二氧化锰晶型对MSMFCs阴极电化学性能的影响

海水环境中较低的阴极催化活性严重限制海泥电池(MSMFCs)长期输出功率。碳毡阴极经二氧化锰(MnO_(2))改性可显著提高海泥电池阴极溶氧还原动力学和电化学性能,进而提升电池输出功率。利用水热法合成4种晶型(α、β、γ和δ)MnO_(2)用于海泥电池阴极改性,研究了4种晶型MnO_(2)对海泥电池阴极电化学性能的影响并进行了机理分析。结果表明,与空白对照组相比,4种晶型MnO_(2)均可显著提高阴极抗极化性能、电容性能、交换电流密度和最大输出功率;其中,β-MnO_(2)由于具有高浓度的Mn3+和氧空位,大幅提高了阴极氧还原活性和电化学性能,使比电容最高达846.08 F/m^(2),功率密度最高达700.2 mW/m^(2)。该结果有利于促进设计低溶氧海水条件下海泥电池阴极,进而开发高功率海底原位电源。

室温下介孔MnO2降解低浓度甲醛的研究

以KMnO4和P123为原料采用溶胶-凝胶法在不同条件下制备了介孔MnO2,研究了反应物比和pH对催化剂结构和催化降解性能的影响。合成材料的结构和性能采用XRD、N2吸脱附、FT-IR的测试方法表征。最后讨论了介孔MnO2催化氧化HCHO的影响因素。结果表明,溶胶-凝胶法制备介孔MnO2的最佳条件为:原料配比为10:1,pH值为7。P123和KMnO4合成的介孔MnO2具有较大的比表面积和孔径,且有良好的HCHO催化降解性能。在pH=7的情况下最有利于介孔MnO2的活性稳定;在原料比为10:1情况下生成的介孔MnO2比表面积较大,催化降解性能较强,在10 h内保持在对甲醛的降解率为95%以上。

Analytical optimization for field emission of carbon nanotube array

To optimize field emission (FE) property of carbon nanotube (CNT) array on a planar cathode surface, the Fowler-Nordheim formula has been used to discuss the maximum of the emission current density with the floating sphere model in this paper. The emission current density is dominating as the analytical Fowler-Nordheim function of the intertube distance, and the maximum of the emission current density is deduced and discussed. The results indicate that the intertube distance in CNT array critically affects the field enhancement factor and the emission current density, whose maximum occurs at the intertube distance approximating a tenth of the tube height. Considering the emission current density and the field enhancement factor, the FE can be optimized analytically when the intertube distance is about a tenth of the tube height.