Pd micro-nanoparticles electrodeposited on graphene/polyimide membrane for electrocatalytic oxidation of formic acid

A novel Pd electrocatalyst with flowerlike micro-nanostructures was synthesized by electrochemical deposition on a flexible graphene/polyimide（Gr/PI） composite membrane and characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD）.The Pd micro-nanoparticles were prepared on a COOH-CNTs/PI membrane as a comparative sample.The XRD and SEM investigations for Pd electrodeposition demonstrate that the particle size of Gr/PI composite membrane is smaller than that of COOH-CNTs/PI membrane,while the uniform and dense distribution of Pd micro-nanoparticles on the Gr/PI composite membrane is greater than that on the COOH-CNTs/PI membrane.The electrocatalytic properties of Pd/Gr/PI and Pd/COOH-CNTs/PI catalysts for the oxidation of formic acid were investigated by cyclic voltammetry（CV） and chronoamperometry（CA）.It is found that the electrocatalytic activity and stability of Pd/Gr/PI are superior to those of Pd/COOH-CNTs/PI catalyst.This is because smaller metal particles and higher dense distribution desirably provide abundant catalytic sites and mean higher catalytic activity.Therefore,the Pd/Gr/PI catalyst has better catalytic performance for formic acid oxidation than the Pd/COOH-CNTs/PI catalyst.

多壁羧基化碳纳米管改性水泥砂浆抗氯离子渗透性能研究

研究了一种多壁羧基化碳纳米管(CNT-COOH)对水泥砂浆抗氯离子渗透性能的影响。为了得到均匀的悬浮液,将CNT-COOH分散在蒸馏水中,再进行超声波处理。分别按水泥质量的0.01%、0.05%和0.10%的CNT-COOH进行配合设计,制备了水泥砂浆试件,并根据RCM法测定了氯离子扩散系数。结果表明:当CNT-COOH掺量从0.01%增加至0.05%,氯离子扩散深度和扩散系数均增加;但CNT-COOH掺量继续增加至0.10%时,氯离子扩散深度和扩散系数大幅下降。此外,压汞试验结果表明,当CNT-COOH掺量为0.10%时,CNT-COOH通过消除大孔和降低孔隙率细化了孔径,使得水泥砂浆的微观结构更加密实。

工业设计用碳纤维与环氧树脂材料的接枝改性研究

基于工业设计用碳纤维的表面改性需求,分别对碳纤维进行了接枝CNT—COOH和接枝CNH-NH2的表面改性处理,对比分析了改性前后碳纤维的结构、显微形貌和界面剪切性能。结果表明,CNT—COOH和CNH—NH2都成功接枝到碳纤维表面,相较于接枝CNH—NH2碳纤维,接枝CNT—COOH碳纤维表面CNTs分布更加均匀,接枝CNT—COOH碳纤维和接枝CNH—NH2碳纤维的接触角都小于未改性碳纤维,接枝CNT—COOH碳纤维具有最小的接触角和最大的表面能。接枝CNT—COOH和接枝CNH—NH2碳纤维的界面剪切强度都高于未改性碳纤维,二者的界面剪切强度分别为83.2、89.4 MPa,断裂模式为混合断裂。

海藻酸钠/CNTs-COOH纳米纤维膜的制备及对Cu^(2+)离子的吸附性能

通过静电纺丝法成功制备了海藻酸钠/CNTs—COOH复合纳米纤维膜。采用扫描电镜、红外光谱、X射线衍射、接触角及力学性能测试对复合纳米纤维膜进行了表征。结果表明,复合纳米纤维膜表面光滑,纤维呈三维杂乱排列;加入CNTs—COOH后,纳米纤维的平均直径略有下降,断裂强度增强,但亲水性大幅提升。Cu^(2+)吸附试验结果表明,溶液pH、Cu^(2+)初始浓度和吸附时间是影响吸附效果的重要因素,Cu^(2+)的最大平衡吸附量可达82.71 mg/g。Cu^(2+)在海藻酸钠/CNTs—COOH复合纳米纤维膜上的吸附符合Langmuir和Freundlich等温吸附模型,从相关系数来看,用Freundlich模型描述更为合理。

羧基碳纳米管对甲基橙溶液的吸附

采用羧基碳纳米管(CNT-COOH)为吸附剂,以甲基橙为模拟污染物,研究了甲基橙在吸附剂上的吸附规律.考察了pH,吸附剂的量,时间,温度对吸附的影响并进一步研究了动力学和热力学.研究结果表明,CNTCOOH对甲基橙具有强烈的吸附作用,吸附行为符合假二阶方程和Langmuir吸附等温模型.通过对吸附过程中的ΔG0、ΔH0、ΔS0等热力学参数的研究,表明吸附过程是一个自发放热过程.溶液的pH值会对吸附容量产生明显的影响,这主要是由于不同的pH值会改变CNT-COOH上的电荷分布.本研究中CNT-COOH在25℃时对甲基橙的吸附量为466.6mg/g.