Small" carbon nano-onions (CNOs) are spherical, ca. 5 nm in diameter, concentric shells of graphitic carbon that can be also described as multi-shelled fullerenes. Given the easy functionalization and high thermal stability of the CNOs produced from nanodiamond, they are the most obvious choice for studying the potential applications of these multi-shelled fullerenes in electrochemical supercapacitors (ES). Since limited accessibility of the carbon surface to electrolyte penetration is observed for carbon nano-onions, performance enhancement was accomplished by modifying the CNO surfaces with pseudocapacitive redox materials: Ni(OH) 2 and NiO. These composites were characterized by TEM, SEM, XRD, TGA-DTG-DTA and Raman spectroscopy. The electrochemical properties of these composites were also investigated. Compared with pristine CNOs (30.6 F g À1 at 5 mV s À1 ), modified CNOs (1225.2 F g À1 for CNOs/Ni(OH) 2 and 290.6 F g À1 for CNOs/NiO, both at 5 mV s À1 ) show improved electrochemical performance, promising for the development of supercapacitors.

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The asymmetric unit of the title compound, [Ru(C15H11N3)2](ClO4)2·0.5H2O, contains one ruthenium–terpiridine complex cation, two perchlorate anions and one half-mol­ecule of water. Face-to-face and face-to-edge π-stacking inter­actions between terpyridine units [centroid–centroid distances = 3.793 (2) and 3.801 (2)  Å] stabilize the crystal lattice The partially occupied water mol­ecule inter­acts with two perchlorate ions via O—H⋯O hydrogen bonds. In the crystal lattice, the complex cations, perchlorate ion-water pairs and the second perchlorate anions are arranged into columns along b direction.

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The photodecolourization of Direct Yellow 9, a member of the group of azo dyes which are commonly used in the various branches of the industry, was investigated. The photostability of this dye was not previously examined. Photocatalytic degradation method was evaluated. Solar simulated light (E=500 W/m2), titanium dioxide, and zinc oxide were used as irradiation source and photocatalysts, respectively. Kinetic studies were performed on a basis of a spectrophotometric method. Degradation efficiency was assessed by applying high performance liquid chromatography. Disappearance of a dye from titanium dioxide and zinc oxide surfaces after degradation was confirmed by thermogravimetry and Raman microscopy. Direct Yellow 9 was found to undergo the photodegradation with approximately two times higher efficiency when zinc oxide was applied in comparison with titanium dioxide. A simple and promising way to apply the photocatalytic removal of Direct Yellow 9 in titanium dioxide and zinc oxide suspensions was presented.