Three-Dimensional N-Doped Carbon Nanotube/Graphene Composite Aerogel Anode to Develop High-Power Microbial Fuel Cell

Optimizing the structure of electrode materials is one of the most effective strategies for designing high-power microbial fuel cells(MFCs).However,electrode materials currently suffer from a series of shortcomings that limit the output of MFCs,such as high intrinsic resistance,poor electrolyte wettability,and low microbial load capacity.Here,a three-dimensional(3D)nitrogen-doped multiwalled carbon nanotube/graphene(N-MWCNT/GA)composite aerogel is synthesized as the anode for MFCs.Comparing nitrogen-doped GA,MWCNT/GA,and N-MWCNT/GA,the macroporous hydrophilic N-MWCNT/GA electrode with an average pore size of 4.24μm enables high-density loading of the microbes and facilitates extracellular electron transfer with low intrinsic resistance.Consequently,the hydrophilic surface of N-MWCNT can generate high charge mobility,enabling a high-power output performance of the MFC.In consequence,the MFC system based on N-MWCNT/GA anode exhibits a peak power density and output voltage of 2977.8 mW m^(−2)and 0.654 V,which are 1.83 times and 16.3%higher than those obtained with MWCNT/GA,respectively.These results demonstrate that 3D N-MWCNT/GA anodes can be developed for high-power MFCs in different environments by optimizing their chemical and microstructures.

Nitrogen-doped hierarchical porous carbon derived from metal–organic aerogel for high performance lithium–sulfur batteries

Nitrogen-doped three-dimensional(3 D) porous carbon materials have numerous applications due to their highly porous structures, abundant structural nitrogen heteroatom decoration and low densities. Herein,nitrogen doped hierarchical 3 D porous carbons(NHPC) were prepared via a novel metal–organic aerogel(MOA), using hexamethylenetetramine(HMT), 1,3,5-benzenetricarboxylic acid and copper(II) as starting materials. The morphology, porous structure of the building blocks in the NHPC can be tuned readily using different amount of HMT, which makes elongation of the pristine octahedron of HKUST-1 to give rise to different aspect ratio rod-like structures. The as-prepared NHPC with rod-like carbons exhibit high performance in lithium sulfur battery due to the rational ion transfer pathways, high N-doped doping and hierarchical porous structures. As a result, the initial specific capacity of 1341 m A h/g at rate of 0.5 C(1 C = 1675 m A h/g) and high-rate capability of 354 m A h/g at 5 C was achieved. The decay over 500 cycles is 0.08% per cycle at 1 C, highlighting the long-cycle Li–S batteries.

N-doped interconnected carbon aerogels as an efficient SeS2 host for long life Na-SeS2 batteries

Selenium sulfide(SeS2)cathodes have attracted much concern as an optimized choice comparing to sulfur and selenium for lithium and sodium storage.However,it also suffers from poor cycling stability due to the dissolution of reaction intermediate products.In this study,N-doped Interconnected carbon aerogels was applied as an efficient SeS2 host by infiltrating selenium sulfide into its microporous structure(denoted as SeS2@NCAs),which could effectively accommodate the volume change of SeS2 during cycling and alleviate the dissolution of reaction intermediate products.Therefore,as for Na storage,the SeS2@NCAs cathode delivers a superior long-term cycling performance of 536 mA·h·g^-1 at a current density of 0.5 A·g^-1 after 1,000 cycles with only 0.04%capacity decline per cycle and a high rate performance(524 mA·h·g^-1 at 2 A·g^-1 and 745 mA·h·g^-1 at 0.1 A·g^-1 retained),indicating the remarkable cycling stability of SeS2@NCAs cathodes.

Immobilization of NiS nanoparticles on N-doped carbon fiber aerogels as advanced electrode materials for supercapacitors

NiS nanoparticles (NPs) with excellent electrochemical capacitance have attracted considerable attention as cost-effective energy-storage materials for supercapacitors in recent years. Preventing the aggregation and increasing the conductivity of NiS NPs are key to fully realizing their excellent electrochemical properties. In this work, NiS/N-doped carbon fiber aerogel (N-CFA) nanocomposites were obtained easily through the combination of polymerization, carbonization, and a one-step solvothermal reaction. N-CFA derived from polydopamine (PDA)-coated cotton wool was used as a template for the construction of hierarchical NiS/N-CFA nanocomposites, in which NiS NPs are uniformly immobilized on the surface of N-CFA. In this nanostructured system, N-CFA containing abundant nanofibers not only provides active regions for the growth of NiS NPs to prevent their aggregation, but also offers short pathways for the transport of electrons and ions. The electrochemical properties of the obtained NiS/N-CFA nanocomposites were investigated by cyclic voltammetry, galvanostatic charge–discharge, and alternating current impedance measurements. The optimized NiS/N-CFA nanocomposite exhibits a high specific capacitance of 1,612.5 F·g1at a charge/discharge current density of 1 A·g1and excellent rate capacitance retention of 66.7% at 20 A·g1. The excellent electrochemical properties of NiS/N-CFA nanocomposites make these materials promising electrode materials for supercapacitors. [Figure not available: see fulltext.] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

CPI/PI气凝胶复合材料的制备及光催化性能

为了提高聚酰亚胺(PI)气凝胶的光催化活性,采用两步复合的方法制备CPI/PI气凝胶复合材料。首先以3,3′,4,4′联苯四甲酸二酐和4,4′二氨基二苯醚为前驱体,采用乙醇超临界干燥技术得到PI气凝胶,并将PI气凝胶在600℃煅烧成含氮的碳化PI气凝胶(CPI);然后将CPI气凝胶与PI气凝胶前驱体复合并经超临界干燥制备CPI/PI气凝胶复合材料。对PI和CPI/PI气凝胶的表面形貌、比表面积、力学性能和光催化性能进行表征分析。结果表明:CPI/PI气凝胶具有良好的多孔结构,比表面积达到245 m^(2)/g,PI气凝胶的力学性能优异(弹性模量在10 MPa以上);煅烧后的CPI有效提高了PI气凝胶对土霉素溶液的光催化效率并具有良好的循环再生稳定性能,5次循环使用后土霉素溶液降解率为76%。