Natural nanomaterial as hard template for scalable synthesizing holey carbon naonsheet/nanotube with in-plane and out-of-plane pores for electrochemical energy storage

Tuning porous structure of carbon nanomaterials has been found to be important for their performance enhancement in electrochemical energy storage applications. In this work we employed a natural nanomaterial kaolinite, which is abundant and cheap, as hard template to synthesis porous carbon nanomaterial. By tuning the structure of hard template kaolinite, we have achieved a template directed formation of holey carbon nanosheet/nanotube materials. This carbon nanomaterials with hierarchical in-plane and out-of-plane pores have shown electrochemical energy storage capacity of 286 F/g（equal to 314 F/cm^3） at 0.1 A/g and 85 F/g（equal to 93 F/cm^3） at 100 A/g, which is comparable to variety of reported carbon based electrochemical energy storage electrode materials.

A general synthesis of inorganic nanotubes as high-rate anode materials of sodium ion batteries

Ino rganic tubular materials have an exceptionally wide range of applications,yet developing a simple and universal method to controllably synthesize them remains challenging.In this work,we report a vaporphase-etching hard-template method that can directly fabricate tubes on various thermally stable oxide and sulfide materials.This synthesis method features the introduction of a vapor-phase-etching process to greatly simplify the steps involved in preparing tubular materials and avoids complicated postprocessing procedures.Furthermore,the in-situ heating transmission electron microscopy(TEM)technique is used to observe the dynamic formation process of TiO_(2-x) tubes,indicating that the removal process of the Sb2S3 templates first experienced the Rayleigh instability,then vapor-phase-etching process.When used as an anode for sodium ion batteries,the TiO_(2-x) tube exhibits excellent rate performance of134.6 mA h g^(-1) at the high current density of 10 A g^(-1) and long-term cycling over 7000 cycles.Moreover,the full cell demonstrates excellent cycling performance with capacity retention of 98%after 1000 cycles,indicating that it is a promising anode material for batteries.This method can be expanded to the design and synthesis of other thermally-stable tubular materials such as ZnS,MoS_(2),and SiO_(2).

Self-deposition for mesoporous carbon nanosheet with supercapacitor application

Porous carbon sheets have wide application prospects in many fields,especially in energy storage of supercapacitor due to the features combining both 2D structure and porous architectures.Herein,a self-deposition approach is proposed to obtain N-doped mesoporous carbon nanosheets (N-MCNs),using 3-aminophenol (3-AF) as precursor and Mg(OH)_(2) sheet as hard template.This process realizes the direct carbon formation using 3-AF monomer as carbon precursor under the catalysis of hard template avoiding the polymerization and utilization of solvent.The mass ratio of 3-AF to Mg(OH)_(2) plays an important role in determining the pore structures and the resulting capacitance behavior.The results show that N-MCNs with a mass ratio of 3-AF and Mg(OH)_(2) of 1:1 have good electrochemical behavior for supercapacitors.This N-MCNs based electrode exhibits a high capacitance of 240 F·g^(-1)at 1 A·g^(-1),good rate performance(75.4%retention ratio at 20 A·g^(-1)),and high cycling stability with 98.3% initial capacitance retained after 10000 cycles.Symmetric supercapacitors on N-MCNs achieve energy density of 18.2 W·h·kg^(-1) and power density of 0.4 kW·kg^(-1) operated within a wide potential range of 0–1.6 V in 1.0 mol·L^(-1) Na_(2)SO_(4) solution,exhibiting its potential for electrode materials with high performance.

Effect of the pore length and orientation upon the electrochemical capacitive performance of ordered mesoporous carbons

By utilizing hard template method to adjust the mesopore length, and alkali activation to generate micro pores, two hierarchical porous carbons (HPCs) were prepared. With controlling of their mesopore length and the activation conditions, the complex system composed by HPCs and electrolyte was simplified and the effect of mesopore length on the performance of HPCs as electrodes in supercapacitors was investigated. It is found that with the mesopore length getting smaller, the ordered area gets smaller and the aggregation occurs, which is caused by the high surface energy of small grains. HPC with long pores (HPCL) exhibits a donut-like morphology with well-defined ordered mesopores and a regular orientation while in HPC with short pores (HPCS), short mesopores are only orderly distributed in small regions. Longer ordered channels form unobstructed ways for ions transport in the particles while shorter channels, only orderly distributed in small areas, results in blocked paths, which may hinder the electrolyte ions transport. Due to the unobstructed structure, HPCL exhibits good rate capability with a capacitance retention rate over 86% as current density increasing from 50 mA/g to 1000 mA/g. The specific capacitance of HPCL derived from the cyclic voltammetry test at 10 mV/s is up to 201.72 F/g, while the specific capacitance of HPCS is only 193.65 F/g. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Lithium-storage properties of SiO_(2)nanotubes@C using carbon nanotubes as templates

Silica-based anode material is the most concerned material at present,which has the advantages of good cycle stability,high theoretical specific capacity and abundant reserves.However,silica suffers from inherent low conductivity,severe volume expansion effect and low initial coulombic efficiency,which limits its application in lithium-ion batteries.Nanotubes structure can mitigate the volume expansion during lithiation/delithiation.In this article,silica nanotubes(SNTs)were prepared using carbon nanotubes(CNTs)as a template,and then the uniform carbon layer was coated on their surface by carbonization of citric acid.The hollow structure of nanotubes provides more sites for the insertion of Li+during lithiation and additional channels for Li+migration in the cycles,which improves the electrochemical performance.Conductivity can be enhanced by coating carbon layer.The specific capacity of the composite material is about 650 mAh g^(-1)at 0.1 A g^(-1)after 100 cycles.With a specific capacity of 400 mAh g^(-1)even at 1 A g^(-1)after 100 cycles.The silica-based material is a competitive anode material for lithium-ion batteries.

Hard Templating Synthesis of Mesoporous and Nanowire SnO_2 as Lithium Battery Anode Materials

1 Results Recently,Ryoo's group reported the preparation of ordered mesoporous carbon using highly ordered mesoporous silica[1-2]. Mesoporous and nanowire SnO2 anode materials for lithium batteries were prepared using KIT-6 and SBA-15 SiO2 templates. The as-prepared SnO2 nanowires had a diameter of 6 nm and a length of ≈3 μm and Brunauer-Emmett-Teller (BET) surface area of 80 m2/g while mesoporous SnO2 showed a pore size of 3.8 nm and a BET surface area of 160 m2/g. The charge capacities of these two an...

Coupling Fe and Mo single atoms on hierarchical N-doped carbon nanotubes enhances electrochemical nitrogen reduction reaction performance

Electrochemical nitrogen reduction reaction(NRR)paves a new way to cost-efficient production of ammonia,but is still challenging in the sluggish kinetics caused by hydrogen evolution reaction competition and chemical inertness of N≡N bond.Herein,we report a“dual-site”strategy for boosting NRR performance.A high-performance catalyst is successfully constructed by anchoring isolated Fe and Mo atoms on hierarchical N doped carbon nanotubes through a facile self-sacrificing template route,which exhibits a remarkably improved NH3 yield rate of 26.8μg·h^(−1)·mg with 11.8%Faradaic efficiency,which is 2.5 and 1.6 times larger than those of Fe/NC and Mo/NC.The enhancement can be attributed to the unique hierarchical structure that profits from the contact of electrode and electrolyte,thus improving the mass and electron transport.More importantly,the in situ Fourier transform infrared spectroscopy(in situ FTIR)result firmly demonstrates the crucial role of the coupling of Fe and Mo atoms,which can efficiently boost the generation and transmission of*N2Hy intermediates,leading to an accelerated reaction rate.

Facile Synthesis of Porous Carbon Nitride Spheres with Hierarchical Three-Dimensional Mesostructures for CO_(2) Capture

Porous carbon nitride(CN)spheres with partially crystalline frameworks have been successfully synthesized via a nanocasting approach by using spherical mesoporous cellular silica foams(MCFs)as a hard template,and ethylenediamine and carbon tetrachloride as precursors.The resulting spherical CN materials have uniform diameters of ca.4μm,hierarchical three-dimensional(3-D)mesostructures with small and large mesopores with pore diameters centered at ca.4.0 and 43 nm,respectively,a relatively high BET surface area of~550 m^(2)/g,and a pore volume of 0.90 cm^(3)/g.High-resolution transmission electron microscope(HRTEM)images,wide-angle X-ray diffraction(XRD)patterns,and Raman spectra demonstrate that the porous CN material has a partly graphitized structure.In addition,elemental analyses,X-ray photoelectron spectra(XPS),Fourier transform infrared spectra(FT-IR),and CO_(2) temperature-programmed desorption(CO_(2)-TPD)show that the material has a high nitrogen content(17.8 wt%)with nitrogen-containing groups and abundant basic sites.The hierarchical porous CN spheres have excellent CO_(2) capture properties with a capacity of 2.90 mmol/g at 25℃and 0.97 mmol/g at 75℃,superior to those of the pure carbon materials with analogous mesostructures.This can be mainly attributed to the abundant nitrogen-containing basic groups,hierarchical mesostructure,relatively high BET surface area and stable framework.Furthermore,the presence of a large number of micropores and small mesopores also enhance the CO_(2) capture performance,owing to the capillary condensation effect.

A mussel-inspired delivery system for enhancing self-healing property of epoxy coatings

Dopamine(DA), one type of mussel-inspired biological molecules with adhesive nature and corrosion inhibitor property, are often used to functionalize the surfaces of various materials. Herein, we report the application of polydopamine(PDA) microcapsules as novel nanocontainers for the purpose, loading corrosion inhibitor(benzotriazole) in its shell structure, and then were embedded into epoxy coatings to provide self-healing and anti-corrosion protection for carbon steel. Fast release of benzotriazole in acidic environment caused by local corrosion and the chelating effect of PDA-Fe^(3+)can synergistically promote the formation of protective film on bare steel surface, which endows coatings with self-healing functionality. Electrochemical impedance spectroscopy(EIS), local electrochemical impedance spectroscopy(LEIS), and spray tests were conducted to evaluate the active inhibition and corrosion resistance of the loaded coatings. The scratched coating with incorporation of nanocontainers presented better protection performance, exhibiting increased Ro(oxide layer resistance) and R ct(charge transfer resistance) during initial immersion periods. The EIS tests in long-term immersion were also performed to confirm the anti-corrosion effect of composited coatings. These results demonstrated that benzotriazole-decorated PDA capsules dramatically enhanced the self-healing properties and anti-corrosion performance of epoxy coatings with the synergistic help of PDA and benzotriazole.

Effect of Structural Properties of Mesoporous Co3O4 Catalysts on Methane Combustion

Highly ordered 2D and 3D-Co3O4 catalysts were prepared using SBA-15 and KIT-6 as templates. Na- no-Co304 catalyst was obtained by calcination of cobalt nitrate as a comparison. The BET surface area of nano- CO304, 2D-Co3O4 and 3D-Co3O4 catalysts was 16.2, 63.9 and 75.1 mE/g, respectively. All the catalysts were tested for the total combustion of methane and their catalytic performance was in the order of 3D-Co3O4（T90=355℃）〉 2D-CoaO4（T90=383℃）〉nano-Co3O4（T90=455℃）. It was also found that the order of the areal specific reaction rates for the combustion of methane followed the same order of total activity. The characterization result demonstrates that enhanced catalytic performance of methane of the 2D-Co3O4 and 3D-Co3O4 catalysts is due to their pronounced reducibility and abundant active Co3O4 species, which was caused by the preferential exposure of {220} crystal planes in 3D-Co3O4 and 2D-Co3O4 catalysts compared to the nano-Co3O4.