Clusterization, Electrophoretic Deposition, and Photoelectrochemical Properties of Fullerene-Functionalized Carbon Nanotube Composites

Noncovalent Functionalization of Few-Layered Antimonene with Fullerene Clusters and Photoinduced Charge Separation in the Composite

Few-layered antimonene (FLSb) nanosheets were noncovalently functionalized with fullerene C₆₀ clusters by quick addition of a poor solvent (i.e., acetonitrile) into a mixed dispersion of FLSb and C₆₀ in a good solvent (i.e., toluene). In a flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurement, the FLSb-C₆₀ composite, (FLSb+C₆₀ )_m , showed a rapid rise in transient conductivity, whereas no conductivity signal was observed in the single components, FLSb and C₆₀ . This demonstrated the occurrence of photoinduced charge separation between FLSb and C₆₀ in (FLSb+C₆₀ )_m . Furthermore, a photoelectrochemical device with an electrophoretically deposited (FLSb+C₆₀ )_m film exhibited an enhanced efficiency of photocurrent generation, compared to those of the single-components, FLSb and C₆₀ , due to the photoinduced charge separation between FLSb and C₆₀ . This work provides a promising approach for fabrication of antimonene-organic molecule composites and paves the way for their application in optoelectronics.

Spontaneous Complexation of Fullerene Aggregates on Nanodiamond Aggregates and Their Enhanced Photocurrent Generation

Supramolecular composites composed of fullerene C₆₀ and carbon nanodiamond (ND) were constructed through spontaneous complexation of C₆₀ aggregates onto the surface of ND aggregates in N-methylpyrrolidone (NMP). The resulting C₆₀ -ND composite was assembled onto a nanostructured SnO₂ electrode by an electrophoretic deposition method. Formation of the C₆₀ -ND composite was confirmed by dynamic light scattering (DLS) and field-emission scanning electron microscopy (FESEM). The C₆₀ -ND composite on the SnO₂ electrode showed high incident photon-to-current efficiencies (IPCEs) in the visible region as compared with the single component system of C₆₀ or ND. The improved photocurrent generation of the C₆₀ -ND composite may result from the photoinduced charge separation at the interface between C₆₀ and ND. These results obtained here will provide valuable information on the design of optoelectronic devices based on all-nanocarbon materials.

Carbon nanotube catalysts: recent advances in synthesis, characterization and applications

Carbon nanotubes are promising materials for various applications.

Phase aggregation and morphology effects on nanocarbon optoelectronics

Controllable morphology and interfacial interactions within bulk heterojunction nanostructures show significant effects on optoelectronic device applications. In this study, a nanocarbon heterojunction, consisting of single-walled carbon nanotubes (s-SWCNTs) and fullerene derivatives, is reported by assembling/blending its structures through solution-based processes. A uniform and dense graphene oxide hole transport layer is used to facilitate the photoconversion at a near infrared (NIR) wavelength. Effective interfacial interaction between the s-SWCNTs and fullerene is suggested by the redshifted photoabsorption and nanoscale/micron-scale fluorescence, which is associated with self-assembled nanocarbon morphology.

Fullerene assemblies toward photo-energy conversions

Manipulating the molecular interaction and assembly of fullerene derivatives leads to their enhanced photoconductivity and applications in photo-energy (electric and thermal) conversion systems.

Single-walled carbon nanotube/polyaniline/n-silicon solar cells: fabrication, characterization, and performance measurements

Carbon nanotube-silicon solar cells are a recently investigated photovoltaic architecture with demonstrated high efficiencies. Silicon solar-cell devices fabricated with a thin film of conductive polymer (polyaniline) have been reported, but these devices can suffer from poor performance due to the limited lateral current-carrying capacity of thin polymer films. Herein, hybrid solar-cell devices of a thin film of polyaniline deposited on silicon and covered by a single-walled carbon nanotube film are fabricated and characterized. These hybrid devices combine the conformal coverage given by the polymer and the excellent electrical properties of single-walled carbon nanotube films and significantly outperform either of their component counterparts. Treatment of the silicon base and carbon nanotubes with hydrofluoric acid and a strong oxidizer (thionyl chloride) leads to a significant improvement in performance.

Synthesis of C60-decorated SWCNTs (C60-d-CNTs) and its TiO2-based nanocomposite with enhanced photocatalytic activity for hydrogen production

A novel nanostructured carbon/TiO(2) nanocomposite photocatalyst is firstly fabricated via a facile hydrothermal process by using fullerene (C(60)) decorated single-walled carbon nanotubes (SWCNTs) as carbon source, which is denoted as C(60)-d-CNTs. The obtained nanostructured carbon/TiO(2) nanocomposites are characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectra (DRS), Raman spectra, X-ray photoelectron spectroscopy (XPS) and photoluminescence spectra (PL), and then are used as catalysts for photocatalytic hydrogen production. It is found that the kinds and contents of various carbon nanostructured materials (such as SWCNTs, C(60) and C(60)-d-CNTs) coupled with TiO(2) can significantly enhance the photoactivity for hydrogen production, and the 5 wt% C(60)-d-CNTs/TiO(2) nanocomposite exhibits the best performance. Experimental results suggest that the C(60)-d-CNTs as a novel carbon nanostructured material could be more beneficial for the photogenerated carrier separation than SWCNTs and C(60) when these carbon nanostructured materials are coupled with TiO(2).

Photoconductivity and enhanced memory effects in hybrid C60-graphene transistors

We describe the observation of photoconductivity and enhanced memory effects in graphene devices functionalized with clusters of alkylated C(60) molecules. The alkylated C(60) clusters were adsorbed on chemical vapor deposition-grown graphene devices from an aprotic medium. The resulting alkylated C(60)-graphene hybrid devices showed reproducible photoconductive behavior originating from the electron-accepting nature of the C(60) molecules. Significantly enhanced gate hysteresis was observed upon illumination with visible light, thereby enabling the use of C(60)-graphene hybrid devices in three-terminal photo-memory applications.

Endohedral and exohedral hybrids involving fullerenes and carbon nanotubes

Since fullerenes and carbon nanotubes (CNTs) were discovered, these materials have attracted a great deal of attention in the scientific community due to their unique structures and properties. The properties of both carbon allotropes can be modulated by chemical functionalization, and merging fullerenes and CNTs combines the electronic and optical properties of CNTs with the excellent electron acceptor characteristic of fullerenes; moreover, a synergistic effect of these hybrids can be found, as the properties of both the nanotube and the fullerene are affected by the presence of the other. In these hybrids, the fullerene can be located inside (endohedral) or outside (exohedral) the CNT and both types of hybrid have specific features. CNT-fullerene hybrids have been studied for various applications, including photovoltaics, optical limiting and flame retardancy amongst others. This review outlines the progress in research on CNT-fullerene hybrids, including endohedral and exohedral combinations, their properties, functionalization, applications and outlook.

Self-assembling porphyrins and phthalocyanines for photoinduced charge separation and charge transport

Large π-conjugated compounds are promising building blocks for organic thin-film electronics such as organic light-emitting diodes, organic field-effect transistors, and organic photovoltaics. Utilization of porphyrins and phthalocyanines for this purpose is highly fascinating because of their excellent electric, photophysical, and electrochemical properties as well as intense self-assembling abilities arising from π-π stacking interactions. This paper focuses on fundamental aspects of self-assembled structures that have been obtained from porphyrin and phthalocyanine building blocks and more complex composites for photoinduced charge separation and charge transport toward the potential applications to organic thin-film electronics.

Photoelectrochemical properties of donor-acceptor nanocomposite films composed of porphyrin-functionalized cup-shaped nanocarbon materials

Porphyrin-functionalized cup-shaped nanocarbons (CNC-H2P) have been assembled onto nanostructured SnO2 films using an electrophoretic deposition method to examine the photoelectrochemical properties. The obtained CNC-H2P nanohybrid films were examined by a series of steady-state and time-resolved spectroscopic measurements and photoelectrochemical measurements. The resulting nanohybrid film afforded drastic enhancement in the photoelectrochemical performance as well as broader photoresponse in the visible region as compared with the reference CNC system without porphyrins. The enhancement of photocurrent generation may be caused by the efficient electron injection from the long-lived charge-separated state of CNC-H2P upon photoexcitation. This feature makes cup-shaped nanocarbon materials a useful candidate for developing efficient photoelectrochemical and photovoltaic cells.

Photosensitized hydrogen evolution from water using a single-walled carbon nanotube/fullerodendron/SiO2 coaxial nanohybrid

A coaxial nanohybrid consisting of a single-walled carbon nanotube (SWCNT), fullerodendron, and SiO(2) shows high-efficiency light-driven hydrogen evolution from water. Upon visible light irradiation, SWCNT/fullerodendron/SiO(2) coaxial nanohybrid shows hydrogen evolution activity in the presence of methyl viologen (MV(2+)), benzyldihydronicotinamide (BNAH), and a colloidal polyvinyl alcohol(PVA)-Pt.

[60]-fullerene and single-walled carbon nanotube-based ultrathin films stepwise grafted onto a self-assembled monolayer on ITO

A step-by-step method was used to prepare homogeneous ultrathin films composed of [60]-fullerene (C60) and single-walled carbon nanotubes (SWNTs), grafted onto the functional surface of an alkylsilane self-assembled monolayer (SAM) on an ITO substrate with an ITO-C60-SWNT sequence using amine addition across a double bond in C60 followed by amidation coupling with acid-functionalized SWNTs. Atomic force microscope and scanning electron microscope images of the resulting composite film showed two-component ball-tube microstructures with high-density coverage, where C60 was homogeneously distributed in the SWNT forest. The attachment of SWNTs to the residual amine units in the SAM on the ITO substrate (SAM-ITO) as well as on the C60 sphere results in the C60 molecules in the aggregated clusters being more separately dispersed, which forms a densely packed composite film as a result of the pi-pi interaction between the C60 buckyballs and the SWNT walls. It was found using ferrocene as an internal redox probe that the oxidative and reductive processes at the film-solution surface were effectively retarded because of obstruction from the densely packed film and the electronic effect of SWNT and C60. In addition, the electrochemical properties of C60 on SAM-ITO plates observed by cyclic voltammetry were significantly modified by chemical anchorage using SWNTs. X-ray photoelectron spectroscopy (XPS) analysis also indicated the successful grafting of C60 and SWNT. The XPS chemical shift of the binding energy showed the presence of electronic interactions between C60, SWNT, and ITO components. Such a uniformly distributed C60-SWNT film may be useful for future research in electrochemical and photoactive nanodevices.