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Manganese oxide nanofoam prepared by pulsed laser deposition for high performance supercapacitor electrodes
摘要： Manganese oxide nanofoam has been prepared by pulsed laser deposition, from a metallic Mn target in a 5 Torr pressure O2 buffer atmosphere. The as-prepared samples were heat-treated at different temperatures (300?C-500?C) in air. Both as-deposited and heat-treated samples have a high porosity foam-like morphology, as shown by Field Emission Scanning Electron Microscopy. High Resolution Transmission Electron Microscopy revealed that the nanofoam is composed by linked nanoparticles with slight crystallization and growth of the nanoparticles due to heat-treatment, which was confirmed by X-ray diffraction, Raman Spectroscopy and X-ray Photoelectron Spectroscopy. These techniques also showed a variable oxide composition upon heat treatment. The supercapacitive properties of manganese oxide nanofoam treated at 300?C exhibited a specific capacitance higher than 1000 F/g, in the 0 to +1.0 V potential range. After heat treatment at 400?C and 500?C, the specific capacitance decreased compared to that of the 300?C treated sample. An increase of about 130% in the initial capacitance was obtained after 500 cycles for this sample. However, it decreases to one third of the maximum value after 5000 cycles. The results shows that the obtained manganese oxide nanofoam has very high specific capacitance but need to improve the cycle stability.
关键词： microstructures,pulsed laser deposition,porous materials,supercapacitors,nanofoam,manganese oxides
更新于2025-09-11 14:15:04
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TiO2 Nanofoam-Nanotube Array for Surface-Enhanced Raman Scattering
摘要： By tuning the anodic voltage and the electrochemical reaction time, we have synthesized a serial of TiO2 nanofoam-nanotube array structures via a two-step anodic oxidation process. The produced nanofoam-nanotube array demonstrated a remarkable Raman scattering enhancement. The maximum enhancement factors are 2.3×105 for methylene blue. Factors such nanotube pore size, nanofoam and solute concentration have been investigated. The Raman scattering enhancement is attributed to the existence of the nanofoam structure, which enables multiple laser scattering among the periodic voids and allows for the occurrence of Raman scattering. The proposed simple and inexpensive approach can promote the use of TiO2 materials for SERS applications in chemistry, biology and nanoscience.
关键词： nanotube,SERS,nanofoam,anodic oxidation,TiO2
更新于2025-09-10 09:29:36