Xuchun Gui

Carbon Nanotube Sponges

[*] Prof.D.Wu,X.Gui,Prof. J.Wei.Prof. K.Wang, Prof.H.Zhu, Y. Jia,Q.Shu Key Laboratory for Advanced Materials Processing Technology, Ministry of Education Department of Mechanical Engineering, Tsinghua University Beijing 100084 (P. R. China) E-mail: wdh-dme@tsinghua.edu.cn Prof. A. Cao Department of Advanced Materials and Nanotechnology College of Engineering, Peking University Beijing 100871 (P. R. China) E-mail: anyuan@pku.edu.cn

Magnetic and Highly Recyclable Macroporous Carbon Nanotubes for Spilled Oil Sorption and Separation

Development of sorbent materials with high selectivity and sorption capacity, easy collection and recyclability is demanding for spilled oil recovery. Although many sorption materials have been proposed, a systematic study on how they can be reused and possible performance degradation during regeneration remains absent. Here we report magnetic carbon nanotube sponges (Me-CNT sponge), which are porous structures consisting of interconnected CNTs with rich Fe encapsulation. The Me-CNT sponges show high mass sorption capacity for diesel oil reached 56 g/g, corresponding to a volume sorption capacity of 99%. The sponges are mechanically strong and oil can be squeezed out by compression. They can be recycled using through reclamation by magnetic force and desorption by simple heat treatment. The Me-CNT sponges maintain original structure, high capacity, and selectivity after 1000 sorption and reclamation cycles. Our results suggest that practical application of CNT macrostructures in the field of spilled oil recovery is feasible.

Carbon nanotubes filled with ferromagnetic alloy nanowires: Lightweight and wide-band microwave absorber

Thin-walled carbon nanotubes (CNTs) filled with different ferromagnetic alloy (FeCo, FeNi, and FeCoNi) nanowires were prepared by using trichlorobenzene as carbon precursor. They were dispersed into epoxy resin and then coated onto 180×180u2002mm2 aluminum substrates to form microwave-absorption coatings with 2.0 mm thickness. Reflection loss exceeding −5u2002dB was obtained between 5 and 18 GHz for coating containing 1.3u2002wtu2009% FeCo-filled CNTs. A minimum reflection loss value of −28.2u2002dB was achieved at 15.2 GHz in FeCoNi-filled CNTs/epoxy coating. The areal densities of coatings are only 2.35u2002kg/m2, which is favorable for the applications requiring low density.

Capacitive deionization of NaCl solutions using carbon nanotube sponge electrodes

Capacitive Deionization (CDI) is a promising method for desalination of brackish water because of its energy-efficiency as compared with conventional techniques such as membrane separation and thermal distillation. Carbon nanotube (CNT) sponges, prepared by chemical vapor deposition, are very flexible and have three-dimensional continuous and mesoporous structures, making them promising electrode materials for capacitive deionization. The CDI characteristics of CNT sponges were investigated for the first time by simply compressing them into a CDI cell without any additives. Desalination of NaCl solutions at different concentrations was conducted with a flow-through CDI cell at 1.2V. Experimental data fit well with the Langmuir model, and the deduced maximum desalination capacity was 40 mg g−1, almost 50% higher than the optimal result reported in the literature. By comparing with other carbon-based materials, the excellent CDI performance of CNT sponges was attributed to higher conductivity and larger effective surface area due to their monolithic continuous flexible framework, crystalline microstructure and preferred pore size distribution.

Graphene Nanoribbon Aerogels Unzipped from Carbon Nanotube Sponges

Graphene nanoribbon aerogels are fabricated by directly unzipping multi-walled carbon nanotube sponges. These fascinating materials have potential applications as high performance nanocomposites and supercapacitor electrodes.

Encapsulated carbon nanotube-oxide-silicon solar cells with stable 10% efficiency

We report a metal-insulator-semiconductor heterojunction solar cell by depositing a carbon nanotube film onto silicon substrate, followed by acid oxidation of the Si surface to form a thin oxide layer at the junction interface. The nanotube-oxide-Si solar cells with polymer encapsulation show stable efficiencies of above 10%, owing to enhanced photon absorption, inhibited charge recombination, and reduced internal resistance. Parallel and series connections without sacrificing cell efficiencies were demonstrated.

Carbon nanotube sponge filters for trapping nanoparticles and dye molecules from water

Carbon nanotube sponges show effective filtration for nanoparticles and dye molecules with different sizes and concentrations from water. The three-dimensional interconnected porous structure formed by entangled nanotubes can trap nanoparticles and molecules by physisorption without the need for chemical functionalization. The sponge filters are potential environmental materials for water treatment.

Three‐Dimensional Carbon Nanotube Sponge‐Array Architectures with High Energy Dissipation

Carbon nanotube sponges and aligned arrays are seamlessly integrated into numerous possible configurations such as series, parallel, package, and sandwich complex structures, leading to significantly broadened stress plateau and enhanced energy dissipation.

Large area, highly transparent carbon nanotube spiderwebs for energy harvesting

Carbon nanotubes possess excellent electronic properties, and when self-assembled into thin films, they form conductive and transparent networks that are useful for many applications. Here, we synthesized large-area (100 cm2) spiderwebs consisting of interconnected single-walled nanotubes by floating catalyst chemical vapor deposition and a solvent-induced condensation process. These spiderwebs are sticky and robust, can be directly deposited or transferred to various materials and structures such as metal, paper, texture surface, and micro carbon fibers. The spiderwebs offer tunable transparency in the range up to 95%, and show enhanced conductivity compared with most of previous directly grown or post treatment films. Serving as transparent electrodes of solar cells, the nanotube spiderwebs can extract charge carriers from industrial semiconductors with a power conversion efficiency of 7.3% under AM 1.5 G, 100 mW cm−2 illumination.

Carbon nanotube sponge-array tandem composites with extended energy absorption range.

Controlled assembly of carbon nanotubes (CNTs) represents an exciting research area and provides opportunities for fabrication of various three-dimensional macroscopic structures with unexpected properties. Given that CNTs are one-dimensional with large aspect-ratios, synthesis of vertically aligned CNT arrays has stimulated tremendous interest with a series of important progressions made about one decade ago. [ 1–5 ] In an aligned array, individual CNTs grow vertically from the substrate creating a forest-like morphology with millimeter length over large area. Alignment of CNTs results in an anisotropic structure in which the excellent mechanical and electronic properties along the nanotube axis can be fully exploited. [ 6–10 ] For example, under large strain compression CNTs buckle collectively and then unfold during releasing, forming a highly compressible yet elastic foam with fatigue resistance over many cycles. [ 6 , 7 ] Solvent-induced zipping and densifi cation of aligned single-walled nanotube fi lms creates solid wafers that could be used as electromechanical actuators or stretchable strain sensors, [ 11 ] as well as other geometry-tunable multi-walled nanotube columns. [ 12 ]