伽马射线辐照制备还原氧化石墨烯

Preparation of reduced graphene oxide via gamma-ray irradiation

在氮气气氛中,以乙二胺(EDA)作为自由基捕获剂,利用γ射线辐照技术在水体系中将氧化石墨烯(GO)辐照还原功能化,制备高分散性的氨基功能化还原氧化石墨烯(rGO)。考察吸收剂量(5.3、15、20、35.3 kGy)对rGO还原程度和功能化程度的影响,并通过傅里叶变换红外光谱(FT-IR)、紫外-可见光吸收光谱(UV-vis)、X射线光电子能谱(XPS)、X射线衍射(XRD)和热重分析(TGA)等方法分析GO的化学结构及还原程度。直观上看,辐照后,GO溶液逐渐呈现棕黑色,随着吸收剂量的增加,溶液颜色加深,且具有良好分散性。FT-IR谱显示,经过γ射线辐照后,初始GO上的羰基被还原去除,EDA小分子被连接到了rGO片层上。UV-vis、XPS、TGA及XRD谱图表明,随着吸收剂量的增大可以使氧化石墨烯还原程度提高,当吸收剂量35.3 kGy时,C/O可达7.21。EDA有机小分子与氧化性的·OH反应,在无氧条件下转化为还原性的自由基,参与到与GO之间的氧化还原反应中,并被接枝到GO层的表面。

We report here a rapid and cost-effective approach for reduction and functionalization of graphene oxide（GO） using ethylenediamine（EDA） in water medium by gamma-ray irradiation in a nitrogen atmosphere. The reduction degree, which can be controlled by varying the absorbed doses（5.3, 15, 20, and 35.3 kGy）, was investigated in detail by ultra-violet visible（UV-vis） spectroscopy, Fourier transform infrared spectroscopy（FT-IR）, X-ray diffract meter（XRD）, X-ray photoelectron spectroscopy（XPS）, and thermogravimetric analysis（TGA）. It was found that the GO dispersion changed from yellow to black with increasing absorbed doses. The results of FT-IR, UV-vis, TGA, and XPS demonstrated that the reduction degree increased with absorbed dose and modification of GO with N-H from EDA molecules occurred. The rGO dispersion in water was stable without precipitate. The ratio of C/O reached 7.21 in rGO-at 35.3 kGy. In addition, a reduction mechanism for determining interactions among the EDA molecules, active radicals from the radiolysis of water, oxygen-containing groups on GO sheets, and some EDA molecules attached onto the rGO sheet because of the recombination of radicals is proposed.