Gas-assisted growth of boron-doped nickel nanotube arrays: rapid synthesis, growth mechanisms, tunable magnetic properties, and super-efficient reduction of 4-nitrophenol

Magnetic tubular nickel@silica-graphene nanocomposites with high preconcentration capacity for organothiophosphate pesticide removal in environmental water: Fabrication, magnetic solid-phase extraction, and trace detection

Organothiophosphate pesticides (OPPs) are the most common water contaminants, significantly endangering human health and bringing serious public safety issues. Thus, developing effective technologies for the removal or trace detection of OPPs from water is urgent. Herein, a novel graphene-based silica-coated core-shell tubular magnetic nanocomposite (Ni@SiO₂-G) was fabricated for the first time and used for the efficient magnetic solid-phase extraction (MSPE) of the OPPs chlorpyrifos, diazinon, and fenitrothion from environmental water. The experimental factors affecting extraction efficiency such as adsorbent dosage, extraction time, desorption solvent, desorption mode, desorption time, and adsorbent type were evaluated. The synthesized Ni@SiO₂-G nanocomposites showed a higher preconcentration capacity than the Ni nanotubes, Ni@SiO₂ nanotubes, and graphene. Under the optimized conditions, 5 mg of tubular nano-adsorbent displayed good linearity within the range of 0.1-1 μg·mL^-1, low limits of detection (0.04-0.25 pg·mL^-1), low limits of quantification (0.132-0.834 pg·mL^-1), good reusability (n = 5; relative standard deviations between 1.46% and 9.65%), low dosage (5 mg), and low real detection concentration (< 3.0 ng·mL^-1). Moreover, the possible interaction mechanism was investigated by density functional theory calculation. Results showed that Ni@SiO₂-G was a potential magnetic material for the preconcentration and extraction of formed OPPs at ultra-trace levels from environmental water.

Direct growth of flower like-structured CuFe oxide on graphene supported nickel foam as an effective sensor for glucose determination

In this report, a novel flower like-structured CuFe oxides was directly grown on graphene nanosheets supported nickel foam substrates (CuFe-O/GR/NF) via a hydrothermal method followed by an additionally pyrolysis process. The different morphologies consistent with varied synthesis conditions, along with their catalytic activity were discussed. The CuFe-O/GR/NF material was successfully applied as an electrocatalyst for sensing glucose with a wide linear concentration range of 0.0079 μM-21.504 μM, sensitivity of 0.368 mA μM^-1 cm^-2, and limit of detection of 0.0079 μM. Impressively, the CuFe-O/GR/NF showed much higher electrocatalytic activity, lower overpotential and greater stability as compared to that of mono Cu-O/GR/NF or Fe-O/GR/NF synthesized by the same method. The higher electrocatalytic activity was due to the high electron conductivity, large surface area of CuFe-O/GR/NF and the fast ion/electron transport in the electrode and at the electrolyte-electrode interface. This is important for further development of high performance electrocatalysts for sensor application.

Green synthesis of Ag/TiO2 composite coated porous vanadophosphates with enhanced visible-light photo-degradation and catalytic reduction performance for removing organic dyes

As environmental pollution and energy shortages have become global concerns, the construction of highly efficient catalysts using facile and green methods remains a long-term goal. In the present study, we proposed a facile catalyst preparation method in which Ag/TiO₂ composites were coated on the surface of the porous pure inorganic crystalline vanadium phosphates (VPO) by a one-step strategy. More importantly, the in situ reduction of Ag nanoparticles was achieved at room temperature without severe conditions or hydrogen atmosphere in which the porous VPO was employed as the reductant. The prepared Ag/VPO@TiO₂ composites act as a class of efficient bifunctional catalysts for visible light photodegradation of MB molecules and catalytic reduction of p-nitrophenol (4-NP). Among these samples, the 6.82%Ag/VPO@TiO₂ composite exhibited a superior photocatalytic activity in the degradation of MB and an ultrafast reduction rate for 4-NP of about 0.1 mM/40 s. The photocatalytic mechanistic studies revealed that the encapsulated VPO with a narrow band gap not only efficiently enhances the photosensitivity of the TiO₂ but also largely facilitates the photogenerated charge separation. The subsequent deposition of Ag NPs is able to further promote electron transfer ability, which leads to the higher photocatalytic activity. Moreover, the contact of Ag NPs with the surface of semiconductor TiO₂ can result in an electron-enhanced area in their interface that could effectively facilitate the uptake of electrons by the 4-NP molecules and then improve the reduction activity.

Hydrothermal control, characterization, growth mechanism, and photoluminescence properties of highly crystalline 1D Eu(OH)3 nanostructures

Six types of 1D Eu(OH)₃ nanostructures with typical morphologies, including short hexagonal prism, long hexagonal prism, coiling rod, short rod, long rod, and nanobunch, were synthesized via the hydrothermal route using EuCl₃ and NaOH as raw materials. The morphologies, sizes, structures, and compositions of the as-prepared products were characterized by scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, X-ray diffraction, and Fourier transform infrared spectroscopy. The effects of different reaction conditions on the morphology and size of the products were also investigated, and the relevant growth mechanism was assessed. Results showed that the geometric features of Eu(OH)₃ are affected by the precursor pH and reaction time and temperature; among these factors, precursor pH played a key role in controlling the morphologies of the resulting Eu(OH)₃ nanostructures. The fluorescence properties of the six Eu(OH)₃ nanostructures were analyzed, and typical photoluminescence emission peaks due to the ⁵D₀–⁷F_J (J = 1–4) transition of Eu³⁺ were noted. Moreover, the intensity of the emission peak of the products at 616 nm was slightly weaker than that at 592 nm. This finding reflects the high site symmetry of Eu³⁺ in the Eu(OH)₃ nanostructures.

Six types of 1D Eu(OH)₃ nanostructures with typical morphologies, including short hexagonal prism, long hexagonal prism, coiling rod, short rod, long rod, and nanobunch, were synthesized via the hydrothermal route using EuCl₃ and NaOH as materials.

Bi-Metal Phosphide NiCoP: An Enhanced Catalyst for the Reduction of 4-Nitrophenol

Porous phosphide NixCoyP composite nanomaterials are successfully synthesized at different Ni/Co ratios (=0, 0.5, 1, and 2) to reduce 4-nitrophenol. The X-ray diffraction and X-ray photoelectron spectroscopy results demonstrate that the products are CoP, NiCoP/CoP, NiCoP, and NiCoP/Ni₂P when the Ni/Co ratio is 0, 0.5, 1, and 2, respectively. The products exhibit different catalytic performance for reduction of 4-nitrophenol at room temperature. Among them, the pure NiCoP delivers a better catalytic efficiency with k app = 677.4 × 10 - 2   min - 1 and k = 338.7   ( Lg - 1 min - 1 ) , due to the synergy between Ni and Co atoms. The sequence of catalytic efficiency of different samples is CoP < NiCoP/CoP < NiCoP/Ni₂P < NiCoP.

PdAu alloy nanoparticles supported on nitrogen-doped carbon black as highly active catalysts for Ullmann coupling and nitrophenol hydrogenation reactions

The PdAu/NCB catalyst with a Pd/Au mole ratio of 1/1 shows the highest activity towards both Ullmann coupling reactions of aryl halides and the hydrogenation reaction of nitrophenols.

Free-Standing Networks of Core-Shell Metal and Metal Oxide Nanotubes for Glucose Sensing

Nanotube assemblies represent an emerging class of advanced functional materials, whose utility is however hampered by intricate production processes. In this work, three classes of nanotube networks (monometallic, bimetallic, and metal oxide) are synthesized solely using facile redox reactions and commercially available ion track membranes. First, the disordered pores of an ion track membrane are widened by chemical etching, resulting in the formation of a strongly interconnected pore network. Replicating this template structure with electroless copper plating yields a monolithic film composed of crossing metal nanotubes. We show that the parent material can be easily transformed into bimetallic or oxidic derivatives by applying a second electroless plating or thermal oxidation step. These treatments retain the monolithic network structure but result in the formation of core-shell nanotubes of altered composition (thermal oxidation: Cu₂O-CuO; electroless nickel coating: Cu-Ni). The obtained nanomaterials are applied in the enzyme-free electrochemical detection of glucose, showing very high sensitivities between 2.27 and 2.83 A M^-1 cm^-2. Depending on the material composition, varying reactivities were observed: While copper oxidation reduces the response to glucose, it is increased in the case of nickel modification, albeit at the cost of decreased selectivity. The performance of the materials is explained by the network architecture, which combines the advantages of one-dimensional nano-objects (continuous conduction pathways, high surface area) with those of a self-supporting, open-porous superstructure (binder-free catalyst layer, efficient diffusion). In summary, this novel synthetic approach provides a fast, scalable, and flexible route toward free-standing nanotube arrays of high compositional complexity.

Amorphous NiB/carbon nanohybrids: synthesis and catalytic enhancement induced by electron transfer

Amorphous NiB/C shows synergistic catalysis for 4-nitrophenol reduction, induced by the electron transfer from NiB alloy to carbon support.

Facile Decoration of Polyaniline Fiber with Ag Nanoparticles for Recyclable SERS Substrate

Facile synthesis of polyaniline@Ag composite has been successfully demonstrated by a simple solution-dipping method using high-aspect-ratio benzene tetracarboxylic acid-doped polyaniline (BDP) fiber as a nontoxic reducing agent as well as template cum stabilizer. In BDP@Ag composite, BDP fibers are decorated with spherical Ag nanoparticles (Ag NPs), and the population of Ag NPs on BDP fibers is controlled by changing the molar concentration of AgNO3. Importantly, Ag-NP-decorated BDP fibers (BDP@Ag composites) have been evolved as a sensitive materials for the detection of trace amounts of 4-mercaptobenzoic acid and rhodamine 6G as an analyte of surface-enhanced Raman scattering (SERS), and the detection limit is down to nanomolar concentrations with excellent recyclability. Furthermore, synthesized BDP@Ag composites are applied simultaneously as an active SERS substrate and a superior catalyst for reduction of 4-nitrothiophenol.

Self-assembled material of palladium nanoparticles and a thiacalix[4]arene Cd(ii) complex as an efficient catalyst for nitro-phenol reduction

A cadmium complex based on the thiacalix[4]arene scaffold is utilized to synthesize a material with palladium nanoparticles, which behaves as an efficient catalyst for the conversion of 4-nitrophenol to 4-aminophenol.

Controllable synthesis of Ni nanotube arrays and their structure-dependent catalytic activity toward dye degradation

Ni nanotube (nanorod) arrays are controllably fabricated by a one-step approach, the GDDATG and DDCG growth mechanisms are introduced. The Ni nanostructures present higher catalytic activities for dye degradation, the relationship between structures and catalytic properties is also studied.