The Preparation Of Co-/Mn- Perovskite Oxides By Electrospinning And Study On Their Photocatalytic Water Oxidation Performance

To meet the growing global demand for energy is an important challenge for the 21st century. Currently, more than 80%of the energy supply is from the burning of fossil fuels, which not only leads to the greenhouse effect, but also causes all sorts of harm to the environment. In addition, fossil fuels are non-renewable energy, and ultimately also depleted because of the increasing consumption. Therefore, we urgently need a clean, reusable, low and new energy. Solar energy is a steady stream of clean energy which can be used by photocatalytic water splitting to split water into oxygen and hydrogen. From the point of view of sustainable development, photocatalytic water splitting is an effective way to solve the energy problem!Currently the development of efficient catalysts is a big challenge for the photocatalytic water splitting! Urmimala Maitra studied a series of Mn and Co oxides and found spinel Li2Co2O4 and perovskite LaCoO3 containing trivalent Co3+(t2g5eg1) exhibiting high catalytic activity in water oxidation. Manganese oxides containing Mn3+(t2g5eg1), the bixbyite Mn2O3, perovskite LaMnO3 and spinel MgMniO4, also show good catalytic effect.To improve the catalytic activity, we prepared Lao.7Sro.3Mn03 and LaCoO3 by electro spinning method combined with heat treatment. For La0.7Sr0.3MnO3, we prepared hollow balls by three ways of regulating the ratio of inorganics and polymer PVP, the calcination temperature and heating rate. By means of SEM, TEM, XRD, we find the sample is 1-2μm, hexagonal perovskite structure and space group R3c. We performed the photocatalytic water oxidation tests for Lao.7Sro.3Mn03 hollow microspheres prepared by electro spinning and nanoparticles prepared by direct sol-gel. The results show Lao.7Sro.3Mn03 hollow spheres have longer catalyst life. For LaCoO3, we prepared a series of samples by adjusting the calcination temperature. SEM shows that the temperature has an effect on the morphology of samples. Photocatalytic water oxidation tests show the highest catalytic effect is sample obtained at 500℃. BET datas show that the sample prepared at 500℃ has the highest ratio surface area. After correction by BET, the best production of oxygen per unit surface area is sample obtained at 800℃, and the amount of oxygen produced per unit surface area is gradually reduced with the decrease of calcination temperature. Combined XPS and XRD datas, we concluded that in addition to BET, the crystallinity of the crystalline also plays an important role in catalytic properties of samples, enhancing the crystallinity beneficial to catalytic effect of catalysts.