Water-soluble GO–Gd@C82 nanohybrids exhibit high relaxivities and could be explored as potential magnetic resonance imaging (MRI) contrast agents. To better understand the relaxation mechanism in the novel carbon nanohybrids, in the present paper, after layers of in-depth analysis and exploration, we propose that the structure and the physicochemical properties of the carbon nanohybrids contribute significantly to the enhanced relaxivity. Better electron transfer from Gd@C82 to the GO nanosheet, appropriate electric conductivity and size of the GO used, an increased number of H proton exchange sites and an adequate concentration of Gd3+ should result in optimal equilibrium for high relaxivity of the GO–Gd@C82. These results are important for constructing and optimizing novel nanoscale architectures with higher relaxivity.

•Several novel fullerene derivatives were synthesized as the electron transport layer for tin-lead perovskite solar cells.•Power conversion efficiency of 10% were achieved with incident photon conversion efficiency spectra onset reaching 1050 nm.•The hybrid excitonic feature of tin-lead perovskite (CH3NH3Sn0.5Pb0.5I3) was reported for the first time.The design of organic-inorganic trihalide perovskite solar cells with higher performance, lower environmental pollution, lower cost and easier of fabrication should be a significant stride towards their practical application. Nevertheless, the contribution of exciton dissociation behavior of the perovskite to this strategy has not been recognized comparing with film morphology, device architecture and fabrication process. Here we demonstrated a series of solution-processed solid-state tin-lead organohalide perovskite photovoltaic solar cells using carefully selected fullerene derivatives as the electron transport layer. The hybrid excitonic feature of CH3NH3Sn0.5Pb0.5I3 was revealed for the first time by comparing the exciton dissociation behaviors of CH3NH3Sn0.5Pb0.5I3 with conventional excitonic semiconductor in both planar heterojunction solar cells and lateral architecture photosensors. By optimizing the lowest unoccupied molecular orbital level of electron transport layer materials, high open circuit voltage of 0.69 V, short circuit photocurrent density of 22.8 mA cm−2 and power conversion efficiency of more than 10% were achieved with the incident photon conversion efficiency spectra onset reaching 1050 nm. These devices may work as high performance photodetectors with a broad spectral response expanding from UV–visible to near-infrared. Our results have suggested the exciton dissciation behavior to be an efficient perspective for the improvement of provskite solar cells.

A practicable means of significantly reducing the energy consumption and speeding up the operating rate of computer chips is to place the processor and memory into one device, which processes and stores information simultaneously like the human brain. Here we demonstrate a novel sandwich architecture where organic–inorganic hybrid perovskite materials could be used as building-block materials for non-volatile memristors, accompanied with photoresponsive performance. Owing to the distinct photo-response of the two resistance states of the memristor, it is feasible to utilize the device as a logic OR gate by employing an electrical field and light illumination as input sources. This study provides potential applications in logic circuits, optical digital computation and optical quantum information for beneficial supplementation of the von Neumann architecture, or even for computing beyond it.

Red-emission phosphor europium-doped yttria (Eu3+:Y2O3) nanoparticles have been successfully filled into the nanocavity of carbon nanotubes (CNTs) via supercritical reaction and supercritical fluids followed by calcination. The existence of Eu3+:Y2O3 nanoparticles inside CNTs was characterized by TEM, EDS and XRD. The as-prepared nanomaterials (Eu3+:Y2O3@CNTs) exhibited strong red-emission at 610 nm, which corresponded to 5D0 → 7F2 transition within Eu3+ ions. It showed that the existence of the walls of the CNTs did not quench the luminescence of Eu3+:Y2O3. Due to the surface modification with Tween 80, Eu3+:Y2O3@CNTs had good water solubility. In vitro cytotoxicity studies showed that the as-prepared nanomaterials had low toxicity on HeLa cells at concentrations of 10–1000 μg mL−1. And their use as luminescence probes for live cell imaging was demonstrated by using inverted fluorescence microscopy. With the advantages of the easy dispersion in water, low toxicity, and good photoluminescence (PL) properties, the as-prepared Eu3+:Y2O3@CNTs could potentially be used as nanophosphors in bio-imaging.

Novel carbon nanohybrids based on unmodified metallofullerenes have been successfully fabricated for use as a new magnetic resonance imaging (MRI) contrast agent. The nanohybrids showed higher R1 relaxivity and better brightening effect than Gd@C82(OH)X, in T1-weighted MR images in vivo. This is a result of the proton relaxivity from the original gadofullerenes, which retained a perfect carbon cage structure and so might completely avoid the release of Gd3+ ions. A “secondary spin-electron transfer” relaxation mechanism was proposed to explain how the encaged Gd3+ ions of carbon nanohybrids interact with the surrounding water molecules. This approach opens new opportunities for developing highly efficient and low toxicity MRI contrast agents.

Two new isomeric fullerene derivatives, {6}-1-(3-(Benzoyl)propyl)-{5}-1-phenyl [5,6] C61 and 1-(3-(Benzoyl)propyl)-1-phenyl[6,6] C60, have been synthesized efficiently through a 1,3-dipolar cycloaddition of a tosylhydrazone to provide relatively high photovoltaic performances. A systematic study on the optical, electrochemical and photovoltaic properties of the fullerene derivatives has been performed. In particular, the polymer solar cell (PSC) based on {6}-1-(3-(Benzoyl)propyl)-{5}-1-phenyl [5,6] C61 and poly(3-hexylthiophene) showed a power conversion efficiency of 2.81%, which is higher than that of PCBM (2.53%) under the same device conditions.

•Metallofullerene-grafted polymer (Gd@C82-PVK) is applied in nonvolatile memory device for the first time.•The new device exhibits typical bistable electrical switching and a nonvolatile rewritable memory effect.•DFT calculations explain mechanism of the memory device fabricated with PVK-Gd@C82.The ITO/Gd@C82-PVK/Al sandwich nonvolatile memory device was developed based on polymer containing carbazole moieties as electron donors and Gd@C82 as electron acceptors for the first time. The results of I–V characteristic test indicated that the new material exhibited typical bistable electrical switching and a nonvolatile rewritable memory effect, with a turn-on voltage of about −1.5 V and an ON/OFF-state current ratio of more than 104. We propose that such a low turn-on voltage is caused due to the encaged metal and the DFT calculation indicated that the encaged metal served as an important electron trapping center, which facilitated the arrival of turn-on voltage.

Because of their unique physical, chemical, electrical, and mechanical properties, carbon nanotubes (CNTs) have attracted a great deal of research interest and have many potential applications. As large-scale production and application of CNTs increases, the general population is more likely to be exposed to CNTs either directly or indirectly, which has prompted considerable attention about human health and safety issues related to CNTs. Although considerable experimental data related to CNT toxicity at the molecular, cellular, and whole animal levels have been published, the results are often conflicting. Therefore, a systematic understanding of CNT toxicity is needed but has not yet been developed.In this Account, we highlight recent investigations into the basis of CNT toxicity carried out by our team and by other laboratories. We focus on several important factors that explain the disparities in the experimental results of nanotoxicity, such as impurities, amorphous carbon, surface charge, shape, length, agglomeration, and layer numbers. The exposure routes, including inhalation, intravenous injection, or dermal or oral exposure, can also influence the in vivo behavior and fate of CNTs. The underlying mechanisms of CNT toxicity include oxidative stress, inflammatory responses, malignant transformation, DNA damage and mutation (errors in chromosome number as well as disruption of the mitotic spindle), the formation of granulomas, and interstitial fibrosis. These findings provide useful insights for de novo design and safe application of carbon nanotubes and their risk assessment to human health.To obtain reproducible and accurate results, researchers must establish standards and reliable detection methods, use standard CNT samples as a reference control, and study the impact of various factors systematically. In addition, researchers need to examine multiple types of CNTs, different cell lines and animal species, multidimensional evaluation methods, and exposure conditions. To make results comparable among different institutions and countries, researchers need to standardize choices in toxicity testing such as that of cell line, animal species, and exposure conditions. The knowledge presented here should lead to a better understanding of the key factors that can influence CNT toxicity so that their unwanted toxicity might be avoided.

The adsorption and self-assembly of Gd@C82 molecules on Cu(100) surface have been investigated using scanning tunneling microscopy (STM). The metallofullerene molecules in the assemblies showed two characteristic apparent heights in the STM images. STM manipulation and spectroscopy was performed and revealed the formation of Cu adatom islands underneath the Gd@C82 molecules. The monolayered Cu aggregates were resulted from the adatom–molecule complexation, which is supported by density functional theory (DFT) calculations that show charge transfer and electrostatic interactions between Gd@C82 and adatoms. In addition, sub-molecularly resolved STM images demonstrated the structural and orientational ordering of Gd@C82 assemblies upon thermal annealing. DFT calculations demonstrated that Gd atom located at the lower part of the carbon cage is a favored adsorption configuration for Gd@C82 molecules adsorbed on Cu(100).Highlights► The adsorption and self-assembly of Gd@C82 molecules on Cu(100) were studied by STM. ► The formation of Cu monolayer islands underneath Gd@C82 molecules was revealed. ► The Cu adatoms aggregated upon adatom–metallofullerene complexation. ► The assembled molecules show orientational ordering, agreeing with DFT calculation.

We have studied for the first time the structural change of high-purity metallofullerene (Gd@C82) upon heat treatment in an ultra-high vacuum system (10−10 Torr) and examined the decomposition product through successive analysis with MS, IR, Raman, TEM, EDS and XPS. It was found that metallofullerene (Gd@C82) had fully collapsed at 580 °C which was lower than that for the complete destruction of C60. The easier decomposition should be ascribed to the encapsulated metal in the carbon cage which could induce the deformation of the C–C bond. The analysis indicated that the broken metallofullerene (Gd@C82) became a kind of graphite-like material with a lot of defects. The Gd atoms leaked out from the carbon cage and aggregated together to form a regular arrangement.

The present study developed a novel, fast and efficient method to synthesize one dimensional nanotube-based materials via supercritical reactions and supercritical fluids. It was proved that supercritical organic fluids were good media to take materials into the nanocavity, not only as solvents but also as reaction agents. Different kinds of metals (Ni, Cu, Ag) and fullerenes (C60, C70, C78, C84, Gd@C82, Er@C82, Ho@C82, Y@C82) were successfully inserted into nanotubes with small diameters by this technique, with various supercritical fluids such as C2H5OH, CH3OH or C6H5CH3. The filling rates were proved to be more than 90%. The high filling efficiency and the properties of the as-generated materials were characterized by TEM, Raman, EDS and XPS. In principle, this technique can be applied to construct new types of nanomaterials, if we choose the appropriate supercritical reaction and fluid in the CNTs.

The electrochemistry of C84 isomer-modified electrodes was investigated in aqueous solutions. It is found that the C84-C2(IV) (denoted as C2(IV) for short)-modified electrode shows one pair of redox peaks, and its electrochemical responses depend on the nature of cations of the supporting electrolyte. Scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), and ultraviolet−visible-near-infrared (UV−vis-NIR) spectral characterizations reveal that the pair of redox peaks originate from one-electron-transfer reduction and reoxidation of C2(IV) in the aqueous solution. Furthermore, interaction between C2(IV) and guanine has been investigated by electrochemistry, XPS, and UV−vis-NIR, and the results illustrate that C2(IV) and guanine have formed a charge-transfer complex.

The structural and electronic properties of Gd@C82 adsorbed on Cu(111) and Cu(100) surfaces were investigated by scanning tunneling microscopy (STM). STM images showed that the lattice structure of the underlying metal substrates affected the arrangement of the metallofullerene molecules. Preferred adsorption orientations of the molecules were found from STM images with submolecular resolution. Differences in the scanning tunneling spectroscopy of molecules adsorbed on Cu(111) and Cu(100) were observed and attributed to the work function difference between the substrates. In addition, the electronic properties of the fullerene monomer, dimer, and monolayer were characterized and compared, revealing the roles played by the molecule−substrate interaction and the intermolecular interaction.

Metallofullerene-containing copolymers (0.12, 0.20, 0.40, and 0.60 wt % Gd@C82) were first synthesized via radical bulk copolymerization. The structures and the properties of the new polymers, Gd@C82-PS, were investigated by GPC, UV−vis spectroscopy, FTIR, 13C NMR, CV/DPV, and XPS. The polymerization behavior of the metallofullerene and the properties of the Gd@C82-PS polymers were different from those of C60-PS and PS. Gd@C82 exhibited a stronger radical-scavenging ability than that of hollow fullerenes in the polymerization. Molecular weights and the electron-accepting ability of the polymers were discussed and possible mechanisms of the influences were proposed.

C121 and C121/didodecyldimethylammonium bromide (DDAB) film modified electrodes have been constructed and their electrochemistry has been studied. In the acetonitrile solution containing 0.1 M tetrabutylammonium perchlorate, the C121 films show three couples of relatively stable redox peaks corresponding to three two-electron transfer processes involving reduction of two fullerene units in the dimers. In an aqueous solution containing 0.1 M tetrabutylammonium bromide, the C121 films display an irreversible reduction peak, whereas the C121/DDAB films display two couples of quasi-reversible redox peaks with the splitting first peak, and the C121/DDAB films have good reversibility and stability in the aqueous solution due to existence of DDAB. All of these experimental results indicate that voltammetric behaviors of the C121 films are different from those of C60 films due to different structures though C121 is carbon-bridged C60 dimer, and the common characteristics are that their electrochemical behaviors are dependent on the nature of solvent and cation of supporting electrolyte. Furthermore, electrocatalysis of H2O2 at the C121/DDAB films was explored in the aqueous solution, which indicates that C121 is a good electron-transfer mediator.

A practicable means of significantly reducing the energy consumption and speeding up the operating rate of computer chips is to place the processor and memory into one device, which processes and stores information simultaneously like the human brain. Here we demonstrate a novel sandwich architecture where organic–inorganic hybrid perovskite materials could be used as building-block materials for non-volatile memristors, accompanied with photoresponsive performance. Owing to the distinct photo-response of the two resistance states of the memristor, it is feasible to utilize the device as a logic OR gate by employing an electrical field and light illumination as input sources. This study provides potential applications in logic circuits, optical digital computation and optical quantum information for beneficial supplementation of the von Neumann architecture, or even for computing beyond it.