Nanotube-Like Electronic States in [5,5]-C90 Fullertube Molecules

Fullertubes, that is, fullerenes consisting of a carbon nanotube moiety capped by hemifullerene ends, are emerging carbon nanomaterials whose properties show both fullerene and carbon nanotube (CNT) traits. Albeit it may be expected that their electronic states show a certain resemblance to those of the extended nanotube, such a correlation has not yet been found or described. Here it shows a scanning tunneling microscopy (STM) and spectroscopy (STS) characterization of the adsorption, self-assembly, and electronic structure of 2D arrays of [5,5]-C90 fullertube molecules on two different noble metal surfaces, Ag(111) and Au(111). The results demonstrate that the shape of the molecular orbitals of the adsorbed fullertubes corresponds closely to those expected for isolated species on the grounds of density functional theory calculations. Moreover, a comparison between the electronic density profiles in the bands of the extended [5,5]-CNT and in the molecules reveals that some of the frontier orbitals of the fullertube molecules can be described as the result of the quantum confinement imposed by the hemifullerene caps to the delocalized band states in the extended CNT. The results thus provide a conceptual framework for the rational design of custom fullertube molecules and can potentially become a cornerstone in the understanding of these new carbon nanoforms.

The Rise of Hydrogen Peroxide as the Main Product by Metal-Free Catalysis in Oxygen Reductions

One of the recent trends in electrocatalytic reactions involves the oxygen reduction reaction (ORR), where a new paradigm has been shaped to exploit this reaction for the synthesis of hydrogen peroxide (H₂ O₂ ). H₂ O₂ is a very versatile chemical of high commercial value, prepared currently through poorly sustainable processes. The emergence of metal-free carbon catalysts for the selective synthesis of H₂ O₂ is expected to revolutionize ORR research, beckoning at the development of new industrial schemes. The complexities of the mechanism and the factors dominating the selectivity of the process have been unveiled through a combination of theoretical and experimental studies.