 2–30 min and result in the formation of fine metallic iridium powder with a characteristic mosaic structure. The average size of the iridium(0) nanoparticles varies from 8 to 300 nm, depending on synthesis conditions, and the crystallite size is no greater than 10 nm. According to low-temperature nitrogen gas adsorption measurements, the specific surface area of the materials prepared in acid solutions ranges from 1 to 10 m2/g, and that of the materials prepared in alkaline solutions reaches 25 m2/g. X-ray photoelectron spectroscopy results demonstrate that the surface of the 8-nm-diameter iridium nanoparticles is covered with an oxide film. As shown by differential scanning calorimetry and thermogravimetry in an argon atmosphere, the fraction of iridium oxide compounds in the material with a specific surface area of 25 m2/g does not exceed 5 wt %. [ABSTRACT FROM AUTHOR]

Leachate produced from hazardous waste landfills has been observed to exhibit very complex characteristics including the presence of a high amount of refractory organics and toxic elements which make it unfit for conventional treatment. This study is focused on the characterization and treatability of "hazardous waste landfill leachate" through electrocoagulation for the reduction of chemical oxygen demand (COD). Effect of different operating parameters, such as electrode material, interelectrode distance (IED), current density (CD), and electrolysis time (ET), has also been studied. For galvanized iron (GI) electrodes, a significant reduction in phenolic compounds, cadmium, lead, and zinc concentration was observed and more than 80% reduction in COD and color was achieved on a bench-scale reactor for a CD value of 41.64 A/cm2 at IED of 1.5 cm and for ET equating to 240 min. Substantiated by experimental results and statistical analysis like ANOVA and post hoc analysis, it appears that electrocoagulation is a proficient technology for the treatment of hazardous waste landfill leachate which has a huge potential for further research. [ABSTRACT FROM AUTHOR]

The interplay between electron correlation and topology of relativistic electrons may lead to a fascinating stage of the research on quantum materials and emergent functions. The emergence of various collective electronic orderings/liquids, which are tunable by external stimuli, is a remarkable feature of correlated electron systems, but has rarely been realized in the topological semimetals with high-mobility relativistic electrons. Here, we report that the correlated Dirac electrons in perovskite CaIrO3 show unconventional field-induced successive metal–insulator–metal crossovers in the quantum limit accompanying a giant magnetoresistance (MR) with MR ratio of 3500 % (18 T and 1.4 K). In conjunction with the numerical calculation, we propose that the insulating state originates from the collective electronic ordering such as charge/spin density wave promoted by electron correlation, whereas it turns into the quasi-one-dimensional metal at higher fields due to the field-induced reduction of chemical potential, highlighting the highly field-tunable character of correlated Dirac electrons. [ABSTRACT FROM AUTHOR]

Co–Fe bimetallic nanoparticles-affixed polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP) nanofiber membrane is fabricated using the electrospinning and chemical reduction techniques. The semicrystalline polymeric backbone decorated with the highly crystalline Co–Fe bimetallic nanoparticles enunciates the mechanical integrity, while the incessant and swift electron mobility is articulated with the consistent dissemination of bimetallic nanoparticles on the intersected and multi-layered polymeric nanofibers. The diffusion and adsorption of glucose are expedited in the extended cavities and porosities of as-formulated polymeric nanofibers, maximizing the glucose utilization efficacy, while the uniformly implanted Co4+/Fe3+ active centers on PVdF-HFP nanofibers maximize the electrocatalytic activity toward glucose oxidation under alkaline regimes. Thus, the combinative sorts including nanofiber and nanocomposite strategies of PVdF-HFP/Co–Fe membrane assimilate the enzyme-less electrochemical glucose detection concerts of high sensitivity (375.01 μA mM−1 cm−2), low limit of detection (0.65 μm), and wide linear range (0.001 to 8 mM), outfitting the erstwhile enzyme-less glucose detection reports. Additionally, the endowments of high selectivity and real sample glucose-sensing analyses of PVdF-HFP/Co–Fe along with the binder-less and free-standing characteristics construct the state-of-the-art paradigm for the evolution of affordable enzyme-less electrochemical glucose sensors. [ABSTRACT FROM AUTHOR]

Photocatalytic treatment is one of the techniques used for the treatment of dyes-contaminated wastewater. It is important to develop an effective visible-light-driven catalyst for the treatment of dyes-contaminated wastewater. This study reports the synthesis of ZnO-reduced graphene oxide catalyst for the degradation of methylene blue. Graphene oxide was prepared by Hammer and Offeman process, while ZnO-rGO (1:1) was prepared by the chemical reduction method. The prepared ZnO-rGO composite was characterized by XRD, TEM, SEM, UV-Vis, DRS, N2 adsorption-desorption, FTIR, and XPS analyses. The photocatalytic activity was evaluated by photodegradation of methylene blue solution under irradiation. It was found that ZnO-rGO is capable of removing the dye from water and achieved the highest dye degradation efficiency of ~99% within 60 min. Furthermore, the ZnO-rGO was recycled in degradation experiments without any loss in its catalytic performance. The reaction kinetics was described in terms of the Langmuir-Hinshelwood mechanism, one of the kinetics mechanisms of surface catalyzed reaction. 36.2 and 13.1 kJ/mol were calculated as the apparent and true activation energy for photodegradation of methylene blue respectively. [ABSTRACT FROM AUTHOR]

The quest for novel synthesis method of silver nanoparticles (AgNPs) is still an active field of research due to their usefulness in different levels of therapeutic and sensing applications. Owing to the better biodegradability and biocompatibility, plant extract-assisted synthesis processes of AgNPs have gained considerable attention in recent years. Here, we report a novel synthesis approach for AgNPs using banana root bulb (BRB) extract. The BRB extract was used as solvent as well as reducing agent in this synthesis process. The nanoparticles obtained through this process possessed hydrodynamic size of the order of 40 nm and a broad surface plasmon resonance peak at ~ 411 nm. In order to validate this process, the properties of the product were compared with properties of the nanoparticles obtained from other two established approaches viz- chemical reduction method involving trisodium citrate as reducing agent and green synthesis method involving mixed fruit peel waste extract as solvent and reducing agent. It was observed that surface plasmon resonance peaks entitled to AgNPs prepared through all the three approaches were quite consistent with each other. Besides, the broad surface plasmon resonance peaks suggest that the nanoparticles obtained through all the approaches were polydispersed. [ABSTRACT FROM AUTHOR]

Silver-substituted Fe–Ni nano invar alloy is a new and innovative field of research due to their interesting invar, magnetic and electrical properties. Due to these properties, Fe65Ni35−xAgx (x = 0.0, 0.5) alloys are studied comprehensively in this research work. The method used for synthesis of Fe65Ni35−xAgx (x = 0.0, 0.5) alloys is chemical reduction method in which cetrimonium bromide was used as capping agent, sodium borohydride as reducing agent, and hydrochloric acid to control the pH. X-ray diffraction, scanning electron microscopy, I-V characteristics, and vibrating-sample magnetometer were used for phase determination, surface morphology, electrical resistivity, and study of magnetic properties, respectively. Both alloys have face-centered cubic structure, lattice parameter is increased while crystallite size is decreased, agglomeration forms, electrical resistivity decreases, and saturation magnetization is increased by adding Ag content. Thus, properties of Fe–Ni invar alloys are improved by addition of Ag. Fe–Ni-Ag alloys have attractive magnetic properties as soft granular material and magnetoresistive materials particularly. [ABSTRACT FROM AUTHOR]

Investigating the possibility of a straightforward formation of tetrazoline or tetrazolidine structures, the reactivity of a tetrazole derivative towards reducing conditions has been studied. The catalytic hydrogenation of 1,1'-dimethylbistetrazole (DMBT) was carried out using various catalysts (Pd/C, Pt/C, Rh/C, Pd/Pt/C, Lindlar, PtO2 and Raney Ni) over a wide range of hydrogen pressure (35–150 bar) and a temperature range from 20 to 60 °C. This exhaustive study enabled to find the optimal conditions for DMBT hydrogenation and to suggest a plausible reaction mechanism. The chemical reduction of DMBT was conducted using several hydrides (BH3, NaBH4, DIBAL and LiAlH4). The reduction products were identified subsequently to conditions optimizing. The suggested reaction mechanism, featuring a retro-[3 + 2]-cycloaddition, was validated by both experimental and theoretical approaches. [ABSTRACT FROM AUTHOR]

Electropulsing treatment was imposed on SUS303 free-cutting steels to analyze the evolution of MnS inclusions. SUS303 steels were treated in argon atmosphere under various conditions: before the formation of MnS inclusions (1773 K), at the beginning of the formation of MnS inclusions (1678 K), and after the formation and growth of MnS inclusions (1583 K). The results show that the sizes of globular MnS inclusions decrease with an increase of current density when the electropulsing treatment is treated in the melting stage. Meanwhile, electropulsing treatment restrains the growth of inclusions due to the different conductivities between the molten steel and MnS inclusions when electropulsing treatment is treated in the solidification process. However, the number of fine rodlike MnS inclusions increases with the increase of current density in the samples treated in the inclusion nucleation stage and solidification stage because the reduction in chemical potential produced by electropulsing treatment will require less undercooling. Experimental data demonstrate that the application of electropulsing treatment is a fantastic new method to control the morphology and size of MnS inclusions in the melting stage. [ABSTRACT FROM AUTHOR]

Effluents from the food industry regularly contain synthetic dyes that cause damage to ecosystems and water bodies. The present work aimed to evaluate homogeneous advanced oxidation processes for the mixed degradation of food dyes blue 1 and yellow 6. Through preliminary studies of advanced oxidation processes by photolysis, UV/H2O2, Fenton, and photo-Fenton, applying UV-C, artificial solar (sunlight), and natural solar radiation, the system with the best performance for the integral optimization of the treatment was determined. Based on the treatment with the best results, the multilevel factorial design 22 × 31 and central composite design 2^2 + star were created to optimize the variables [H2O2], [Fe], and pH. The kinetics of the process was evaluated based on the percentages of degradation of the chromophore groups and reduction of the chemical oxygen demand. The post-treatment samples were tested for toxicity on lettuce Lactuca sativa germination to verify the effect of the advanced oxidation process employed. The most efficient treatment determined in the preliminary study was photo-Fenton assisted by sunlight radiation. Under the best conditions developed and analyzed with the experimental designs, a 99% degradation of the chromophore groups was achieved, and a 98.72% decrease in chemical oxygen demand, in 120 min. The experimental data were well represented by the nonlinear kinetic model proposed by Chan and Chu with values of R2 > 0.95. The toxicity test results demonstrated a decrease in the root growth of the species Lactuca sativa. The results demonstrate that the photo-Fenton system assisted by sunlight radiation is an efficient method to remove food dyes in aqueous matrices. [ABSTRACT FROM AUTHOR]

Biosynthesized silver nanoparticles (Ag-NPs) displayed altogether particular physical, concoction, and natural properties, drawing high consideration for a variety of new applications in different fields due to their cost-effective and eco-friendly procedure. The current work delineates a methodology for the green synthesis of Ag-NPs from the roots of Pueraria Lobata. The Ag-NPs were synthesized at room temperature through a reduction method from the methanolic crude extract of the roots of Pueraria Lobata. UV–vis absorption spectra of Ag-NPs demonstrated the synthesis by giving an intense peak at 248 nm. Transmission electron microscopy (TEM) revealed the synthesis of Ag-NPs was spherical with a size range of 30–60 nm. Fourier transformation infrared spectroscopy (FTIR) results showed the binding properties of bio-constituents responsible for stabilizing the nanoparticles. The synthesis method of Ag-NPs was optimized and the most stable Ag-NPs were achieved after 13 h at pH 9. The in vitro anti-diabetic ability of Ag-NPs was tested against carbohydrate digestion enzyme α-amylase. The result suggests that the Ag-NPs demonstrated remarkable potential of anti-diabetic activity against the key enzyme of diabetes and were found to be appropriate for nano bio-medical application. [ABSTRACT FROM AUTHOR]

Free-standing reduced graphene oxide (rGO) papers were prepared by chemical reduction, thermal reduction and combined chemical-thermal reduction, respectively. Four-point probe and nanoindentation experiments were conducted to investigate the electrical and mechanical properties of rGO papers. The rGO paper prepared by soaking in L-ascorbic acid and thermal annealing in argon at 1000 °C (labeled rGO-AsA-T) showed superior electrical and mechanical properties when compared with rGO papers prepared merely by chemical reduction or thermal reduction. The as-prepared rGO-AsA-T paper exhibited an electrical conductivity of 5.7 × 104 S/m, showing an increase of 90% compared to that in the thermally annealed rGO paper and nearly 40 times that of rGO paper reduced by L-ascorbic acid. It was also found that the rGO-AsA-T paper had the lowest elastic modulus of 288 MPa, showing enhanced flexibility. The nearly free voids in rGO-AsA-T paper proved by scanning electron microscopy (SEM) were due to the capillary action in chemical reduction and were significant in improving the electrical conductivity and flexibility of the paper. The rGO-AsA-T paper with high conductivity and flexibility has a promising application in flexible electronics. [ABSTRACT FROM AUTHOR]

A novel and simple flotation technique has been developed to prepare high-purity graphite from impure graphite. In this method, a suspension of pristine powdered graphite (PG) is dispersed and stirred in water without adding froth formers or supportive chemicals. This makes fine particles of graphite move upwards and float on water. X-ray diffraction (XRD) analysis reveals that the floated graphite (FG) has a lower c-axis parameter, indicating the removal of interlayer impurities. A notable increase in the intensity ratio of the D band to G band in the Raman spectra indicates that the FG has more edge defects due to their smaller crystallite sizes. Transmission electron microscopic (TEM) analysis shows the number of layers in FG has been reduced to 16 from 68 in PG. The absence of C=O vibration of Fourier Transformed Infrared (FT-IR) spectroscopy in treated and untreated samples suggests that their layers are not significantly oxidized. However, X-ray photoelectron spectroscopic (XPS) analysis shows the presence of C–O–C ether functionalities, possibly on edge planes. Further, the product has higher purity with increased carbon content. Therefore, the technique is helpful for the value enhancement of graphite, the reduction of the chemical cost of the conventional techniques, environmental friendliness, and improvement of its applications. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction to high-value-added chemicals is one of the most promising and challenging research in the energy conversion field. An efficient ECR catalyst based on a Cu-based conductive metal-organic framework (Cu-DBC) is dedicated to producing CH4 with superior activity and selectivity, showing a Faradaic efficiency of CH4 as high as ~80% and a large current density of −203 mA cm−2 at −0.9 V vs. RHE. The further investigation based on theoretical calculations and experimental results indicates the Cu-DBC with oxygen-coordinated Cu sites exhibits higher selectivity and activity over the other two crystalline ECR catalysts with nitrogen-coordinated Cu sites due to the lower energy barriers of Cu-O4 sites during ECR process. This work unravels the strong dependence of ECR selectivity on the Cu site coordination environment in crystalline porous catalysts, and provides a platform for constructing highly selective ECR catalysts. Crystalline porous catalysts with single Cu sites are dedicated to exploring the dependence of CO2 electroreduction selectivity on the coordination environment of catalytic sites. The conductive MOF Cu-DBC with oxygen-coordinated Cu sites shows a high Faradaic efficiency ~80% of CO2-to-CH4. [ABSTRACT FROM AUTHOR]

The purpose of this work is activity evaluation of optimized Pd–Cu/rGO as an anode catalyst for electrooxidation of low ethanol concentrations (5–50 mM) in order to use in fuel cell-based breath alcohol analyzer. Accordingly, a simple and one-step synthesis of Pd/rGO and Pd–Cu/rGO with an optimized Pd/Cu ratio was performed via the chemical reduction method and evaluated for ethanol oxidation reaction (EOR). According to the transmission electron microscopy (TEM) and cyclic voltammetry (CV), the particle size and electrochemical active surface area (ECSA) of Pd0.9–Cu0.1/rGO were 4.5 nm and 181.5 m2 g−1, respectively. The ratio of If/Ib was measured to be 0.7 and 2.6 for Pd/rGO and Pd0.9–Cu0.1/rGO in the 0.5 M KOH solution containing 50 mM ethanol, thus indicating that the presence of Cu in the alloyed catalyst structure improved the catalytic activity by removing carbonaceous intermediates from the catalyst surface. Obtained results revealed that the onset potential (Eonset) of Pd0.9–Cu0.1/rGO was negatively shifted to 240 mV, as compared to Pd/rGO and no carbonate blockage of Pd–Cu/rGO sites happened in the presence of K2CO3. Therefore, Pd0.9–Cu0.1/rGO could be regarded as a superior anode catalyst for use in the anion exchange membrane fuel cell-based breath alcohol analyzer. [ABSTRACT FROM AUTHOR]

Ag nanoparticles (NPs) of varied concentrations are implemented in the hole transport layer (PEDOT:PSS) of organic solar cells to enhance the photoconversion efficiency through near field effects, one of the basis of surface plasmonic resonances. The Ag NPs were synthesized through a wet chemistry reduction process by varying the reaction times to yield different sizes and shapes of Ag NPs, with diameters/effective sizes in the range 20–30 nm. The morphology, shape and size of the Ag NPs are examined by Transmission Electron Microscopy (TEM). Selected Area Electron Diffraction has confirmed that the dispersed and regularly shaped Ag NPs are polycrystalline with an underlying face centered cubic structure. The dependence of the plasmonic resonances on the shape (size) of the nanoparticles is exhibited by broad optical absorption in the 350–550 nm spectral range. Efficient device performance is ascribed to PEDOT:PSS layers incorporated with 2% Ag NPs reporting a Photoconversion efficient of 3%. The addition of Ag NP creates strong localized fields, and we investigate their effects on the carrier mobility in the trap free space charge limited region through the corresponding Langevin recombination constants. Our results show an increase in barrier height associated with NPs addition as supported by the varying values of the ideality factors and series resistances. [ABSTRACT FROM AUTHOR]

Developing novel technologies for the effectual treatment of wastewater comprising contaminated organic pollutants is of extraordinary importance across the globe. In the last few years, removal of organic pollutants using various nanocatalysts from aqueous solution by chemical reduction in the presence of NaBH4, as a reducing agent, has become an established route. Nanomaterials show great potential for the improvement of water treatment technologies. Recently, catalytic reduction of dyes by using various nanoparticles has received significant attention due to their effectiveness in degradation and producing less toxic and environmentally benign products. Herein, this comprehensive review discusses the classification of nanocatalysts, mechanisms involved in catalytic degradation of various types of dyes, recyclability of nanocatalysts and characterization techniques for various nanocomposites. We aim to review and summarize the recently published literature and R&D progress in catalytic reduction of various water pollutants. Different nanocatalytic assemblies used for reduction of dyes and their division based on nature of nanoparticles and composition of supporting materials have been described critically. A mechanism for chemical reduction of nitrophenols, methylene blue, Congo red, and methyl orange in the presence of nanocatalysts has been elaborated in this study. [ABSTRACT FROM AUTHOR]

Ag-LaFeO3 was prepared by chemical reduction method with NaBH4 ethanol solution. It can be seen from X-ray diffraction (XRD) that all samples are still perovskite structure. Two distinct Ag peaks were observed in X-ray photoelectron spectroscopy (XPS). The experimental results show that at 190 °C, the gas response of Ag-LaFeO3 sensor to 100 ppm ethanol is 155, which is much higher than that of LaFeO3 sensor. Meanwhile, the response time and recovery time are 30 s and 5 s, respectively. The results show that Ag-LaFeO3 has excellent ethanol gas-sensing properties. [ABSTRACT FROM AUTHOR]

In this study, we reported the development of Prussian blue (PB), poly(pyrrole-2-carboxylic acid) (PPCA), and glucose oxidase (GOx) biocomposite modified graphite rod (GR) electrode as a potential biocathode for single enzyme biofuel cell fuelled by glucose. In order to design the biocathode, the GR electrode was coated with a composite of PB particles embedded in the PPCA shell and an additional layer of PPCA by cyclic voltammetry. Meanwhile, GOx molecules were covalently attached to the carboxyl groups of PPCA by an amide bond. The optimal conditions for the biocathode preparation were elaborated experimentally. After optimization, the developed biocathode showed excellent electrocatalytic activity toward the reduction of H2O2 formed during GOx catalyzed glucose oxidation at a low potential of 0.1 V vs Ag/AgCl, as well as good electrochemical performance. An electrocatalytic current density of 31.68 ± 2.70 μA/cm2 and open-circuit potential (OCP) of 293.34 ± 15.70 mV in O2-saturated 10 mM glucose solution at pH 6.0 were recorded. A maximal OCP of 430.15 ± 15.10 mV was recorded at 98.86 mM of glucose. In addition, the biocathode showed good operational stability, maintaining 95.53 ± 0.15% of the initial response after 14 days. These results suggest that this simply designed biocathode can be applied to the construction of a glucose-powered single enzyme biofuel cell. [ABSTRACT FROM AUTHOR]

Herein, we fabricated oxygen vacancy-Fe2O3@polyaniline (O-Fe2O3@PANI) composites directly grown on surface of carbon cloth via successively hydrothermal process, annealing process, chemical reduction, and in situ polymerization. Polyaniline (PANI) is fabricated in situ on oxygen vacancy-Fe2O3 (O-Fe2O3), and forms a porous PANI skeleton at the same time, thus forming a hierarchical structure of O-Fe2O3 particles connected by conductive skeleton. The designed O-Fe2O3@PANI not only shows enhanced cycling stability (90% after 10,000 cycles at 10 A g−1), but also exhibits an improved specific capacitance (309 F g−1 at 0.5 A g−1). Furthermore, the symmetrical supercapacitor (SSC) assembled by O-Fe2O3@PANI presents high energy density of 12.125 Wh kg−1 at high power density of 250 W kg−1 and notable cycling life (100% retention over 10,000 cycles). The results demonstrate that the O-Fe2O3@PANI electrode is promising as electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]

Excellent mechanical and electrical properties of graphene-based paper-like materials are essential for applications in flexible conductors, energy-storage devices, etc. The graphene oxide (GO) supernatant separated by centrifugation and ultrasonication has been used to prepare graphene oxide paper and reduced graphene oxide paper (rGOP) with high strength and conductivity. However, this method has cumbersome steps and low supernatant concentration, which greatly increases time and energy consumption, and is not suitable for rapid batch preparation of high-strength and high-thickness rGOP. Herein, a high-speed mechanical shearing method has been used to efficiently exfoliate graphite oxide suspension into high-concentration GO slurry with large lateral size, and rGOP has been further prepared by blade coating and HI acid chemical reduction. Compared with the product prepared by ultrasonic exfoliation method, the average area of GO sheets obtained via the mechanical shear exfoliation method can reach around 16.31 μm2. As a result, the mechanical properties and conductivity of the prepared rGOP have been increased by 30% and 23.5%, respectively, with the tensile strength and electrical conductivity of 478.2 MPa and 208.4 S/cm being obtained. The developed method is of great significance for the large-scale production and emerging applications of lightweight and high-performance rGOP. [ABSTRACT FROM AUTHOR]

Modern agricultural policies across the globe are committed to a significant reduction in chemical pesticide dependency; however, pest management strategies are still based on the use of synthetic pesticides. There is an urgent need to find new, sustainable and biorational tools for pest management programs. Plants communicate with each other and activate defense mechanisms against pests using herbivore-induced plant volatiles (HIPVs). The use of such HIPVs could be an ecologically sustainable alternative. However, as of now, there have been no comprehensive studies on HIPVs, from selection to practical use in industry production. Here, we describe the first case of an HIPV successfully implemented for pest control under commercial greenhouse conditions. In this research, tomato plants induced with (Z)-3-hexenyl propanoate [(Z)-3-HP] were less susceptible to the attack of economically important tomato pests. We designed and calibrated polymeric dispensers for the constant release of (Z)-3-HP. These dispensers maintained commercial tomato plant defenses activated for more than two months reducing herbivore pest damage without reducing plant productivity. Transcriptomic and metabolomic analyses of plants induced with (Z)-3-HP confirmed that genes involved in specialized anti-herbivore defense were up-regulated, resulting in an increased production of fatty acid-derived compounds, activation of the lipoxygenase pathway and accumulation of specific defense compounds. Our work demonstrates under commercial greenhouse conditions how the release of HIPVs as elicitors of plant defenses via designed polymeric dispensers can be successfully integrated as a new biorational and sustainable tool for pest control. [ABSTRACT FROM AUTHOR]

A low-cost Ni-B alloy catalyst was prepared by chemical reduction method and used for partial hydrogenation of fatty acid methyl esters. The conditions for catalyst preparation, including Ni to B ratio, pH of NaBH4 solution, types and quantity of metal modifiers were optimized. Ni-La-B, prepared by modification of Ni-B with La, showed significantly high catalytic partial hydrogenation activity. The optimum textural properties (small particle size, high specific surface area and well-defined pore structure) and electron enrichment of active Ni sites were the favorable factors for the high hydrogenation activity of Ni-La-B catalyst, which showed reasonable stability in catalyst recycle experiments. [ABSTRACT FROM AUTHOR]

Purpose: Prior versions of the Tool for Reduction and Assessment of Chemical and other environmental Impacts (TRACI) have recognized the need for spatial variability when characterizing eutrophication. However, the method's underlying environmental models had not been updated to reflect the latest science. This new research provides the ability to differentiate locations with a high level of detail within the USA and provides global values at the country level. Methods: In previous research (Morelli et al. 2018), the authors reviewed a broad range of domain-specific models and life cycle assessment methods for characterization of eutrophication and ranked these by levels of importance to the field and readiness for further development. The current research is rooted in the decision outcome of Morelli et al. (2018) to separate freshwater and marine eutrophication to allow for the most tailored characterization of each category individually. The current research also assumes that freshwater systems are limited by phosphorus and marine systems are limited by nitrogen. Using a combination of spatial modeling methods for soil, air, and water, we calculate midpoint characterization factors for freshwater and marine eutrophication categories and evaluate the results through a US-based case application. Results and discussion: Maps of the nutrient inventories, characterization factors, and overall impacts of the case application illustrate the spatial variation and patterns in the results. The importance of variation in geographic location is demonstrated using nutrient-based activity likelihood categories of agricultural (rural fertilizer), non-agricultural (urban fertilizer), and general (human waste processing). Proximity to large bodies of water, as well as individual hydraulic residence times, was shown to affect the comparative values of characterization factors across the USA. Conclusions: In this paper, we have calculated and applied finely resolved freshwater and marine eutrophication characterization factors for the USA and country-level factors for the rest of the globe. Additional research is needed to provide similarly resolved characterization factors for the entire globe, which would require expansion of publicly available data and further development of applicable fate and transport models. Further scientific advances may also be considered as computing capabilities become more sophisticated and widely accessible. [ABSTRACT FROM AUTHOR]

Bimetallic nanoparticles (BNPs) have drawn significant attention due to their numerous applications. They demonstrate enhanced optical, electrical, thermal, and catalytic properties due to the synergistic effects of monometals present in them. In this work, CuAg and AuAg BNPs have been synthesized using a facile and economical chemical reduction method. Optical characterization was carried out using UV–visible spectroscopy, and effect of pH on optical absorbance was studied. For CuAg and AuAg BNPs, optimum pH was observed to be at 9.4 and 6.39, respectively. Morphological investigation confirms the average diameters of CuAg and AuAg BNPs were to be 65 nm and 30 nm, respectively. Photocatalytic property illustrates the reduction of 4-nitrophenol to 4-aminophenol with a 92% conversion percentage in the presence of CuAg BNPs in 4 min, and rate constant for the reaction was measured to be 8.98 × 10–3 s−1. But for the AuAg BNPs, the conversion percentage was 97% in 8 min and rate constant was found to be 7.95 × 10–3 s−1. Thermal conductivity and viscosity measurements of the nanofluids obtained with CuAg and AuAg BNPs have ascertained them to be efficient candidates for the heat transfer and catalytic applications. [ABSTRACT FROM AUTHOR]

Cartap is a thiocarbamate pesticide widely-used to protect rice crops, one of the most mass-produced cereals worldwide. Effluents containing cartap pose serious environment and health risks due to the acute toxicity of this emerging contaminant. This work evaluates the capabilities of the Fenton process to efficiently remove cartap from water matrices. Process parameters such as hydrogen peroxide dosage, ferrous ion concentration and operating pH were optimized using Box-Behnken design. Results showed complete cartap removal with Fenton oxidation in a fluidized-bed reactor while eliminating sludge generation during treatment. Fluidized-bed Fenton process had improved reduction in chemical oxygen demand and total organic carbon due to the contribution of heterogeneous Fenton catalysis to the overall degradation of cartap species compared to conventional Fenton in a batch reactor. Furthermore, competitive reactions and scavenging effects in complex natural water matrices were simulated with the use of inorganic ions such as nitrate, chloride, and phosphate. Results demonstrated the detrimental effect of phosphate ions on Fenton oxidation due to the precipitation of soluble catalysts as iron phosphates, which stops the catalytic Fenton cycle and thus the production of oxidants for contaminant degradation. [ABSTRACT FROM AUTHOR]

The electrodeposition of tin and tin-nickel on a highly dispersed carbon material is used to obtain composite supports. These composite supports were used in the Pt(0) nanoparticles deposition from Pt(IV) solution by chemical reduction. The composition, structure, and activity of the obtained Pt(SnO2/C) and PtSnNi/C catalysts in the oxygen reduction and alcohol electrooxidation reactions were studied. The composite-support-based platinum catalysts exhibit higher activity in the reactions of alcohols electrooxidation in comparison with the commercial Pt/C analogue. Trimetallic PtSnNi/C catalysts are the most promising materials for the electrooxidation of alcohols. [ABSTRACT FROM AUTHOR]

In this study, Vitex negundo leaf extract (VN) were utilized as a potential reducing agent to enable greener synthesis of iron nanocatalyst (VN-FeNCs). The synthesis time and ratio of extract to precursor and pH of extract for green synthesis of VN-FeNCs were optimized. Furthermore, the synthesized VN-FeNCs were characterized for morphological, functional and spectral properties. VN-FeNCs were supplemented for the anaerobic digestion of the sludge. Augmentation of VN-FeNCs improvised the methane yield with reduction of chemical oxygen demand up to 86% and volatile solids up to 93.6% with a retention time of 12 days. The highest biogas yield of 0.45 (L/g VS reduced) is obtained with VN-FeNCs aided digestion whereas digestion with bulk salt and control yielded 0.13 (L/g VS reduced) and 0.07 (L/g VS reduced) respectively. The central composite matrix under the response surface optimization was employed to estimate the optimal process conditions, and the outcome reveals that reactions when maintained at pH 7.0 with 0.2 g/L of VN-FeNCs escalated good biogas production on 6th day. Conclusively, the remarkable reduction in the digestion time would contribute to increase the life span of biogas digester and will reduce the overall maintenance cost. [ABSTRACT FROM AUTHOR]

Solar-light driven CO2 reduction into value-added chemicals and fuels emerges as a significant approach for CO2 conversion. However, inefficient electron-hole separation and the complex multi-electrons transfer processes hamper the efficiency of CO2 photoreduction. Herein, we prepare ferroelectric Bi3TiNbO9 nanosheets and employ corona poling to strengthen their ferroelectric polarization to facilitate the bulk charge separation within Bi3TiNbO9 nanosheets. Furthermore, surface oxygen vacancies are introduced to extend the photo-absorption of the synthesized materials and also to promote the adsorption and activation of CO2 molecules on the catalysts' surface. More importantly, the oxygen vacancies exert a pinning effect on ferroelectric domains that enables Bi3TiNbO9 nanosheets to maintain superb ferroelectric polarization, tackling above-mentioned key challenges in photocatalytic CO2 reduction. This work highlights the importance of ferroelectric properties and controlled surface defect engineering, and emphasizes the key roles of tuning bulk and surface properties in enhancing the CO2 photoreduction performance. Solar-driven CO2 reduction into value-added chemicals and fuels is attracting worldwide attention. Here, substantially enhanced photocatalytic CO2 reduction activity is achieved via the synergy of surface oxygen vacancies and ferroelectric polarization over Bi3TiNbO9 photocatalyst. [ABSTRACT FROM AUTHOR]

The features of distribution are studied and a complex technology for the separation of samarium, europium, and gadolinium is proposed. This technology involves the initial isolation of 70–80% of the europium concentrate by extraction with organophosphorus acids, which makes it relatively easy to obtain pure compounds of samarium and gadolinium in subsequent operations. At the last stage, europium is isolated by chemical reduction and the captured samarium and gadolinium are returned to the beginning of the process. The content of the main substance in the resulting oxides is 99.9–99.99 wt %. [ABSTRACT FROM AUTHOR]

Landfill leachate is the liquid formed by the decomposition of waste in the landfill and infiltration of water through that waste. It contains high concentrations of ammonia and organic contaminants (measured in terms of chemical oxygen demand, COD). Biochar, produced from woody residues separated from municipal waste, was used for the reduction of COD of the leachate. The produced biochar was characterized by scanning electron microscopy, Raman spectroscopy, Brunauer–Emmett–Teller surface area analysis and x-ray photoelectron spectroscopy. By following response surface methodology and specifically the Box–Behnken design, the optimum conditions and effects of time, temperature and biochar dosage were determined. It was stated that biochar dosage was the most influential factor, whereas adsorption time and temperature had a lesser effect on the process. The optimum conditions for COD removal from the leachate were the following: treatment time 140 min, temperature 31 °C and biochar dosage of 1.95 g, where a 75.5% COD removal was achieved. At these conditions, the NH4+-N concentration was reduced by 23%. The spent biochar sample was regenerated by successively washing it with HF, ethanol and NaOH, and the regenerated sample achieved COD removal rates of 71%, indicating the potential for multiple uses. [ABSTRACT FROM AUTHOR]

Toxic metal contamination in soils is a major problem that poses risk to public health and the environment. Among the metal contaminants, hexavalent chromium (Cr(VI)) is known to be highly toxic and mobile in the soils, creating major environmental liabilities around the world. This study evaluates the efficiency of applying the pressure injected nanoscale zero-valent iron (nZVI) suspension to remediate Cr(VI)-contaminated clay soil. After nZVI injection, soil samples were collected in different depths, radial distances, and time intervals. The nZVI dosage used was 12.5 g/kg. The effect of nZVI on Cr(VI) reduction was observed at all radial and depth locations analyzed, with an initial reduction of up to 51.08% for the deepest layer. nZVI dispersivity was found to be homogeneous in the analyzed sample, with an average Cr(VI) reduction of 76.52% in 15 days. The nZVI migration patterns had an influence on the experimental results, with Cr(VI) reduction up to 56.92% higher at deeper points of the experiment. Moisture content was a key parameter for the effectiveness of the remediation and its control was necessary. Overall, the application of nZVI by the pressure injection technique was found to be an effective alternative for the remediation of Cr(VI)-contaminated clay soil. [ABSTRACT FROM AUTHOR]

Porous platinum is a frequently used catalyst material in electrosynthesis and a robust broadband absorber in thermoelectrics. Pore size distribution and localization determine its properties by a large extent. However, the pore formation mechanism during the growth of the material remains unclear. In this work we elucidate the mechanism underlying electrochemical growth of nanoporous platinum layers and its control by ionic concentration and current density during electrolysis. The electrode kinetics and reduction steps of PtCl4 on platinum electrodes are investigated by cyclic voltammetry and impedance measurements. Cyclic voltammograms show three reduction steps: two steps relate to the platinum cation reduction, and one step relates to the hydrogen reduction. Hydrogen is not involved in the reduction of PtCl4, however it enables the formation of nanopores in the layers. These findings contribute to the understanding of electrochemical growth of nanoporous platinum layers in isopropanol with thickness of 100 nm to 500 nm. Porous platinum is a frequently used electrocatalyst and thermoelectric material, but the growth mechanism of nanopores in platinum layers is still not fully understood. Here, the authors show that hydrogen is not involved in the reduction process of PtCl4, however it enables the formation of nanopores. [ABSTRACT FROM AUTHOR]

In this study, Ag–Ni@MWCNTs nanocomposites with different Ag/Ni ratios have been prepared through a simple and effective chemical reduction strategy. Morphological, structural and elemental composition of the as-prepared nanocomposites has been examined by using SEM, TEM, EDS and XRD, respectively. Electrochemical study of all the samples was carried out via cyclic voltammetry. Successful synthesis, desired surface morphology and expected elemental composition of the obtained nanocomposites have been confirmed from the above mentioned analytical techniques. The Ag–Ni@MWCNTs nanocomposites show better electrocatalytic activity toward glucose oxidation owing to a greater number of active sites provided by support material (MWCNTs) and synergistic effect present among the atoms of Ag and Ni. The optimized Ag1–Ni9@MWCNTs catalyst displayed high sensitivity (1485 µA mM−1 cm−2), wide linear range (4 mM) and low limit of detection (7 µM) toward glucose sensing. [ABSTRACT FROM AUTHOR]

The presence of deoxygenated hemoglobin (Hb) results in a drop in T2 and T2* in magnetic resonance imaging (MRI), known as the blood oxygenation level-dependent (BOLD-)effect. The purpose of this study was to investigate if deoxygenated myoglobin (Mb) exerts a BOLD-like effect. Equine Met-Mb powder was dissolved and converted to oxygenated Mb. T1, T2, T2*-maps and BOLD-bSSFP images at 3Tesla were used to scan 22 Mb samples and 12 Hb samples at room air, deoxygenation, reoxygenation and after chemical reduction. In Mb, T2 and T2* mapping showed a significant decrease after deoxygenation (− 25% and − 12%, p < 0.01), increase after subsequent reoxygenation (+ 17% and 0% vs. room air, p < 0.01), and finally a decrease in T2 after chemical reduction (− 28%, p < 0.01). An opposite trend was observed with T1 for each stage, while chemical reduction reduced BOLD-bSSFP signal (− 3%, p < 0.01). Similar deflections were seen at oxygenation changes in Hb. The T1 changes suggests that the oxygen content has been changed in the specimen. The shortening of transverse relaxation times in T2 and T2*-mapping after deoxygenation in Mb specimens are highly indicative of a BOLD-like effect. [ABSTRACT FROM AUTHOR]

Silver powders were prepared by a chemical reduction method. Effects of different surfactants during this preparation process were examined. Using these silver powders, silver pastes were prepared for low temperature co-fired ceramics (LTCC) applications. Another batch of different surfactants were added into the silver paste and evaluated. Moreover, various organic thixotropic agents were used to modify the thixotropy behavior of the silver paste. It was found that the surfactants of PVP (Polyvinyl pyrrolidone, for preparation of the silver powder) and Span-85 (for the preparation of silver paste) exhibited the best performance, with an electrical resistivity of 0.11 mΩ mm. The silver paste with the thixotropic agent of hydrogenated castor oil shows the largest thixotropic index of 1.56. Using different organic additives, the microstructural, rheological and electrical properties of the silver paste can be considerably improved, and our results shed light on the optimization of the silver paste for LTCC applications. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction is a significant component of water splitting, and the design of anode electrocatalysts is the key to achieving efficient electrochemical water oxidization. However, the high price of anode electrocatalysts like RuO2 or IrO2 limits their wide application. Herein, we introduce the employment of FePx grown on C as a catalyst with high activity and low cost, containing a special nanocluster structure formed by a simple chemical reduction combined with an electroless plating method. The performance of FePx/C shows a low overpotential of 273 mV at 10 mA cm−2, a Tafel slope of 56 mV dec−1 and a long continuous oxygen evolution for 5 h in 1.0 M potassium hydroxide. Such superior performance can be attributed to the porous structure of the iron phosphide nanoclusters. Our work not only shows excellent performance, but also provides a workable design for non-noble catalysts. [ABSTRACT FROM AUTHOR]

Green synthetic method for the graphene sheet's production has precisely attracted the researcher's interest. Currently, most of the conventional practices for graphene oxide (GO) reduction into reduced graphene oxide (RGO) included chemical reduction using highly toxic and hazardous reducing agents. In this respect, here we are introducing a facile, sustainable, economically feasible, and green method to graphene sheet's synthesis by reducing the GO using natural monoterpenoid thymol. The phenolic groups present in thymol have the ability to convert exfoliated GO to RGO under reflux condition. The quality of the T-RGO was confirmed using characterization techniques. The electrochemical results showed that the T-RGO has a high specific capacitance and energy density of 400 F g−1 and 55 W h kg−1, respectively, at a current density of 1 A g−1. These characterization data obtained show that this green approach holds an excellent standpoint in the synthesis of energy-storage graphene materials. [ABSTRACT FROM AUTHOR]

Metal nanoparticles with plasmonic properties have gained significant attention due to their unique physical, chemical and antimicrobial properties. Among different metal nanoparticles, copper nanoparticles (CNPs) are especially important because of their antimicrobial activities against multidrug resistant strains. Synthesis of stable CNPs in feasible amounts remains a challenge due to the poor chemical stability of CNPs against oxidation. In this article, CNPs were synthesized with moderate yield (191.2 ± 9.5 µg/mL) by a chemical reduction method. The effects of various factors (type of copper precursor, temperature and reaction time) on the plasmonic properties, hydrodynamic size and the yield values were studied by UV-visible spectroscopy, photon correlation spectroscopy and inductively coupled plasma atomic emission spectroscopy. The CNPs synthesized by the optimized procedure (CuCl2 as copper precursor, reaction time of 5 min and reaction temperature of 80°C) possess small hydrodynamic size (38 ± 0.52 nm) and stable plasmon resonance (571.5 ± 10 nm). These CNPs may find potential applications in development of cost-effective antimicrobial agents against multi-drug resistant strains. [ABSTRACT FROM AUTHOR]

The sustainable production of hydrogen and oxygen through the electrolysis of water requires the development of an efficient electrocatalyst. In this work, we report the electrocatalytic activity of Pd nanoparticles dispersed on CeO2/N, S-rGO (where N, S-rGO represents nitrogen and sulfur-doped reduced graphene oxide). The CeO2/N, S-rGO and Pd nanoparticles were synthesized by hydrothermal and chemical reduction methods, respectively. Electrochemical measurements towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) show a high electrocatalytic activity of the catalyst. Among the synthesized electrocatalysts Pd/CeO2/N, S-rGO exhibits lower overpotential (75 mV and 240 mV) at 10 mA/cm2 and lower Tafel slope value (44 mV/dec and 42 mV/dec) for HER and OER, respectively. The chronoamperometric and linear sweep voltammetry (LSV) of the electrocatalyst shows a negligible decrease in the current density for twelve hours and a minor change in the polarization curve after 10,000 cycles, respectively. The high electrocatalytic activity and superior stability of the synthesized electrocatalyst could be attributed to the synergetic effect between Pd nanoparticles and CeO2/N, S-rGO support. This work demonstrates a facile way to develop effective and stable electrocatalysts by exploiting the Pd/Metal oxide interface. [ABSTRACT FROM AUTHOR]

Nitrate as a diffusive agricultural contaminant has been causing substantial groundwater quality deterioration worldwide. In situ groundwater remediation techniques using permeable reactive barriers (PRBs) have attracted increasing interest. Particularly, PRBs based on biological denitrification, using the organic substrate as a biostimulator, and chemical nitrate reduction, using zero-valent iron (ZVI) as a reductant, are two major PRB approaches for groundwater denitrification. This review paper analyzed the published studies over the past 10 years (2010–2020) using laboratory, modeling, and field-scale approaches to explore the performance and mechanisms of these two types of PRBs. Important factors affecting the denitrification efficiencies as well as the influential mechanisms were discussed. Several research gaps have been identified and further research needs are discussed in the end. [ABSTRACT FROM AUTHOR]

As a common heavy metal, chromium and its compounds are widely used in industrial applications, e.g., leather tanning, electroplating, and in stainless steel, paints and fertilizers. Due to the strong toxicity of Cr(VI), chromium is regarded as a major source of pollution with a serious impact on the environment and biological systems. The disposal of Cr(VI) by biological treatment methods is more favorable than traditional treatment methods because the biological processes are environmentally friendly and cost-efficient. This review describes how bacteria tolerate and reduce Cr(VI) and the effects of some physical and chemical factors on the reduction of Cr(IV). The practical applications for Cr(VI) reduction of bacterial cells are also included in this review. [ABSTRACT FROM AUTHOR]

Copper nanoparticles were prepared by chemical reduction method of CuSO4 in aqueous solution in the presence of polyvinyl pyrrolidone and cetyltrimethylammonium bromide as double capping agents without input of extra inert gases. These nanoparticles with average particle size 61 nm diameter were obtained by varying polyvinyl pyrrolidone concentration. Copper nanoparticles/polyindole composite was further fabricated via a facile in situ polymerization method. The morphology, structure and thermal stability of copper nanoparticles and copper nanoparticles/polyindole composites were studied by different techniques. The effect of copper weight percent on the conductivity of the composite was investigated, and the obtained data exhibited that only 25% weight of copper nanoparticles has the greatest effect in increasing polyindole conductivity. Furthermore, the performance of copper nanoparticles in the alteration of polyindole conductivity was investigated by SEM images. [ABSTRACT FROM AUTHOR]