As a type of thin film,two dimensional(2D) reticulate architectures built of freestanding single-walled carbon nanotube(SWCNT) bundles are suitable for scalable integration into devices and nanocomposites for many applications.The superior properties of these films,such as optical transparency,unique electrical properties and mechanical flexibility,result not only from the outstanding properties of individual SWCNTs but also from the collective behavior of the individual tubes,with additional properties arising from the tube-tube interactions.In this review,the synthesis,structure and fundamental properties,such as conductivity,transparency,optical nonlinearity and mechanical performance,of "freestanding SWCNT bundle network" thin films and nanocomposites,as well as their application as supercapacitors are highlighted.Some long-standing problems and topics warranting further investigation in the near future are addressed.
The predicted extraordinary properties of carbon nanotubes(CNTs)from theoretical calculations have great potential for many applications.However,reliable experimental determination of intrinsic properties at the single-tube level is currently a matter of concern,and many challenges remain because of the unhandled and nanoscale size of individual nanotubes.Here,we demonstrated a prototype to detect the intrinsic thermal conductivity of the single-wall carbon nanotube(SWCNT)and verify the significant non-resonant optical absorption behavior on tiny nanotubes by integrating the nanotube and ice into a new core-shell design.In particular,a reversible optical visualization method based on the individual suspended ultra-long SWCNT was first developed by wrapping a nanotube with ice in the cryogenic air environment.The light-induced thermal effect on the hybrid core-shell structure was used tomelt the ice shell,which subsequently acted as a temperature sensor to verify the intrinsic thermal conductivity of the core-like nanotube.More interestingly,we successfully determined for the first time the thermal response phenomenon of the tiny absorption cross section in SWCNT in the vertical-polarization configuration and the significant non-resonant absorption behavior in the parallel-polarization configuration.These investigations will provide a better understanding for the unique optical behaviors of CNT and enable the detection of intrinsic properties of various one-dimensional nanostructures such as nanotubes,nanowires,and nanoribbons.
Research interest in ZnO nanostructures derives from their excellent luminescent properties and availability of low cost fabricating and processing,which hold promise for the development of electronic and optoelectronic nanodevices.In this review,we focus on the progress in synthesis,properties and nanodevices of ZnO nanorod(NR)arrays and nanotetrapods(NTPs).Recent work done by the authors are also presented.After a brief introduction to the controlled fabrication methods for the highly-ordered ZnO NR arrays and NTPs,we present some aspects of the fundamental properties,especially optical performance,of ZnO NRs/NTPs.Then,we provide an overview of the applications to functional nanodevices based on individual NR and NTP of ZnO.It is demonstrated that different morphologies of ZnO nanostructures have salient effects on their properties and applications.Although much progress has been achieved in the fundamental and applied investigations of ZnO NRs/NTPs over the past decade,many obstacles still remain,hampering further development in this field.Finally,some longstanding problems that warrant further investigation are addressed.
