Mechanical properties of nanocomposites reinforced by carbon nanotube sponges

Carbon nanotube(CNT)sponge exhibits unique porous and hierarchical structure that are beneficial to the design of ultralight and tough composites.In this study,CNT sponges(undoped and boron doped)reinforced polydimethylsiloxane(PDMS)composites were fabricated.Mechanical properties of the composite,including compressive modulus,rate-dependent modulus,stress relaxation behaviors,dynamic viscoelastic properties,and their dependency on temperature,were systematically investigated.A micromechanical model,Mori-Tanaka model,was validated to describe the mechanical behaviors of CNT sponge reinforced composites.By coupling with boron-doped CNT sponge,PDMS composites showed remarkable improvement of mechanical properties,including compressive modulus(70%),viscous modulus(243%)and damping capacity(50%).Such reinforcement effects can be controlled by the morphology of CNT sponges,as the boron-doped and undoped nanocomposites showed distinct viscoelastic behaviors.The results proved that CNT sponge reinforcement is a promising strategy to develop engineering composites with both outstanding mechanical stiffness and controllable viscoelastic performances.

Carbon nanotube-polypyrrole core-shell sponge and its application as highly compressible supercapacitor electrode

A carbon nanotube （CNT） sponge contains a three-dimensional conductive nano- tube network, and can be used as a porous electrode for various energy devices. We present here a rational strategy to fabricate a unique CNT@polypyrrole （PPy） core-shell sponge, and demonstrate its application as a highly compressible supercapacitor electrode with high performance. A PPy layer with optimal thickness was coated uniformly on individual CNTs and inter-CNT contact points by electrochemical deposition and crosslinking of pyrrole monomers, resulting in a core-shell configuration. The PPy coating significantly improves specific capacitance of the CNT sponge to above 300 F/g, and simultaneously reinforces the porous structure to achieve better strength and fully elastic structural recovery after compression. The CNT@PPy sponge can sustain 1,000 compression cycles at a strain of 50% while maintaining a stable capacitance （〉 90% of initial value）. Our CNT@PPy core-shell sponges with a highly porous network structure may serve as compressible, robust electrodes for supercapacitors and many other energy devices.

Templated synthesis of Ti02 nanotube macrostructures and their photocatalytic properties

Controlled synthesis of hierarchically assembled titanium dioxide （TiO2） nano- structures is important for practical applications in environmental purification and solar energy conversion. We present here the fabrication of interconnected TiO2 nanotubes as a macroscopic bulk material by using a porous carbon nanotube （CNT） sponge as a template. The basic idea is to uniformly coat an amorphous titania layer onto the CNT surface by the infiltration of a TiO2 precursor into the sponge followed by a subsequent hydrolysis process. After calcination, the CNTs are completely removed and the titania is simultaneously crystallized, which results in a porous macrostructure composed of interconnected anatase TiO2 nanotubes. The TiO2 nanotube macrostructures show comparable photocatalytic activities to commercial products （AEROXIDE TiO2 P25） for the degradation of rhodamine B （RhB）. Moreover, the TiO2 nanotube macrostructures can be settled and separated from water within 12 h after photocatalysis, whereas P25 remains suspended in solution after weeks. Thus the TiO2 nanotube macrostructures offer the advantage of easy catalyst separation and recycle and can be a promising candidate for wastewater treatment.

Atomic layer deposition of core-shell structured V_(2)O_(5)@CNT sponge as cathode for potassium ion batteries

Potassium-ion batteries(KIBs)represent one of the most promising alternatives to lithium-ion batteries(LIBs)considering the potential low cost and abundant potassium resource.In this work,we demonstrate a core-shell structured sponge cathode for KIBs,where amorphous V_(2)O_(5) uniformly coats on carbon nanotube(CNT)sponge via atomic layer deposition(ALD).The V_(2)O_(5)@CNT sponge shows several advantages as cathode:(1)the three-dimensional(3D)conductive network of CNT sponge offers a fast electron transport pathway,(2)the porous nature and high surface area of CNT sponge enables enough access for electrolyte to V_(2)O_(5),(3)the amorphous structure of V_(2)O_(5) offers a fast kinetics upon K-ion insertion/deinsertion.The V_(2)O_(5)@CNT sponge cathode delivers a high capacity of 206mA h/g and moderate cycling and rate performance in common carbonate-based electrolyte system.