Nano

The WSe₂/g-C₃N₄ (graphite carbon nitride) composite with photocatalytic properties was synthesized using a hydrothermal method. This synthesis pathway can be characterized by being simple, inexpensive and nonpolluting, integrating the concept of green chemistry. The WSe₂/g-C₃N₄ composite could effectively degrade methyl orange solution under visible light irradiation. The decolorization experiment of methyl orange solution shows that the degradation rate of the 30wt.% WSe₂/g-C₃N₄ composite can reach 98.7% after 100min of illumination, while the degradation rate of pure g-C₃N₄ was only 87.6% under the same conditions. This can be attributed to the fact that the combination of WSe₂ and g-C₃N₄ nanosheets can increase the number of active binding sites, increasing the rate of charge separation and transport ability, decreasing the recombination rate of the photogenerated electron–hole pairs. Therefore, the WSe₂/g-C₃N₄ composite will have potential development as a new material with low cost, easy synthesis and excellent performance in photocatalytic degradation of water pollution.

We report a one-step electrochemical deposition technique to prepare three-dimensional (3D) Ag hierarchical micro/nanostructured film consisting of well-crystallized Ag nanosheets grown on an indium tin oxide (ITO) conductive substrate. The Ag hierarchical micro/nanostructures were fabricated in the mixed solution of AgNO₃ and sodium citrate in a constant current system at room temperature. Through reduction of Ag${}^{+}$ electrodeposited on the surface of ITO substrate, nanoparticles were grown to form nanosheets which further combined into 3D sphere-like microstructures. The 3D Ag micro/nanostructures have many sharp edges and nanoscale gaps which can give rise to good Raman-enhanced effect. Due to localized surface plasmon resonance (LSPR) effects, these special Ag micro/nanostructures exhibited good Raman-enhanced performance. Using Rhodamine 6G (R6G) molecules as probe molecule, we studied the influence of excitation wavelength on Raman enhancement. The results showed that the 532nm excitation wavelength is the best to obtain the strongest Raman signal and to reduce the influence of other impurity peaks. Using the as-synthesized Ag hierarchical micro/nanostructures, we can detect the 10${}^{-10}$mol/L R6G aqueous solution, exhibiting great Raman-enhanced effect.

Platanus fruit-like nickel cobalt ammonium phosphate/MWCNTs composites for high-performance supercapacitors were successfully prepared by a two-step hydrothermal method using NiSO${}_4\cdot$6H₂O, CoSO${}_4\cdot$7H₂O, (NH₄)H₂PO₄ and MWCNTs as raw materials, respectively. The effects of MWCNTs addition on the structure and properties of the composites were investigated. The results showed that when the doped amount of MWCNTs is 7.3wt.%, the as-prepared NCAP/M7.3 composite presented an obvious platanus fruit likeness, its surface is rough and porous with a diameter of 3–5$\mu$m. Compared with the other MWCNTs contents, the NCAP/M7.3 electrode obtained under this condition showed the best capacitive performance. The discharge specific capacity was up to 1270Fg${}^{-1}$ at current density of 1Ag${}^{-1}$, which remains to be 902Fg${}^{-1}$ even at a high density of 10Ag${}^{-1}$. The results show that the target sample can be the ideal electrode material for supercapacitor.

Brookite TiO₂ was synthesized by a hydrothermal method, g-C₃N₄ was prepared by a pyrolytic method, brookite/g-C₃N₄ composites were prepared by a calcining method, and brookite/g-C₃N₄/BiOBr ternary composites were prepared by loading BiOBr on the surface of brookite/g-C₃N₄. XRD and XPS analysis of the composites confirmed the formation of brookite TiO₂/g-C₃N₄/BiOBr. SEM and TEM results confirmed the as-prepared composites were nanosized. The optimum loading amount of BiOBr was 30%. The photocatalytic results showed that the brookite/g-C₃N₄/30%BiOBr composites degraded rhodamine B completely under visible light irradiation. The degradation ratio of brookite/g-C₃N₄/30%BiOBr toward rhodamine B was nearly 100% for 2h, which was much higher than that of brookite TiO₂ and brookite/g-C₃N₄ catalysts. The reason for the improvement of photocatalytic activity might be because the composites promoted the formation of superoxide radicals and the separation efficiency of photogenerated electron-hole pairs. The photocurrent density of the brookite/g-C₃N₄/30%BiOBr was about 10 times higher than that of pure brookite. In addition, the brookite/g-C₃N₄/BiOBr showed a good repeatablity of photocatalysis.

Nanofiber mats produced by electrospinning, with the advantages of specific surface area, porosity and chemical tenability, are an ideal support material for deposition of metal$-$organic framework (MOF) crystals. In this study, four types of MOFs (MIL-53(Al), ZIF-8, UiO-66-NH₂ and NH₂-MIL-125(Ti)) were deposited on polydopamine (PDA)-modified electrospun polyvinyl alcohol (PVA)/SiO₂ organic$-$inorganic hybrid nanofiber mats by bulky synthesis. Because of the formation of Si–O–C–O–Si bridges between PVA chains and silica network, electrospun PVA/SiO₂ organic$-$inorganic hybrid nanofiber mats are quite stable in water or organic solvents and at high temperature are suitable as supports for MOFs deposition. The PDA layer, which exhibits a powerful adhesive ability to attach foreign objects, can effectively improve growth of MOFs on the surface of PVA/SiO₂ nanofiber mats. The obtained MOF composites combining the unique properties of electrospun nanofibers mats and MOFs particles become flexible and tailorable, greatly expanding the application range of MOFs materials. The synthesized MOF composites were used to adsorb chloramphenicol (CAP) in water. It was found that the four MOF composites could remove CAP from water effectively and MIL-53(Al) composite had the highest adsorption capacity due to the higher specific surface area.

A hybrid adsorbent with inverse opal (IO) structure was prepared for removing Cd(II) from aqueous solution. The functional polymeric chains were grafted from the pore wall of IO silica to prepare the porous hybrid material by surface-initiated atom-transfer radical polymerization. Furthermore, the amidation reaction was carried out to obtain diethylenetriamine-modified hybrid adsorbent (IO SiO₂-g-PAA-DETA). Batch adsorption of removing Cd(II) onto IO SiO₂-g-PAA-DETA was studied as the effect of solution pH, adsorbent doses, contact time, ionic concentration, and temperature. When the grafted amount was 73%, the maximum adsorption capacity was obtained. The optimum adsorbent dose and pH value for adsorbing Cd(II) were found to be 5g/L and 0.5g/L, respectively. The adsorption capacity was almost unaffected by Na${}^{+}$ at low concentrations. The adsorption data was depicted by the corresponding models and the results displayed that adsorbing Cd(II) on IO SiO₂-g-PAA-DETA followed the Freundlich and pseudo-first-order model. In addition, after six adsorption–desorption cycles, IO adsorbent could remain above 80% of the first adsorption ability while it was washed using 0.025M EDTA.

Magnetic and fluorescent-based sensors have demonstrated widely applications due to their easily recycle and quickly optical response. However, the complex synthesis and weaker function of these sensors limit their practical applications. Herein, an unmodified, magnetic-functionalized carbon dots-based fluorescent sensor has been developed for label-free detection of pH and Cu${}^{2+}$ with high sensitivity. The sensors can not only reversibly quench and recover the fluorescence signals in response to the variation of surrounding environment including pH and Cu${}^{2+}$, but also be used as a high-efficiency recyclable adsorbent for removing Cu${}^{2+}$, Hg${}^{2+}$, Cr${}^{3+}$ and Pb${}^{2+}$ from aqueous solution.

Piezoelectric principle is one of the popular choices when it comes to mechanical energy recovery and conversion of energy into electrical energy which can be either stored or used straightaway. In general, ceramic-based piezoelectric materials like Lead Zirconate Titanate (PZT) had been the popular choice for piezoelectric devices even though they are brittle in nature and found to be toxic in long uses. At the same time, organic-based Polyvinylidene Fluoride (PVDF) and similar polymeric materials have been used in different applications with an offer of flexibility, lightweight and biocompatibility. One major factor dragging down the usage of organic materials in piezoelectric applications is their poor piezoelectric responses. In this work, authors are reporting the enhanced piezoelectric properties of nanofibers of PVDF in composite with copper nanoparticles and Multiwalled Carbon Nanotubes (MWCNTs). Fourier Transformation Infrared (FTIR) analysis has been carried out for nanofibers and was able to prove the higher beta phase conversion of PVDF in composite nanofibers when compared with pristine nanofibers. Composite nanofibers were later fabricated into a piezoelectric device with two electrodes and have shown a peak voltage of 6.78 V upon a drop test. As a proof of concept, the mentioned piezoelectric device was integrated into a shoe-based prototype where it has shown 18–20V energy harvesting upon walking at leisurely pace.

In this work, a MoS₂-based binder-free electrode has been fabricated via a simple hydrothermal deposition approach. In this electrode, the MoS₂ nanosheets are orderly assembled and immobilized on macroporous titanium (Ti) mesh with exposed active sites for Li-storage. The Ti mesh with a 3D porous network provides a stable skeleton and large surface area for loading MoS₂ nanosheets. Meanwhile, the intimate contact with conductive Ti mesh facilitates fast charge transfer in the electrode reactions. When applied as an anode in lithium-ion battery, the binder-free electrode exhibits a greatly promoted Li-storage property, including desirable cycling durability and superior rate capability.

Ti₃C₂T_x, a new type of two-dimensional material, is a prospective anode material in lithium-ion batteries (LIBs) for its low lithium-ion diffusion barrier, high conductivity and many other excellent properties. In this paper, multilayer Ti₃C₂T_x and delaminated Ti₃C₂T_x samples are prepared by etching Ti₃AlC₂ powder with HF and $\mathrm{\text{HCl}}+\mathrm{\text{LiF}}$, respectively. We explore the application of the two samples in LIBs, and analyze their electrochemical behavior and kinetic mechanism. At the current densities of 0.1Ag${}^{-1}$, the delaminated Ti₃C₂T_x electrode delivered higher capacities of 255mAhg${}^{-1}$ than multilayer Ti₃C₂T_x electrode (100mAhg${}^{-1}$). Even after 1000 cycles, the specific capacity of the delaminated Ti₃C₂T_x is still up to 205mAhg${}^{-1}$ at 1Ag${}^{-1}$. This work proves the great potential of the delaminated Ti₃C₂T_x for lithium-ion storage.

Porous hybrid nanosheets of g-C₃N₄/$\beta$-Ni(OH)₂(CN/$\beta$-NiOH) were constructed via gas bubble method in the NiCl${}_2\cdot 6$H₂O-NH₃$\cdot$H₂O-C₂H₅OH-CN system at 140^∘C for 6h. The resulting CN(5.3wt.%)/$\beta$-NiOH nanosheets show a porous texture and a large interface contact area, which facilitates the electrolyte ion diffusion during reversible insertion/deinsertion processes. The fabricated CN(5.3wt.%)/$\beta$-NiOH hybrid-based electrode displays an enhanced specific capacitance of 887Fg${}^{-1}$ at a current density of 0.5Ag${}^{-1}$ when compared with single phase $\beta$-NiOH (480Fg${}^{-1}$). Using CN(5.3wt.%)/$\beta$-NiOH porous nanosheets and activated carbon (AC) as cathode and anode, an asymmetric supercapacitor (ASC) was assembled and the energy density achieves 28.3Whkg${}^{-1}$ and 10.9Whkg${}^{-1}$ at a power density of 798.4Wkg${}^{-1}$ and 7991.9Wkg${}^{-1}$, respectively.

In order to reduce the negative volume effect of Silicon (Si) and Silica (SiO${}_2)$ as anode materials, CNTs@SiO₂/Si@C is prepared by sol–gel method and magnesiothermic reduction process. SEM and TEM results show that the surface of Carbon nanotubes (CNTs) is uniformly coated with active materials including SiO₂ and Si. Active materials (SiO₂/Si) closely contact with the conductive network constructed by CNTs, which greatly improves the conductivity of the composite anode material. Moreover, the large specific surface area of the tubular structure provides more Li${}^{+}$ diffusion channel. The cushion space of the hollow tube structure effectively alleviates the volume effect of SiO₂/Si and enables the anode material excellent electrochemical performance in the cycling test. The initial discharge capacity of CNTs@SiO₂/Si@C is 1064mAh/g at current density of 200 mA/g. The specific discharge capacity of CNTs@SiO₂/Si@C is higher than 960 mAh/g after 100 cycles, and the coulomb efficiency maintains over 98% in the range from 30th to 100th cycle.

Graphene oxide (GO), a 2D nanomaterial, is a promising material for medical application, thanks to its water solubility, antibacterial activity and relatively low cytotoxicity. However, many factors, such as lateral dimension, purity and surface chemistry, may influence its antibacterial activity, its exact mechanism is still unknown. In this work, E. coli was used as model bacterium to determine the antibacterial activity of well-dispersed GO which was obtained by a modified Hummer method and dialyzed to remove the salts and acid used in the oxidation process. After co-culture with GO for 2h, up to 90% E. coli cells were inactivated when GO concentration at 8$\mu$g/mL. The direct interaction was not detected in FE-SEM images and the results of $\zeta$ potential showed that the interaction between GO and E. coli are repulsive$.$ Our results showed that GO can produce ROS and inactivate SOD and CAT enzymes in low concentration after co-cultured with E. coli which explained the antibacterial activity of GO in aqueous solution. Meanwhile, GO, with high purity, showed low cytotoxicity towards mammalian cells and did not cause any observable hemoglobin after co-cultured with blood cells. The data presented here prove that GO is effectively inhibit E. coli through inactivating SOD, CAT enzymes and the oxidative stress produced by ROS. Furthermore, the good biocompatibility promised its future application.

MOF-based composite material is adopted to modify photoanode, and the obtained large BET area is found meaningful to the dye loading amount, which brings about a high short circuit current and incident photon to current conversion efficiency. Meanwhile, three-dimensional graphene networks (3DGNs) are employed to provide a fast transport channel for photo-induced electrons. The morphology is analyzed by SEM, TEM, XRD and Raman spectrum, and the photovoltaic performances are recorded to reveal the specific functions of MOF and 3DGNs. The synergy between MOF, 3DGNs and TiO₂ is achieved by adjusting their mass fraction. Moreover, the average size of MOF exerts a significant influence on the resulting properties resulting from the scattering ability to incident light. After corresponding optimizing, the short circuit current, open circuit voltaic, fill factor and energy conversion efficiency reach 20.5mAcm${}^{-2}$, 680mV, 0.619% and 8.63%.