Polyaniline hollow spheres (PANI-HS)@electrochemical reduced graphene oxide (ERGO) hybrids with core-shell structures have been fabricated via a solution-based coassembly process. The hollow nanostructured designing for the PANI-HS greatly enlarges the specific surface area, providing high electroactive regions and short diffusion lengths for both charge and ion transport. The wrapping of ERGO sheets on the PANI-HS can offer highly conductive pathways by bridging individual PANI-HS together, thus facilitating the rate and cycling performance of supercapacitors. The specific capacitance of PANI-HS36@ERGO hybrids can reach 614 F g(-1) at a current density of 1 A g(-1). Furthermore, the capacitance of the PANI-HS36@ERGO hybrids maintains 90% after 500 charging/discharging cycles at a current density of 1 A g(-1), indicating a good cycling stability. The greatly enhanced electrochemical performance can be ascribed to the synergic effects of the two components of PANI-HS and ERGO, suggesting that the PANI-HS@ERGO hybrids as novel electrode materials may have potential applications in high-performance energy storage devices.

Graphene oxide (GO) is an emerging material for surface-enhanced Raman scattering (SERS) due to its strong chemical enhancement. Studying the SERS performance of plasmonic nanoparticle/GO hybrid materials at the single particle level is crucial for direct probing of the chemical effect of GO on plasmonic nanoparticles. In this work, we integrate GO and shape-controlled Ag nanoparticles to create hybrid nanomaterials, and the chemical enhancement arising from GO is investigated using single-particle SERS measurements. Ag nanoparticle@GO hybrid nanostructures are prepared by assembling Ag nanoparticles, including spheres, cubes and octahedra with GO sheets. The SERS behaviors of the hybrid nanostructures are characterized, and 2-3 times enhanced SERS intensities are detected from the Ag nanoparticle@GO hybrid nanostructures as compared to pure Ag nanoparticles. Furthermore, we probe the mechanism of SERS enhancement in the hybrid nanostructures by changing the surface coverage of GO on Ag octahedra, by using reduced GO in place of GO as well as by using probe molecules of different electronegativities. This hybrid system is an excellent candidate for single-particle SERS sensors. Sub-nanomolar levels of aromatic molecules are detected using a single Ag/GO hybrid nanomaterial. This as-prepared GO and shape-controlled Ag nanoparticle hybrid is capable of serving as a high performance SERS platform, providing new opportunities for efficient chemical and biological sensing applications.

Hollow polyaniline (PANI) nanofibers with controllable wall thickness are fabricated by in situ polymerization of aniline using the electrospun poly(amic acid) fiber membrane as a template. A maximum specific capacitance of 601 F g(-1) has been achieved at 1 A g(-1), suggesting the potential application of hollow PANI nanofibers for supercapacitors. The superior electrochemical performance of the hollow nanofibers is attributed to their hollow structure, thin wall thickness, and orderly pore passages, which can drastically facilitate the ion diffusion and improve the utilization of the electroactive PANI during the charge-discharge processes. Furthermore, the high flexibility of the self-standing fiber membrane template provides possibilities for the facile construction and fabrication of conducting polymers with hollow nanostructures, which may find potential applications in various high-performance electrochemical devices.

Magnetic graphene-Fe 3 O 4 @carbon (GFC) hybrids with hierarchical nanostructures have been synthesized and their application as an adsorbent for the removal of organic dyes has been investigated. Graphene-Fe 3 O 4 hybrids were first prepared via a facile one-pot solvothermal process, then carbonaceous coatings on Fe 3 O 4 nanoparticles of nanometer thickness were synthesized by a hydrothermal carbonization process using eco-friendly glucose as a carbon source. Graphene sheets acting as two-dimensional (2D) substrates can effectively prevent the Fe 3 O 4 nanoparticles from aggregating and enable a good dispersion of these magnetic nanoparticles. The carbonaceous layer protects the Fe 3 O 4 nanoparticles in acidic environments and greatly enhances the specific surface area of the hybrids which is beneficial for the removal of organic dyes, such as methylene blue (MB). The resultant GFC hybrids exhibit great adsorption properties not only in water but also in acidic environments, and about 86% and 77% of the dye removal efficiency can be retained after five adsorption-desorption cycles in water and 1 M HCl, respectively. The rapid and efficient adsorption of organic dyes from water as well as acid suggests that the GFC hybrids have potential environmental applications as alternatives to commercial materials in wastewater treatment for the removal of organic dyes.