No abstract

Few-layer graphenes (FLG) produced by dispersion and exfoliation of graphite in N-methylpyrrolidone were successfully functionalized using the 1,3-dipolar cycloaddition of azomethine ylides. The amino functional groups attached to graphene sheets were quantified by the Kaiser test. These amino groups selectively bind to gold nanorods, which were introduced as contrast markers for the identification of the graphene reactive sites. The interaction between gold nanorods and functionalized graphene was followed by UV-vis spectroscopy. The presence of the organic groups was confirmed by X-ray photoelectron spectroscopy and thermogravimetric analysis. The sheets were characterized by transmission electron microscopy, demonstrating the presence of gold nanorods distributed uniformly all over the graphene surface. This observation indicates that reaction has taken place not just at the edges but also at the internal C horizontal lineC bonds of graphene. Our results identify exfoliated graphene as a considerably more reactive structure than graphite and hence open the possibility to control the functionalization for use as a scaffold in the construction of organized composite nanomaterials.

Effective techniques to reduce graphene oxide are in demand owing to the multitude of potential applications of this two-dimensional material. A very promising green method to do so is by exposure to ultraviolet irradiation. Unfortunately, the dynamics behind this reduction remain unclear. Here we perform a series of transient absorption experiments in an effort to develop and understand this process on a fundamental level. An ultrafast photoinduced chain reaction is observed to be responsible for the graphene oxide reduction. The reaction is initiated using a femtosecond ultraviolet pulse that photoionizes the solvent, liberating solvated electrons, which trigger the reduction. The present study reaches the fundamental time scale of the ultraviolet photoreduction in solution, which is revealed to be in the picosecond regime.

Hf-based hybrid photoresist materials with three different organic ligands were prepared by a sol-gel based method and their patterning mechanism was investigated in detail. All hybrid nanoparticle resists are patternable using UV exposure. Their particle sizes show a dramatic increase from the initial 3-4 nm to sub-micron size after exposure, with no apparent inorganic content or thermal properties change detected. XPS results showed that the mass percentage of the carboxylic group in the structure of nanoparticles decreased with increasing exposure duration. The particle coarsening sensitivities of those hybrid nanoparticles are consistent with their EUV performance. The current work provides an understanding for the development mechanism and future guidance for the design and processing of high performance resist materials for large-scale microelectronics device fabrication.