麻豆淫院

A study conducted by researchers at the University of S茫o Paulo (USP) in Brazil and the Universit脿 degli Studi di Roma "La Sapienza" in Italy has synthesized fullerenes and hollow spherical graphene particles using only natural graphite, ethanol, water, and sodium hydroxide under ambient conditions. in the journal Diamond and Related Materials, the research showed the feasibility of producing structures that previously required extremely high temperatures using an electrochemical route.

"Our work indicates that it's possible to obtain fullerenes, including so-called giant fullerenes, with up to 190 carbon atoms through a simple electrochemical process, without catalysts or high temperatures," says Jos茅 Mauricio Rosolen, a USP researcher, professor at the Department of Chemistry at the Ribeir茫o Preto Faculty of Philosophy, Sciences, and Letters (FFCLRP-USP), and coordinator of the study.

"This method paves the way for new forms of organic synthesis and technological applications that are still unexplored," the researcher predicts.

Fullerenes are spherical molecules composed entirely of carbon atoms. One famous example is C60, also known as "buckminsterfullerene," because its carbon spheres have the same configuration as the geodesic dome created by American designer, architect, and inventor Buckminster Fuller (1895鈥�1983).

Since their discovery in 1985, these structures have been studied for their unique electronic and structural properties. In 2010, fullerenes were detected for the first time in outer space through observations made with NASA's Spitzer Space Telescope. More precisely, they were found in the planetary nebula Tc 1, which is located about 6,000 light-years from Earth.

However, producing fullerenes with more than 100 carbon atoms, known as "giants," under laboratory conditions has remained challenging due to the high temperatures required for carbon atoms to arrange themselves in a spherical configuration, typically in the range of 3,000 掳C to 4,000 掳C.

In the new study, the researchers demonstrated that anodic polarization of graphite in an electrochemical cell induces the formation of likely oxidized graphene sheets that spontaneously self-assemble into fullerenes and hollow spheres. The final product was characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), high-resolution transmission electron microscopy (HRTEM), mass spectrometry (MALDI-TOF), and visible ultraviolet spectroscopy (UV-Vis).

"We observed clusters of spherical particles of various sizes, ranging from soap bubble-like structures measuring 10 nanometers to large deformable spheres measuring up to 320 nanometers trapped between networks of carbon nanotubes," Rosolen says.

The study also used mass spectrometry to identify characteristic peaks of well-investigated fullerenes (C鈧嗏個 and C鈧団個) and larger fullerenes (C鈧佲倓鈧�, C鈧佲倖鈧�, C鈧佲倗鈧�, and C鈧佲倝鈧�). Successive peaks, separated by approximately 160 units, indicate fragmentation due to the loss of C鈧佲倐 groups. This suggests the presence of hierarchical assembly processes.

"The formation of the structures critically depends on the presence of hydroxyl radicals [鈼廜H] and hydroxyl ions [OH鈦籡, generated by the electrochemical oxidation of water and the effect of ethanol. These radicals attack the edges and defects of graphite, fragmenting the sheets and promoting the exfoliation of the material," Rosolen explains.

The article shows that when the applied electrical voltage exceeds 10 V, the production of fullerenes decreases dramatically, and carbon nanodots (quantum dots) predominate over spherical structures. The results suggest that the self-assembly of oxidized graphene into fullerenes hinges on a delicate balance of several factors: the concentration of 鈼廜H radicals and OH鈦� ions, the type and size of graphite particles used, polarization time, and applied voltage.

The presence of oxygenated functional groups in the structures was also observed. Depending on the desired application, these groups may facilitate future chemical modifications. Since the entire process takes place in a liquid medium, adding other components of interest is easy.

"With this work, we've opened up the possibility of producing giant fullerenes via an accessible and environmentally friendly electrochemical route," says Rosolen. "There's still much to understand about the formation mechanisms of these structures, but the results are promising."