Fast and Efficient Removal of Uranium onto a Magnetic Hydroxyapatite Composite: Mechanism and Process Evaluation

The exploration and rational design of easily separable and highly efficient sorbents with satisfactory capability of extracting radioactive uranium (U)-containing compound(s) are of paramount significance. In this study, a novel magnetic hydroxyapatite (HAP) composite (HAP@ CoFe2O4), which was coupled with cobalt ferrite (CoFe2O4), was rationally designed for uranium(VI) removal through a facile hydrothermal process. The U(VI) ions were rapidly removed using HAP@ CoFe2O4 within a short time (i.e., 10 min), and a maximum U(VI) removal efficiency of 93.7% was achieved. The maximum adsorption capacity (Qmax) of the HAP@CoFe2O4 was 338 mg/g, which demonstrated the potential of as-prepared HAP@CoFe2O4 in the purification of U(VI) ions from nuclear effluents. Autunite [Ca(UO2)2(PO4)2(H2O)6] was the main crystalline phase to retain uranium, wherein U(VI) was effectively extracted and immobilized in terms of a relatively stable mineral. Furthermore, the reacted HAP@CoFe2O4 can be magnetically recycled. The results of this study reveal that the suggested process using HAP@CoFe2O4 is a promising approach for the removal and immobilization of U(VI) released from nuclear effluents.

Formation of BaF2 Microcrystals as Superhydrophobic Materials via a Hydrothermal Method

Controllable BaF2 microcrystals with super-hydrophobic property have been successfully synthesized via a facile hydrothermal process. XRD, SEM and CA are used to study the structure, morphology and the hydrophobic properties of the BaF2 materials. The effects of reaction time, surfactants and pH are also detailed investigated in order to get a series of accurate reaction conditions for the preparation of BaF2 material. The results show that uniform BaF2 tetragonal phase structure was fabricated when the reaction temperature was controlled at 180 oC for 24 h. In addition, the BaF2 materials showed excellent super-hydrophobic properties. The results about the influence of time and substrates exhibit that the sample can maintain the stable super-hydrophobic property for over 10 days. As a promising super hydrophobic materials, the studies of BaF2 reported in this paper is quite practical and it has a certain guiding meaning for the future study about super hydrophobic materials.

“Double guarantee mechanism” of Ca2+-intercalation and rGO-integration ensures hydrated vanadium oxide with high performance for aqueous zinc-ion batteries

Ca2+-Intercalated hydrated V2O5/rGO (CaVOH/rGO) is synthesized via a facile hydrothermal process and applied as a cathode for ARZIBs with an admirable specific capacity (409 mA h g−1 at 0.05 A g−1) and excellent energy density (381 W h kg−1).

Enhanced photocatalytic performance of NaNbO3 nanorods by loading Al2O3 nanoparticles

Herein, we report the fabrication of UV-active NaNbO3/Al2O3 (30 wt.%) ferroelectric heterojunction photocatalyst with enhanced photoelectrochemical activity to Methylene Blue (MB). Pure NaNbO3 nanorods (NRs) were synthesized by a facile hydrothermal process and NaNbO3/Al2O3 composite was prepared by an ultrasonic vibration method. The heterostructures showed a remarkable increase in photocurrent density and the MB degradation ratio reached 88% in the initial 15 min and eventually reached 98.6% in 75 min. The high photocatalytic efficiency is attributed to the ferroelectric polarization of NaNbO3 with the forming of heterojunction electric fields assisted by Al2O3. These properties demonstrate that NaNbO3/Al2O3 ferroelectric heterojunction photocatalyst shows promising photoactivity and provides an effective method to improve the photocatalytic properties of other ferroelectrics.

Synthesis and enhanced photocatalytic performance of 0D/2D CuO/tourmaline composite photocatalysts

Photocatalysis is considered to be a green and promising technology for transforming organic contaminants into nontoxic products. In this work, a CuO/tourmaline composite with zero-dimensional/two-dimensional (0D/2D) CuO architecture was successfully obtained via a facile hydrothermal process, and its photocatalytic activity was evaluated by the degradation of methylene blue (MB). Surface element valence state and molecular vibration characterization revealed that CuO chemically interacted with tourmaline via Si–O–Cu bonds. The specific surface area of the CuO/tourmaline composite (23.60 m2 g−1) was larger than that of the pristine CuO sample (3.41 m2 g−1). The CuO/tourmaline composite exhibited excellent photocatalytic activity for the degradation of MB, which was ascribed to the increase in the quantity of the adsorption-photoreactive sites and the efficient utilization of the photoinduced charge carriers. This study provides a facile strategy for the construction of 0D/2D CuO structures and the design of tourmaline-based functional composite photocatalysts for the treatment of organic contaminants in water.

Electrochemical Properties of Nanoflower-Like NiCo2O4 Electrode Material

A nanoflower-like NiCo2O4 was successfully synthesized on Ni foam by a facile hydrothermal process with sodium dodecyl sulfate (SDS) by annealing in air atmosphere. The special architecture consists of uniform ultra-thin layers with a lateral size of several hundred nanometers intercrossed with each other, which promote the surface Faraday reaction and relive the volume expansion. The as-fabricated NiCo2O4 nanoflower delivers a specific capacitance of 752 F g–1 at 1 A g–1, and 78.6% retainable capacitance after 5000 cycles.

A polar mineral tourmaline enables synthesis of 0D/2D CuO photocatalyst with enhanced photocatalytic activity

Photocatalysis is considered to be a green and promising technology for transforming organic contaminants into nontoxic products. In this work, the CuO/tourmaline composite with zero-dimensional/two-dimensional (0D/2D) CuO architecture was obtained via a facile hydrothermal process. CuO chemically interacted with tourmaline via Si-O-Cu bond. The specific surface area of the CuO/tourmaline composite (23.60 m2 g-1) was larger than that of pristine CuO (3.41 m2 g-1). Three predominant reactive species of superoxide radical (O2 •-), hydroxyl radical (•OH), and h+ were generated by the CuO/tourmaline composite aqueous suspension system under light irradiation. The CuO/tourmaline composite exhibited excellent photocatalytic capacity for the decomposition of organic pollutants, which was ascribed to the increase in the quantity of adsorption-photoreactive sites and the efficient utilization of photoinduced charge carriers benefited from tourmaline. This study offered a facile strategy for the construction of 0D/2D CuO structure and the design of tourmaline-based functional composite photocatalysts for the treatment of organic contaminants in waster.

Development of Ethanol Gas Sensor Using α-Fe2O3 Nanocubes Synthesized by Hydrothermal Process

Herein, α-Fe2O3 nanocubes were synthesized, characterized and employed as functional and promising material for the development of ethanol gas sensor. Facile hydrothermal process was used to synthesized the nanocubes and characterized by several techniques which confirmed the large-quantity synthesis, wellcrystallinity with rhombohedral structure of α-Fe2O3. The Raman-scattering spectrum of the synthesized nanocubes exhibited several Raman-active modes which further confirmed the formation of pure α-Fe2O3. As a functional material, the synthesized α-Fe2O3 nanocubes were used as electrode material to fabricate ethanol gas sensor which was tested at various working temperatures, i.e., 300 °C, 400 °C and 450 °C which revealed that the 400 °C was the optimal working temperature. Thus, at 400 °C working temperature, in presence of 100 ppm ethanol gas, the fabricated sensor exhibited highest gas response of 1.69 with response time < 1 s and recovery time of 1485 s.

Highly Sensitive Picric Acid Chemical Sensor Based on Samarium (Sm) Doped ZnO Nanorods

Herein, we report the synthesis, characterization and picric acid chemical sensing application of samarium (Sm) doped ZnO nanorods. The Sm-doped ZnO nanorods were synthesized by facile hydrothermal process and characterized using various analytical methods which confirmed the large-scale synthesis and wurtzite hexagonal crystal structure for the synthesized nanorods. The doping of Sm ions in the lattices of the synthesized nanorods was evaluated by the energy dispersive X-ray spectroscopy (EDS). The synthesized Sm-doped ZnO nanorods were used as potential scaffold to fabricate high sensitive and reproducible picric acid chemical sensor based on I–V technique. The fabricated picric acid chemical sensor based on Sm-doped ZnO nanorods exhibited a high sensitivity of 213.9 mA mM−1 cm−2 with the limit of detection of ∼0.228 mM and correlation coefficient of R═0.9889. The obtained results revealed that the facile grown Sm-doped ZnO nanorods can efficiently be used to fabricate high sensitive and reproducible chemical sensors.