A hierarchical CoCo layered double hydroxide (LDH) nanostructure was constructed through a facile topochemical transformation route under a dynamic oxygen atmosphere. Self-assembled coral-like CoAl LDH nanostructures via the homogeneous precipitation method were also inspected under different ammonia-releasing reagents and solvents. Benzene and toluene were chosen as probe molecules to evaluate their catalytic performance over the metal oxide CoCoO and CoAlO calcined from their corresponding LDH precursors. Nanocatalyst of trivalent Co ions replaced Al(3+) ions in the bruited-like layer had a higher catalytic activity (T99(benzene) = 210 °C and T99(toluene) = 220 °C at a space velocity = 60 000 mL g(-1) h(-1)). Raman spectroscopy, XPS and H2-TPR demonstrated the existence of abundant high valence Co ions that serve as active sites. TPD verified the types of active oxygen species and surface acid properties. It was concluded that the high valence Co ions induced excellent low-temperature reducibility. Surface Lewis acid sites and the surface Oads/Olatt molar ratio (0.61) played relevant roles in determining its catalytic oxidation performance. Our design in this work provides a promising approach for the development of nanocatalysts with exposed desirable defects.

No abstract

No abstract

No abstract

A HKUST-1 metal–organic framework membrane was constructed on porous Al2O3 granules for the first time for the removal of low concentration CH3SH.

No abstract

We present a general and facile synthesis strategy, on the basis of metal-ammine complex chemistry, for synthesizing hollow transition-metal oxides (Co O , NiO, CuO-Cu O, and ZnO)/nitrogen-doped graphene hybrids, potentially applied in high-performance lithium-ion batteries. The oxygen-containing functional groups of graphene oxide play a prerequisite role in the formation of hollow transition-metal oxides on graphene nanosheets, and a significant hollowing process occurs only when forming metal (Co , Ni , Cu , or Zn )-ammine complex ions. Moreover, the hollowing process is well correlated with the complexing capacity between metal ions and NH molecules. The significant hollowing process occurs for strong metal-ammine complex ions including Co , Ni , Cu , and Zn ions, and no hollow structures formed for weak and/or noncomplex Mn and Fe ions. Simultaneously, this novel strategy can also achieve the direct doping of nitrogen atoms into the graphene framework. The electrochemical performance of two typical hollow Co O or NiO/nitrogen-doped graphene hybrids was evaluated by their use as anodic materials. It was demonstrated that these unique nanostructured hybrids, in contrast with the bare counterparts, solid transition-metal oxides/nitrogen-doped graphene hybrids, perform with significantly improved specific capacity, superior rate capability, and excellent capacity retention.

Low concentration CH3SH adsorption by MOF-199 with controllable size and shape.