Aerobic oxidation of cyclohexene over [Cu 2 (OH)(BTC)(H 2 O)] n ?2nH 2 O (Cu-MOF, BTC = 1,3,5benzenetricarboxylic acid) and [M 2 (DOBDC)(H 2 O) 2 ]?8H 2 O (Co-and Ni-MOF, DOBDC = 2,5dihydroxyterephthalic acid) in the absence of solvent under mild conditions was studied. It is observed that both Cu-MOF and Co-MOF can selectively oxidize cyclohexene to give 2-cyclohexen-1-ol and 2-cyclohexen-1-one as the main products, while Ni-MOF is totally inactive for cyclohexene oxidation. The mechanism of the catalytic oxidation of cyclohexene over Cu-MOF and Co-MOF has been proposed. These MOF-based catalysts are stable and recyclable under current reaction conditions. This study highlights the great potential of developing MOFs as highly stable, molecularly tunable, recyclable and reusable heterogeneous catalysts for alkenes oxidation.

The compressive toughness evaluation index of HDC (high ductile fiber reinforced concrete) is studied through three groups of uniaxial compressive tests of HDC specimens with different fiber mixing amounts, and an equivalent analysis of their deformability is carried out, coming to the following conclusion:(1)the peak strain of HDC under uniaxial compression can be up to 3.41~3.67 times as large as that of the mortar matrix;(2)the equivalent compressive toughness index reflects the unit volume deformation energy of specimens under uniaxial compression and it can be used as the compressive toughness evaluation index of HDC;(3)the fiber bridging effect of HDC increases the equivalent compressive toughness index and the compressive deformability up to 3 times of the mortar matrix;(4)the relationship between the equivalent compressive toughness indexWcu0.85and the fiber mixing amountφis established according to the test results; and(5)the fiber bridging effect of the matrix in HDC can be equaling as a large number of constraint stirrups installed in the specimens, which significantly enhances the compressive toughness and the compressive deformability of specimens.

This work reports on the synthesis of rare earth-doped Li4Ti5O12 nanosheets with high electrochemical performance as anode material both in Li half and Li4Ti5O12/LiFePO4 full cell batteries. Through the combination of decreasing the particle size and doping by rare earth atoms (Ce and La), Ce and La doped Li4Ti5O12 nanosheets show the excellent electrochemical performance in terms of high specific capacity, good cycling stability and excellent rate performance in half cells. Notably, the Ce-doped Li4Ti5O12 shows good electrochemical performance as anode in a full cell which LiFePO4 was used as cathode. The superior electrochemical performance can be attributed to doping as well as the nanosized particle, which facilitates transportation of the lithium ion and electron transportation. This research shows that the rare earth doped Li4Ti5O12 nanosheets can be suitable as a high rate performance anode material in lithium-ion batteries.

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Reasonable design and feasible preparation of low-cost and stable oxygen reduction reaction (ORR) catalysts with excellent performance play a key role in the development of fuel cells and metal−air batteries. A 3D porous superimposed nanosheet catalyst composed of metal manganese covered with MnO 2 nanofilms (P-NS-MnO 2 @Mn) was designed and synthesized by rotating disk electrodes (RDEs) through one-step electrodeposition. The catalyst contains no carbon material. Therefore, the oxidation and corrosion of the carbon material during use can be avoided, resulting in excellent stability. The structural and composition characterizations indicate that the nanosheets with sharp edges exist on the surface of the wall surrounding the macropore (diameter ∼ 5.07 μm) and they connect tightly. Both the nanosheets and the wall of the macropore are composed of metal manganese covered completely with MnO 2 film with a thickness of less than 5 nm. The half-wave potential of the synthesized P-NS-MnO 2 @Mn catalyst is 0.86 V. Besides, the catalyst exhibits good stability with almost no decay after a 30 h chronoamperometric test. Finite element analysis (FEA) simulation reveals the high local electric field intensity surrounding the sharp edges of the nanosheets. Density functional theory (DFT) calculations reveal that the novel nanosheet structure composed of MnO 2 nanofilms covered on the surface of the Mn matrix accelerates the electronic transfer of the MnO 2 nanofilms during the ORR process. The high local electric field intensity near the sharp edge of the nanosheets effectively promotes the orbital hybridization and strengthens the adsorbing Mn−O bond between the active site Mn in the nanosheets and the intermediate OOH* during the ORR process. This study provides a new strategy for preparing transition metal oxide catalysts and a novel idea about the key factors affecting the catalytic activity of transition metal oxides for the ORR.