Using ammonia and Co(CH3COO)2·4H2O as starting materials, a facile and surfactant-free route to controlled synthesis of Co3O4 nanoparticles was proposed. Co3O4 nanoparticles with average sizes of 3.5, 6, 11, 19 and 70 nm were obtained through adjusting the ethanol amount in the solvent (the ratio of ethanol to water) or the concentration of raw materials. In this process, the presence of enough O2 was crucial for the formation of pure Co3O4 phase. The environmental catalytic properties of as-obtained Co3O4 nanoparticles were investigated. The results indicated their remarkable catalysis for ozonation degradation of phenol, which denoted a promising application as catalyst in waste-water treatment.

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Van der Waals (vdW) semiconductors are attractive for highly scaled devices and heterogeneous integration since they can be isolated into self-passivated, two-dimensional (2D) layers that enable superior electrostatic control. These attributes have led to numerous demonstrations of field-effect devices ranging from transistors to triodes. By exploiting the controlled, substitutional doping schemes in covalently-bonded, three-dimensional (3D) semiconductors and the passivated surfaces of 2D semiconductors, one can construct devices that can exceed performance metrics of "all-2D" vdW heterojunctions. Here, we demonstrate, 2D/3D semiconductor heterojunctions using MoS 2 as the prototypical 2D semiconductor laid upon Si and GaN as the 3D semiconductor layers. By tuning the Fermi levels in MoS 2 , we demonstrate devices that concurrently exhibit over seven orders of magnitude modulation in rectification ratios and conductance. Our results further suggest that the interface quality does not necessarily affect Fermi-level tuning at the junction opening up possibilities for novel 2D/3D heterojunction device architectures.

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Zeolite was synthesized from coal fly ash by a fusion method and was used for the removal of heavy metal ions (Pb(2+), Cd(2+), Cu(2+), Ni(2+), and Mn(2+)) in aqueous solutions. Batch method was employed to study the influential parameters such as adsorbent dosage, pH, and coexisting cations. Adsorption isotherms and kinetics studies were carried out in single-heavy and multiheavy metal systems, respectively. The Langmuir isotherm model fitted to the equilibrium data better than the Freundlich model did, and the kinetics of the adsorption were well described by the pseudo-second-order model, except for Cd(2+) and Ni(2+) ions which were fitted for the pseudo-first-order model in the multiheavy metal system. The maximum adsorption capacity and the distribution coefficients exhibited the same sequence for Pb(2+) > Cu(2+) > Cd(2+) > Ni(2+) > Mn(2+) in both single- and multiheavy metal systems. In the end, the adsorption capacity of zeolite was tested using industrial wastewaters and the results demonstrated that zeolite could be used as an alternative adsorbent for the removal of heavy metal ions from industrial wastewater.

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