Hierarchical Porous Carbon Nanotubes Research Articles

Self-assembled hierarchical porous carbon nanotube sponge bioanode for energy harvesting and gaseous toluene removal

Microbial fuel cells (MFCs) have emerged as a promising technology with potential for volatile organic compounds (VOCs) treatment and energy recovery. However, the low efficiency of electron transfer between microorganisms and electrodes has limited their degradation ability and power output. To address this issue, we designed a macroscopic hierarchical porous super-aligned carbon nanotube (SACNT) sponge bioanode. The hierarchical structure of the SACNT anode exhibited an appropriate distribution of macro/mesopores. The large pores facilitated biofilm formation and mass transfer, enhancing direct electron transfer between bacteria and SACNTs. The abundant mesopores augmented adsorption and electrochemical reaction sites, thereby enhancing flavin-mediated indirect electron transfer. This hierarchical pore structure induced the formation of biofilms mainly composed of electroactive bacteria and toluene-degrading bacteria, promoting toluene removal and power generation. The MFC demonstrated an exceptional power density of 726.18 mW m−2, surpassing existing toluene-fueled MFCs, while achieving the toluene elimination capacity of 61.29 g m−3 h−1.

Development of hierarchical MOF-based composite phase change materials with enhanced latent heat storage for low-temperature battery thermal optimization

Most of the composite phase change materials (PCMs) based on metal-organic frameworks (MOFs) have much lower latent heat than pure PCMs due to nanoconfined effects, which limits their application in the field of battery insulation. In this work, a series of hierarchical porous carbon nanotubes (CNT)/MOF-199 were synthesized by adjusting the content of N-methyl pyrrolidone (NMP) in the solvent components, and scattered in stearic acid (SA) to obtain a novel composite PCM. The results show that there is a nearly linear relationship between the impregnation ratio, crystallization fraction and impregnation efficiency of PCMs and the mesoporous content of the supporting materials at the maximum loading rate of 70 wt%, which may provide an idea for selecting MOFs supporting materials for PCMs. The latent heat of SA/CNT/MOF-199-2 (SA/CM-2) composite PCM is 97.1/96.2 J·g−1, with a heat loss percentage of only 0.96%. Furthermore, when the lithium-ion battery is discharged 2C at −20 °C, SA/CM-2 used as insulation material can increase the discharge energy by 8.27%. Accordingly, this novel composite PCMs would be hopefully applied to thermal optimization of batteries at low temperatures.

Coaxial 3D printed anisotropic thermal conductive composite aerogel with aligned hierarchical porous carbon nanotubes and cellulose nanofibers

Thermal management materials are obtaining increasing research interest, due to the requirement on energy conservation and environment protection. However, the complex designs and energy-consuming manufacturing processes prohibit their wide spread practical account. 3D printing is an intriguing revolutionary technology in fabricating anisotropic thermal conductive materials because of its inherent virtues on directional additive manufacturing a complicated subject with designed microstructure. We demonstrate the coaxial 3D printing along with directional freezing processes to obtain anisotropic thermal conductive composite aerogel consisting of carbon nanotubes (CNTs) and cellulose nanofibers (CNFs). The as prepared composite aerogel, with the thermal conductive CNTs as inner layer, and the insulate CNFs as outer layer, presented remarkable anisotropic thermal conductivity with 0.025 W (m K)−1 in the axial direction and 0.302 W (m K)−1 in the radial direction. The Young’s modulus of the CNTs/CNFs composite aerogel was tested to be 10.91 MPa in the axial direction, and 2.62 MPa in the radial direction, respectively. The coaxial 3D printed CNTs/CNFs composite aerogel has great potential application in electronics, especially for those custom-tailored products and the related field.

Li–S Batteries: “Sauna” Activation toward Intrinsic Lattice Deficiency in Carbon Nanotube Microspheres for High‐Energy and Long‐Lasting Lithium–Sulfur Batteries (Adv. Energy Mater. 26/2021)

In article number 2100497, Xin Wang, Zhongwei Chen and co-workers develop a hierarchical porous carbon nanotube microsphere with abundant intrinsic topological defects in the carbon lattice, which promotes sulfur reaction kinetics. The intrinsic carbon defect engineering holds great promise in the development of high-performance Li–S batteries as well as other related energy storage areas.

Hierarchical Porous Carbon Nanotube Skeleton Supported Polydimethylsiloxane Composite with Electrical Continuity for High‐Performance Electromagnetic Shielding

AbstractElectromagnetic (EM) shielding materials have attracted significant attention, owing to their widespread potential in preventing EM irradiation in electrical devices and human bodies. In this study, a hierarchical porous carbon nanotube (CNT) skeleton with electrical continuity is presented, which is rapidly fabricated via the facile microwave pyrolysis of CNT‐coated organic templates, for constructing high‐performance EM shielding materials. Furthermore, the CNT skeleton, which comprises countless intertwined CNTs, can be easily designed into various configurations, such as CNT foams and CNT sheets, with varying conductivities and pore densities. In the as‐constructed CNT‐skeleton‐supported polydimethylsiloxane (PDMS)/CNT‐foam composites, the continuity of intertwined CNTs leads to a high conductivity of 271.2 S m−1 at a CNT loading of 2 wt%. Owing to the multiple reflections and reabsorption of the EM waves in the hierarchical porous CNT skeleton with macroporous, microporous, and hollow structures, the PDMS/CNT‐foam composites exhibit a high EM shielding effectiveness (SE) of 43 dB, mainly via absorption. Additionally, the electrical continuity of the CNT skeleton allows the dissipation of heat in the PDMS/CNT‐skeleton.

Engineering All-Purpose Amorphous Carbon Nanotubes with High N/O-Co-Doping Content to Bridge the Alkali-Ion Batteries and Li Metal Batteries.

All-purpose electrode materials (APEMs), which can be effectively available on not only alkali-ion batteries but also emerging Li metal batteries, are urgently pursued to open up cost-efficient tactics for practical application of energy storage systems (ESSs), but still remain challenging. Herein, the hierarchical porous carbon nanotubes network (NOPCT) with well-tailored nanoarchitecture and high N/O-co-doping content (20.6 at%) is developed to present large-span application on ESSs. As for Li/Na-ion batteries, the NOPCT delivered excellent cycle stability and robust rate performance in a conventional ester-based electrolyte. Moreover, NOPCT also serving as a metal Li host can effectively guide smooth and uniform Li nucleation/growth to enhance the cycle stability of hybrid Li metal anodes. In addition, the NOPCT played an important role in the sustainability of sulfur electrodes, promising the feasibility of shared NOPCT for practical Li-S batteries. First-principle calculations demonstrate that graphitic-N and CO function groups favor for improving electron conductivity while the pyridinic-N and CO function group make sense for improved Li/Na adsorption and affinity through Lewis acid-base interaction, enlightening the interplay between various doped categories on improved electrochemical performance of NOPCT. This work provides profound theoretical and experimental insight into the design and development of APEMs for advanced ESSs.

CNT network crosslinked by metal Co2+ for stabilizing SnO2 anodes

Porous carbon materials are considered potential replacements for metal carriers in Li–SnO2 batteries. Here, a 3D hierarchical porous carbon nanotube (CNT) scaffold was used as a collector to host SnO2. The novel collector comprised Co2+-doped porous carbon (PC) slices and a CNT network. The new Co–PC/CNT electrode demonstrated a high loading capacity of SnO2, accommodated the volume expansion of SnO2, and prevented its aggregation. Co played an important role in improving the initial discharge capacity and coulombic efficiency of the electrode. The SnO2–Co–PC/CNT electrodes exhibited outstanding electrochemical performance. The first-discharge specific capacity reached 2067 mAh·g−1, and the utilization rate of active materials reached 82.92% at a current density of 100 mAh·g−1. After 100 cycles, the specific discharge capacity remained greater than 698 mAh·g−1, with a coulombic efficiency of 99.53%.

Anthraquinone on Porous Carbon Nanotubes with Improved Supercapacitor Performance

Anthraquinone (AQ) molecules were selected to decorate the lab-made hierarchical porous carbon nanotubes (HPCNTs) to obtain electrode materials (AQ-HPCNTs) for supercapacitors, which showed a remarkable capacitance increment in comparison with pure HPCNTs when tested in 1 M H2SO4 aqueous solution. At a current density of 1 A g–1, the AQ-HPCNTs (mass ratio 7:5) electrode showed an ultrahigh specific capacitance of 710 F g–1, which is much larger than that of the unmodified HPCNTs (304 F g–1). Even at a high discharge current density of 20 A g–1, the specific capacitance of the AQ-HPCNTs (mass ratio 7:5) electrode was still as high as 419 F g–1, indicating an excellent rate capability. Furthermore, all the AQ-HPCNTs electrodes exhibited a long cycle life. Electrochemical behaviors of AQ on the HPCNTs’ surface showed a double pair of redox peaks, which are appropriate for two types of π–π stacking interactions supported by infrared spectra. The excellent capacitive behaviors of the AQ-HPCNTs electrode materials are due to a strong positive synergistic effect between AQ and HPCNTs on the improvement of electrochemical performances.