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• Clay spatially confined the growth of layered basic zinc acetate nanosheets. • Thermal-induced nano-cracking leaded to clay-supported ZnO nanoparticles. • Layered basic zinc acetate improve clay to adsorb Congo red. • Well-dispersed ZnO nanoparticles endowed clay with photocatalytic activity. Here, hierarchical nanostructures of clay-based hybrids were synthesized via a space-confined growth of layered basic zinc acetate (LBZA) nanosheets standing upright on both sides of bentonite clay platelets. These thermally instable LBZA nanosheets were thermally decomposed and fragmented into ZnO nanoparticles well-dispersed on bentonite platelets. The morphology and structure of LBZA/bentonite and ZnO/bentonite was characterized by SEM, TEM, XRD, TG-DSC, and FTIR. Surface density of LBZA nanosheets on bentonite platelets was simply controlled by tuning the amount of zinc acetate. LBZA/bentonite and ZnO/bentonite was used for the adsorption of Congo red (CR) and photodegradation of methyl orange (MO), respectively. Results showed that LBZA/bentonite exhibited higher adsorption capacity for Congo red (CR) than original bentonite. In addition, bentonite-supported ZnO nanoparticles efficiently promoted the photodegradation of MO under UV light irradiation. [ABSTRACT FROM AUTHOR]

Abstract: α-Fe2O3 nanoparticles were synthesized through calcining the as-synthesized spindle-like β-FeOOH precursors at 600°C. X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) results showed that β-FeOOH nanospindles with a diameter of ~50nm and lengths up to 100–150nm were readily changed to α-Fe2O3 nanoparticles with a size of 30–150nm after heat-treatment for 2h. The photocatalytic performances of the as-prepared samples were evaluated by photocatalytic decolorization of methylene blue (MB) in the presence of H2O2 at ambient temperature. The results indicated that the α-Fe2O3 nanoparticles exhibited the highest photocatalytic activity compared with the β-FeOOH nanospindles and the commercial α-Fe2O3 powders. The gas-sensing measurement results demonstrated that the products showed an excellent gas response to ethanol and acetone. The results showed that these α-Fe2O3 nanoparticles may have potential applications in gas sensor and photocatalysts. [Copyright &y& Elsevier]

American football-shaped, angular American football-shaped and cubic α-Fe2O3 micro-crystals with different gas-sensing properties have been achieved by an in situ pH-dependent hydrothermal synthesis using β-FeOOH nanospindles as the sacrificing template. XRD, SEM and TEM have been employed to characterize the products. It was found that the morphology and phase evolution occurred in the hydrothermal process. With the increase of the pH value of the hydrothermal system, the morphology evolves from spindle to American football, angular American football and cube, whereas the crystal sizes decrease from 1–1.2 mm to 140 nm. The effect of the reaction time on the phase and morphology of the final products has been studied and a possible dissolution–recrystallization growth mechanism is proposed. Furthermore, the gas sensing properties of the prepared α-Fe2O3 crystals were investigated for a series of organic vapors at different operation temperatures and vapor concentrations, demonstrating that their gas sensing behavior was influenced by the different morphologies and that the as-prepared α-Fe2O3 polyhedral crystals exhibit excellent gas sensing selectivity to acetone vapor. The experimental results revealed that the gas-sensing performance of the α-Fe2O3 crystals is closely related to the morphology of the samples. [ABSTRACT FROM AUTHOR]

Abstract: In this work, CuO nanoparticles of varying shape (tadpole-shaped, spindly, leaf/sphere-like and fusiform) have been prepared by a facile microwave-assisted hydrothermal (MH) method. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy FTIR and transmission electron microscopy (TEM). XRD and TEM results revealed pure phase monoclinic CuO nanoparticles with uniform shapes and sizes. FTIR and UV–vis measurements of these nanoparticles with varying shape showed a highly shape-dependent nature. The gas sensing performance of the obtained nanoparticles was analyzed by detection of target gases, including methanol, ethanol and acetone at 220°C. The tadpole-shaped CuO nanoparticles displayed the best response of ∼5 toward 1000ppm methanol, ∼7 toward 1000ppm ethanol, and ∼8 toward 800ppm acetone, respectively. All these CuO-based sensors exhibited a relatively higher response to acetone when compared to their response toward methanol and ethanol. The enhanced sensing performance of the tadpole-shaped CuO sensor may be attributed to their unique shape and small size, which is more favorable in rapid and efficient diffusion of organic vapors than the other shaped CuO nanoparticles. [Copyright &y& Elsevier]

Abstract: In this paper, triclinic WO3 nanoplates with prominent cyclohexene sensing and photocatalytic properties were fabricated via a facile hydrothermal method assisted with p-aminobenzoic acid. The as-prepared product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD, SEM and TEM images illustrated that the WO3 nanoplates have a triclinic phase with the length of 100–200nm and the thickness of 50–80nm. The gas sensing properties of the WO3 nanoplates were measured by detection of methanol, ethanol, cyclohexane, benzene, ethyl acetate and acetone at 160–300°C, and their photocatalytic activities were investigated by the degradation of methyl blue (MB). The as-prepared product exhibited not only excellent photocatalytic property for the degradation of MB, but also high response (1000ppm of cyclohexene, R a /R g =140) and excellent selectivity for the detection of cyclohexene. [Copyright &y& Elsevier]

Abstract: Flower-like 3D ZnO microstructures constructed from nanorods of different sizes were prepared by a microwave hydrothermal (MH) process in the presence of o-, m- and p-nitrobenzoic acid, respectively. Well-crystallized flower-like ZnO microstructures were obtained after 10min MH treatment. The X-ray powder diffraction (XRD) test indicated that all the products were consistent with the hexagonal ZnO phase, and scanning electron microscopy (SEM) investigation revealed that the flower-like 3D ZnO microstructures were built with sword-like nanorods 60–100nm in width and several micrometers in length. The formation mechanism of these flower-like 3D ZnO microstructures is discussed briefly. The gas sensitivity of the as-prepared ZnO microstructures to ethanol at different operation temperatures and concentrations was also studied. The results indicated that the gas sensitivity of the ZnO microstructures was influenced by the particle size and microcosmic configuration, the larger particles with crowded nanorods having higher gas sensitivity. [Copyright &y& Elsevier]

Abstract: P-type CuO nanorods with the breadth of 15–20nm and the length of 60–80nm, have been synthesized using a microwave-assisted hydrothermal (MH) method. The band gap of CuO nanorods was calculated to be 2.75eV based on the UV–vis absorption spectrum of the product. The gas sensing property of the CuO nanorods to several organic vapors was tested in temperatures ranging from 160°C to 300°C. The response of the CuO sensor to ethanol (1000ppm) was 9.8 at the working temperature of 210°C. The response time and the recovery time were within the range of 13–42s and 17–51s, respectively. Further measurements exhibited stronger response to ethanol than to other target gases. The enhanced gas sensing performance of the sensor to ethanol may be attributed to the small size of the CuO particles. [Copyright &y& Elsevier]

Abstract: Nearly monodisperse Co3O4 nanocubes have been prepared by a microwave-assisted solvothermal (MS) method at 180°C for 20min. The samples are characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD pattern and TEM images of the products illustrated that Co3O4 nanocubes had a cubic phase with a lateral size of ∼20nm. The gas response of the Co3O4 nanocubes was studied to several typical organic gases. The Co3O4 nanocubes showed good gas sensing performance towards xylene and ethanol vapors with rapid and high responses at a low-operating temperature. The results showed that the Co3O4 nanocubes can be used to fabricate high performance gas sensors. [Copyright &y& Elsevier]

Abstract: Flower-like ZnO 3D microstructures composed of nanorods have been successfully prepared via a facile hydrothermal method using p-nitrobenzoic acid as the structure-directing agent. The structures and morphologies of the final products have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscope (HRTEM). The possible mechanism for the synthesis of the flower-like ZnO microstructures has been proposed primarily. The gas sensitivity of the flower-like ZnO microstructures has been studied to a series of organic vapors at different operation temperatures and vapor concentrations. The results show that the flower-like ZnO microstructures composed of nanorods have good gas sensor properties to ethanol. [Copyright &y& Elsevier]

Abstract: A novel hydrothermal process using p-nitrobenzoic acid as structure-directing agent has been employed to synthesize plate-shaped WO3 nanostructures containing holes. The p-nitrobenzoic acid plays a critical role in the synthesis of such novel WO3 nanoplates. The morphology, structure and optical property of the WO3 nanoplates have been characterized by transmission electron microcopy (TEM), scanning electron microcopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL). The lateral size of the nanoplates is 500–1000nm, and the thickness is about 80nm. The formation mechanism of WO3 nanoplates is discussed briefly. The gas sensitivity of WO3 nanoplates was studied to ethanol and acetone at different operation temperatures and concentrations. Furthermore, the WO3 nanoplate-based gas sensor exhibits high sensitivity for ethanol and acetone as well as quick response and recovery time at low temperature. [ABSTRACT FROM AUTHOR]

Abstract: Tungsten oxide nanorods have been prepared by a simple microwave hydrothermal (MH) method via Na2SO4 as structure-directing agent at 180°C for 20min. The structure and morphology of the products are characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The obtained nanorods are about 20–50nm in diameter and several micrometers in length. The ethanol sensing property of as-prepared tungsten oxide nanorods is studied at ethanol concentration of 10–1000ppm and working temperature of 370–500°C. It was found that the sensitivity depended on the working temperatures and also ethanol concentration. The results show that the tungsten oxide nanorods can be used to fabricate high performance ethanol sensors. [Copyright &y& Elsevier]

Millions of tons of hazardous spent sulfuric acid and coagulation sediments from water treatment facilities are produced annually. In this work, a green approach for the synthetic gypsum and high-quality binders was proposed. The results obtained were confirmed by XRD, SEM, TEM, and DTA. Optimal parameters for the synthesis, including stirrer rotation speed, reactor temperature, acid concentration, acid feed rate, thickening time were investigated. Synthesized sample was identified as gypsum with a monoclinic structure with high degree of crystallinity and crystals of prismatic shape. The required fraction of more than 50 µm was 86.57 wt.%. Obtained gypsum binders had grades up to G23. Different options for the use of filtrate were proposed. High concentration of iron sulfate demonstrate a good coagulation result which was 5 % lower compared to commercial iron sulfate. Additionally, high concentration of iron made it possible of its use as a precursor for the synthesis of magnetic sorbents and photocatalysts. Neutralized filtrate contains sulfur, calcium, magnesium, and sodium and were tested as a complex fertilizer. [Display omitted] • Optimal parameters for the gypsum synthesis from industrial wastes were found. • High-quality gypsum was obtained from coagulation precipitates. • High-quality gypsum binders with grade up to G23 were obtained. • Synthesis beneficial from technological, environmental and economic point of view. [ABSTRACT FROM AUTHOR]

• Non-aqueous phase synthesis of halloysite-supported Co 3 O 4 nanoparticles. • Halloysite-induced generation of Co3+-rich and small-sized Co 3 O 4 nanoparticles. • Co 3 O 4 /halloysite for enhancing catalytic reduction of 4-nitrophenol and organic dyes. • Co 3 O 4 /halloysite promoting to shorten induction time of 4-nitrophenol reduction. Nanosized clay minerals have been widely used as efficient supports to immobilize catalyst nanoparticles. However, clay support-induced interactions and their influences on the catalyst structure and performance currently have not been fully understood. Here, Co 3 O 4 nanoparticles supported on halloysite nanotubes (HNTs) were synthesized by a facile deposition-precipitation approach followed by thermal treatment. A series of characterization methods were employed for the Co 3 O 4 /HNTs hybrid nanostructure to identify its crystal phase, chemical composition, morphology, specific surface area, surface chemical states, and redox property. Characterization results showed that HNTs not only impacted the particle size of Co 3 O 4 nanoparticles, but also modified surface chemical surface states of the later, which ultimately promoted the effective catalytic reduction of 4-nitrophenol (4-NP) and azo dyes with sodium borohydride. The interaction between HNTs and Co 3 O 4 nanoparticles was found to shorten the induction period of the 4-NP reduction. Meanwhile, the Co 3 O 4 /HNTs catalyst for the 4-NP reduction achieved an apparent rate constant of 0.265 min−1 and an activity parameter of 1.63 × 104 min−1 g−1 as well as a turnover frequency of 4.37 min−1. In addition, Co 3 O 4 /HNTs showed an improvement in reduction efficiency of the azo dyes when compared to bare Co 3 O 4 nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: Two kinds of tungsten oxide (WO3) square nanoplates have been prepared by a simple hydrothermal method using l(+)-tartaric acid or citric acid as assistant agents. The products are characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). XRD, SEM and TEM images of the products illustrate that WO3 square nanostructures prepared in the presence of l(+)-tartaric acid have a hexagonal phase, length of ∼200nm and thickness of ∼100nm, while WO3 nanostructures synthesized in the presence of citric acid have an orthorhombic phase, length of ∼500nm and thickness of ∼100nm. Selected area electron diffraction (SAED) suggests that both of the as-prepared WO3 square nanoplates are single crystalline. The plausible growth mechanism for the formation of WO3 square nanostructures is also proposed. [Copyright &y& Elsevier]

Upcycling Cr-containing sulfate waste into catalysts for CO2 hydrogenation reaction benefits both pollution mitigation and economic sustainability. In this study, FeCrO3/Fe2O3 catalysts were successfully prepared by a simple hydrothermal method using Cr-containing sodium sulfate (Cr-SS) as a Cr source for efficient conversion and stable treatment of Cr. The removal rate of Cr in Cr-SS can reach 99.9% at the optimized hydrothermal conditions. When the synthesized catalysts were activated and used for the CO2 hydrogenation reaction, a 50% increase in CO2 conversion was achieved compared with the catalyst prepared by impregnation with a comparable amount of Cr. According to the extraction and risk assessment code (RAC) of the Reference Office of the European Community Bureau (BCR), the synthesized FeCrO3/Fe2O3 is risk-free. This work not only realizes the detoxification of the Cr-SS but transfers Cr into stable FeCrO3 for application in a catalytic field, which provides a strategy for the harmless disposal and resource utilization of Cr-containing hazardous waste. [ABSTRACT FROM AUTHOR]

In this paper, WO3·0.33H2O nanorods were prepared through a simple hydrothermal method using p-aminobenzoic acid (PABA) as an auxiliary reagent. X-ray diffraction (XRD) and transmission electron microscopy (TEM) images showed that the products with PABA addition were orthorhombic WO3·0.33H2O, which were mainly composed of nanorods with different crystal planes. The sensing performance of WO3·0.33H2O nanorod bundles prepared by the addition of PABA (100 ppm cyclohexene, Ra/Rg = 50.6) was found to be better than the WO3 synthesized without PABA (100 ppm cyclohexene, Ra/Rg = 1.3) for the detection of cyclohexene. The new synthesis route and sensing characteristics of as-synthesized WO3·0.33H2O nanorods revealed a promising candidate for the preparation of the cost-effective gas sensors. [ABSTRACT FROM AUTHOR]

Environmental pollution has been widely considered by researchers, especially the heavy metals damage to the human and ecological environment is irreversible. Adsorption is an important method to remove heavy metal ions from the environment. In this paper, humic acid (HA) was functionalized by the improved Hummers method, and its adsorption capacity for Pb(II) was studied. The results of scanning electron microscope (SEM), X-ray diffraction (XRD), Roman, and Brunauer-Emmett-Teller (BET) showed that the thickness of irregular particles decreases to a layered structure during the transformation process. In addition, X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared spectra (FT-IR) spectra showed that the surface of oxidized-biochar (OBC) was rich in reactive oxygen species, which was conducive to the formation of coordination bonds with Pb(II). Further adsorption experiments showed that it was a spontaneous monolayer chemisorption. The results of the DFT calculation showed that -COOH had the lowest adsorption energy for Pb(II), and it was easier to form stable chemical bonds than -OH, -C=O, and -C-O-C-. Because those oxygen-containing functional groups not only can promote electrostatic attraction but also are more favorable for forming a covalent bond with Pb(II). This study had guiding significance for the deep modification and application of weathered coal as a heavy metal ion adsorbent or cation exchanger. [ABSTRACT FROM AUTHOR]

Based on the Kirkendall effect, a facile calcination method was used to synthesize p-type semiconductor NiO hollow nanoparticles. The composition, structure, morphology and specific surface of NiO hollow nanospheres were characterized by means of XRD, TEM and BET and their gas sensing properties were studied. It was found that the hollow NiO nanospheres have certain gas sensing properties to methanol, ethanol and n-butanol. The results showed that NiO-4 prepared at 500 °C for 4 h had excellent sensitivity and selectivity to n-butanol gas at the optimized operating temperature of 240 °C (1000 ppm of n-butanol, R g / R a = 9.0). The sensing mechanism of responses is proposed considering the unique material structure. Thin and permeable shell is the key factor to improve the n-butanol reaction, which is beneficial to complete electron consumption and effective gas diffusion. This strategy offers a facile way for the design of hollow nano-materials and may also extend to prepare other metal oxides such as CoO, SnO 2 or Bi 2 O 3 hollow nanostructures. • The hollow NiO nanospheres were successfully prepared based on the nanoscale Kirkendall effect. • The hollow NiO nanospheres exhibits excellent sensitivity and selectivity to n-butanol at operating temperature of 240 °C. • This work provides an effective way to design hollow structure nanomaterials with high sensing performance. [ABSTRACT FROM AUTHOR]

Abstract: A facile molten salt method was utilized for the synthesis of carbon anchored nickel/heazlewoodite nanoparticles (Ni/Ni3S2@C nanosheets) with potassium humate as the carbon and sulfur source and NaCl as template. The morphology, particle size and crystallinity of the products were characterized by various techniques containing TEM, FE‐SEM and XRD. Furthermore, the mesoporous Ni/Ni3S2@C own easy accessibility of active sites and high surface area (149.04 m2 g−1). Thus, the as‐prepared Ni/Ni3S2@C exhibited prominent performance for catalytic reduction of 4‐nitrophenol (4‐NP). Catalytic reduction of other nitrophenols (NPs) were also tested which can prove that the catalyst own selectivity on reduction of NPs. For durability, the property of the catalyst does not decrease obviously after five cycles. More significant correlations concerning effect of activation parameters (Ea=37.21 kJ mol−1) on 4‐NP reduction were scrutinized and discussed. Hence, we provide a facile method for fabrication of metal/metal sulfide@C which own better dispersity, small dimension and excellent catalytic performance for further studies. [ABSTRACT FROM AUTHOR]

• MoS 2 -500 is prepared by direct high-temperature heat treatment of MoS 2. • The NH 3 yield of MoS 2 -500 was 17.18 μg h-1mg-1 cat. and the FE was 16.71 %. • The increased number of dangling bonds on MoS 2 -500 edge improves NRR performance. Under environmental conditions, molybdenum-based catalysts have been extensively studied as efficient nitrogen reduction reaction (NRR) electrocatalysts. However, the NRR performance of molybdenum-based electrocatalysts is far below expectations. In this study, MoS 2 -500 nanotubes were synthesized by heating the MoS 2 nanotube precursor at high temperatures. These electrocatalysts exhibited a remarkable NH 3 yield of 17.18 µg h−1 mg-1 cat. and faradaic efficiency (FE) of 16.71 %. The enhanced performance is attributable to the increase in MoS 2 dangling bonds at the edge. This work demonstrates the way to develop inexpensive and efficient NRR electrocatalysts. [ABSTRACT FROM AUTHOR]

Atomically dispersed metal catalysts show potential advantages in N2 reduction reaction (NRR) due to their excellent activity and efficient metal utilization. Unfortunately, the reported catalysts usually exhibit unsatisfactory NRR activity due to their poor N2 adsorption and activation. Herein, we report a novel Sn atomically dispersed protuberance (ADP) by coordination with substrate C and O to induce positive charge accumulation on Sn site for improving its N2 adsorption, activation and NRR performance. The extended X‐ray absorption fine structure (EXAFS) spectra confirmed the local coordination structure of the Sn ADPs. NRR activity was significantly promoted via Sn ADPs, exhibiting a remarkable NH3 yield (RNH3) of 28.3 μg h−1 mgcat−1 (7447 μg h−1 mgSn−1) at −0.3 V. Furthermore, the enhanced N2Hx intermediates was verified by in situ experiments, yielding consistent results with DFT calculation. This work opens a new avenue to regulate the activity and selectivity of N2 fixation. [ABSTRACT FROM AUTHOR]

Atomically dispersed metal catalysts show potential advantages in N2 reduction reaction (NRR) due to their excellent activity and efficient metal utilization. Unfortunately, the reported catalysts usually exhibit unsatisfactory NRR activity due to their poor N2 adsorption and activation. Herein, we report a novel Sn atomically dispersed protuberance (ADP) by coordination with substrate C and O to induce positive charge accumulation on Sn site for improving its N2 adsorption, activation and NRR performance. The extended X‐ray absorption fine structure (EXAFS) spectra confirmed the local coordination structure of the Sn ADPs. NRR activity was significantly promoted via Sn ADPs, exhibiting a remarkable NH3 yield (RNH3) of 28.3 μg h−1 mgcat−1 (7447 μg h−1 mgSn−1) at −0.3 V. Furthermore, the enhanced N2Hx intermediates was verified by in situ experiments, yielding consistent results with DFT calculation. This work opens a new avenue to regulate the activity and selectivity of N2 fixation. [ABSTRACT FROM AUTHOR]

Sodium ion batteries (SIBs) have been considered as a promising cost-effective alternative for grid energy storage for renewable energy sources such as wind- and solar power. In this work, a bismuth nano-spheres and porous carbon composite (Bi-NS@C) is developed via an oleate-oriented dual-phase interfacial reaction and a molten salt calcination process. Materials characterizations suggest that the Bi-NS with a size of 20–30 nm are uniformly distributed in the sponge-like porous carbon network. Such a structure could enable a conductive network, prevent particle aggregation, shorten the ions transportation pathways, accommodate volume change and prevent the collapse of the electrode. As a result, this anode delivers a reversible discharge capacity of 106 mAh g −1 after even 1000 cycles at 0.2 A g −1 . Even at 2 A g −1 , the specific capacity of the electrode can still retain at ∼110 mAh g −1 . The remarkable electrochemical performance of the Bi-NS@C composite suggests that the as-prepared nanocomposite can simultaneously enhance the Na + ion conductivity and electronic conductivity in the charge/discharge processes, which offer guidance in anode materials design and synthesis in SIBs. [ABSTRACT FROM AUTHOR]

A new adsorbent with chromium removal function was synthesized by carbon thermal method using iron-containing waste Fenton sludge and carbon-containing solid waste fly ash to treat high pH scoring wastewater generated from industrial processes. The results showed that the adsorbent used T = 273.15 K, pH = 10, t = 1200 min, C0 = 100 mg/L, had a removal rate of Cr(VI) of more than 80%, and the adsorption capacity could reach 393.79 mg/g. The characterization results show that the synthesized mesoporous nitrogen-doped composite material has a large specific surface area and mesoporous structure, and the surface of the material is rich in oxygen-containing functional groups and active sites. Compared with other studies, the adsorption capacity of the material is larger, which indicates that the removal effect of Cr(VI) in this study is better. The adsorption kinetic results show that the adsorption follows a pseudo second kinetic model, and the adsorption process is a chemisorption involving electron sharing or electron exchange. This experiment designed a simple method to synthesize mesoporous nitrogen-doped composites using industrial solid waste, with raw materials from cheap and easily available industrial solid waste, and solved the dual problems of heavy metals in wastewater and solid waste, providing a new idea for the resource utilization of Fenton sludge while not producing secondary pollution. [ABSTRACT FROM AUTHOR]

It is a challenge to achieve the harmless treatment and resourceful use of various metal elements in electroplating sludge, and converting them into functional materials has become an important technological direction. Based on the existence of various metal ions in electroplating sludge, sodium oleate intercalated Zn−Cr‐LDHs (Zn−Cr‐layered double hydroxides) were prepared by two‐phase solution heating method. The adsorption process of the prepared LDHs for Congo red (CR) in aqueous solution can be described by Langmuir isotherm model and pseudo‐second‐order kinetic model and the maximum adsorption capacity is 2750.43 mg/g. The results of TEM and XPS show that the adsorption mechanism is dominated by electrostatic adsorption, ion exchange process, hydrogen bonding interaction and surface complexation. Therefore, this paper provides a strategy for recovering metal elements from electroplating sludge to prepare LDHs adsorption materials with ultra‐high adsorption capacity. [ABSTRACT FROM AUTHOR]

• (0D/2D) Co 3 O 4 /GO composites with good visible light response were successfully prepared by two-phase solvothermal method. • The photocatalytic water oxidation performance of the Co 3 O 4 /Go is higher than that of pure Co 3 O 4. • The photocatalytic mechanism relies on the enhancement of effective electron transport. Zero-dimensional/two-dimensional (0D/2D) Co 3 O 4 /GO composites with good visible light response were successfully prepared by adding a certain amount of GO to the nano Co 3 O 4 synthesized by two-phase solvothermal method. The results show that the photocatalytic water oxidation performance of the synthesized Co 3 O 4 /Go is higher than that of pure Co 3 O 4. The turnover frequency (TOF) of Co 3 O 4 /GO (15%) is 1.62 × 10-2s−1 per metal atom, and the initial quantum yield is 25.12%. The improvement of photocatalytic water oxidation activity and stability of Co 3 O 4 /Go were attributed to the enhancement of effective electron transport, which helps to reduce photoelectric recombination rate. The application of 0D/2D composites in the field of photocatalysis is expanded. [ABSTRACT FROM AUTHOR]

• Adsorbents of Li+ ions based on Li 4 Ti 5 O 12 and Li 2 TiO 3 oxides were obtained. • Effect of Ti-containing precursors on structure and adsorption properties was performed. • The optimal conditions of Li-Ti oxides conversion to H-form were established. • Adsorbents prepared from a -TiO 2 compared to r -TiO 2 showed higher adsorption efficiency. Using solid-phase synthesis method, Li 4 Ti 5 O 12 and Li 2 TiO 3 oxides were synthesized and used as adsorbents for Li+ ions. The physical–chemical properties were studied, using X-ray diffraction analysis, IR-spectroscopy, low-temperature adsorption–desorption of nitrogen, and scanning electron microscopy. It was shown that, using anatase as a Ti-containing precursor, single-phase oxides Li 4 Ti 5 O 12 (d 26.5 nm , a 8.401 Å , V 569.5 Å3) and Li 2 TiO 3 (d 26.5 nm , a 7.731 Å , V 462.1 Å3) with macro-mesoporous structure (A BET 11 and 16 m2/g, V BJH des 0.03 and 0.03 cm3/g, D BJH des 6 and 6 nm, respectively) and spherical-like morphology were obtained. For the samples obtained from rutile, an impurity of unreacted Ti-containing precursor was detected. The effect of the nature of Ti-containing precursors, concentration and temperature of HCl regeneration solution, and contact time on the degree of conversion to H-form and adsorption capacity of the obtained adsorbents was studied. The highest efficiency of ion exchange of Li+ ions with H+ (γH+ 96.7–100 %) was reached in conversion of adsorbents to H-form, during treatment with 0.1 M HCl at temperature of 70 °C for 48 h. Adsorbents H 4 Ti 5 O 12 and H 2 TiO 3 prepared from anatase showed higher adsorption efficiency of Li+ ions (q e 95.1 and 84.0 mg/g, α 34.7 and 32.9 %, respectively) compared to samples obtained from rutile (q e 75.7 and 81.2 mg/g, α 23.8 and 29.9 %, respectively). After three cycles of acid regeneration, the adsorption capacity was maintained at 40.6–47.0 mg/g for Li 4 Ti 5 O 12 , and at 34.8–38.4 mg/g for Li 2 TiO 3 , respectively. The hydrogen demonstration during adsorption–desorption cycles increased from 8.4 to 10.8 for Li 4 Ti 5 O 12 , and from 8.0 to 11.2 for Li 2 TiO 3. Anatase Ti-containing precursor recrystallization into rutile modification and further amorphization was determined. The presented results are interesting for developing highly efficient adsorbents for Li+ ions recovery from aqueous solutions. [ABSTRACT FROM AUTHOR]

• Fenton conditioning facilitated the formation of persistent free radicals (PFRs). • Achieved the yield of PFRs with the total number spins of 9.533×1019 spins/g DS. • Pyrolysis cleavage of the EPS fractions produced carbon-centered PFRs. • Maillard reaction provided abundant precursors for the formation of PFRs. • Phenoxyl or semiquinone-type PFRs were formed by iron ions with aromatic protein. The present study provided an innovative insight into the formation mechanism of persistent free radicals (PFRs) during the pyrolysis of Fenton-conditioned sludge. Fenton conditioners simultaneously improve the dewatering performance of sewage sludge and catalyze the pyrolysis of sewage sludge for the formation of PFRs. In this process, PFRs with a total number of spins of 9.533×1019 spins/g DS could be generated by pyrolysis of Fenton-conditioned sludge at 400°C. The direct thermal decomposition of natural organic matter (NOM) fractions contributed to the formation of carbon-centered radicals, while the Maillard reaction produced phenols precursors. Additionally, the reaction between aromatic proteins and iron played a crucial role in the formation of phenoxyl or semiquinone-type radicals. Kinetics analysis using discrete distributed activation energy model (DAEM) demonstrated that the average activation energy for pyrolysis was reduced from 178.28 kJ/mol for raw sludge to 164.53 KJ/mol for Fenton conditioned sludge. The reaction factor (f i) indicated that the primary reaction in Fenton-conditioned sludge comprised of 27 parallel first-order reactions, resulting from pyrolysis cleavage of the NOM fractions, the Maillard reaction, and iron catalysis. These findings are significant for understanding the formation process of PFRs from NOM in Fenton-conditioned sludge and provide valuable insight for controlling PFRs formation in practical applications. The proposed pathways for the dissociation of EPS to generate PFRs. (T• Transient radical, PO• Oxygen-centered persistent free radicals, PC• Carbon-centered persistent free radicals, PCO• Carbon-centered neighboring oxygen atoms persistent free radicals, MRP Maillard reaction products) [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] Modification methods for sludge-based biochar are often complex and generally ineffective. In this study, sludge-based biochars were prepared at low cost using a simple air roasting-oxidation modification method and the adsorption performance on U(VI) was investigated. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results together indicated that more carbon–oxygen functional groups were formed on the surface of oxidized biochar (OBC) compared to unoxidized biochar (BC). The adsorption performance of 550-OBC (biochar oxidized at 550 °C) on U(VI) was explored in batch experiments. The maximum adsorption capacity was up to 490.2 mg/g at 25 °C and pH 6, exceeding most of the reported biochars. 550-OBC also showed good adsorption performance at low U(VI) concentration, with 96% removal at pH 6 and an initial U(VI) concentration of 1 mg/L. Density functional theory (DFT) calculations indicated that the H-bond length between the solvated U(VI) and functional groups on the OBC was about 1.7 Å, which forms stronger H-bonds between them compared to that between U(VI) and BC (4.21 Å), and the adsorption energy value for this complex was highly negative −31.82 kcal/mol. In addition, 550-OBC exhibited high selectivity for U(VI) adsorption and excellent regeneration performance, making it a cost-effective and high-performance adsorbent. [ABSTRACT FROM AUTHOR]

This finding not only provides a profound understanding of the role of oxygen vacancy in reducing the adsorption energy (E ads OH*) of OH- in Co-Ga-LDHs, but also paves the way to design advanced LDH-based electrode materials for a high-performance energy storage device. [Display omitted] • A oxygen-defect-rich, porous and ultrathin nanosheets is prepared by a facile one-step strategy. • The Co 0.50 -Ga 0.50 -LDH exhibits high capacity and extraordinary cycling stability. • Theoretical calculation reveal introduced the oxygen-defect and Ga ions could enhance the adsorption of the LDH on OH–. In this work, oxygen-defect-rich, three-dimensional (3D) cobalt-gallium layered double hydroxides (Co 0.50 -Ga 0.50 -LDH) assembled by porous and ultrathin nanosheets are prepared by a simple one-step strategy. Briefly, an aqueous solution containing Co2+ and Ga3+ is quickly pouring into the aqueous solution of hexamethylenetetramine, the state-of-the-art LDH was obtained followed by a mild and fast hydrothermal reaction. This mild and rapid synthesis strategy introduces a large number of pores into the ultrathin LDH nanosheets, resulting in a high concentration of oxygen vacancies in the Co 0.50 -Ga 0.50 -LDH, and the concentration of oxygen vacancies can be arbitrarily modulated, which has been corroborated by X-ray photoelectron spectroscopy and electron spin resonance measurements. The synergistic effect of the oxygen vacancy and the introduced Ga ions in the LDH nanosheets enhances the adsorption of the LDH nanosheets on OH–, endowing Co 0.50 -Ga 0.50 -LDH with outstanding performance for the supercapacitor application. Co 0.50 -Ga 0.50 -LDH offers a high specific capacity (0.62C·cm−2) at 10 mV·s−1 and extraordinary cycling stability. An aqueous asymmetric supercapacitor (ASC) constructed with Co 0.50 -Ga 0.50 -LDH and activated carbon (AC) materials exhibits high energy density and a long lifespan. This result encourages the wide application of porous ultrathin LDH nanosheets in energy storage, catalysis and light response. [ABSTRACT FROM AUTHOR]

Abstract: CuO nanorods have been prepared through a facile microwave-hydrothermal method with the aid of polyethylene glycol 400, ethylene glycol and urea. The X-ray diffraction and transmission electron microscopy results showed that the prepared CuO nanocrystalline had a rod-like shape with diameters of 15–20nm and the average length of 80nm. Compared with commercial CuO powder, the CuO nanorods showed an enhanced catalytic activity for the synthesis of sodium humate and the degradation of Rhodamine B. The yield of sodium humate catalyzed by CuO nanorods was 75.78%, which was higher than that of the commercial CuO powder (52.8%). In addition, the CuO nanorods showed a relatively faster degradation rate of RhB. The CuO nanorods prepared by this facile method demonstrated their potential applications in the field of catalysis. [Copyright &y& Elsevier]

Abstract: CuO/Bi2O3 (CuO/Bi2O3/MCM-41) nanoparticles supported on MCM-41 were synthesized by a facile impregnation method. The products were characterized by nitrogen adsorption/desorption, X-ray diffraction (XRD), H2 temperature programmed reduction (H2-TPR) and scanning electron microscopy (SEM). XRD patterns indicated the presence of crystalline CuO and Bi2O3 phase for CuO/Bi2O3/MCM-41 catalyst. TPR results revealed CuO nanoparticles were dispersed well on MCM-41. SEM results showed that the nanoparticles were located on the MCM-41. The activity of the catalysts towards ethynylation of formaldehyde for 1,4-butynediol synthesis was evaluated at atmospheric pressure. Compared with unsupported CuO/Bi2O3 and commercial Cu/Bi-based catalyst, CuO/Bi2O3/MCM-41 catalyst showed maximum conversion (51%) and selectivity (94%) towards 1,4-butynediol. The results show that CuO/Bi2O3 catalysts supported on MCM-41 have potential for 1,4-butynediol synthesis in industrial application. [Copyright &y& Elsevier]

Microbial treatment of Cr(VI) is an environmentally friendly and low-cost approach. However, the mechanism of mutualism and the role of interspecies electron transfer in Cr(VI) reducing microflora are unclear. Herein, we constructed an intersymbiotic microbial association flora to augment interspecies electron transfer via functionalizing electroactive Shewanella oneidensis MR-1 with metal-reducing microflora, and thus the efficiency of Cr(VI) reduction. The findings suggest that the metal-reducing active microflora could converts glucose into lactic acid and riboflavin for S. oneidensis MR-1 to act as a carbon source and electron mediator. Thus, when adding initial 25 mg/L Cr (VI), this microflora exhibited an outstanding Cr (VI) removal efficiency (100%) at 12 h and elevated Cr (III) immobilization efficiency (80%) at 60 h with the assistance of 25 mg/L Cu(II). A series of electrochemical experiments proved this remarkable removal efficiency were ascribed to the improved interspecies electron transfer efficiency through direct interspecies electron transfer and riboflavin through mediated interspecies electron transfer. Furthermore, the metagenomic analysis revealed the expression level of the electron transport pathway was promoted. Intriguing high abundance of genes participating in the bio-reduction and biotransformation of Cr(VI) was also observed in functional microflora. These outcomes give a novel strategy for enhancing the reduction and fixation of harmful heavy metals by coculturing function microflora with electrogenic microorganisms. [Display omitted] • An intersymbiotic microflora was constructed by functionalizing S. oneidensis MR-1 with metal-reducing bacteria. • The microflora achieved Cr(VI) removal efficiency of 100% and Cr (III) immobilization efficiency of 80%. • The removal efficiency was ascribed to the improved interspecies electron transfer. • The metal-reducing active microflora converted glucose to lactate and riboflavin for S. oneidensis MR-1 to utilize. • The metagenomic analysis revealed the expression level of the electron transport pathways were promoted. [ABSTRACT FROM AUTHOR]

Chromium-containing wastewater causes serious environmental pollution due to the harmfulness of Cr(VI). The ferrite process is typically used to treat chromium-containing wastewater and recycle the valuable chromium metal. However, the current ferrite process is unable to fully transform Cr(VI) into chromium ferrite under mild reaction conditions. This paper proposes a novel ferrite process to treat chromium-containing wastewater and recover valuable chromium metal. The process combines FeSO 4 reduction and hydrothermal treatment to remove Cr(VI) and form chromium ferrite composites. The Cr(VI) concentration in the wastewater was reduced from 1040 mg L−1 to 0.035 mg L−1, and the Cr(VI) leaching toxicity of the precipitate was 0.21 mg L−1 under optimal hydrothermal conditions. The precipitate consisted of micron-sized ferrochromium spinel multiphase with polyhedral structure. The mechanism of Cr(VI) removal involved three steps: 1) partial oxidation of FeSO 4 to Fe(III) hydroxide and oxy-hydroxide; 2) reduction of Cr(VI) by FeSO 4 to Cr(III) and Fe(III) precipitates; 3) transformation and growth of the precipitates into chromium ferrite composites. This process meets the release standards of industrial wastewater and hazardous waste and can improve the efficiency of the ferrite process for toxic heavy metal removal. [Display omitted] • FeSO 4 hydrothermal treatment removes most Cr(VI) from alkaline wastewater. • Cr(VI) turns into magnetic chromium ferrite composites. • Hydrothermal treatment boosts ferrochromium spinel multiphase formation and growth. [ABSTRACT FROM AUTHOR]

Production of artificial humic substances (AHS) from waste biomass will contribute to environmental protection and agricultural productivity. However, there is still a lack of a faster, more efficient and eco-friendly way for sustainable production. In this study, we proposed a method to accelerate the production of AHS from cotton stalks by mild pyrolysis and H 2 O 2 oxidation in only 4 hours, and investigated the formation of AHS during biomass transformation. We found that the process increased the aromatic matrix and facilitated biomass transformation by enhancing the depolymerization of lignin into micromolecular phenolics (e.g., guaiacol, p-ethyl guaiacol, etc.). The optimum conditions of pyrolysis at 250 °C and oxidation with 6 mL H 2 O 2 (5 wt%) yielded up to 19.28 ± 1.30 wt% artificial humic acid (AHA) from cotton stalks. In addition, we used iron oxyhydroxide (FeOOH) to catalyze biomass transformation and investigated the effect of FeOOH on the composition and properties of AHS. 1.5 wt% FeOOH promoted the increased content of artificial fulvic acid (AFA) in AHS from 10.1% to 26.5%, eventually improving the activity of AHS. FeOOH raised the content of oxygen-containing groups, such as carboxylic acids and aldehyde, and significantly increased polysaccharide (10.94%–18.95%) and protein (1.95%–2.18%) derivatives. Polymerization of amino acid analogs and many small-molecule carbohydrates (e.g., furans, aldehydes, ketones, and their derivatives) promoted AFA formation. Finally, carbon flow analysis and maize incubation tests confirmed that AHS were expected to achieve carbon emission reductions and reduce environmental pollution from fertilizers. This study provides a sustainable strategy for the accelerated production of AHS, which has important application value for waste biomass resource utilization. [Display omitted] • Mild pyrolysis and oxidation of cotton stalks gave 19.28 wt% humic acid yield. • Production and properties of artificial humic substances were improved by FeOOH. • FeOOH catalyzed biomass transformation to artificial fulvic acids. • Converting waste biomass to humic substances reduced carbon emissions. [ABSTRACT FROM AUTHOR]

Hollow α-Fe 2 O 3 nanospindles have been designed and fabricated via a facile wrap–bake–peel process consisting of silica coating, calcination treatment and the removal of the silica coating layer. The excellent photocatalytic performance was attributed to the obtained hollow structure and the improved crystallinity of the photocatalyst, which also has good reusability in photocatalytic water oxidation, achieving up to 4 times higher activity than pristine Fe 2 O 3 and the apparent quantum efficiency (AQE) of H 2 evolution reaches up to 2.14%. These results demonstrate that the hollow α-Fe 2 O 3 nanospindles can be acted as a promising candidate for highly efficient photocatalyst of water oxidation. Hollow α-Fe 2 O 3 nanospindles was obtained by convenient wrap–bake–peel process, which exhibited high activity and good reusability in photocatalytic water oxidation [Display omitted] • Hollow α-Fe 2 O 3 nanospindles was obtained by a convenient wrap–bake–peel process. • The unique hollow nanostructures exhibits high photocatalytic activity in oxygen production. • The nanospindles have good reusability in photocatalytic water oxidation. [ABSTRACT FROM AUTHOR]

Summary: Effective utilization of the wasted high‐ash coal liquefaction residue (CLR) becomes increasingly important with the fast development of the coal chemical industry. Herein, a self‐template porous carbon is prepared using CLR as the raw material. The ashes contained in the CLR reacted with potassium hydroxide (KOH), and soluble salts were formed during the heat treatment. After washing, micropores and mesoporous were obtained at the original positions of ashes, while micropores were etched out from the carbon material by KOH. As a result, the carbon substrate with hierarchically porous structure had a maximum surface area of 1787.2 m2 g−1, when used as a supercapacitor electrode material, reaching a strong electrical dual‐layer capacitance of 250 F g−1 at 1 A g−1 and maintaining 57% capacitance at 100 A g−1. The optimized hierarchical porous carbons (HPCs) show small equivalent resistance, high capacitance, and strong period reliability at various charging and discharging rates. HPCs derived from CLR display great potential in supercapacitors, which benefit from plentiful cavity construction, large specific surface area, and high conductivity. [ABSTRACT FROM AUTHOR]

• CoNi-LDH with a hierarchical hollow cage structure has been synthesized. • Two-step water-assisted coprecipitation method is utilized at room temperature. • The synergic effect of nickel nitrate adsorption on bimetallic CoNi-ZIF is optimized. • The assembled ASC supercapacitor device delivers excellent energy density, power density and cyclic stability. Single imidazolate framework-67 (ZIF-67) is commonly used as a template to prepare layered double hydroxides (LDHs) with specific morphology to improve the performance of materials. Herein, the Co2+ ion in ZIF-67 is partially substituted by Ni2+ to obtain the dodecahedron bimetallic imidazolate framework (CoNi-ZIF). Subsequently, using bimetallic CoNi-ZIF as the sacrificial template, CoNi-LDH hierarchical hollow cage structures with wrinkled nanosheet arrays are synthesized at room temperature and in aqueous solution by an inexpensive and environment friendly surfactant-free approach. The optimized etched CoNi-LDH4 has a maximum specific capacitance of 1877 F g−1 at a current density of 1 A g−1, and cycling stability of 99.89% after 5000 cycles, which is significantly better than that of ZIF-67 derived CoNi-LDH67 (1357 F g−1 at 1 A g−1, cycling stability of 73.35%). The asymmetric supercapacitor with CoNi-LDH4 as a cathode and activated carbon (AC) as anode has an energy density of 49.3 Wh kg−1 at 750 W kg−1 power output and stable cycling performance (capacity retention of 92.13% after 5000 cycles). This study shows the prospect of bimetallic CoNi-ZIF derived LDHs nanostructures prepared at room temperature and in aqueous solution to improve the performance and stability of supercapacitors. [ABSTRACT FROM AUTHOR]

In this paper, fly ash (FA) was successfully prepared into graphene‐like carbon composite materials (GCC) with good adsorption properties for heavy metals by alkali activation‐Hummer oxidation method. What's more, the sulfate in the waste liquid can be collected by concentration, and sulfuric acid can be recycled several times after treatment. FA has been fully recycled in an inexpensive and environmentally friendly way. Compared with FA, the specific surface area of GCC increased about 50 times, and the pore size decreased from 9.49 nm to 4.5 nm. The adsorbing amount of GCC could attain 79.38 mg g−1 within 90 min at pH=6. The experimental data of lead adsorption by GCC showed that the results were very consistent with the Freundlich adsorption model. The adsorbent prepared in this work has a good application prospect in water pollution control, which provides a new approach for resource recovery of FA. [ABSTRACT FROM AUTHOR]

The integration of two transition metals with carbon materials provides a great potential to boost the catalytic and electrochemical properties of supercapacitor. However, a scalable fabrication of such composite materials remains a challenge. Here, ternary composites of NiS–NiCo 2 O 4 @C nanosheets were derived from nickel and cobalt oleate using Na 2 SO 4 as both hard template and sulfur source. The NiS–NiCo 2 O 4 @C composites were then tested as catalysts toward rapid reduction of 4-nitrophenol (4-NP) and as electrode materials for supercapacitors. It was found that the catalytic and electrochemical properties of the composites were tuned by adjusting the ratios of Co to Ni and annealing temperature. The optimized composite showed the highest reduction rate constant for 4-NP reduction (1.78 min−1). In addition, this composite has also shown high specific capacitance of 1411 F g−1 at 1 A g−1and 99.5% capacity retention after 2000 continuous charge-discharge cycles at a current density of 3 A g−1, which is much higher than their respective monometallic Co and Ni composites. Furthermore, the ASC device (CN14//AC) achieved a high energy density of 37.2 W h kg−1 at a power density of 799.9 W kg−1, and a good cycling performance of retention(89%) after 5000 cycles. Image 1 [ABSTRACT FROM AUTHOR]

The development of high performance magnetic nanomaterials has a good application prospect in wastewater treatment. Herein, Fe3O4/C nanocomposites was synthesized by eco‐friendly hydrolysis‐calcination method using potassium fulvic acid (FA−K) and FeCl3⋅6H2O as raw materials. The morphology of Fe3O4/C nanocomposites exhibited a loose pore structure with uniform size (a diameter ∼ 27 nm). The prepared Fe3O4/C nanocomposites possessed excellent dispersibility and magnetic properties in aqueous solution. The removal efficiency and maximum adsorption capacity of Fe3O4/C nanocomposites were 98% and 64.0 mg g−1, respectively. Moreover, it was confirmed that the adsorption mechanism of Cr(VI) contains electrostatic attraction and redox reaction. In this work, we provide a convenient means for manufacturing Fe3O4/C nanocomposites, and prove that FA−K is a cheap carbon source for manufacturing Fe3O4/C nanocomposites, which makes Fe3O4/C nanocomposites have potential application value in the effective adsorption of Cr(VI). [ABSTRACT FROM AUTHOR]

Ultrafine WO 3−x (0 < x < 1) nanowires with aspect ratio greater than 100 were successfully synthesized by two-phase strategy. The crystal structure, morphology evolution and thermal stability of the samples were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectrum (XPS), high resolution transmission electron microscopy (HRTEM), and thermal gravimetric analysis (TGA). The morphology of WO 3−x nanowires is closely related to the pH value and oleamine content of the reaction system. By controlling the reaction conditions, a linear product with a diameter of less than 2 nm can be obtained, and the exposed active lattice plane is 110 crystal face. On this basis, the prepared ultrafine WO 3−x nanowire sensor was tested for a series of harmful gases. The sensitivity of WO 3−x -based gas sensors can reach 57.9 for 10 ppm NO 2 at 100 °C, which is much higher than most reported values. The sensor has the excellent sensing performance of ppm NO 2 at low operating temperature, which is due to its nanowire structure and oxygen vacancies. These results demonstrate that this type of sensor is a competitive candidate for NO 2 -sensing applications. [ABSTRACT FROM AUTHOR]

• New uranyl uptake strategy with combined complexation and photoreduction is shown. • An ultrahigh uranyl uptake capacity not limited by the sorption site is achieved. • Uranyl can be removed completely regardless of its initial concentration. • Uranyl extraction is not affected by the coexisting metal cations. Uranium enrichment is perhaps the most critical chemical process throughout the nuclear fuel cycle including uranium mining, uranium extraction from seawater, used fuel reprocessing and disposal, and environmental contamination remediation. New uranium extraction technology is still highly desirable at current stage, although a variety of extraction methods have been established and developed in the past several decades but all with clear demerits. Herein we present a new uranium extraction strategy with combined ligand complexation and photocatalytic reduction based on postsynthetically functionalized metal-organic frameworks (MOFs). The highly robust and photoactive MOF PCN-222 is modified with phosphono- and amino groups that can capture U(VI) from solution. Upon visible light irradiation, the photo-induced electrons from the MOF host can efficiently reduce U(VI) pre-enriched in MOF, affording neutral uranium species that evacuate the MOF structure and regenerating the active site readily for capturing additional U(VI). This auto-recycled process offers an ultrahigh uranium extraction capacity not limited by the number of adsorption sites and more importantly an extra uranium uptake selectivity over these non-redox-active competing metal cations, and can be utilized for uranium separation over extremely wide uranium concentrations and pH ranges, showing a powerful application potential. [ABSTRACT FROM AUTHOR]

Graphical abstract The NA-LDH-OA-2//AC ASC device deliver a high energy density of 40.26 Wh kg−1 at a power density of 943 W kg−1, and good cycling performance. Highlights • The NA-LDH-OA ultrathin nanosheets were synthesized by two-phase solvothermal method. • Excellent cycling stability of 94.5% capacitance retention after 5000 cycles. • The asymmetric supercapacitor achieved a high energy density of 40.26 Wh kg−1 at a power density of 943 W kg−1. Abstract Using sodium oleate as surfactant and intercalating agent, a regulated Ni-Al layered double hydroxide (NA-LDH-OA) nanosheets with a high interlayer space were prepared by two-phase method combined with a short reflux process and mild solvothermal reaction. In the process of electrochemical reaction, the electron transport is accelerated by the higher base spacing of the NA-LDH-OA ultrathin nanosheets. The as-prepared material exhibited a high specific capacity (1.040 C cm−2 at a current density of 1.68 mA cm−2) and good cycling performance (capacity retention of 88.25% after 2000 cycles) in a three-electrode system. Moreover, an aqueous asymmetric supercapacitor (ASC) was assembled using the synthesized NA-LDH-OA nanosheets as the positive electrode and activated carbon (AC) as the negative electrode. The aqueous ASC device (NA-LDH-OA-2//AC) achieved a high energy density of 40.26 Wh kg−1 at a power density of 943 W kg−1, and a good cycling performance of 94.5% retention after 5000 cycles. These results demonstrated that the NA-LDH-OA nanosheets possess the potential for upcoming energy storage devices. [ABSTRACT FROM AUTHOR]

Abstract A Hybrid magnetic composite material Fe 3 O 4 @Cu x O y /C (where, x = 1–2; y = 0–1) was prepared via pyrolysis of FeOOH decorated Cu 3 (BTC) 2 (where, BTC = 1, 3, 5-benzenetricarboxylic acid) as a precursor. The obtained products was successfully applied to reduction reaction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) as a catalyst. Compared with other reported materials, Fe 3 O 4 @Cu x O y /C exhibits high catalytic activity with excellent recyclability. Graphical abstract Unlabelled Image Highlights • Non-aqueous deposition of FeOOH on Cu-MOF • Magnetic Fe 3 O 4 @Cu x O y /C composite derived from Cu-MOF@FeOOH • Fe 3 O 4 @Cu x O y /C was tested for catalytic reduction of 4-NP. • Magnetic Fe 3 O 4 @Cu x O y /C facilitated the recovery of the spent catalyst. [ABSTRACT FROM AUTHOR]

Development of novel methods to obtain highly active catalysts for photocatalytic hydrogen evolution is desired. This work reports a facile preannealing‐quenching strategy to synthesize oxygen vacancy‐rich anatase TiO2 hollow spheres. TiO2 hollow spheres are first synthesized via a versatile kinetics‐controlled coating method and then subjected to high temperature preannealing followed by rapid quenching in liquid‐nitrogen (−196 °C). The as‐quenched samples appear light grey suggesting the presence of abundant surface oxygen vacancies, which are subsequently confirmed by the comprehensive analyses of XRD, XPS and EPR spectra. The oxygen vacancies induced by quenching process are proved to have promoted the light adsorption and inhibited the recombination of photo‐induced charges for TiO2 hollow spheres, which obviously improve the photocatalytic performance of those samples. The results showed that the TiO2 hollow spheres quenched at 500 °C exhibited a robust stability and the most excellent photocatalytic performance for hydrogen evolution (413.5 μmol h−1) over other quenched samples and it displayed 1.51 times higher performance than that of samples normally cooled at 500 °C (273.7 μmol h−1). Herein, this liquid‐nitrogen quenching strategy presented here provides an effective route for the synthesis of high‐performance TiO2 for water splitting and have a promising prospect in the other application. It's a vacancy‐rich world! During the liquid‐nitrogen quenching process, the isolated O atoms on the TiO2 surface are partially frozen and lose the opportunity to return the crystallographic sites, leaving abundant oxygen vacancy on the surface. The oxygen vacancy‐rich TiO2 prepared via liquid‐nitrogen quenching exhibited outstanding advantages on photocatalytic H2 evolution. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Potassium humate possesses a wide variety of oxygen-containing functional groups and has good adsorption and complexation properties for many kinds of transition metal ions. In this work, a simple and separable route had been developed to synthesize Fe 3 O 4 /graphene nanocomposite, derived from potassium humate, were employed for the effective adsorption of Cr(VI) in aqueous phase. In addition, the Fe 3 O 4 /graphene nanocomposite prepared at 600 °C (S-600) showed a maximum adsorption capacity of 280.6 mg/g for Cr(VI) and good cycling performance, which was much higher than those reported graphene-based adsorbents and other conventional adsorbents. The adsorptive behavior was well fitted to the Langmuir isotherm model. The adsorption kinetics for removal of Cr(VI) agreed with pseudo-second-order equation, which indicates a kind of chemical adsorption. Its superior adsorption performance might be due to the effective adsorption sites at the surface and formation of FeOH2+ on the surface of Fe 3 O 4 /graphene. This work provided a promising approach for the removal of Cr(VI) from wastewater using a Fe 3 O 4 /graphene nanocomposite, which shows a huge number of application prospects. [ABSTRACT FROM AUTHOR]

Abstract In this work, a novel rhombic dodecahedral structure of Ca-Al-layered double hydroxides (Ca-Al-LDHs) was synthesized by a two-phase solvothermal method. Subsequently, Ca-Al layered double oxides (Ca-Al-LDOs) were obtained by calcinating Ca-Al-LDHs at 600 °C which maintained the rhombic dodecahedral structures well. The morphologies of as-obtained samples were characterized by both transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The phase structure and elemental composition were analyzed by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS), respectively. Fourier transformed infrared (FT-IR) spectra were performed to confirm the existence of LDH structures. The Ca-Al-LDOs exhibited high adsorption rates and superb adsorption capacities for removal of Congo red (CR) from aqueous solution. The maximum adsorption capacities of Ca-Al-LDOs towards CR reached to 1536.1 mg g−1, which is extremely higher than most of hydrotalcite-like materials. The adsorption process of Ca-Al-LDHs and Ca-Al-LDOs were described by the Langmuir isotherm model and pseudo-second-order model well. The adsorption mechanisms mainly dominated by electrostatic adsorption, ion exchange process, hydrogen bonding interactions and surface complexation. This general strategy afforded a wide possibility to prepare a novel and advanced LDOs adsorption material for water treatment. Graphical abstract Image 1 Highlights • Ca-Al-LDHs were synthesized via a two-phase solvothermal method. • Ca-Al-LDHs and Ca-Al-LDOs with rhombic dodecahedral morphology. • The Ca-Al-LDOs has the maximum adsorption capacity of 1536.1 mg g−1. [ABSTRACT FROM AUTHOR]

Ultrathin semiconductor nanosheets decorated with metallic nanoparticles (NPs) are promising in photocatalysis due to the multi-component interactions. The materials with a series of monometallic Pd and bimetallic Au-Pd NPs anchored on Bi 2 WO 6 ultrathin nanosheets were synthesized and developed as photocatalysts for selective oxidation of aromatic alcohols to aromatic aldehyde. By optimizing the metallic contents, a typical sample of Au(0.25)Pd(0.25)-Bi 2 WO 6 exhibited the highest photocatalytic activity among all the prepared photocatalysts including Au(0.5)-Bi 2 WO 6 , Pd( x )-Bi 2 WO 6 , Au( x )Pd( x )-Bi 2 WO 6 ( x represents the weight percentage of metal in the photocatalyst), along with the improved selectivity for producing benzaldehyde. The extended absorption in visible range, higher efficiency for the transfer and separation of photogenerated charge carriers, and the superior ability for generating active radicals of Au(0.25)Pd(0.25)-Bi 2 WO 6 were demonstrated by DRS spectra, photoelectrochemical measurements, and ESR detection. The effect of the active species for selective oxidation of aromatic alcohols was proved to follow the order of h +  +  O 2 −  > h +  >>  O 2 − . Accordingly, a possible mechanism based on the interfacial cooperation between bimetallic Au-Pd NPs and Bi 2 WO 6 ultrathin nanosheets was proposed to illustrate the photocatalytic process, where the holes accumulated in Bi 2 WO 6 ultrathin nanosheets and O 2 − produced on metallic NPs synergistically promote the selective oxidation of aromatic alcohols. [ABSTRACT FROM AUTHOR]

Abstract: The unique physicochemical properties of silver nanoparticles offer a large potential for biomedical application, however, the serious biotoxicity restricts their usage. Herein, nanogalvanic couple Ag–Fe@Fe3O4 heterostructures (AFHs) are designed to prevent Ag+ release from the cathodic Ag by sacrificial anodic Fe, which can reduce the cytotoxicity of Ag. AFHs are synthesized with modified galvanic displacement strategy in nonaqueous solution. To eliminate the restriction of lattice mismatch between Fe and Ag, amorphous Fe@Fe3O4 nanoparticles (NPs) are selected as seeds, meanwhile, reductive Fe can reduce Ag precursor directly even at as low as 20 °C without additional reductant. The thickness of the Fe3O4 shell can influence the amorphous properties of AFHs, and a series of Janus‐ and satellite‐like AFHs are synthesized. A “cut‐off thickness” effect is proposed based on the abnormal phenomenon that with the increase of reaction temperature, the diameter of Ag in AFHs decreases. Because of the interphase interaction and the coupling effect of Ag and Fe@Fe3O4, the AFHs exhibit unique optical and magnetic properties. This strategy for synthesis of monodisperse heterostructures can be extended for other metals, such as Au and Cu. [ABSTRACT FROM AUTHOR]