Simple Wet Chemistry Research Articles

Magnetic-Based Coreshell Nanoparticles as Potential Adsorbents for the Removal of Cu2+ Under Ultraviolet (UV) Light

The magnetite (Fe3O4) and maghemite (γFe2O3) nanopartides, magnetite-silica-silver chloride (Fe3O4-SiO2-AgCl) and maghemite-silica-silver chloride (γFe2O3-SiO2-AgCl) coreshell structures have successfully been synthesized by using a simple wet chemistry method. The efficiency of these particles as the adsorbents for the removal of copper ion, Cu2+ in aqueous solution under UV light was investigated. Two different parameters were studied, namely the adsorbents contact time (60, 120, 180, 240 and 300s) and the solution-stirring rate (100, 200 and 300 rpm). From the results, the removal percentage of the copper ions from the solution were above 90% after 5 hours of adsorption process at 300 rpm by using Fe3O4 (94%) and γFe2O3 (92%) nanoparticles. The maximum removal of copper ions was nearly 100% when yFe2O3-SiO2-AgCl & Fe3O4-SiO2-AgCl coreshell particles were used. The samples that were prepared without magnetic core such as AgCl-SiO2, AgCl and SiO2 particles, showed lower percentage of the copper ions removal (78%, 60% and 20%, respectively). This situation shows that the magnetic nanoparticles plays and important role during the adsorption process due to their large active sites for the adsorption to occur.

Preparation of Powders Containing Sb, Ni, and O for the Design of a Novel CO and C3H8 Sensor

In this work, powders of NiSb2O6 were synthesized using a simple and economical microwave-assisted wet chemistry method, and calcined at 700, 800, and 900 °C. It was identified through X-ray diffraction that the oxide is a nanomaterial with a trirutile-type structure and space group P42/mnm (136). UV–Vis spectroscopy measurements showed that the bandgap values were at ~3.10, ~3.14, and ~3.23 eV at 700, 800, and 900 °C, respectively. Using scanning electron microscopy (SEM), irregularly shaped polyhedral microstructures with a size of ~154.78 nm were observed on the entire material’s surface. The particle size was estimated to average ~92.30 nm at the calcination temperature of 900 °C. Sensing tests in static atmospheres containing 300 ppm of CO at 300 °C showed a maximum sensitivity of ~72.67. On the other hand, in dynamic atmospheres at different CO flows and at an operating temperature of 200 °C, changes with time in electrical resistance were recorded, showing a high response, stability, and repeatability, and good sensor efficiency during several operation cycles. The response times were ~2.77 and ~2.10 min to 150 and 200 cm3/min of CO, respectively. Dynamic tests in propane (C3H8) atmospheres revealed that the material improved its response in alternating current signals at two different frequencies (0.1 and 1 kHz). It was also observed that at 360 °C, the ability to detect propane flows increased considerably. As in the case of CO, NiSb2O6’s response in propane atmospheres showed very good thermal stability, efficiency, a high capacity to detect C3H8, and short response and recovery times at both frequencies. Considering the great performance in propane flows, a sensor prototype was developed that modulates the electrical signals at 360 °C, verifying the excellent functionality of NiSb2O6.

Individual Ni atoms on reduced graphene oxide as efficient catalytic system for reduction of 4-nitrophenol

The intelligent design of surface active sites and their manipulation on the atomic level is a new research paradigm both in surface science and in catalysis. In this study, we synthesize a composite material, comprising atomically dispersed nickel on reduced graphene oxide support (rGO/Ni), in a simple wet chemistry procedure. The as-prepared material is fully characterized by the set of experimental techniques, including TEM with atomic resolution. Nickel atoms uniformly cover the rGO surface, and do not coalesce into nanoparticles. Individual Ni atoms are situated on the oxidized domains of rGO, being strongly coordinated by remaining oxygen functionalities. The as-prepared rGO/Ni demonstrates extraordinary efficiency in catalyzing reduction of 4-nitrophenol. For the first time, the catalysis of this reaction was successfully demonstrated in a prototype of a continuous flow reactor. The excellent catalytic properties of rGO/Ni are explained by the high surface area of the catalyst particles and high lateral density of the active sites. The reaction can be considered as an example of a single-atom catalysis. The low cost of materials and ease of preparation in the environmentally friendly conditions, open the doors for potential usage of this catalyst in the real industrial processes.

Spontaneous exfoliation of large-sized graphene oxide with low defect concentration by simple wet chemistry

The conventional Hummers' method involves intercalation, oxidation, hydrolysis, and exfoliation reactions for graphene oxide (GO) preparation, which generate atomic scale defects in the basal plane and unzip the plane to diminish lateral size. In this paper, processing conditions of the Hummers’ method was engineered, especially graphite material, dose-by-dose injection of KMnO4 oxidant, oxidation temperature, and exfoliation conditions, for less defect concentration and larger size of GO. Natural graphite material processed under 10 °C throughout the whole reaction steps and dose-by-dose addition scheme of the oxidant result in GOs with reduced defect density. Additional carboxylation reaction facilitates the exfoliation of GO sheets, showing ∼35 μm in diameter and mass yield of 140%. This simple wet chemistry-based methodology reported here paves a way to facile and scaled-up production of large-sized GOs with low defect concentration.

Porous polyetheretherketone microcarriers fabricated via hydroxylation together with cell-derived mineralized extracellular matrix coatings promote cell expansion and bone regeneration.

Porous microcarriers have aroused increasing attention recently by facilitating oxygen and nutrient transfer, supporting cell attachment and growth with sufficient cell seeding density. In this study, porous polyetheretherketone (PEEK) microcarriers coated with mineralized extracellular matrix (mECM), known for their chemical, mechanical and biological superiority, were developed for orthopedic applications. Porous PEEK microcarriers were derived from smooth microcarriers using a simple wet-chemistry strategy involving the reduction of carbonyl groups. This treatment simultaneously modified surface topology and chemical composition. Furthermore, the microstructure, protein absorption, cytotoxicity and bioactivity of the obtained porous microcarriers were investigated. The deposition of mECM through repeated recellularization and decellularization on the surface of porous MCs further promoted cell proliferation and osteogenic activity. Additionally, the mECM coated porous microcarriers exhibited excellent bone regeneration in a rat calvarial defect repair model in vivo, suggesting huge potential applications in bone tissue engineering.

Shape-controlled template-driven growth of large CuS hexagonal nanoplates

Ultrathin 2D metal sulphide nanostructures have revealed extraordinary properties, applications and thus, the subject matter of current research. However, synthesis of shape-controlled large-sized (approximately few µms) plates/sheets are not well known, specifically due to the colloidal synthesis process resulting in the distribution of shape/size. Here, we report the template-assisted growth of large-sized CuS nanoplates (~0.5–9 µm) by simple wet chemistry, where the Au microplates serve as a template. The Au microplates act as seed and facilitate the Au-Cu via epitaxial growth of Cu. Later, the Au-Cu acts as the source of Cu and in presence of aqueous S2−, the CuS hexagons form, however, the edge of the hexagons are parallel to the Au seed and thus, hinting to be controlled by the seed. Interestingly, the substrate independent Au-Cu can even provide the platform for the spiral nanoplates, by simply decorating the outer surface of the Cu with pillar-like features.

Polyacrylonitrile Nanofiber Membrane Modified with Ag/GO Composite for Water Purification System.

Silver nanoparticle-modified graphene oxide (Ag/GO) was reliably prepared by using sodium borohydride (NaBH4) in the presence of citric acid capping agent via a simple wet chemistry method. This rapidly formed Ag/GO composite exhibited good dispersity in a solution containing hydrophilic polyacrylonitrile (PAN). Subsequent electrospinning of this precursor solution resulted in the successful formation of nanofibers without any notable defects. The Ag/GO-incorporated PAN nanofibers showed thinner fiber strands (544 ± 82 nm) compared to those of GO-PAN (688 ± 177 nm) and bare-PAN (656 ± 59 nm). Subsequent thermal treatment of nanofibers resulted in the preparation of thin membranes to possess the desired pore property and outstanding wettability. The Ag/GO-PAN nanofiber membrane also showed 30% higher water flux value (390 LMH) than that of bare-PAN (300 LMH) for possible microfiltration (MF) application. In addition, the resulting Ag/GO-PAN nanofiber membrane exhibited antibacterial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). Furthermore, this composite membrane exhibited outstanding anti-fouling property compared to the GO-PAN nanofiber membrane in the wastewater treatment. Therefore, the simple modification strategy allows for the effective formation of Ag/GO composite as a filler that can be reliably incorporated into polymer nanofiber membranes to possess improved overall properties for wastewater treatment applications.

Orthorhombically distorted perovskite SeZnO3 nanosheets as an electrocatalyst for lithium-oxygen batteries

Perovskite ABO3 provides higher catalytic activity than binary metal oxides owing to crystallographic defects and oxygen vacancies due to the multivalence of the A and B cations. In this study, perovskite SeZnO3 nanosheets were synthesized via a simple wet chemistry method with sodium dodecyl sulfate as the surfactant. Material surface analysis using O 1s X-ray photo-electron spectroscopy confirmed an Ovacancy concentration of 50%, confirming the presence of large amounts of defects on the surface of the SeZnO3 nanosheets. The lithium-oxygen batteries with SeZnO3 nanosheet as an oxygen-electrode electrocatalyst exhibited a high reversibility (140 cycles) and a stable rate capability (50–500 mA g−1). Additionally, electrochemical impedance spectroscopy measurements indicated that the electronic conductivity of a SeZnO3 nanosheet was higher than that of ZnO. Therefore, we propose that the unique SeZnO3 structure exhibits excellent catalytic activity and electrical conductivity and can serve as a route towards improved lithium-oxygen batteries.

Silver nanoparticles decorated graphene oxide nanocomposite for bone regeneration applications

Different ultra-lightweight carbon nanostructures with superb mechanical properties have made them attractive materials for reinforcing nanocomposites. However, the preparation of an ideal bone reinforcement is still a challenging task. Therefore, in the present study, a simple wet chemistry method was employed to synthesize silver nanoparticles (AgNPs) decorated graphene oxide (GO) nanocomposite as potential reinforcement in orthopedic applications. A well-dispersed nearly oval-shaped AgNPs with the mean size of 9 ± 6 nm were homogeneously formed on the surface of GO due to its supporting role in preventing agglomeration of fine particles. The results of the antibacterial activities revealed that the anchor of AgNPs on the surface of GO improved its antibacterial properties, in which the composite structure exhibited higher antibacterial activity against Escherichia coli (E. coli) than Staphylococcus aureus (S. aureus) bacteria. The proposed protocol can keep steady the scattering of the AgNPs in nanocomposite and prolong the antibacterial activity of the system. Highlights AgNPs-GO nanocomposite was prepared via a facile wet chemistry approach. AgNPs (9 ± 6 nm) were homogeneously formed on GO. GO dictated the formation of nearly oval AgNPs in the system. The highest reactivity was found to be -0.315 eV.atom−1. Nanocomposite showed higher antibacterial activity versus E. coli than S. aureus bacteria.

Electrochemical oxidative valorization of lignin by the nanostructured PbO2/MWNTs electrocatalyst in a low-energy depolymerization process

In this study, we have investigated the application of the non-precious β-PbO2/MWNTs nanocomposites, which were developed via a simple wet-chemistry procedure, toward electrochemical oxidation of lignin. Structural characterization of the synthesized electrocatalysts was performed through X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and BET surface area analysis. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), and chronoamperometry (ChA) measurements were carried out to evaluate and compare the performance of different electrocatalysts toward lignin oxidation. The 33.3 wt% β-PbO2 nanocomposite possessed the highest electro-catalytic activity and stability for depolymerization of lignin. Several oxidation products such as vanillin and methyl salicylate were also identified by gas chromatography-mass spectroscopy (GS-MS) analysis. The enhanced electrochemical surfaces areas of the low-cost β-PbO2/MWNTs electrocatalyst combined with its good stabilities offer a promising route for developing an energy-efficient lignin depolymerization process. Electrochemical conversion of lignin-rich waste streams to functionalized compounds is appropriate for production of targeted biofuel and platform chemicals.

AuPt/MOF-Graphene: A Synergistic Catalyst with Surprisingly High Peroxidase-Like Activity and Its Application for H2O2 Detection.

Here, we report ZIF-8-reduced graphene oxide (ZIF-8-rGO)-supported bimetallic AuPt nanoparticles (AuPtNPs) as a novel peroxidase mimic for high-sensitivity detection of H2O2 in neutral solution. ZIF-8-graphene oxide (ZIF-8-GO) is first synthesized via a simple wet-chemistry process and subsequently immobilized with AuPtNPs via a reduction method. The resultant AuPt/ZIF-8-rGO shows enhanced peroxidase-like catalytic activity and it is applied for the electrochemical detection of H2O2 in a wide concentration range, from 100 nM to 18 mM, with a very low detection limit of 19 nM (S/N = 3). This good electroanalytical performance of AuPt/ZIF-8-rGO is owing to the ultrasmall size and high dispersion of the AuPtNPs, the strong metal-support interaction between the AuPtNPs and ZIF-8-rGO bisupport, and the sandwich-like structure comprising porous ZIF-8 and loosely packed rGO nanosheets. The AuPt/ZIF-8-rGO is employed for the practical detection of H2O2 in human serum samples with desirable properties. Therefore, the novel AuPt/ZIF-8-rGO is a promising nanozyme for various biotechnological and environmental applications.

Buffer effect of In2O3 interlayer on band offset at CuO/ZnO interface for enhanced photoelectrocatalytic water splitting

Multiple heterojunction made of CuO nanocrystals building on ZnO scaffold buffered by an In2O3 interlayer is fabricated through simple wet chemistry. Scanning and transmission electron microscopy reveal this CuO/In2O3/ZnO heterojunction forming multi-core-shell nanostructure. X-ray photoelectron spectroscopy is performed to analyze the chemical compositions. Such system is further employed in sunlight-driven photoelectrochemical water splitting, wherein Mott-Schottky analysis demonstrates its flat-band potential negatively shifted. This originates from the lower electron affinity of CuO compared to that of ZnO, favoring photocurrent generation at early onset potential. More importantly, the entire gamut of visible-light is harnessed by CuO, as manifested in the photocurrent action spectrum. Last but not least, the charge-separation is promoted at the In2O3 interface, as reflected in the impedance measurement. The synergistic effect endows the CuO/In2O3/ZnO photoelectrode with the highest photocurrent of 1.22 mA⋅cm−2 (at ∼1.6 V vs. RHE) that outperforms those of the CuO/ZnO and ZnO photoanodes, respectively.

Iron Vacancies Induced Bifunctionality in Ultrathin Feroxyhyte Nanosheets for Overall Water Splitting.

Exploring of new catalyst activation principle holds a key to unlock catalytic powers of cheap and earth-abundant materials for large-scale applications. In this regard, the vacancy defects have been proven to be effective to initiate catalytic active sites and endow high electrocatalytic activities. However, such electrocatalytically active defects reported to date have been mostly formed by anion vacancies. Herein, it is demonstrated for the first time that iron cation vacancies induce superb water splitting bifunctionality in alkaline media. A simple wet-chemistry method is developed to grow ultrathin feroxyhyte (δ-FeOOH) nanosheets with rich Fe vacancies on Ni foam substrate. The theoretical and experimental results confirm that, in contrast to anion vacancies, the formation of rich second neighboring Fe to Fe vacancies in δ-FeOOH nanosheets can create catalytic active centers for both hydrogen and oxygen evolution reactions. The atomic level insight into the new catalyst activation principle based on metal vacancies is adaptable for developing other transition metal electrocatalysts, including Fe-based ones.

Centimeter-scale continuous silica isoporous membranes for molecular sieving

Nanoporous molecular sieving membranes with high densities of uniform pores over macroscopic areas are highly desired to achieve a high permeation rate and a high molecular selectivity. In the first part of this work, our primary calculation using a quasi-steady state model indicates that the effective way of achieving a high molecular permeation is to increase the pore density and area of sieving membrane. Then the experimental work has been projected to prepare the centimeter-scale continuous silica isoporous membrane (SIM) consisting of parallel nanochannels under the support of porous polyethylene terephthalate (PET) film. Without using any expensive facilities or harsh conditions, simple wet-chemistry growth followed by membrane transfer was used to produce SIM with a large area up to 2.5 cm × 2.5 cm with ultrasmall thickness (ca. 90 nm) and high pore density (ca. 4.0 × 1012 cm−2). The prepared SIM-PET membrane demonstrated a molecular permeation rate almost one order of magnitude larger than commercial dialysis and nanoporous polycarbonate membranes. Moreover, thanks to uniform pore size (2.3 nm in diameter) and negatively charged surface of silica nanochannels, the membrane showed a precise selectivity at the molecular level in terms of molecular size and charge. Simultaneous achievement of high permeability and high selectivity, as well as simple fabrication and low cost, proves the potential of centimeter-scale SIM in molecular sieving and other applications.

Trimetallic Hybrid Nanoflower-Decorated MoS2 Nanosheet Sensor for Direct in Situ Monitoring of H2O2 Secreted from Live Cancer Cells.

In situ monitoring of hydrogen peroxide (H2O2) secreted from live cells plays a critical role in elucidating many cellular signaling pathways, and it is a significant challenge to selectively detect these low levels of endogenous H2O2. To address this challenge, we report the establishment of a trimetallic hybrid nanoflower-decorated MoS2 nanosheet-modified sensor for in situ monitoring of H2O2 secreted from live MCF-7 cancer cells. The Au-Pd-Pt nanoflower-dispersed MoS2 nanosheets are synthesized by a simple wet-chemistry method, and the resulting nanosheet composites exhibit significantly enhanced catalytic activity toward electrochemical reduction of H2O2, due to the synergistic effect of the highly dispersed trimetallic hybrid nanoflowers and the MoS2 nanosheets, thereby resulting in ultrasensitive detection of H2O2 with a subnanomolar level detection limit in vitro. Also the immobilization of the laminin glycoproteins on the surface of the nanocomposites increases its biocompatibility for cell adhesion and growth, which enables in situ electrochemical monitoring of H2O2 directly secreted from live cells for potential application of such sensor in cellular biology, clinical diagnosis, and pathophysiology.

Nickel-cysteine nanoparticles: Synthesis, characterization and application for direct electron transfer studies.

Nickel-cysteine nanostructures (Ni-CysNSs) are prepared by a simple wet chemistry procedure under mild conditions, in which l-cysteine acts both as precursor and structure directing agent. This method involves the reaction of nickel chloride with l-cysteine, followed by simultaneous adjusting the pH in the range of 6-8.5 by addition of an aqueous NaOH solution. The structure and morphology of the prepared products are characterized using various techniques, including X-ray powder diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, CHNS elemental analysis, Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). The effects of a variety of synthetic conditions on the structure and morphology of the Ni-CysNSs are studied, including the molar ratio of precursors, dispersing solvent, pH value of the reaction solution, reaction time and reaction temperature. FT-IR measurements reveal that synthesized Ni-CysNSs contain many free carboxylic groups on the surface, which could be used as binding sites to anchor biological molecules in order to develop various bioelectronic devices. In this work, the applicability of synthesized nanostructure in biosensing is studied by using Ni-CysNSs as a platform for covalently immobilization of GOx, as a model enzyme, on the surface. Cyclic voltammetric measurements reveal that the direct electron transfer from the active center of GOx to the glassy carbon electrode facilitated upon its immobilization on the Ni-CysNSs film. More importantly, GOx preserves its native structure and catalytic activity for the oxidation of glucose after immobilization on the Ni-CysNSs surface. The electrocatalytic characteristics of the GC/NiCysNS/GOx electrode toward the oxidation of glucose are investigated by cyclic voltammetry, which displayed acceptable electrical and sensing performance. Simple preparation of Ni-CysNPs and their biocompatibility make them attractive platforms for integration of various biomolecules such as proteine/enzymes with surface.

Electrochemical sensing of 4-nitrochlorobenzene based on carbon nanohorns/graphene oxide nanohybrids

Owing to the harmful nature of 4-nitrochlorobenzene (4-NCB, one toxic organic pollutant) and the low cost, high sensitivity and ease of operation of electrochemical method, it is highly desirable to develop effect electrochemical sensor for the detection of 4-NCB. Herein, by partially unzipping carbon nanohorns (CNHs) via a simple wet-chemistry method, CNHs and graphene oxide (GO) (CNHs/GO) nanohybrids were produced for sensing 4-NCB with synergistic properties. While the retained CNHs offer a path for rapid electron transport, the GO sheets formed by partially unzipping CNHs provide abundant active sites, further increase in surface area as well as improved dispersibility of the CNHs/GO. Our results show that the CNHs/GO modified electrode has excellent sensitivity to 4-NCB with a wide linear response range and a detection limit as low as 10 nM.

One dimensional hierarchical nanostructures composed of CdS nanosheets/nanoparticles and Ag nanowires with promoted photocatalytic performance

One dimensional Ag@CdS core–shell hierarchical nanostructures with excellent photocatalytic performance have been fabricated via a simple wet-chemistry approach at low temperature.

Enhanced Negative Photoconductivity in InAs Nanowire Phototransistors Surface‐Modified with Molecular Monolayers

AbstractNegative photoconductivity (NPC) mechanisms are widely investigated for high‐performance InAs nanowire (NW) phototransistors, where these mechanisms are usually attributed to severe carrier scattering centers, light‐assisted hot electron trapping in the surface oxide, and/or defects induced photogating layer. However, further insights into their photodetecting mechanisms, as well as corresponding performance enhancement of these NW phototransistors, are still very limited. This work reports the NPC behavior in surface‐modified InAs NW phototransistors based on photoexcitation induced majority electron trapping in the bonded sulfur monolayer under optical illumination. In order to enhance hot electron trapping ability of the bonded sulfur layer, aromatic thiolate (ArS−)‐based molecular monolayer with strong electron‐withdrawing group is employed using simple wet chemistry for the surface modification of InAs NW phototransistors. The magnitude of the photoexcitation induced hot electron trapping is increased by the stronger electron‐withdrawing ability of the ArS−‐based molecular monolayer, enabling the hot electrons to be trapped and released more efficiently, resulting in NW phototransistors with good sensitivity, fast photoresponse, and long‐term stability to low intensity visible light. These results confirm the potential of InAs NW phototransistors surface‐passivated with molecular monolayers in the application and realization of high‐sensitive and long‐term stable room temperature nanoscale photodetectors.

Electrical and Optical Properties of Rectifying ZnO Homojunctions Fabricated by Wet Chemistry Methods

Rectifying ZnO homojunctions are fabricated by simple wet chemistry methods. The p–n junction is formed between a p‐type nanostructured seed layer deposited by sol–gel method on phosphorus doped Si substrates and an array of n‐type nanorods grown by chemical bath deposition. The p‐type conductivity in the nanostructured layer is achieved by thermal diffusion of phosphorus from the Si substrate. The diffusion of phosphorus is supported by the observation of optical transitions related to neutral acceptor bound exciton in low‐temperature photoluminescence spectra. The p–n junction shows a high value of rectification ratio. Charge transport through the p‐n junction is discussed in terms of non‐ideal interface.