Kumar Prabhat, Šilhavík Martin, Zafar Zahid Ali, Červenka Jiří
Department of Thin Films and Nanostructures, Institute of Physics of the Czech Academy of Sciences, Cukrovarnická 10/112, Prague 162 00, Czech Republic.
J Phys Chem C Nanomater Interfaces. 2023 May 30;127(22):10599-10608. doi: 10.1021/acs.jpcc.3c01534. eCollection 2023 Jun 8.
The production of highly stable, defect-free, and electrically conducting 3D graphene structures from graphene oxide precursors is challenging. This is because graphene oxide is a metastable material whose structure and chemistry evolve due to aging. Aging changes the relative composition of oxygen functional groups attached to the graphene oxide and negatively impacts the fabrication and properties of reduced graphene oxide. Here, we report a universal strategy to reverse the aging of graphene oxide precursors using oxygen plasma treatment. This treatment decreases the size of graphene oxide flakes and restores negative zeta potential and suspension stability in water, enabling the fabrication of compact and mechanically stable graphene aerogels using hydrothermal synthesis. Moreover, we employ high-temperature annealing to remove oxygen-containing functionalities and repair the lattice defects in reduced graphene oxide. This method allows obtaining highly electrically conducting graphene aerogels with electrical conductivity of 390 S/m and low defect density. The role of carboxyl, hydroxyl, epoxide, and ketonic oxygen species is thoroughly investigated using X-ray photoelectron and Raman spectroscopies. Our study provides unique insight into the chemical transformations occurring during the aging and thermal reduction of graphene oxide from room temperature up to 2700 °C.
从氧化石墨烯前驱体制备高度稳定、无缺陷且导电的三维石墨烯结构具有挑战性。这是因为氧化石墨烯是一种亚稳态材料，其结构和化学性质会因老化而发生变化。老化会改变附着在氧化石墨烯上的氧官能团的相对组成，并对还原氧化石墨烯的制备和性能产生负面影响。在此，我们报道了一种使用氧等离子体处理来逆转氧化石墨烯前驱体老化的通用策略。这种处理减小了氧化石墨烯薄片的尺寸，并恢复了其负ζ电位以及在水中的悬浮稳定性，从而能够通过水热合成制备致密且机械稳定的石墨烯气凝胶。此外，我们采用高温退火来去除还原氧化石墨烯中的含氧官能团并修复晶格缺陷。该方法能够获得电导率为390 S/m且缺陷密度低的高导电石墨烯气凝胶。使用X射线光电子能谱和拉曼光谱对羧基、羟基、环氧基和酮基氧物种的作用进行了深入研究。我们的研究为氧化石墨烯从室温到2700°C的老化和热还原过程中发生的化学转变提供了独特的见解。
