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Monodispersed and uniform hexagonal thin plate-like magnesium-aluminum layered double hydroxide intercalated with CO 3 2− (MgAl–CO 3 2− -LDH) is synthesized by an ethanol–water mediated solvothermal method. The maximum adsorption capacities of the as-synthesized and calcined MgAl − CO 3 2 − − LDH are 129.9 and 143.27 mg g −1 , respectively, which are higher than those of the other metal oxide nanostructures reported to date. More importantly, although N 2 adsorption–desorption analysis indicates that the BET surface area changed from 24.74 m 2 g −1 for the as-synthesized MgAl − CO 3 2 − − LDH to 165.07 m 2 g −1 for the calcined MgAl − CO 3 2 − − LDH , the as-synthesized and calcined hexagonal thin plate-like MgAl − CO 3 2 − − LDH structures show similar adsorption capacity of Congo red (CR) from aqueous solution. The adsorption mechanism for the as-prepared LDH is anion exchange while adsorption mechanism for the calcined LDH is reconstruction. Our study opens a new insight for understanding and preparing high-performance adsorbents for organic dye removal. [ABSTRACT FROM AUTHOR]

Many nanomaterials have been widely reported for removal of toxic inorganic metal ions. However, some nanoscale adsorbents are subject to serious aggregation. For example, it is very difficult to directly synthesize the monodispersed Fe(OH) 3 nanomaterials. Here, through using the monodispersed hierarchical γ-Al 2 O 3 nanoflowers as adsorbent supports, the Fe(OH) 3 colloid nanoparticles have been well deposited onto the surfaces of the hierarchical γ-Al 2 O 3 nanostructures to form γ-Al 2 O 3 /Fe(OH) 3 composites with hierarchical structures via an electrostatic attraction without forming large aggregates. The γ-Al 2 O 3 /Fe(OH) 3 composites with hierarchical structures have high specific surface areas and large pore volumes, which are used as adsorbents to remove anion species of As(V) and Cr(VI) from aqueous solution. The maximum capacities of the monodispersed γ-Al 2 O 3 /Fe(OH) 3 composites with hierarchical structures for As(V) and Cr(VI) are determined at 61.99 mg g −1 and 24.13 mg g −1 , respectively, which are higher than those of the other metal oxide nanostructures reported. In addition, the adsorption rates of As(V) and Cr(VI) onto the monodispersed γ-Al 2 O 3 /Fe(OH) 3 composites with hierarchical structures are rather fast. The γ-Al 2 O 3 /Fe(OH) 3 hierarchical micro/nanoflower structures show high adsorption capacity for removing anion species of As(V) and Cr(VI), demonstrating a promising potential in environmental remediation. [ABSTRACT FROM AUTHOR]

Accurate determination of highly toxic organic pollutants in the water environment is urgent for the protection of environment and human health. Nevertheless, the development of sensitive nanomaterials for p-nitrophenol (PNP) and o-nitrophenol (ONP) electroanalysis remains a big challenge due to the electrochemical redox inertness of organics, which requires the nanomaterials to own considerable catalytic performance. In this work, FeSe 2 with high electronic conductivity and large active area was successfully prepared by hydrothermal synthesis and thermally induced selenization method. The results under the optimized conditions show that the FeSe 2 modified electrode exhibits high sensitivity (0.397 and 0.377 μA μM−1) and low detection limit (0.030 and 0.036 μM) for PNP and ONP, respectively. Besides, the catalytic rate constant, diffusion coefficient and adsorption capacity determined by chronoamperometry and adsorption experiments are 4745.06 M−1 s−1, 2.98 × 10−4 cm2 s−1 and 5.81 mg g−1, respectively, which indicate that the impressive electrochemical behavior of the prepared electrode should attribute to the combined effect of adsorption and catalysis. Moreover, the constructed high-efficiency sensor exhibits superior selectivity, stability, reproducibility, and also realizes the electrochemical detection of organic pollutants in subsidence area water samples. [Display omitted] • Combining hydrothermal method and thermally induced selenization, FeSe 2 was successfully prepared. • Hypersensitive detection of PNP and ONP was achieved by FeSe 2. • The impressive sensitivities for PNP and ONP are 0.397 and 0.377 μA μM−1, respectively. • The sensor exhibits high anti-interference and robust stability. • The synergistic effect of adsorption and catalysis improves the sensitivity of detection. [ABSTRACT FROM AUTHOR]

• Simple fabrication of small sized Co 3 O 4 /ZnO nanocomposite with oxygen vacancy. • Surface abundant oxygen vacancy enhanced the sensitivity of electroanalysis. • Co 3 O 4 /ZnO achieves high sensitivity (504.74 μA cm−2 μM-1) for Hg(II) detection. • The sensor exhibits high anti-interference and robust stability. Metal-oxide based nanocomposites have superior benefits to fabricate sensing interface for electroanalysis of heavy metal ions (HMIs) due to the introduction of various advantages (i.e. environmentally friendly, low-cost and high activity) into one material. Herein, Co 3 O 4 /ZnO nanocomposite with small size (sub-40 nm) and abundant oxygen vacancy was successfully prepared through one-step hydrothermal synthesis and subsequent annealing treatment, as well as the engineering of Co-Zn molar ratio. Moreover, the loose structure of Co 3 O 4 /ZnO nanocomposite can effectively improve the exposure of active sites on surface and enhance mass transfer. As a result, the as-obtained Co 3 O 4 /ZnO sensor has an impressive performance with sensitivity of 504.74 μA μM-1 cm-2 for electroanalysis of Hg(II) by square wave anodic stripping voltammetry (SWASV). Otherwise, diverse detection performances of the product with different Co:Zn molar ratio are investigated, proving the superiority for constructing Co 3 O 4 /ZnO sensor with molar ratio of 2Co/Zn. In addition, the electroanalytical behavior of the proposed sensors toward Hg(II) in subsidence area water was also realized with considerable result. By designing multifunctional nanocomposite with bimetal oxide nanomaterials, this work will provide a novel strategy to gain nanocomposite with controlling morphology and enriching oxygen vacancies, which are expected to be excellent candidate electrode materials for electroanalysis. [ABSTRACT FROM AUTHOR]