Nano

The upcoming energy crisis and the increasing power requirements of electronic devices have drawn enormous attention to research in the field of energy storage. Owing to compelling electrochemical and mechanical properties, two-dimensional nanomaterials can be used as electrodes on lithium-ion batteries to obtain high capacity and long cycle life. This review summarized the recent advances in the application of 2D nanomaterials on the electrode materials of lithium-ion batteries.

A novel ternary Cu₂O/BiVO₄/RGO photocatalyst is successfully constructed by hydrothermal and evaporation-induced method, and it exhibits superior photocatalytic performance for degradation tetracycline (TC). Meanwhile, the visible light absorption range of composite photocatalyst is effectively broadened by the formation of heterojunction with narrow band gap semiconductor Cu₂O. And the separation efficiency of the photogenerated electron–hole pairs is significantly enhanced by the synergistic effect of Cu₂O and RGO. More importantly, the adsorption of TC by ternary Cu₂O/BiVO₄/RGO possesses high adsorption capacity, which is 23.73 times higher than that of pure BiVO₄. Additionally, the possible reaction mechanism is clearly revealed by radical trapping experiment, electron spin-resonance (ESR) spectroscopy. This work provides a new insight to design a photocatalyst with excellent adsorption to remove organic contaminants in water.

Owing to weak interfacial bonding and incompatibility between graphene and polymer, there are several challenges in the fabrication of graphene-based polymer composites with an effective gas barrier. Hence, it is necessary to enhance the affinity between polymers and graphene. We selected graphene oxide (GO) as filler and brominated butyl rubber (BIIR) as a substrate to prepare GO/BIIR composites via the simple latex mixed route. The tortuous path of diffusion of helium molecules is extended after insertion of GO nanosheets, thus improving the gas barrier of composites. GO/BIIR composite with the GO content of 0.3wt.% exhibits favorable barrier efficiency to helium with a helium gas transmission rate of 12.79cm³ cm m${}^{-2}$ day${}^{-1}$ bar${}^{-1}$.

The pursuit for efficient conversion of methane under ambient conditions remains a challenge. Here, we reported photoelectrocatalytic oxidation of methane into methanol over ZnO nanowire arrays (NWAs) decorated with Au nanoparticles (NPs) under simulated sunlight illumination with ambient conditions. The photoelectrochemical (PEC) performances of the ZnO and ZnO/Au photoanodes were investigated to analyze the behavior and intensity of the reaction process of methane oxidation. The Faradaic efficiency of ZnO/Au was calculated to be 32.11%, nearly three times of 11.69% for ZnO. The above results show that ZnO NWAs exhibited exceptional activity as photoanode for photoelelctrocatalytic methane oxidation, and the decoration of Au NPs further enhanced the photo-activity via the surface plasmon resonance expanding its absorption spectra to visible region. On the other hand, as a co-catalyst, Au can promote the oxidation of methane by providing the trapping sites and active sites to facilitate the separation and also suppress the recombination of photogenerated charges and the existence of Au can boost the reaction by lowering the activation energy. This research demonstrates that ZnO NWAs decorated with Au NPs hold great promise for photoelectrocatalytic methane oxidation.

Nitro-oxidizers (nitric acid-27S, nitrogen tetroxide and mixed nitrogen oxide) are common liquid oxidants widely used in liquid rockets and missile weapons. How to deal with large quantities of scrapped nitro-oxidizers is a complex, costly and dangerous project. We pretreated it with hydrogen peroxide (H₂O${}_2)$ and converted the active oxidant component of nitro-oxidizers into nitric acid, which can be used as oxidant source to prepare graphite oxide from natural graphite. The comprehensive oxidation ability of the reaction system can be effectively controlled by adding different volumes of H₂O₂, and the oxidation ability can be expressed by the redox potential of the system. Combined with FT-IR, Raman and XRD characterization analysis, the optimal redox potential interval, [1700, 1800]mV, has been determined for the synthesis of graphite oxide. With the help of data interpolation and function nonlinear fitting and the initial potential of rejected nitro-oxidants obtained, the composition ratio of nitric acid and nitrogen tetroxide (N₂O${}_4)$ has been preliminarily determined with the optimum amount of H₂O₂. Furthermore, the optimum oxidizing atmosphere for the synthesis of graphite oxide can be formed in spite of a wide range of concentrations of oxidant components, and the resulting graphite oxide has been proven to be a qualified and effective product.

Fe₃O₄ nanoparticles coating with poly dimethyl diallyl ammonium chloride (Fe₃O₄/PDDA) as novel magnetic adsorbents were synthesized with chemical co-precipitation method to study the removal capacity of organic phosphonates from aqueous solution. The as-prepared magnetic absorbents were characterized for the morphology, material structure and surface properties by SEM, TEM, FT-IR, XRD, TGA and BET. HEDP was employed as a common organic phosphonate to investigate the adsorption performance. Substantial quaternary ammonium groups existing on the surface of Fe₃O₄/PDDA could enhance the absorption of HEDP with electrostatic attraction. In the optimum condition (4mg adsorbent dosage, 11.0 pH, 36mg/L HEDP solution and 120min adsorption time), the maximum adsorption capacity ($q_m$) for HEDP could reach 254.86mg/g. The kinetic study revealed that the adsorption process followed the pseudo-second-order model. The adsorption isotherm fitted closely to the Freundlich model. The as-prepared magnetic adsorbents exhibited notable reusability in some cycles and were easily separated from the solution with the external magnetic field. These as-prepared Fe₃O₄/PDDA nanoparticles have the potential as an environmental-friendly adsorbent for organic phosphonates removal from waste-water.

Different dosages of hexamethyldisilazane (denoted as HMDS), a silane coupling agent, were adopted to modify nanosilica (denoted as NS) to afford a series of HMDS-NS nanoparticles with different hydrophilic-lipophilic balance governed by the amount of surface hydroxyl. The amounts of the hydrophilic hydroxyl of the as-prepared HMDS-NS nanoparticles and their water contact angles were measured, and their dispersing behavior in water and oil was examined in relation to their transfer behavior therein. Moreover, the effects of the as-prepared HMDS-NS nanofluids on the oil–water interfacial tension as well as the oil recovery were investigated based on interfacial tension measurements and simulated rock core flooding tests. Findings indicate that the hydrophilic-lipophilic balance of HMDS-NS nanoparticles highly depends on the amount of the surface hydroxyl, and the surface hydroxyl amount can be well adjusted by properly selecting the dosage of HMDS modifier. Besides, the transfer behavior of HMDS-NS nanoparticles in oil and water is closely related to their hydrophilic-lipophilic balance, and they can greatly reduce the oil–water interfacial tension and increase the oil recovery by 7.7–11.1% as compared with conventional water flooding. This is because the surface grafting of the hydrophobic segments of HMDS leads to a significant increase in the hydrophobicity of nanosilica, thereby changing the wettability of oil on the sand surface and favoring the stripping of oil droplets. Particularly, the HMDS-NS nanofluid obtained with 2wt.% of HMDS modifier has a water contact angle of 83.6^∘ and can dramatically reduce the oil–water interfacial tension from 20.22mN/m to 0.28mN/m, showing desired hydrophilic-lipophilic balance and potential for enhanced oil recovery associated with chemical flooding.

Mg${}_{0.2}$Mn${}_{0.8}$Y_xFe${}_{2-x}$O₄ ($x=0.000$, 0.025, 0.050 and 0.075) nanocrystalline is synthesized via hydrothermal technique. Single cubic spinel phase is confirmed by XRD and the formation of Mg${}_{0.2}$Mn${}_{0.8}$Y_xFe${}_{2-x}$O₄ is verified by EDS. The average size of the nanoferrites is around 80 nm, which is examined by TEM image. Y${}^{3+}$ substituted Mg-Mn nanoferrites exhibit low saturation magnetization ($M_s)$ and coercivity ($H_c)$. Especially, the nanoferrites with $x=0.075$ show the lowest $M_s$ and $H_c$ of 46.96emu/g and 12.04Oe, respectively. The ferrite composites present that the resistivity and the magnetic loss are less than $4.5\times 10^7\mathrm{\Omega }\cdot \mathrm{\text{cm}}$ and 0.7 in the range of 2–18GHz, respectively. The low coercivity and high resistivity indicate that the addition of Y${}^{3+}$ contributes to the synthesis of the excellent soft magnetic materials.

Remarkable progress has been achieved in organometallic halide perovskite solar cells (PSCs). However, poor environmental stability of PSCs has been proved to be challenging and needs further improvement. Here, a strategy of butylated hydroxytoluene (BHT) antioxidant additive with hydrophobic tert butyl and hydrophilic hydroxyl is developed to enhance the hydrophobicity, control nucleation rate and passivate the defect states of perovskite. The tert butyl group effectively prevents the penetration of moisture, as well as the formed hydrogen bond between hydroxyl group and iodine controls the assembly process of BHT and perovskite. By optimizing weight ratio of BHT and MAPbI₃ in precursor solution, the power conversion efficiency of PSCs increased from 14.93% to 18.28% and greatly enhanced device stability compared with control device. We believe that our tactic of BHT additive can be applied to various perovskite films and will facilitate the realization of stable perovskite optoelectronics.

Here, band gap-tunable oxygen-doped graphitic carbon nitride (g-C₃N₄) with outstanding “two-channel” photocatalytic H₂O₂ production ability was prepared via hydrothermal treatment assisted by dissolution–precipitation process. XRD, N₂ adsorption, UV–Vis, Fourier-transform infrared spectra, SEM, electrochemical impedance spectra, XPS and photoluminescence were used to characterize the obtained catalysts. The photocatalytic H₂O₂ production ability of as-prepared catalyst was investigated. The results show that oxygen doping not only changes the morphology of catalyst, decreases the band gap energy and promotes the separation efficiency of photogenerated electrons and holes, but also tunes the CB and VB potentials. As-prepared oxygen-doped g-C₃N₄ displays a H₂O₂ concentration of 3.8mmolL${}^{-1}$, more than 7.6 times higher than that of neat g-C₃N₄. Because of the shift of CB and VB potentials, not only the CB electrons of oxygen-doped g-C₃N₄ reduce O₂ to form H₂O₂, but also the VB holes can oxidize OH⁻ to form $•$OH, which subsequently react with each other to form H₂O₂. Such “two-channel pathway” causes the remarkably promoted H₂O₂ production ability.

An abundant manganese complex-anchored BiOI hybrid system for CO₂ photocatalytic conversion was constructed. Layered BiOI and tricarbonyl Mn bipyridyl complex with carboxyl acid groups were connected with covalent bonds and used as visible light antenna and CO₂ reduction reaction centers, respectively. The covalent connection of this hybrid system benefits the transfer of electrons from the semiconductor to the Mn complex. The anchoring group (carboxyl) is the key to CO₂ reduction for the direct coupling of the two units, facilitating the transfer of electrons from BiOI to the manganese complexes. The photocatalytic properties and stability of the tricarbonyl Mn–bipyridyl complex were significantly enhanced with the aid of anchored BiOI. A high turnover number ($\mathrm{\text{TON}}=74$) of HCOO⁻ formation from CO₂ could be achieved using this hybrid system under visible light irradiation.

High purity emodin is in great demand with the development of medical treatment. Molecularly imprinted membranes (MIMs) have gained wide attention for selective separation of emodin due to its preferable selectivity. In this work, we describe a simple two-step method for developing emodin-imprinted TiO₂@CA (ETMIMs) and emodin-imprinted SiO₂@CA (ESMIMs) based on organic–inorganic nanoparticle (SiO₂/TiO₂) modified cellulose acetate membranes at room temperature. SiO₂/TiO₂ is used to improve the structural stability and roughness of membranes, and dopamine is used as the functional monomer and crosslinker. Importantly, the as-prepared membranes not only exhibited enhanced rebinding capacity ($\mathrm{\text{ETMIMs}}=30.73\mathrm{\text{mg}}{\mathrm{\text{g}}}^{-1}$ and $\mathrm{\text{ESMIMs}}=46.04\mathrm{\text{mg}}{\mathrm{\text{g}}}^{-1}$) but also possessed superior rebinding selectivity (2.76 and 2.99 for physcion and 2.42 and 3.30 for aloe emodin onto ETMIMs and ESMIMs) as well as permselectivity (7.59 and 6.69 for physcion and 5.94 and 5.78 for aloe emodin onto ETMIMs and ESMIMs). The regeneration ability of ETMIMs and ESMIMs still maintained 90.4% and 89.2% of the original rebinding capacity after 10 cycling steps, respectively. The ETMIMs and ESMIMs obtained in this work show potential applications for selective separation and purification of emodin from analogs.

Nanocarrier-based biological fluorescent probes for ketamine and amphetamine have been prepared by conjugating red and green fluorescent nanoparticles (150-nm-sized) with anti-ketamine and anti-amphetamine antibodies, respectively, with the assistance of carbodiimide/$N$-hydroxysuccinimide. Biological fluorescent probes for ketamine and amphetamine could simultaneously detect these two drugs within a single fingermark by one-step test. Nanoparticles as carrier played dual-functional roles for not only fingermark visualization but also drug recognition. Latent fingermarks were visualized by the fluorescence signal generated from nanoparticles. The developed fingermarks clearly revealed ridge pattern and sufficient minutiae for individual identification. Ketamine and amphetamine were recognized by simply observing the colors of fluorescent images when the fingermark was checked in red and green channels. Detection limit of ketamine or amphetamine was 50ng in fingermark. This work therefore provides a novel nanocarrier-based strategy of drug detection as well as personal identification with high selectivity, low background interference and fast testing, which can be further broadened to other drugs and molecules.

Many current sorbents are limited for U(VI) concentration from aqueous solutions due to their inappropriate structures and surface chemistry. Herein, we report the rapid sorption of U(VI) with high capacities and selectivity by amidoxime modified ordered mesoporous SBA-15 with two typical morphologies (i.e., rods and plates) via a post-grafting method. Variables of the geochemical conditions (contact time, pH value, initial concentration, temperature and coexisting metal ions) are investigated. The results show that the mesostructures including morphologies and pore length of SBA-15 perform the dominant function for the fast sorption kinetics (10min for plates, 20min for rods), while the modified amidoxime groups make the excellent U(VI) sorption capacities (646.2mg$\cdot$g${}^{-1}$ for plates, 499.8mg$\cdot$g${}^{-1}$ for rods at pH 5.0 and $T$ 298.15K) and high selectivity possible. U(VI) adsorbed amidoxime-functionalized SBA can also be effectively regenerated by HCl solutions and reused well after six cycles.