•Pr@D3h(14246)-C74(C6H3Cl2) was prepared and isolated.•MS and UV–vis-NIR spectroscopy of Pr@D3h(14246)-C74(C6H3Cl2) are available.•Structures of Pr@D3h(14246)-C74(C6H3Cl2) and Pr@D3h(14246)-C74 were determined.Pr@C74(C6H3Cl2), a novel dichlorophenyl-functionalized derivative of the Pr-containing monometallofullerene Pr@C74, was successfully prepared and isolated. Its molecular structure was determined as Pr@D3h(14246)-C74(C6H3Cl2) by a combined mass spectrometry (MS), UV–visible-near-infrared (UV–vis-NIR) absorption spectroscopy, and quantum-mechanics characterization. Using the computed theoretical data, we evaluated the isomeric structures, metal-to-cage electron transfer, and metal-cage interactions of Pr@C74(C6H3Cl2) and the pristine Pr@C74. Furthermore, the relative reactivity of C74, Pr@C74, and Pr@C74(C6H3Cl2) was estimated by the calculated electronic structures and band gaps, and the results indicated that the open-shell structure and relatively small gap should be responsible for the unsuccessful isolation of C74 and Pr@C74.Prime novelty statementWe successfully prepared and isolated a novel Pr-based monometallofullerene derivative, Pr@C74(C6H3Cl2), for the first time. Its structure, together with the nonderivatized Pr@C74, was discussed in detail based on a combined UV–visible-near-infrared and quantum-mechanics characterization.

An improved Hummers method was developed for the simple and efficient production of high-quality graphene oxide (GO), and the composite of GO and nickel foam (NF) (GO/NF) was fabricated by ultrasonication-vacuum-assisted deposition of an aqueous solution of GO on NF. After chemical or thermal reduction, the composite of reduced GO and nickel foam (rGO/NF) was obtained. The electrochemical capacitance performance of rGO/NF was investigated using cyclic voltammetry and galvanostatic charge/discharge measurements. The chemically reduced rGO/NF composite (C-rGO/NF) exhibited high specific capacitance of 379 F/g at 1.0 A/g and 266.5 F/g at 10 A/g. We also prepared thermally reduced graphene oxide at 473 K in order to illuminate the difference in effect between the chemical and low-temperature thermal reduction methods on electrochemical properties. The cycling performance of thermally reduced rGO/NF composite (T-rGO/NF) and C-rGO/NF had ~91% and ~95% capacitance retention after 2000 cycles in a 6 mol/L KOH electrolyte, respectively. Electrochemical experiments indicated that the obtained rGO/NF has very good capacitive performance and could be used as a potential application of electrochemical capacitors. Our work revealed high electrochemical capacitor performance of rGO/NF composite and provided a facile method of rGO/NF preparation.

Water soluble polymethyl(1-undecylic acidyl)silane, synthesized by the hydrosilylation of 10-undecylenic acid with polymethylsilane catalyzed by 2,2′-azobisisbutyronitrile, demonstrates selective extraction ability toward metallic single-walled carbon nanotubes (SWNTs) produced by the arc discharge method. After heating in air at a temperature of 673 K and treatment with concentrated hydrochloric acid, the arc-discharged SWNTs are ultrasonically dispersed in an aqueous solution of polymethyl(1-undecylic acidyl)silane. Such obtained dispersions are subjected to ultracentrifugation, and then the supernatant is collected. Optical absorption spectra show that the supernatant is enriched in the metallic SWNTs. Moreover, Raman spectra confirm the selective extraction of (14,2), (15,0), (13,1), (12,3) and (19,1) metallic SWNTs, which have larger diameters and smaller chiral angles than those reported previously. Additionally, FT-IR spectroscopy and Raman scattering evidence the charge transfer between polymethyl(1-undecylic acidyl)silane and SWNTs. It is conjectured that polymethyl(1-undecylic acidyl)silane could wrap chiral-index-selectively onto SWNTs through a fairly weak CH–π interaction. Thus, we believe that the stiffness and length of main chains and side chains as well as the charge state of the polymethylsilane derivative play vital roles in the selective extraction of SWNTs.

A novel Pr-based monometallofullerene derivative, Pr@C72(C6H3Cl2), was successfully prepared and isolated. Its molecular composition was determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The molecular structure of Pr@C72(C6H3Cl2) was verified as Pr@C2(10612)-C72(C6H3Cl2) by combined UV-visible-near-infrared absorption spectroscopy and quantum mechanics characterization, as well as a comparison with the structurally characterized analogue La@C72(C6H3Cl2). Furthermore, an additional computation indicated that the nonderivatized Pr@C72 has the lowest-lying structure of Pr@C2(10612)-C72, followed by Pr@C2v(11188)-C72, which lies only 0.62 kcal mol−1 above Pr@C2(10612)-C72. In addition, the temperature dependence of their thermodynamic distribution was estimated. We also analyzed the charge transfer and orbital interaction between the endohedral Pr atom and the carbon cage as well as the electronic configuration and formal charge state of the encapsulated Pr atom based on the computed quantum mechanics data.

First-principles density functional theory calculations were performed to study the effect of Li adsorption on the structural and electronic properties, particularly the work function, of boron α-sheet. The calculated binding energies indicated that boron α-sheet could be well stabilized by the adsorption of Li atoms. Furthermore, the work functions of Li-adsorbed boron α-sheets were observed to decrease drastically with increasing Li coverage. The work functions are lower than that of Mg and even, for some of them, lower than that of Ca, indicating a considerable potential application of Li-adsorbed boron α-sheets as field-emission and electrode materials. Based on the calculated geometric and electronic structures, we discuss in details some possible aspects affecting the work function. The Li coverage dependence of the work functions of Li-adsorbed boron α-sheets was further confirmed by electrostatic potential analyses. The relationship between the work function variation and the Fermi and vacuum energy level shifts was also discussed, and we observed that the variation of the work function is primarily associated with the shift of the Fermi energy level. It is the surface dipole formed by the interaction between adatoms and substrate that should be responsible for the observed variation of the work function, whereas the increasing negative charge and rumpling for boron α-sheet only play minor roles. Additionally, the effect of Li adatoms on the work function of boron α-sheet was confirmed to be much stronger than that of graphene or a graphene double layer.Keywords: binding energy; buckled boron α-sheet; electronic population; electronic structure; electrostatic potential; work function

Regioselective cycloaddition of adamantylidene carbene to Pr@C2v(9)-C82 affords the first derivative of praseodymium-containing metallofullerenes. Single-crystal X-ray crystallographic data in combination with theoretical studies demonstrate that the addition is dictated by the single metal ion encapsulated inside the fullerene cage.

Exfoliated graphite oxide was prepared by an improved Hummers method and was then reduced to graphene with hydrazine in the presence of ammonium hydroxide. N2 adsorption-desorption measurement showed that graphene so obtained had a specific surface area as high as 818 m2/g. Galvanostatic charge/discharge curves demonstrated that the as-prepared graphene exhibited a specific capacitance of 186.9 F/g at a current density of 0.1 A/g and that about 96% of the specific capacitance was retained after 2000 cycles at a current density of 5 A/g.

Regioselective cycloaddition of adamantylidene carbene to Pr@C2v(9)-C82 affords the first derivative of praseodymium-containing metallofullerenes. Single-crystal X-ray crystallographic data in combination with theoretical studies demonstrate that the addition is dictated by the single metal ion encapsulated inside the fullerene cage.