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An electrochemical sensor based on carbon quantum dots (CQDs) and zeolitic imidazolate framework-8 (ZIF-8) composite was fabricated to detect lead(II). The CQDs (2.47 ± 0.52 nm) were synthesized from platanus acerifoli leaves by carbonization and the hydrothermal method. Under the optimal conditions, the fabricated electrochemical sensor had excellent performance in detecting Pb2+. The linear range for Pb2+ was 1 nM–1 μM, and the limit of detection (LOD) was 0.04 nM and the limit of quantification (LOQ) was 0.14 nM. Moreover, when the solution contained Pb2+ and Cd2+, the linear range for Pb2+ was 50 nM to 1 μM and the LOD was 0.02 nM. When the solution contained Pb2+ and Cu2+, the linear range for Pb2+ was 50 nM–750 nM and LOD was 0.07 nM. Furthermore, even if the solution contained Pb2+, Cd2+ and Cu2+, the linear range for Pb2+ was 50 nM–1 μM and the LOD was 0.04 nM. The X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FTIR) and Brunauer-Emmet-Teller (BET) results indicated that the composite electrode materials had abundant oxygen-containing functional groups, a large specific surface area and pore structure, which are conducive to the adsorption of heavy metal ions and improve the detection performance.

Helical nanowires are produced through self-assembled helical oligomers, which are synthesized by chemical oxidation polymerization of m-nitroaniline with the assistance of p-phenylenediamine without any chiral reagents.

Traditional liquid electrolytes are volatile, flammable, and easy to leak, which makes the energy storage device easy to burn and explode in the case of overcharge and short circuit. Here, by utilizing the active P-H bond of a flame retardant (DOPO) to graft onto the polymer chain, flame-retardant organic gel electrolytes were fabricated to address these issues. The gel electrolyte had good ionic conductivity of 4 mS cm-1 at 20 °C and good flame retardant ability. By changing the molar ratio of the monomers and the salt concentrations, the mechanical strength of the gel electrolyte could be adjusted (maximum stress≈28 KPa, maximum strain≈305 %). The transport mechanism of lithium ions in the gel polymer electrolyte was proposed. The gel electrolyte-assembled supercapacitor (SC) possessed better electrochemical properties than that of SC assembled by liquid electrolyte. Importantly, the gel-based SC remained basically unchanged under multiple bending cycles. Additionally, the gel electrolyte had good low-temperature tolerance (0.1 mS cm-1 at -40 °C). The gel electrolyte-assembled SC could work normally in the temperature range of -20 to 60 °C. The multiple advantages of gel electrolyte expand the applications in ionic conductor and energy storage devices.

Surface modification offers an alternative strategy to improve both ageing resistance and electrochemical performance of cathode materials for lithium-ion batteries. From the viewpoint of real application, surface modification of the cathode materials should be designed with scientificity, effectiveness, low cost, less Li+ leaching, and remained tap density. In this contribution, a selective adsorption-involved in-situ growth of polyaniline (PANI) nanoparticles on LiNi0.5Mn0.3Co0.2O2 (NMC532) has been designed through a room-temperature-and-pressure chemical vapor deposition technique. The selective growth of PANI on NMC532 is based on theoretical computation results that multivalent Ni, Mn, and Co are capable of specifically conjugating and activating aniline molecules and, hence, initiating in-situ oxidation polymerization. With only trace amount of aniline monomer, the resulting PANI nanoparticles-inlaid NMC532 microparticles can endure four-month ageing in ambient atmosphere and exhibit improved electrochemical performance at both room temperature and 55 °C, compared with pristine NMC532. The improved electrochemical performance of NMC532/PANI is attributed to the enhanced structural stability of NMC532 and inhibited side reactions related to Li2CO3 formation, PVDF degradation, electrolyte decomposition, and transition-metal dissolution, owing to PANI modification.

Hydrogel electrolyte is widely used in solid energy storage devices because of its high ionic conductivity, environmental friendliness, and non-leakage property. However, hydrogel electrolyte is not resistant to freezing. Here, a high proton conductive zwitterionic hydrogel electrolyte with super conductivity of 1.51 mS cm

Designing environment-friendly, scalable superhydrophobic coatings with a wide spectrum of robustness in mechanochemical strength, interfacial adhesion, and flame retardancy is critical to low-carbon economy and green environment, especially for green buildings. Simultaneously achieving these preferred functionalities dominated by either interfacial or bulky properties has proved challenging. Herein, we propose an integral skin-inspired triple-layered coating (STC) that resolves conflicting demands imposed by individual features on the structure, component, and thermal property of materials. The STC demonstrates sustained anti-wetting and anti-corrosion even under harsh environments, strong adhesion and anti-abrasion, and excellent flame retardancy, all of which enhance its durability and lifetime so as to eliminate the maintenance and repair, thereby reducing cost and energy consumption. Together with facile spraying fabrication process, our STC paves the way to construct a green and resource-saving society.

The low-toxicity treatment of chromium-containing wastewater represents an important way of addressing key environmental problems. In this study, a core-shell structural ZIF-8@TiO2 photocatalyst was synthesized by a simple one-step hydrothermal method. The obtained composite photocatalyst possessed improved photocatalytic activity compared with TiO2. The results indicated that the optimized ZIF-8@TiO2 composite exhibited the highest removal efficiency with 93.1% of Cr(VI) after 120 min under UV-vis irradiation. The removal curves and XPS results indicated that the adsorbed Cr(VI) on the ZIF-8 during the dark process was preferentially reduced. The superior removal efficiency of ZIF-8@TiO2 is attributed to the combination of both high adsorption of ZIF-8, which attracted Cr(VI) on the composite surface, and the high separation efficiency of photo-induced electron-hole pairs. For the mixture of wastewater that contained methyl orange and Cr(VI), 97.1% of MO and 99.7% of Cr(VI) were removed after 5 min and 60 min light irradiation, respectively. The high removal efficiency of multiple pollutants provides promising applications in the field of Cr(VI) contaminated industrial wastewater treatment.

Polymer dots are extensively studied in the fields of catalysis, energy storage, light-emitting devices, biomedicine and engineering, and fluorescent sensors. In this paper, we report on synthesis of a new type of sulfur-containing polymer dots (SPDs) through an atomic transfer radical polymerization method. The SPDs exhibit a maximum photoluminescence at 378 nm under excitation wavelength of 280 nm. The deep-blue luminescence of SPDs may be attributed to self-passivation of SPDs by polyethylene glycol oligomers which create surface states between π* band and π energy level. Also, the SPDs show a highly selective sensitivity to Fe3+ in a mixed metal-ion solution containing Ag+, Cu2+, Hg2+, Cd2+, Pb2+, Cr3+, and Fe3+ with every metal-ion concentration set at 50 μmol L‒1. The detection limit of Fe3+ by SPDs is determined to be 1.7 μM at a signal-to-noise ratio of 3, lower than the maximum of Fe3+ tolerance (5.4 μM) in drinking water permitted by the U.S. Environmental Protection Agency.

Micropores, especially ultramicropores with pore size smaller than 1 nm, play a crucial role in hydrogen storage. In this contribution, we report on bulk production of two-dimensional (2D) polyphenylene networks (PPNs) through a solution-based Wurtz reaction. A self-assembled mechanism is proposed for the formation of 2D PPNs based on molecular dynamics simulations. The morphology, structure, surface chemistry, and textural properties of the PPNs are greatly influenced by anneal treatment at 450–550 °C in terms of deep thermal dechlorination and cyclodechlorination. The annealed PPNs are featured with moderate specific surface area (SBET) and wealthy micropores, which can be finely tuned by varying the anneal temperature. For PPNs, there is no direct correlation between the H₂-uptake capacity and individual textural parameters such as SBET, Sₘᵢcᵣₒₚₒᵣₑ, Vₜₒₜₐₗ ₚₒᵣₑ, Vₘᵢcᵣₒₚₒᵣₑ, and Vₘₑₛₒₚₒᵣₑ. The H₂-uptake capacity is highly dependent on the distribution of ultramicropores and the pore volume of ultramicropores in the range of 0.5–0.8 nm (Vᵤₗₜᵣₐₘᵢcᵣₒₚₒᵣₑ ₀.₅–₀.₈ₙₘ). The PPNs annealed at 500–520 °C, possessing moderate SBET (459.3–564.9 m² g–¹), relatively high Vᵤₗₜᵣₐₘᵢcᵣₒₚₒᵣₑ ₀.₅–₀.₈ₙₘ, and ultramicropores concentrated at 0.69–0.71 nm, exhibit superior H₂-storage capacity (4.28–5.39 mmol g–¹) at 77 K and 1 atm.

Metal nitrides are a new type of electrocatalysts applied in energy storage and conversion systems. In this report, hierarchical cobalt nitride micros balls with heterostructure are prepared through nitridation of Co(OH)(CO3)0.5·0.11H2O counterparts. The microballs are composed of nanowires, which enchase nanoparticles with heterostructure in terms of Co5.47N/Co3N. The catalyst presented here exhibits a high power conversion efficiency of 7.3% for reduction of I3−, comparable to that of 7.6% for platinum-based catalysts. In alkaline electrolyte (1 mol L−1 KOH), only 55 and 290 mV of overpotentials are required to achieve a current density of 10 mA cm−2 for hydrogen evolution and oxygen evolution reactions, respectively. The superior electrochemical performance of the catalyst is attributed to the synergistic effect resulting from Co5.47N/Co3Nheterostructure.

Two-dimensional photoluminescent materials have promising applications in optoelectronics, biosensors, and functional inks. However, it remains a big challenge for fabrication of water-soluble photoluminescent nanofilms with relative quantum yield higher than 50%. In this contribution, we report on facile fabrication of water-soluble organic polymer/silica composite nanofilms with relative quantum yield higher than 70%, through surface modification of organic polymer nanofilms with only a trace amount of organosilanes. The photoluminescence intensity, photostability, and quantum yield of the composite nanofilms are improved compared with individual organic polymer nanofilms. The type of organosilanes has minor effect on the enhanced optical properties of organic polymer nanofilms. The enhanced optical properties of the composite nanofilms are attributed to the strong interactions between silica and organic polymer components, based on theoretical calculations and instrumental analysis. The aqueous solution of composite nanofilms can be applied as cultivation medium for the growth of mung bean sprouts and as a fluorescent indicator for imaging the sprout tissue in vivo.

Spent Zn‒Mn batteries (ZMBs) pose a serious threat on eco-system and human health because of the toxic heavy metal ions released from ZMBs into the environment. In this report, carbon package is recycled from spent ZMBs and used as a positive electrode material for flexible supercapacitors. In a three-electrode system using 1 mol L−1 Na2SO4 as the electrolyte, the recycled carbon package (RCP) can deliver a specific capacitance of 100 F g−1 at 1 A g−1. After 5000 cycles at 1 A g−1, a specific capacitance of 86 F g−1 is retained with nearly 100% coulombic efficiency. Nanocomposite of NaTi2(PO4)3 with nitrogen-doped carbon layer (NTP/C) is prepared through a simple co-precipitation plus annealing method. NTP/C can deliver specific capacity of 320 and 273 F g−1 at 1 and 10 A g−1, using 1 mol L−1 Na2SO4 as the electrolyte. The high rate capability of NTP/C is attributed to the high specific surface area and nitrogen-doped carbon layer. Flexible asymmetric supercapacitors are assembled in configuration of NTP/C‖RCP, using 1 mol L−1 Na2SO4 as the electrolyte and stainless steel foil as the current collector. At 0.5 A g−1, the typical flexible supercapacitor cell can deliver a specific energy of 17.8 W h kg−1 with corresponding specific power of 503 W kg−1, and retain 15 W h kg−1 after 2000 cycles.

Capacity fading resulting from graphite exfoliation is a thorny problem for real application of the graphite anodes in lithium-ion batteries. In this paper, we report on diazotization grafting phenol for graphite flakes to settle this issue, using 4-aminophenol and tert-butyl nitrite as the diazonium reagents. Diazotization grafting phenol enables expansion of graphite interlayer spacing and formation of surface protective layer, yielding modified graphite anodes with improved electrode kinetics, and significantly improved cycling stability. Also, the phenol modifier contributes additional specific capacity to the anode through reversible redox reaction of phenol hydroxyls with Li+ ions. The modified graphite anode with mole percent of 4-aminophenol to graphite being 5% retains a discharge specific capacity of 361 mA h g‒1 after 300 cycles at 1C, presenting capacity retention of 90.5% relative to the initial cycle, much higher than that of 156 mA h g‒1 and 54.2% for pristine graphite.

Two-dimensional polymers have received considerable interest because of their potential applications in sensors, molecular electronics, catalysis, drug delivery, etc. However, the synthesis of two-dimensional organic polymers in solution without the assistance of a template, surface, or interface remains a challenge. In this contribution, we report on the formation of photoluminescent organic polymer nanofilms through direct dissolution of the corresponding polymer powders into water with the assistance of ultrasound. A self-assembly mechanism is demonstrated for the formation of polymer nanofilms based on real-time visualization and molecular dynamics simulations. The polymer nanofilms exhibit high fluorescence quantum yield and biocompatibility, and can be applied for imaging organism tissues in vivo.

Electrochemical charge injection (ECI) is proved a powerful technique to maximize the available widen potential range of aqueous electrolyte. In this report, reduced graphene oxide/polymer dots (rGO/PDs) nanocomposites are prepared and tested as electrode materials for flexible supercapacitors. The weight ratio of GO/PDs plays an important role in the electrochemical performance of rGO/PDs nanocomposites. Through the ECI technique, a 1.7-V output potential can be delivered by rGO/PDs-based flexible supercapacitors operating with 1 mol L−1 Na2SO4 aqueous electrolyte. A specific energy of 7.1 W h kg−1 with corresponding specific power of 85 W kg−1 can be achieved for a typical flexible supercapacitor, which exhibits a capacitance retention of 90.6% after 5000 cycles at 0.5 A g−1.

Flexible all-solid-state supercapacitors with specific energy higher than 1 mW h cm−3 after long-term cycles remain a hot research topic in energy storage systems. In this paper, free-standing reduced graphene oxide/polypyrrole films are produced at the ice/ethanol interface following by hydrogen iodide reduction. The reduced graphene oxide/polypyrrole films are featured with high specific surface area, three-dimensional porosity, and tunable thickness and electronic conductivity. The typical flexible all-solid-state supercapacitor based on reduced graphene oxide/polypyrrole films exhibits a high volumetric specific capacitance of 17.3 F cm−3 and a high specific energy of 2.40 mW h cm−3 with corresponding specific power of 136.1 mW cm−3 at a current density of 3 mA cm−2 (ca. 10 A g−1). After 10,000 cycles at 3 mA cm−2, the capacitance retention of the typical flexible supercapacitor retains 73.2%. The enhanced electrochemical properties of the flexible supercapacitors are attributed to the high specific surface area, three-dimensional porosity, and the synergistic effect between reduced graphene oxide and polypyrrole with respect to the composite films.

Multicolored superhydrophobic coating with high durability has been receiving tremendous attention in decorative applications. Herein, a facile method to fabricate multicolored superhydrophobic coating with excellent robustness has been developed by using cellulose and chitosan. The multicolored coatings can be obtained through single dyeing or mixed dyeing based on three primary dyes. The coating can be applied on hard substrates (e.g. glass, aluminum sheet) and soft substrates (e.g. cotton fabric) by diverse methods including spraying, dip-coating and painting. The colorful coating firmly adheres to the substrates due to the multiple interactions (siloxane covalent bonds and hydrogen bonds). The colorful coating exhibits water-repellant behaviors and can withstand sandpaper abrasion, tape-peeling cycles, water impact, salt spray test and UV environments. Furthermore, the multicolored coating can be used as a new type of pigment for painting on different substrates and is expected to have a huge potential application in technological design or decoration.

Chemical oxidation synthesis of graphene oxide (GO) through modified Hummers methods has been widely employed for producing graphene- or reduced GO (rGO)-based advanced functional materials such as rGO/MnO x nanocomposites. However, the manganese species in GO colloids are usually washed out during GO synthesis through modified Hummers methods, causing manganese waste and environmental risk. In this paper, we report preparation of rGO/MnO x nanocomposites, in which MnO x is composed of Mn 2 O 3 , Mn 3 O 4 , and MnO 2 components, through anneal treatment of the precursor counterparts obtained by simple pH tuning of GO colloids. The rGO/MnO x nanocomposites exhibit superior electrochemical performance for supercapacitors. rGO/MnO x -5, derived from GO colloids with pH 5, exhibits a high gravimetric discharge capacitance ( C dis ) of 191 F g −1 at 20 A g −1 and a high capacitance retention (82.9%) relative to C dis at 1 A g −1 . Furthermore, typical symmetric supercapacitor cells made from rGO/MnO x -5 show a high areal capacitance (172 mF cm −2 ) and excellent capacitance retention (96.6%) at 2 A g −1 (10 mA cm −2 ) for 20,000 cycles, holding great potential for practical applications. The superior electrochemical performance of rGO/MnO x nanocomposites is attributed to multiple charge storage mechanisms in association with the coexistence of mixed-valent manganese oxides.

Aqueous rechargeable batteries (ARBs) based on migration of two types of shuttle ions not only enrich the battery families but also make it more available for ARBs with operation potential higher than 1.2 V. In this paper, we report on electrochemical properties of ARBs in configuration of NaTi 2 (PO 4 ) 3 /C||LiMn 2 O 4 , i.e. NTP/C||LMO. NTP/C was prepared through a simple and scalable co-precipitation post annealing treatment method and featured with hierarchical structure, high specific surface area, and abundant mesopores. The electrochemical properties of individual anode and cathode were examined in 1 mol L −1 Li 2 SO 4 , 1 mol L −1 Na 2 SO 4 , and 0.5 mol L −1 Li 2 SO 4 /0.5 mol L −1 Na 2 SO 4 mixed electrolyte, respectively. It is found that NTP/C exhibits superior operation in 1 mol L −1 Na 2 SO 4 and inferior operation in 1 mol L −1 Li 2 SO 4 while the situation is contrary for LMO. However, NTP/C||LMO full cells with Li + /Na + -mixed electrolyte exhibit enhanced electrochemical performance, presenting an anode-dependant electrochemical behavior. When operating at 1C, NTP/C||LMO with Li + /Na + -mixed electrolyte can deliver a discharge specific capacity ( C dis ) of 104.6 mA h g −1 based on the weight of NTP/C, and a specific energy ( E cell ) of 59.5 W h kg −1 with corresponding specific power of 76.8 W kg −1 based on the total weight of active electrode materials. After 220 cycles at 1C, the C dis and E cell remain 75.7 mA h g −1 and 43.0 W h kg −1 , respectively.

Flexible supercapacitors exhibiting high specific energy (˃1 mW h cm−3) and high specific power are of major research interest in energy storage/conversion systems. In this paper, a strategy has been developed for controlled synthesis of polypyrrole (PPy) nanofilms at the ice/alcohol interface through a simple chemical oxidation polymerization method, yielding free-standing PPy nanofilms with decimeter scale. Evidence from molecular dynamics simulations shows monolayer deposition of pyrrole molecules on the ice surface through hydrogen bonding that supports the formation of PPy films at the ice/alcohol interface. Free-standing PPy films can be directly tailored into film electrodes for all-solid-state flexible planar supercapacitor cells (PSCs) and rolled supercapacitor cells (RSCs). Thickness-dependent electrochemical performance for PSCs and RSCs has been constructed in association with PPy nanofilms. The PSCs and RSCs are made from complete PPy films with thickness of 140 ± 5 nm that exhibit specific energy of 0.72 and 2.3 mW h cm−3 with corresponding specific power of 51.7 and 111.1 mW cm−3, respectively. After 10,000 cycles at a current density of 2 mA cm−2, typical RSCs retain a volumetric capacitance of 9.8 F cm−3 and a specific energy of 1.36 mW h cm−3, holding great potential in practical applications.

An in situ chemical oxidation polymerization approach in combination with dedoping treatment was employed for preparing Fe3O4/polyaniline (Fe3O4/PANI) and dedoped Fe3O4/PANI nanocomposites. The two magnetic nanocomposites were featured with relatively high-saturation magnetization, superparamagnetism, and a multicore–shell structure. Both S and Cl species can be doped into PANI shell. The doping level of Fe3O4/PANI nanocomposite was estimated to be 30.9% through X-ray photoelectron spectroscopy. After dedoping treatment, about 95% S and 40% Cl can be removed from PANI shell. More significantly, a spectroscopic method has been developed for estimating the concentration of amino groups on surface of PANI-coated nanocomposites through nucleophilic addition between amino and p-hydroxybenzaldehyde. The concentration of surface amino groups was estimated to be ca. 357.1 and 554.5 μmol g−1, corresponding to the doped and dedoped magnetic nanocomposites, respectively.

Gallium oxynitride (GON) is emerging as an efficient component in the field of energy storage and conversion. However, the structure has not been well understood that is responsible for the improved properties. In this contribution, we devote to correlating the structure of GON with the physi-/electrochemical properties by virtue of experimental and theoretical studies. GON nanoparticles anchoring on the carbon cloth (CC) are prepared through a moisture-assisted ammonolysis method. The physi-/electrochemical properties of GON can be tuned by controlling the nitridation temperature (750–850 °C). The formation of GON, rather than Ga2O3/GaN mixture, is confirmed by XRD, diffuse reflection UV–Vis, and layer-by-layer thinning XPS techniques. The capacitive behavior of GON has been analyzed by combining electrochemical double layer capacitance with faradaic pseudocapacitance, which originates from intercalation/chemisorption of protons upon the GON matrix. After long-term cycling tests, pulverization and amorphization occur in GON. However, the symmetric supercapacitor assembled with GON@CC-800 manifests a nearly 100% capacitance retention relative to the initial capacitance (132 mF cm−2, 10 mA cm−2), after 20,000 charge/discharge cycles with varied current densities of 10–50 mA cm−2. At 1 mA cm−2, the device can deliver a specific energy of 21.1 μW h cm−2, with corresponding specific power of 0.5 mW cm−2. The impressive electrochemical performance of GON is related to the small particle size, defects, and elongated Ga–N bond length, due to the replacement of partial N with O.

Carbon-coated magnetite (Fe 3 O 4 /C) nanocomposites with hierarchical structure have been subjected to extensive research due to their relatively large specific surface area, extra free voids, and thus enhanced electrochemical performance for lithium-ion batteries (LIBs). In this paper, Fe 3 O 4 /C nanosheets with hierarchical structure in the form of carbon matrix supporting Fe 3 O 4 nanocrystals have been prepared by annealing the nanosheet-like iron alkoxide precursor in N 2 atmosphere. The Fe 3 O 4 /C samples are characterized with X-ray powder diffraction, Raman, scanning electron microscopy, transmission electron microscopy, N 2 sorption isotherms, and thermogravimetric–differential scanning calorimetric techniques, and further evaluated in the role of anode materials for LIBs. The specific discharge capacity of Fe 3 O 4 /C nanosheets obtained by annealing the precursor in N 2 at 600 °C for 3 h retains 647 and 546 mAh g −1 after 100 cycles at 100 and 200 mA g −1 , respectively, exhibiting superior electrochemical performance to many other Fe 3 O 4 /C nanocomposites in previous reports. The Fe 3 O 4 /C nanosheets presented here not only enrich the nanomaterial community but also provide a promising candidate functioning as an anode material for effective lithium-ion storage.

A simple approach has been designed for the synthesis of nitrogen-containing carbogenic polymer dots (NPDs) with relatively high nitrogen concentration (10.5 at.%), tunable size distribution, high yield (25%), and a high degree of graphitization, through a microwave-assisted polymerization of polybromopyrroles in an alkaline ethanolthermal environment at 80 °C. The structure, composition, morphology, and optical properties of NPDs were characterized with X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ζ-potential, transmission electron microscopy, scanning probe microscopy, UV–vis absorbance, and photoluminescence techniques. At excitation wavelengths ( λ e x ) before and after 360 nm, NPDs exhibit a dual emission behavior in terms of λ e x -independence and λ e x -dependence, respectively. The absolute quantum yield of NPDs is greatly improved to be 24% from 3% after simple surface reduction by NaBH 4 . The fluorescence quenching mechanism of NPDs has been carefully investigated by using twenty aromatic compounds as quenchers. Through theoretical calculations and instrumental analysis, we conclude that non-photochemical quenching rather than the fluorescence resonance energy transfer and charge transfer dominates the quenching of NPDs by aromatic compounds. This insight shows the way for selective fluorescent detection of trace aromatic compounds with carbogenic dot-based sensors.

Thiol-functionalized Fe3O4/SiO2 microspheres (Fe3O4/SiO2-SH) with high saturation magnetization (69.3 emu g–1), superparamagnetism, and good dispersibility have been prepared by an ethylene glycol reduction method in combination with a modified Stober method. The as-prepared composite magnetic spheres are characterized with fourier transform infrared spectroscopy (FT-IR), zeta potential, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and superconducting quantum interference magnetometer, and tested in separation of Au(III) ions from aqueous solutions. The data for Au(III) adsorption on Fe3O4/SiO2-SH are analyzed with the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models, and the pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetics models. The adsorption behaviors of Au(III) on Fe3O4/SiO2-SH follow the Langmuir isotherm model, and the adsorption process conforms to the pseudo-second-order kinetic model. The maximum adsorption capacity of Au(III) on Fe3O4/SiO2-SH is 43.7 mg g–1. Acetate anions play an important role yet Cu(II) ions have little interference in the adsorption of Au(III) on the adsorbent. A satisfactory recovery percentage of 89.5% is acquired by using an eluent with 1 M thiourea and 5% HCl, although thiols have a high affinity to Au(III) ions based on the hard-soft acid-base (HSAB) theory by Pearson.

Carbon-coated LiTi2(PO4)3 (LTP/C) nano- and/or microcrystals have been subjected to extensive research due to their potential application in aqueous rechargeable lithium-ion batteries (ARLBs) with enhanced electrochemical performance. In this paper, mesoporous LTP/C nanocrystals have been prepared by annealing the precursor obtained through a simple room-temperature co-precipitation method. The mesoporous LTP/C nanocrystals have been evaluated in the role of anode materials for lithium-ion batteries (LIBs) with organic and water electrolyte, respectively. After 1000 cycles at 5 and 20C, the specific discharge capacity of the LTP/C electrode with organic electrolyte retains 116.9 and 80.4 mAh g−1, with capacity retention of 94.4% and 80.4%, respectively. After 1000 cycles at 1.37C, the specific discharge capacity of the LTP/C‖LiMn2O4 pouch cells with 1 mol L−1 Li2SO4 electrolyte retains 20.1 mAh g−1, presenting a discharge voltage plateau around 1.21 V and a capacity retention of 71.5%. The enhanced electrochemical performance of the mesoporous LTP/C nanocrystals makes them a promising candidate functioning as anode materials for LIBs and hybrid supercapacitors.

There are considerable reports on fluorescent detection of ferric ions, which were universally simplified as Fe3+, by using carbon dots-based sensors. Although several mechanisms have been proposed for the fluorescence quenching of the host, it deserves deep understanding on this topic because the hydrolysis of Fe3+ has not been considered in previous reports. In this contribution, we report on fluorescent detection of ferric ions in mixed metal-ion solution and in real water with organic polymer nanofilms (PNFs)-based sensor. The limit of detection of PNFs towards ferric ions is 44 nM. In particular, we focus on demonstration of the fluorescence quenching mechanisms through instrumental analysis and theoretical computations. The electron transfer from the LUMO level of PNFs to the LUMO level of Fe2(OH)24+ and the HOMO levels of Fe(OH)2+ is suggested to be responsible for the impressive fluorescence quenching of PNFs by ferric ions with concentration lower than 80 µM.

Magnetic nanocomposites with surface containing multiform heteroatoms have great potential for metal-ion recovery with a high throughput. In this paper, a copolymer of pyrrole–thiophene (cPPyTh) is formed upon the Fe3O4/SiO2 composite through chemical oxidation polymerization in aqueous medium, using a modified Fenton reagent (FeCl3 plus H2O2) as the oxidant. The resulting Fe3O4/SiO2/cPPyTh nanocomposites exhibit an enhanced acid resistance and an excellent adsorption performance for Au(III) recovery from multiionic aqueous solution. At room temperature, the adsorption capacity of Fe3O4/SiO2/cPPyTh toward Au(III) can dramatically increase to 559.7 mg g−1 within 5 min, and finally reach an equilibrium adsorption capacity of 845.9 mg g−1. Also, Fe3O4/SiO2/cPPyTh exhibits highly selective adsorption toward Au(III) versus interfering ions (Mg(II), Cu(II), Zn(II), As(V), Cd(II), and Pb(II)). After consecutive use for five times, the adsorption/recovery percentages of Au(III) from multiionic solution with Fe3O4/SiO2/cPPyTh retain 93.3%/92.3%, showing a good reusability of the adsorbent. Compared with that of Fe3O4/SiO2/polypyrrole, Fe3O4/SiO2/polythiophene, and many other adsorbents in recent reports, the superior adsorption performance of Fe3O4/SiO2/cPPyTh is attributed to the following facts: (i) the lowest unoccupied molecular orbital energy level with a relatively high upper band for cPPyTh is beneficial for Au(III) recovery upon Fe3O4/SiO2/cPPyTh through an adsorption–reduction mechanism; (ii) the synergistic effect offered by the lower oxidation potential of pyrrole compared with thiophene but the higher affinity of S to gold ion species compared with N.

Magnetic nanocomposites have been well recognized as promising candidates for enzyme immobilization, DNA extraction, targeted drug delivery, and removal of various metal ions. In this paper, dedoped Fe 3 O 4 /PPy nanocomposite has been obtained by simple ammonia-washing of the newly-formed Fe 3 O 4 nanoferrofluid/PPy derived from in situ polymerization approach. The magnetic nanocomposite is characterized with XRD, FT-IR, TEM, BET, zeta potential, and magnetometry techniques, and further tested in the role of separating Ag(I) from mixed metal-ion solutions containing Ag(I), Mg(II), Cu(II), Zn(II), As(III), and Pb(II). The adsorption of Ag(I) upon dedoped Fe 3 O 4 /PPy is an endothermic and spontaneous chemisorption process, ensuring rapid separation of Ag(I) from aqueous solution. The maximum adsorption capacity of Ag(I) upon dedoped Fe 3 O 4 /PPy is 143.3 mg g −1 . The total adsorption process preferably follows the Langmuir model and the pseudo-second order kinetics. Mg(II), Cu(II), Zn(II), and As(III) have minor effects whereas Pb(II) has a relatively remarkable effect on selective separation of Ag(I) from solutions. The magnetic nanocomposite is featured with superparamagnetism, a multicore–shell structure, a soft-base surface, excellent reusability, and a high anti-interfering ability for selective separation of Ag(I) from multiionic solutions, presenting a promising candidate for practical application in selective separation of Ag(I) from silver-containing emissions.

s Magnetic composite nanospheres carrying amino groups have attracted much interest due to their potential applications in the fields of catalysis, sensor, water purification, enzyme immobilization, DNA extraction, and drug delivery. In this paper, dedoped Fe 3 O 4 /polypyrrole (PPy) nanospheres with core–shell structure, high magnetization, superparamagnetism, and size meeting the demand of biorelated applications in vivo have been achieved by an in situ polymerization approach. The amount of the surface amino groups of Fe 3 O 4 /PPy is greatly enhanced by dedoping treatment due to liberation of the amino groups ever sheltered by the dopants, a situation that is responsible for facile conjugation of fluorescein and methotrexate (MTX) onto the magnetic composite through the EDC/NHS coupling chemistry to produce the desirable fluorescent Fe 3 O 4 /PPy/MTX targeting drug with a high MTX loading of ca. 109 μg mg −1 . The as-obtained magnetic targeting drug exhibits controlled drug release, enhanced intracellular drug retention, and specific targeting ability to HeLa cells, presenting a promising candidate for treatment of cancer cells overexpressing folate receptors.