Multiporous Carbon Research Articles

Multiporous carbon allotropes transformed from symmetry-matched carbon nanotubes

Carbon nanotubes (CNTs) with homogeneous diameters have been proven to transform into new carbon allotropes under pressure but no studies on the compression of inhomogeneous CNTs have been reported. In this study, we propose to build new carbon allotropes from the bottom-up by applying pressure on symmetry-matched inhomogeneous CNTs. We find that the (3,0) CNT with point group C3v and the (6,0) CNT with point group C6v form an all sp3 hybridized hexagonal 3060-Carbon crystal, but the (4,0) CNT with point group D4h and the (8,0) CNT with point group D8h polymerize into a sp2+sp3 hybridized tetragonal 4080-Carbon structure. Their thermodynamic, mechanical and dynamic stabilities show that they are potential carbon allotropes to be experimentally synthesized. The multiporous structures, excellently mechanical properties and special electronic structures (semiconductive 3060-Carbon and semimetallic 4080-Carbon) imply their many potential applications, such as gases purification, hydrogen storage and lightweight semiconductor devices. In addition, we simulate their feature XRD patterns which are helpful for identifying the two carbon crystals in future experimental studies.

Photoelectrocatalysis reactivity of independent titania nanotubes

Two types of independent titania nanotube arrays with the separated tube wall structure have been fabricated by a controlled anodization process and used for photoelectrocatalysis (PEC) applications. The photocatalysis degradation efficiency of the organic pollutant is improved from 6.0 to 9.2% through increasing tube length and inter-tube space. The PEC degradation efficiency is 20.4% at an applied potential of 2.885 V for titania long nanotube array. An electro-Fenton-assisted PEC reaction system has been developed using titania long nanotube array and an iron sheet as two anodes in a parallel connection and a multiporous carbon as one cathode. The current distribution among three functional electrodes is conducted to optimize titania PEC reaction and electro-Fenton reaction. Accordingly, the degradation efficiency is improved from 20.4% in PEC to 60.2% in electro-Fenton-assisted PEC, and the mineralization efficiency is also improved from 8.1 to 37.4%. The corresponding reaction rate constant of 5.19 × 10−3 min−1 is even higher than that of 3.98 × 10−3 min−1 for the sum of individual oxidation reactions of titania PEC, electro-Fenton, and anodic electrolysis.

Shape-controlled multi-porous carbon with hierarchical micro–meso-macro pores synthesized by flash heating of wood biomass

We developed a simple synthesis of shape-controlled porous carbon materials that combine a high porosity of over 80% with a high Brunauer–Emmett–Teller surface area of 670 m 2/g. The synthesis involves flash heating of sawdust and subsequent low-temperature heat treatment (380 °C). Flash heating changed the morphology of the sawdust to the specific three-dimensional microtexture of amorphous carbon, and the subsequent heat treatment dramatically increased the surface area of the shape-controlled porous carbon materials. The products consisted of cross-linked carbon beams containing surface micro-pores (pore size < 2 nm) and meso-pores (5 nm < pore size < 50 nm). Moreover, macro-pores (5 μm < pore size < 50 μm) were found between the cross-linked carbon beams.