Ultrasonic synthesis of a 3D Ni(II) Metal–organic framework at ambient temperature and pressure: New precursor for synthesis of nickel(II) oxide nano-particles

Nanostructured materials via green sonochemical routes - Sustainability aspects

The production of environmentally friendly nanostructured materials with well-defined properties is a major challenge. Characteristics of the nanomaterials such as dimensionality, size and morphology strongly affect their performance in various applications. Additionally, sustainability considerations require an acceptable level of efficiency while being economically feasible and environmentally benign. The use of ultrasonic irradiation (UI) is a green and powerful technology, which can be applied for the synthesis of a variety of nanostructured materials. This review critically discusses the progress made in the fabrication of environmentally benign engineered nanomaterials with various dimensionalities (i.e., zero, one, two, or three dimensions) assisted by UI. The evolution and current status in this area are further illustrated using a scientometric approach. Application of UI for the synthesis of nanostructured materials has been also assessed according to the main sustainability pillars including the performance and environmental compatibility, as well as the relevant economic and social considerations. The outlook as well as recommendations for future research has been also provided and discussed towards the promotion of sustainable nanomaterials synthesis and application in various fields.

Sonocrystallisation of ZIF-8 in water with high excess of ligand: Effects of frequency, power and sonication time

A systematic study on the sonocrystallisation of ZIF-8 (zeolitic imidazolate framework-8) in a water-based system was investigated under different mixing speeds, ultrasound frequencies, calorimetric powers and sonication time. Regardless of the synthesis technique, pure crystals of ZIF-8 with high BET (Brunauer, Emmett and Teller) specific surface area (SSA) can be obtained in water after only 5 s. Furthermore, 5 s sonication produced even smaller crystals (~0.08 µm). The type of technique applied for producing the ZIF-8 crystals did not have any significant impact on crystallinity, purity and yield. Crystal morphology and size were affected by the use of ultrasound and mixing, obtaining nanoparticles with a more spherical shape than in silent condition (no ultrasound and mixing). However, no specific trends were observed with varying frequency, calorimetric power and mixing speed. Ultrasound and mixing may have an effect on the nucleation step, causing the fast production of nucleation centres. Furthermore, the BET SSA increased with increasing mixing speed. With ultrasound, the BET SSA is between the values obtained under silent condition and with mixing. A competition between micromixing and shockwaves has been proposed when sonication is used for ZIF-8 production. The former increases the BET SSA, while the latter could be responsible for porosity damage, causing a decrease of the surface area.

Recent advances in the application of magnetic Fe3O4 nanomaterials for the removal of emerging contaminants

Emerging contaminants (ECs) are widely distributed and potentially hazardous to human health and the ecological system. However, traditional wastewater treatment techniques are not sufficient to remove ECs. Magnetic nanomaterials are made of ferromagnetic or superparamagnetic magnetic elements such as iron and nickel, which can be easily separated from the aqueous solution, making them ideal adsorbents for contaminants in water. This review focused on the synthesis approaches of magnetic Fe₃O₄ nanoparticles (MFNs), as well as surface modification in order to improve their stability and functional diversity. Also, a detailed summary on the state-of-art application of magnetic nanomaterials on the removal of ECs was addressed. Additionally, challenges and future prospective of applying magnetic nanomaterials into real-world cases were discussed, in which the green and simple synthesis and evaluation of the toxic effects of MFNs are still of great challenge. This work summarizes the recent progress of using magnetic nanomaterials as promising and powerful tools in the treatment of ECs-contaminated water, benefiting researchers interested in nanomaterials and environmental studies.

3D Hydrangea Macrophylla-like Nickel-Vanadium Metal-Organic Frameworks Formed by Self-Assembly of Ultrathin 2D Nanosheets for Overall Water Splitting

The development of highly efficient and low-cost bifunctional noble metal-free electrocatalysts for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is an effective strategy for improving efficiency. Herein, novel three-dimensional (3D) bimetallic metal-organic frameworks containing Ni and V with adjustable stoichiometry were synthesized on nickel foam successfully. Notably, Ni2V-MOFs@NF only require rather low overpotentials of 244 and 89 mV for the OER and HER, respectively, and expedites overall water splitting with 1.55 V at 10 mA cm^-2 with robust durability during the 80 h test. The high efficiency of the novel obtained electrocatalysts should be attributed to the particular morphological design of the two-dimensional (2D) ultrathin nanosheets self-assembling into a 3D nanoflower and the electronic structure regulation resulting from the synergetic interaction between nickel and vanadium. Subsequent theoretical calculations reveal the following conclusions: (I) the exceptional electronic conductivity of Ni2V-MOFs shows enhanced optimization as a result of electronic structure reconstruction, (II) the energy barrier reduction of the rate-limiting step is responsible for the enhanced dynamics of Ni2V-MOFs for the OER, and (III) the facilitation of the adsorption of H⁺ and H₂O plays a key role in progressing the HER catalytic activity of Ni2V-MOFs.

Metal Organic Frameworks (MOFs) and ultrasound: A review

Metal-organic frameworks (MOFs) have received a lot of attention due to their unique properties and abundant functionalities. Permanent porosity and high surface area are just a few traits that have made them attractive to researchers. They can be prepared as task-specific materials by exploiting the functional group variety and tuning their size and geometry. The main purpose of this review is to present an alternative method of preparing MOF crystals and underline the advantages of ultrasound assisted (sonochemical) synthesis. State of the art ultrasound assisted techniques for the preparation of MOFs in nanoscale are presented. Optimization of morphology and particle size is highlighted throughout this work, as we discuss the effects of various factors, such as energy input, reagent concentration, adequate solvents, reaction time and more.

Design and synthesis of coordination polymers with chelated units and their application in nanomaterials science

The advances and problems associated with the preparation, properties and structure of coordination polymers with chelated units are presented and assessed.

High yield synthesis of Ni-BTC metal-organic framework with ultrasonic irradiation: Role of polar aprotic DMF solvent

Nickel based porous solid was synthesized with 20 kHz ultrasonic irradiation. The reaction of Ni(II) nitrate hexahydrate with 1,3,5-benzene tricarboxylic acid in N,N-Dimethylformamide (DMF) as the sole solvent under ultrasonic radiation produced porous Ni-BTC MOF. Choice of correct solvent for the ultrasonic treatment was proven important. The effect of varying ultrasonic powers (40%, 60% and 80% of 750 W) along with different temperature conditions (50 °C, 60 °C, 70 °C and 80 °C) influenced the respective yield. A very high yield of 88% Ni-BTC MOF was obtained from 80% ultrasonic power at 60 °C. BET surface areas of the MOF crystals measured by N2 gas adsorption isotherms were in the range of 960-1000 m(2)/g.

Enhancement in photocatalytic activity of NiO by supporting onto an Iranian clinoptilolite nano-particles of aqueous solution of cefuroxime pharmaceutical capsule

NiO/nano-clinoptilolite (NiO-NCP) was prepared by ion exchanging process of the prepared ball-mill nano-clinoptilolite particles with nickel(II) chloride aqueous solution. The prepared composite was characterized by XRD, UV-Vis DRS, TEM and FT-IR and then used as a catalyst in the photodegradation of cefuroxime (CF) using Hg lamp. The best experimental parameters were obtained as: 0.025 g L(-1) of the photocatalyst containing 13.3% NiO, 50 times diluted cefuroxime solution at pH 5. The degradation extent was monitored by UV-Vis spectroscopy and the results were confirmed by HPLC and COD. The kinetics of the photodegradation process obeyed the Langmuir-Hinshelwood model.