Singh Manjri, Saini Pooja, Singh Bhanu P, Singh Priti, Tandon Ram P, Mahapatro Ajit K, Singh Surinder P
AcSIR-Academy of Scientific and Innovative Research, CSIR-National Physical Laboratory Campus, New Delhi 110012, India.
Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India.
J Nanosci Nanotechnol. 2018 Mar 1;18(3):1763-1771. doi: 10.1166/jnn.2018.14319.
The tuneability of oxygen containing groups in graphene oxide (GO) that controls physicochemical properties is highly desirable for device applications. In this context, the thermally reduced graphene oxide (r-GO) powders and spin coated thin films with varying sp2/sp3 carbon network have been prepared using highly exfoliated GO (synthesized using modified Hummer's method with an innovative conjunction of lyophilisation). The additional step of lyophilisation results in the formation of highly exfoliated and monodispersed GO nanosheets as evidenced from FESEM, TEM, XRD, and Raman, FT-IR and UV-Vis spectroscopy. Spectroscopic analysis revealed the systematic evolution of r-GO with tuneable structural, optical and electrical properties as results of varying annealing temperatures (100-400 °C), due to restoration of sp2 conducting carbon network i.e., the formation of new -C═C- network and Stones-Wales defect. The tuneability of physical properties is further corroborated by change in the resistance values, as evidenced through the current-voltage characteristics in GO thin film based lateral device structures with Ag and Al top contacts. Controlling physicochemical properties at relatively low processing temperature warrants the utilization of GO and r-GO in various electronic and optoelectronic devices.
对于器件应用而言，氧化石墨烯（GO）中含氧基团的可调控性对控制其物理化学性质非常重要。在此背景下，利用高度剥离的GO（采用改良的Hummer法结合创新的冻干法合成）制备了具有不同sp2/sp3碳网络的热还原氧化石墨烯（r-GO）粉末和旋涂薄膜。冻干的额外步骤导致形成高度剥离且单分散的GO纳米片，这一点通过场发射扫描电子显微镜（FESEM）、透射电子显微镜（TEM）、X射线衍射（XRD）、拉曼光谱、傅里叶变换红外光谱（FT-IR）和紫外可见光谱（UV-Vis）得以证实。光谱分析表明，由于sp2导电碳网络的恢复，即新的-C═C-网络和斯通-威尔士缺陷的形成，r-GO的结构、光学和电学性质随着退火温度（100-400°C）的变化而系统演变。通过基于GO薄膜的具有银和铝顶部接触的横向器件结构中的电流-电压特性所证明的电阻值变化，进一步证实了物理性质的可调控性。在相对较低的加工温度下控制物理化学性质，保证了GO和r-GO在各种电子和光电器件中的应用。
