The Fabrication And Properties Of Manganese-based Oxides Nanostructured Films

Due to the varieties of the composition and properties of manganese-based oxides, their applications are widely investigated in energy storage and environmental protection fields. Compared with pulverous nano materials, nanostructured film materials grown on conducting substrates exhibit enhanced performance in both lithium-ion batteries (LIBs) and catalysis technology because of their larger specific surface area, higher active sites and faster charge transportation. Moreover, it is very convinent to recycle nano nanostructured film materials. In this article, hydrolysis and etching mechanism is successfully employed to design the synthesis of MnO nanosheet arrays on Ni substrate and CuMnO2 nanowall arrays on Cu substrate. Their performances in lithium-ion batteries (LIBs) and catalysis technology have been investigated respectively. The main points are summarized as follows:1. MnO nanosheet arrays fabricated on Ni substrate is produced by the hydrolysis of Mn2+ and the etching of Ni substrate in hydrothermal environment with a subsequent sintering reduction process. Through changing the manganese salts, manganese-based oxides with different morphology can be obtained. The as-prepared free-standing MnO nanosheet arrays on Ni substrate as anode can deliver high rate capability (414 mAh g-1 at 5 C) and good cyclability (690 mAh g-1 after 200 cycles at 0.2 C), demonstrating their excellent electrochemical performance in lithium-ion batteries. A MnO-limited full cell has been assembled directly by adjusting the positive/negative capacity ratio of 1.2:1, which could deliver a discharge capacity of 560 mAh g-1 at 0.2 C rate. The MnO/ LiNi1/3Co1/3Mn1/3O2 full cell exhibits good cycle stability (with capacity retention of 92% at 0.5 C over 50 cycles) and superior rate capability (about 180 mAh g-1 at a high rate of 10 C), which are mainly resulted from the reasonable match between MnO arrays directly constructed on nickle substrate and the hierarchical structured LiNi1/3Co1/3Mn1/3O2 cathode materials.2. CuMnO2 nanowall arrays on copper foils have been successfully synthesized through the reaction of CuO nanosheet arrays with manganese chloride aqueous solution based on hydrolysis and etching mechanism under hydrothermal environment. The as-prepared CuMnO2 nanowall arrays as catalysts exhibit superior catalytic oxidation activity (96.24%) for degradation of methylene blue (MB) dye aqueous solution compared to bare CuO nanosheet arrays (30.88%) in the presence of H2O2. Effects of initial concentration of MB aqueous solution and H2O2 dosage on the catalytic oxidation performance were evaluated, indicating the degradation ratio of MB dye at 20 mg/L is superior to the other concentrations and dilute solution of H2O2 at 0.8 mL is economical to other dosages. The CuMnO2 nanowall array films catalysts show excellent stable catalytic activity in scale-up systems, and MB degradation ratio in life cycle performance varies from 96.24% of the first run to 87.5% of the sixth run, demonstrating an excellent cycle performance and potential engineering application of the CuMnO2 nanowall array films grown on copper substrates for waste water treatment.