Analysis of CO_3O_4/ Mildly Oxidized Graphite Oxide(mGO)Nanocomposites of Mild Oxidation Degree for the Removal of Acid Orange 7

In this study,a series of Co_3O_4/ mildly oxidized graphite oxide(mGO) nanocatalysts(Co_3O_4/ mGO-l,Co_3O_4/ mGO-2 and Co_3O_4/mGO-3) were synthesized through solvothermal method and used as a mediator for the heterogeneous peroxymonosulfate(PMS)activation.The performance of CO_3O_4 / mGO/PMS system was investigated using acid orange 7(AO7).Results showed that Co_3O_4/mGO-3 had the best degradation efficiency of AO7 and the removal rate was above 90%in about 6 min.The phenomenon indicated the catalytic activity of Co_3O_4/mGO composites was related to the oxidation degree of graphite oxide(GO).In addition,experiments showed the content of Co_3O_4 had an effect on the catalytic activity.The composites were characterized with X-ray powder diffraction(XRD),FTIR,Raman,X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM).According to the charactrization and synergistic catalytic mechanism,the generation of Co—OH complexes found to be the initial step to activate PMS in the heterogeneous system of Co_3O_4/mGO hybrid.

TiO_2-GR/MgO的制备及降解刚果红性能研究

采用超声溶胶-凝胶法制备了新型复合光催化剂TiO_2-GR/MgO。采用XRD、SEM、PL、UV-Vis等手段对制备的催化剂进行了表征,并在太阳光下考察了TiO_2-GR/MgO对刚果红的光催化降解性能。结果表明:在TiO_2-GR/MgO中,TiO_2只有锐钛矿型,石墨和MgO的加入有效阻碍了电子/空穴的复合速率,拓宽了复合光催化剂的光谱响应范围,提高了催化剂对可见光的吸收效率。当反应时间为80 min,TiO_2-GR/MgO投加量为2.5 g/L时,在太阳光照射下刚果红去除率可达97.6%。

不同粒度的鳞片石墨对低碳镁碳耐火材料性能的影响

以电熔镁砂和不同粒度的鳞片石墨(分别为100目、1000目和100目+1000目混合型)为主要原料,制备了低碳MgO-C材料,研究了鳞片石墨粒度对低碳镁碳耐火材料的物理性能、抗氧化性能、导热性能及热膨胀性能的影响。结果表明:不同粒度的混合型石墨作为碳源,可以有效改善低碳MgO-C材料的物理性能。综合各个温度试验结果,含有混合型石墨的试样抗氧化效果最好,含混合型石墨的试样热导率最大,只含1000目石墨的试样热导率最小,500℃以上含有混合型石墨的试样膨胀率最大。

膨胀石墨对镁碳耐火材料显微结构和性能的影响

以膨胀石墨为碳源,部分取代镁碳耐火材料(含5wt%的鳞片石墨)中的鳞片石墨,借助X射线衍射仪、场发射扫描电镜、能谱仪以及三点弯曲测试仪等研究了膨胀石墨的添加对热处理后镁碳材料的显微结构、力学性能、抗热震性和抗氧化性的影响。结果表明:镁碳材料中引入0.2wt%的膨胀石墨在高温下可促进材料基体内片状Al N相形成,进而使试样的抗折强度和弯曲模量达到最大,分别为12.35 MPa和2.82 GPa;但是过量的添加将对材料的致密度产生负面影响,从而降低了材料的抗折强度和弯曲模量;膨胀石墨的添加显著提高了镁碳材料的抗热震性但对材料的抗氧化性不利;当膨胀石墨的加入量为0.5wt%时,镁碳材料的综合性能最好,若想加大膨胀石墨的添加量,需对其抗氧化性进行改善。

石墨粒度对低炭镁炭砖性能的影响

以电熔镁砂和4种粒度(≤0.149mm、 ≤0.074mm、≤0.044mm和≤0.01mm)的天然鳞片 石墨为主原料,在石墨含量为4%的条件下,研究了 石墨粒度对低炭镁炭砖的物理性能、抗氧化性和热震 稳定性的影响。结果表明:用细石墨取代较粗石墨 (粒度≤0.149mm)制成的镁炭砖,其物理性能、抗氧 化性和热震稳定性都有了明显的改善,且都以加入粒 度≤0.074mm石墨的效果最好。其原因是细石墨的 加入改善了镁炭砖的基质结构。

Constructing mild expanded graphite microspheres by pressurized oxidation combined microwave treatment for enhanced lithium storage

The modified graphite anode materials have some prominent advantages over other anode materials in the industrial applications.A novel simple and gentle method is proposed to synthesize the mild expanded graphite microspheres(MEGMs) from flake graphite spheres through a combined modified pressurized oxidation combined with the microwave treatment.The microstructural results demonstrate that moderately expanded MEGMs with an expansion volume between 4 and 10 ml·g^(-1)exhibit a highly microporous structure with an enlarged interlayer spacing,a decreased microcrystalline size,as well as an increased number of functional groups on the surface,resulting in the increased storage sites and spaces for lithium ions and the enhanced diffusion rate of lithium ions.When used as the anode material for lithium-ion batteries,the MEGM-T75t30 obtained by oxidation treatment at 75℃ for 30 min followed by microwave irradiation for expansion displays a high reversible capacity of 446.7 mAh·g^(-1) at 100 mA·g^(-1) after 100 cycles and excellent rate performance(330 and 116 mAh·g^(-1) at 800 and 3200 mA·g^(-1),respectively).Therefore,the MEGMs prepared by this convenient and mild method show excellent electrochemical properties and good application potential.

氧化微扩层处理对天然鳞片石墨结构及其电化学性能的影响研究

研究了氧化微扩层处理对天然鳞片石墨晶体结构、表面形貌及其电化学性能的影响。结果表明,经氧化微扩层处理后,鳞片石墨的平均层间距d002略微增大,平均晶粒尺寸显著减小,鳞片石墨颗粒表面出现刻蚀和片层剥落现象。氧化微扩层处理1 h后,鳞片石墨的首次可逆容量从331.9 m A·h/g提高至364.7 m A·h/g,首次库伦效率从86.5%提高至88.8%。经过氧化微扩层处理,石墨的平均晶粒尺寸减小,锂离子在碳层表面及边缘嵌入量增加;在石墨表面引入的纳米级孔隙结构进一步增大了锂离子存储空间;同时,对表面细小颗粒的刻蚀清除,使石墨比表面积减小,是可逆容量和首次库伦效率提高的主要原因。