氧化石墨烯还原方法研究进展

综述了当前比较热门和新颖的氧化石墨烯(GO)的还原方法,特别是直接还原剂还原法、微波辅助还原法、紫外辐照还原法等,并对这些还原方法可能存在的问题进行了分析;评述了当前还原氧化石墨烯(RGO)的常用表征方法,如原子力显微镜(AFM)、拉曼光谱(RS)、X射线光电能谱(XPS)、红外(IR)光谱、X射线衍射(XRD)等测试技术。针对当前GO、RGO及石墨烯(GNS)界定不明导致使用较为混乱的状况,通过前期的研究成果及综合分析文献中相关材料的含氧量,提出可通过三者氧含量来大致区分GO、RGO及GNS,即氧含量在20%以上为GO,5%～20%为RGO,5%以下为GNS;此外,还可通过含氧量将GO还原方法划分为温和还原法、强还原法及超强还原法3种类型。文中最后对还原GO的方法进行了展望。     

氧化石墨烯还原方法研究进展

综述了当前比较热门和新颖的氧化石墨烯(GO)的还原方法,特别是直接还原剂还原法、微波辅助还原法、紫外辐照还原法等,并对这些还原方法可能存在的问题进行了分析;评述了当前还原氧化石墨烯(RGO)的常用表征方法,如原子力显微镜(AFM)、拉曼光谱(RS)、X射线光电能谱(XPS)、红外(IR)光谱、X射线衍射(XRD)等测试技术。针对当前GO、RGO及石墨烯(GNS)界定不明导致使用较为混乱的状况,通过前期的研究成果及综合分析文献中相关材料的含氧量,提出可通过三者氧含量来大致区分GO、RGO及GNS,即氧含量在20%以上为GO,5%～20%为RGO,5%以下为GNS;此外,还可通过含氧量将GO还原方法划分为温和还原法、强还原法及超强还原法3种类型。文中最后对还原GO的方法进行了展望。     

氧化石墨烯还原过程中产生的缺陷表征北大核心

采用Hummer法对鳞片石墨进行氧化得到氧化石墨,之后经过超声剥离制备氧化石墨烯,最后在水合肼的作用下还原制备石墨烯。采用红外光谱、紫外-可见光光谱、拉曼光谱和原子力显微镜对还原前后的氧化石墨烯进行表征。发现化学还原可以除去氧化石墨烯表面一部分含氧官能团,但同时也引入一些缺陷,还原之后石墨烯的sp^2域的平均尺寸减小。AFM照片分析发现含氧官能团去除之后会在原来的位置产生空洞,从而导致石墨烯缺陷增加。     

氧化石墨烯还原方法的研究进展

石墨烯的制备对于石墨烯的理论研究和应用研究起着重要的作用,化学氧化还原法是制备石墨烯最为重要的方法之一。综述了近年来氧化石墨烯的还原剂还原法、高温热处理还原法、电化学还原法、溶剂热还原法、催化还原法、微波还原法等多种还原方法,分析了目前各种常用还原方法的优缺点,并进一步提出氧化石墨烯还原方法未来的几个研究方向：还原前后原子结构变化及还原机理研究;新型还原方法或多种还原方法联用的研究;还原氧化石墨烯和制备复合物同时进行的研究。     

石墨烯的氧化还原法制备与表征

采用Hummers法,在浓硫酸、高锰酸钾等氧化剂存在条件下,将石墨粉氧化制备成氧化石墨烯,将氧化石墨溶解于水中,然后用水合肼还原氧化石墨烯后制备得到石墨烯,同时,采用红外光谱、紫外光谱、透射电镜等手段对得到的氧化石墨烯和石墨烯进行了表征。结果表明:制备得到了氧化石墨烯和石墨烯,且二者已经充分剥离。     

还原氧化石墨烯固定化溶菌酶的研究

为了改善游离酶稳定性差、易失活、不易储存等缺点,将还原氧化石墨烯(RGO)作为载体进行溶菌酶固定化研究。考察了溶菌酶浓度、缓冲液pH和固定化时间对固定化酶活力的影响,通过正交实验得出最佳固定化条件,溶菌酶质量浓度为0.5 mg/mL、缓冲液pH为6.0、固定化时间为2 h时,固定化酶的活力最高。固定化酶的最适温度为55℃、最适pH为6.5,热稳定性、耐酸碱性和储存稳定性都比游离酶有所提高。固定化酶的抑菌性明显优于游离酶,对金黄色葡萄球菌、大肠杆菌和白色念珠菌均具有较好的抑制效果。     

基于氢碘酸还原氧化石墨烯的研究

在石墨烯的多种制备方法中,我们选用氧化-还原法制备以保留石墨烯上的某些官能团,获得较高的电导率。我们采用改进Hummers法,以高锰酸钾与石墨粉质量比9∶1为原料,浓硫酸为溶剂更安全高效地制备氧化石墨烯(GO),避免高温氧化时大量破坏石墨的面内共轭结构。采用氢碘酸法、氢碘酸乙醇法、氢碘酸乙酸法三种途径来制备还原氧化石墨烯(r GO),比较发现氢碘酸乙酸还原法是温和高效的还原策略,即在一定量乙酸及55%的氢碘酸的混合液中,氧化石墨烯粉末在40℃下还原2d,其电导率达14600S/m,高于其它两法。通过改进氧化还原条件,制备了仅边缘修饰,面内共轭结构几乎无破坏的石墨烯。制备的r GO在邻二氯苯中能够很好地分散,其后用含溴修饰剂对其进行了边缘修饰,引入了可作为反应位点的溴原子。     

聚苯乙烯/还原氧化石墨烯核壳微球的制备及性能表征

以阳离子聚苯乙烯微球(PS)为核,氧化石墨烯(GO)和PS之间通过静电和π-π作用力进行静电自组装,制备得到聚苯乙烯/氧化石墨烯核壳微球(PS/GO),然后采用氢碘酸(HI)进行还原得到聚苯乙烯/还原氧化石墨烯核壳微球(PS/rGO),采用XRD、SEM、TEM对PS/GO和PS/rGO进行了结构表征。探究了自组装过程条件,例如分散形式(搅拌或超声)、反应时间、GO质量浓度对核壳微球形貌的影响。对不同壳层还原氧化石墨烯(rGO)厚度的PS/rGO复合材料进行了导电性能和热稳定性测试,结果表明,改变壳层rGO的含量,会直接影响复合材料的导电和热性能。由于PS/rGO具有独特的核壳结构,其导电性能和热稳定性相比PS有所提高,电子电阻从PS的17.3Ω降到PS/rGO[m(PS)∶m(rGO)=50∶1]的8.3Ω,PS/rGO的起始热分解温度提高近120℃。     

不同还原程度氧化石墨烯-水性聚氨酯共混膜的性能研究

采用超声得到氧化石墨烯分散液,利用柠檬酸钠、抗坏血酸、L-半胱氨酸及硼氢化钠4种还原剂对氧化石墨烯进行还原,并与水性聚氨酯共混改性,通过实验探究还原后氧化石墨烯/水性聚氨酯复合材料的力学性能、介电性能。结果表明,还原后共混膜的力学性能、介电性等较未还原共混膜都有不同程度的改善,对导电性影响尤为显著,最好的共混膜提高了近1 150倍,充分体现了石墨烯良好的导电性。     

聚苯乙烯/还原氧化石墨烯核壳微球的制备及表征

以阳离子聚苯乙烯微球(PS)为核,氧化石墨烯(GO)和PS之间通过静电和π-π作用力进行静电自组装,制备得到聚苯乙烯/氧化石墨烯核壳微球(PS/GO),然后采用氢碘酸(HI)进行还原得到聚苯乙烯/还原氧化石墨烯核壳微球(PS/rGO),采用XRD、SEM、TEM对PS/GO和PS/rGO进行了结构表征。探究了自组装过程条件,例如分散形式(搅拌或超声)、反应时间、GO质量浓度对核壳微球形貌的影响。对不同壳层还原氧化石墨烯(rGO)厚度的PS/rGO复合材料进行了导电性能和热稳定性测试,结果表明,改变壳层rGO的含量,会直接影响复合材料的导电和热性能。由于PS/rGO具有独特的核壳结构,其导电性能和热稳定性相比PS有所提高,电子电阻从PS的17.3Ω降到PS/rGO[m(PS)∶m(rGO)=50∶1]的8.3Ω,PS/rGO的起始热分解温度提高近120℃。     

氧化石墨烯的酸性还原及其超级电容性能

采用改进的Hummers法制备氧化石墨烯(GO),在酸性条件(pH=5)下以180°C进行水热还原,通过调节水热反应时间来制备不同还原程度的还原氧化石墨烯(RGO)。研究了不同的水热反应时间对RGO结构及超级电容性能的影响。结果表明：控制水热反应时间可以制备出还原程度不同的RGO,在电化学测试中,随着水热反应时间的延长,RGO电极的比电容呈先上升后下降的趋势。当水热反应时间为6 h时,RGO电极表现出最佳的超级电容性能,其在1 A/g电流密度下比电容达到251 F/g,相对于GO电极提高了225%。经过500次充放电循环后,RGO-6电极比电容保持率达到92%,具有优异的循环稳定性。     

还原温度对氧化石墨烯的湿度-甲醛交叉敏感性能的影响

以氧化石墨烯溶胶为前体,通过旋涂工艺制备薄膜型气敏元件,在低温80～180℃下进行热处理,获得系列不同还原程度的还原氧化石墨烯气敏元件,采用XRD、AFM、FT-IR、XPS对样品的层结构、薄膜厚度及含氧官能团变化属性进行表征,将气敏薄膜元件在相对湿度为11.3%～93.6%的范围内进行预湿处理,并测定元件对甲醛气氛的敏感性能。结果表明：随热还原处理温度的升高,氧化石墨烯的结构逐渐向类石墨结构转变,含氧官能团逐渐脱失,缺陷增多,薄膜的方块电阻呈数量级地减小,从41 MΩ减小至928 Ω;经不同湿度预处理的气敏元件置于甲醛气氛中产生了水分子与甲醛分子的竞争吸附,从而导致电阻的明显变化;在10^?4甲醛气氛下,未还原或热还原温度较低的气敏元件适用于低、高湿环境下甲醛气氛的气敏测试,最大灵敏度为69.1%,而还原温度适中的元件则适用于中湿环境的甲醛测试,最大灵敏度为80.3%。     

Properties and structural characterization of oxide starch/chitosan/graphene oxide biodegradable nanocomposites

Novel chitosan (CS)/oxidized starch (OST)/graphene oxide (GO) nanocomposites (COST/GO‐n) films are prepared in a casting and solvent evaporation method. Fourier transform infrared spectroscopy, X‐ray diffractions, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, thermal gravimetric analysis, tensile testing, and moisture uptake are used to study the structure and properties of these nanocomposites. To indicate the effect of carboxyl groups of OST, some results of the properties of CS/starch/GO nanocomposite (CST/GO‐n) were selected for control experimentation. Compared with the control CST/GO‐n series, COST/GO‐n films, which have the same component ration showed higher tensile strength (σ_b) and lower elongation at break (ε_b). Additionally, in the COST/GO‐n series, the σ_b increased with an increase of GO loading. However, higher proportion of GO could result in aggregations of GO nanosheets and deterioration of the film properties. Compared with the COST/GO‐0, the values of σ_b and water resistance of the COST/GO‐4 containing 2.0 wt % of GO were improved by 57.7 and 20.1%, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

氧化石墨烯浸轧-还原法制备导电棉织物

采用超声氧化剥离法制备氧化石墨烯(GO),通过浸轧-还原法得到一种高效、简单制备还原氧化石墨烯(RGO)导电棉织物的方法。探讨了GO质量浓度、GO溶液pH、还原条件、浸轧-还原次数等因素对RGO整理棉织物表面电阻的影响,采用SEM和Raman光谱对整理棉织物进行表征。结果表明,棉织物用质量浓度2.5 g/L、pH=6的GO溶液浸轧后,再用质量浓度5.0 g/L的保险粉于90℃对浸轧GO烘干后的棉织物还原30 min,得到的整理棉织物表面电阻降低至2220?,经过4次和8次浸轧-还原后棉织物表面电阻可分别降低至0.22和0.13 k?。通过SEM观察整理棉织物发现,RGO能在棉纤维表面形成薄膜并包覆纤维,且随着浸轧-还原次数的增加,棉织物表面沉积的RGO逐渐增多。Raman光谱较好地证实了GO在棉织物表面的沉积,且GO较充分地还原成RGO。通过对整理棉织物的耐洗性能测试发现,整理织物的导电耐久性较好。     

Fabrication and characterization of graphene oxide modified polycarboxylic by in situ polymerization

Graphene oxide (GO) was modified by in situ esterification reaction with isopentenol polyoxyethylene ether (IPEG) to obtain GO precursor (GO-IPEG) with some polymerization activity. GO-modified polycarboxylic (GO-PCE) was prepared by GO-IPEG and acrylic acid (AA) using the method of in situ polymerization. The molecular structure of GO-IPEG and GO-PCE was characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectra, and nuclear magnetic resonance (NMR). The dispersion properties and dispersion stability of GO-IPEG and GO-PCE in water solution were studied by ultraviolet–visible (UV–vis) absorption spectra, zeta potential, and atomic force microscope. The results of FTIR, Raman, ¹H-NMR, and ¹³C-NMR indicate that IPEG was successfully grafted onto the surface of GO and then fabricated with AA by in situ free-radical polymerization. The results of UV–vis and zeta potential show that GO nanosheets have a better dispersion in GO-IPEG or GO-PCE system when the reaction time of GO and IPEG is 1 h, and the dispersion stability can reach up to 1 month. The better dispersion and application property are confirmed by atomic force microscopy image and cement fluidity, water reducing rate, and compression strength. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48316.     

Reduced graphene oxide reinforced PET/PBT nanocomposites: Compatibilization and characterization

This research work focused on the effects of different compatibilizers on the properties of reduced graphene oxide (rGO) reinforced poly(ethylene terephthalate) (PET)/poly(butylene terephthalate) (PBT) nanocomposites. The samples were prepared via melt compounding and injection molding methods. The Joncryl and glycidyl isooctyl polyhedral oligomeric silsesquioxane (GPOSS) were used as compatibilizers at different loading levels (0.5%-4%). The structural, thermal, mechanical, morphological, and electrical properties of the nanocomposites were investigated. The Fourier transform infrared analysis results revealed that no significant interaction was observed when GPOSS was added. On the other hand, there were more obvious changes in the peaks of the nanocomposite containing Joncryl. The thermal results showed that the compatibilizer addition caused small changes while rGO addition did not considerably affect the thermal stability of blend. The glass transition temperature of the nanocomposite significantly decreased with the addition of GPOSS. The tensile test indicated that compatibilizers improved the mechanical performance of PET/PBT/rGO nanocomposite.     

Preparation,characterization, and properties of silanized graphene oxide reinforced biobased benzoxazine-bismaleimide resin composites

Silanized graphene oxide (SiGO) was synthesized and characterized using KH570 as a modifier on graphene oxide (GO). Subsequently, high performance silanized graphene oxide/cardanol based benzoxazine (C-fa)-bismaleimide (BMI) resin composites (SiGO/C-fa/BMI) were prepared by blending and step thermal curing. The reaction and dispersion of SiGO in C-fa/BMI matrix were studied by FTIR and XRD. The effects of SiGO on the thermal and mechanical properties of the SiGO/C-fa/BMI composites were investigated. The results shown that SiGO has good dispersity in CFa-BMI matrix. The thermal decomposition temperature and char yield of SiGO/C-fa/BMI composites was improved markedly. Comparing with that of neat C-fa/BMI resin, the young's modulus and tensile strength of SiGO0.5/C-fa/BMI composite increased by 110.8% and 142.0%. The water absorption of SiGO/C-fa/BMI composites also decreased significantly. The great improvement in thermal and mechanical properties of SiGO/C-fa/BMI composites make them as a potential alternative high performance resin composite candidate in aerospace and electronic area.     

还原法制备石墨烯的研究进展及发展趋势

综述了还原法制备石墨烯的研究现状,主要介绍了金属还原、光催化还原、电化学还原、热还原、化学还原试剂还原等方法的研究进展,并指出了还原法制备石墨烯的发展趋势。