Jing Zhang,Jiajie Huang,Liang Wang,Peiheng Sun,Peijia Wang,Zhujun Yao,Yefeng Yang
As promising electrode materials for supercapacitors, metal-organic frameworks (MOFs) with rich porosity, large surface area and abundant redox sites have attracted increasing attention. Nevertheless, the intrinsically interior electrical conductivity and ease of agglomeration for most MOFs have largely restricted their energy storage application. In this work, we report the controlled fabrication of bimetallic NiMn-MOF nanosheets on the surface of NiCo 2 O 4 nanowire arrays to form NiCo 2 O 4 @NiMn-MOF core-shell structure and investigate the effect of Mn incorporation in Ni-MOF shell on the electrochemical performance of the hybrid arrays in supercapacitors. Benefitting from the delicately designed structures and compositions, the optimal NiCo 2 O 4 @NiMn-MOF electrode presents an extraordinarily high specific capacity of 243.0 mAh/g at 2 mA/cm 2 . We further assembled a flexible solid-state hybrid supercapacitor with NiCo 2 O 4 @NiMn-MOF and activated carbon as electrodes, exhibiting a high energy density of 48.2 Wh/kg at 1606.7 W/kg, accompanied by excellent mechanical flexibility and electrochemical durability. This work demonstrates a new approach for developing novel MOF array-based electrode materials with boosted electrochemical performance in the field of flexible energy storage devices.
The catalytic oxidative depolymerization of lignin and its dimers is key for the effective utilization of biomass. In this work, a metal–organic framework (MOF) was chosen as the precursor, and a series of nickel–manganese bimetallic catalysts with different metal ratios were prepared via a hydrothermal method using 1,3,5-tricarboxylic acid as the ligand. The effects of metal ratio and calcination temperature on the activity of the catalyst were considered, and the oxidative depolymerization of the lignin dimer (2-phenoxy-1-acetophenone) was investigated in detail. The selective conversion of 2-phenoxy-1-acetophenone was achieved over the Ni2Mn1-MOF catalyst in an oxygen atmosphere with methanol as the solvent. Through the optimization of different reaction parameters, including reaction temperature, oxygen pressure, reaction time and solvent, it was found that under optimal reaction conditions (140 °C, 4 h, 0.5 MPa O2), the Ni2Mn1-MOF catalyst exhibited a good catalytic performance for the efficient conversion of 2-phenoxy-1-acetophenone to phenol and methyl benzoate. Furthermore, its specific reaction mechanism was discussed based on the distribution of products in the lignin dimer oxidation process, which was useful for understanding the further oxidative depolymerization of lignin.
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