Carbon Nanotube@N‐Doped Mesoporous Carbon Composite Material for Supercapacitor Electrodes

Here, carbon nanotube@N‐doped mesoporous carbon (CNT@N‐PC) composites were synthesized by using resorcinol‐formaldehyde resin as carbon source, ionic liquids (ILs) as template, and nitrogen sources and tetraethyl orthosilicate (TEOS) as assistant agent. The use of ILs‐modified CNT with nitrogen and TEOS facilitated the generation of a richer mesoporous structure. The obtained CNT@N‐PC was composed of a CNT core and mesoporous carbon particles around it. CNT@N‐PC showed a 3D network structure like “dewy cobwebs” and had a high surface area of 857 m² g^?1, uniform pore size distribution (3.0 nm), and suitable N content (4.9 at.%). When used as supercapacitor electrode, the CNT@N‐PC exhibited a high specific capacitance (244 F g^?1 at 1 A g^?1), good rate capability and favorable capacitance retention (92.5 % capacitive retention after 5000 cycles), demonstrating the potential for application in high‐performance supercapacitors.     

Three‐Dimensional Nitrogen‐Doped Hierarchical Porous Carbon as an Electrode for High‐Performance Supercapacitors

A facile and sustainable procedure for the synthesis of nitrogen‐doped hierarchical porous carbons with a three‐dimensional interconnected framework (NHPC‐3D) was developed. The strategy, based on a colloidal crystal‐templating method, utilizes nitrogenous dopamine as the precursor due to its unique properties, including self‐polymerization under mild alkaline conditions, coating onto various surfaces, a high carbonization yield, and well‐preserved nitrogen doping after heat treatment. The obtained NHPC‐3D possesses a high surface area of 1056 m² g^?1, a large pore volume of 2.56 cm³ g^?1, and a high nitrogen content of 8.2 wt %. The NHPC‐3D is implemented as the electrode material of a supercapacitor and exhibits a specific capacitance as high as 252 F g^?1 at a current density of 2 A g^?1. The device also shows a high capacitance retention of 75.7 % at a higher current density of 20 A g^?1 in aqueous electrolyte due to a sufficient surface area for charge accommodation, reversible pseudocapacitance, and minimized ion‐transport resistance, as a result of the advantageous interconnected hierarchical porous texture. These results showcase NHPC‐3D as a promising candidate for electrode materials in supercapacitors.     

Synthesis of Olive‐Shaped Mesoporous Platinum Nanoparticles (MPNs) with a Hard‐Templating Method Using Mesoporous Silica (SBA‐15)

Well‐ordered mesoporous Pt nanoparticles (MPNs) with uniform olive shapes are synthesized by using two‐dimensional (2D) hexagonal mesoporous silica (SBA‐15) as a hard template. The average particle sizes are controllable in the range of 150 to 230 nm by changing the reduction time. Low‐angle XRD profiles for the obtained MPNs show three distinct peaks assignable to the (10), (11), and (20) planes of a highly ordered 2D hexagonal symmetry. From high‐magnification SEM images, periodically arranged Pt nanowires are observed clearly, which are a negative replica of the 2D hexagonally ordered mesoporous silica (SBA‐15). Furthermore, the single crystallinity of the Pt fcc structure coherently extends over the whole particles. As a result of such unique character as well as high surface area, the obtained MPNs show distinctly enhanced electrocatalytic properties for methanol oxidation reaction compared to other Pt samples, such as Pt black.     

Growth of Single‐Layered Two‐Dimensional Mesoporous Polymer/Carbon Films by Self‐Assembly of Monomicelles at the Interfaces of Various Substrates

Single‐layered two‐dimensional (2D) ultrathin mesoporous polymer/carbon films are grown by self‐assembly of monomicelles at the interfaces of various substrates, which is a general and common modification strategy. These unconventional 2D mesoporous films possess only a single layer of mesopores, while the size of the thin films can grow up to inch size in the plane. Free‐standing transparent mesoporous carbon ultrathin films, together with the ordered mesoporous structure on the substrates of different compositions (e.g. metal oxides, carbon) and morphologies (e.g. nanocubes, nanodiscs, flexible and patterned substrates) have been obtained. This strategy not only affords controllable hierarchical porous nanostructures, but also appends the easily modified and multifunctional properties of carbon to the primary substrate. By using this method, we have fabricated Fe₂O₃–mesoporous carbon photoelectrochemical biosensors, which show excellent sensitivity and selectivity for glutathione.     

High‐Loading Nano‐SnO2 Encapsulated in situ in Three‐Dimensional Rigid Porous Carbon for Superior Lithium‐Ion Batteries

Tin oxide nanoparticles (SnO₂ NPs) have been encapsulated in situ in a three‐dimensional ordered space structure. Within this composite, ordered mesoporous carbon (OMC) acts as a carbon framework showing a desirable ordered mesoporous structure with an average pore size (≈6 nm) and a high surface area (470.3 m² g^?1), and the SnO₂ NPs (≈10 nm) are highly loaded (up to 80 wt %) and homogeneously distributed within the OMC matrix. As an anode material for lithium‐ion batteries, a SnO₂@OMC composite material can deliver an initial charge capacity of 943 mAh g^?1 and retain 68.9 % of the initial capacity after 50 cycles at a current density of 50 mA g^?1, even exhibit a capacity of 503 mA h g^?1 after 100 cycles at 160 mA g^?1. In situ encapsulation of the SnO₂ NPs within an OMC framework contributes to a higher capacity and a better cycling stability and rate capability in comparison with bare OMC and OMC ex situ loaded with SnO₂ particles (SnO₂/OMC). The significantly improved electrochemical performance of the SnO₂@OMC composite can be attributed to the multifunctional OMC matrix, which can facilitate electrolyte infiltration, accelerate charge transfer, and lithium‐ion diffusion, and act as a favorable buffer to release reaction strains for lithiation/delithiation of the SnO₂ NPs.     

Constructing Ordered Three‐Dimensional TiO2 Channels for Enhanced Visible‐Light Photocatalytic Performance in CO2 Conversion Induced by Au Nanoparticles

As a typical photocatalyst for CO₂ reduction, practical applications of TiO₂ still suffer from low photocatalytic efficiency and limited visible‐light absorption. Herein, a novel Au‐nanoparticle (NP)‐decorated ordered mesoporous TiO₂ (OMT) composite (OMT‐Au) was successfully fabricated, in which Au NPs were uniformly dispersed on the OMT. Due to the surface plasmon resonance (SPR) effect derived from the excited Au NPs, the TiO₂ shows high photocatalytic performance for CO₂ reduction under visible light. The ordered mesoporous TiO₂ exhibits superior material and structure, with a high surface area that offers more catalytically active sites. More importantly, the three‐dimensional transport channels ensure the smooth flow of gas molecules, highly efficient CO₂ adsorption, and the fast and steady transmission of hot electrons excited from the Au NPs, which lead to a further improvement in the photocatalytic performance. These results highlight the possibility of improving the photocatalysis for CO₂ reduction under visible light by constructing OMT‐based Au‐SPR‐induced photocatalysts.     

惰性盐辅助合成介孔石墨化碳片及其电容性能

以惰性盐KCl为模板、硝酸镍为金属催化剂镍源、葡萄糖为碳源,通过碳化处理制备了介孔石墨化碳片。利用扫描电子显微镜、透射电子显微镜、X-射线衍射仪和比表面测试仪对介孔石墨化碳片进行了表征。探讨了碳片形成的机理,采用三电极测试体系研究了介孔石墨化碳片电极材料的电化学性能。结果表明,10 g KCl制备的碳片比表面积最大(989 m2·g-1),在6 mol·L-1KOH电解液中,当电流密度为0.5 A·g-1时,比电容达到180 F·g-1;当电流密度达到10 A·g-1时,比电容维持在148 F·g-1,显示了电极具有较好的倍率性能;在10 A·g-1条件下,2 000次循环充放电测试后电容没有发生衰减,展示了在超级电容器方面的应用潜力。     

Ordered Mesoporous Carbon Paste Electrodes for Electrochemical Sensing and Biosensing

Surface renewable ordered mesoporous carbon paste electrodes (OMCPE) were prepared by mechanical mixing ordered mesoporous carbon (OMC) and mineral oil. Electrochemical behavior of the composite electrode was evaluated and compared with the conventional graphite paste (GPE) and carbon nanotubes paste (CNTPE) electrodes. The OMCPE provided improved electron transfer kinetics and catalytic capabilities in connection with oxidation and/or reduction of different redox systems, such as ferricyanide and some biological species, e. g. ascorbic acid (AA), uric acid (UA), β‐nicotinamide adenine dinucleotide (NADH), dopamine (DA), epinephrine (EP), acetaminophenol (AP) and hydrogen peroxide. The substantial decrease in the over voltage of the hydrogen peroxide oxidation along with the facile incorporation of glucose oxidase (GOD) into the composite matrix allowed us successfully to fabricate a sensitive and selective glucose biosensor. A linear response up to 15 mM glucose was obtained for the OMCPE modified with 10% GOD (w/w) with a detection limit of 0.072 mM. In addition, we also successfully applied the OMCPE to the anodic stripping voltammetric analysis of heavy metal ions with improved sensitivities in comparison with CNTPE and GPE. The excellent experimental results implicate that the new developed paste electrode holds great promise in the design of electrochemical devices, such as sensors and biosensors.     

Mesoporous Carbon Nanofibers Embedded with MoS2 Nanocrystals for Extraordinary Li‐Ion Storage

MoS₂ nanocrystals embedded in mesoporous carbon nanofibers are synthesized through an electrospinning process followed by calcination. The resultant nanofibers are 100–150 nm in diameter and constructed from MoS₂ nanocrystals with a lateral diameter of around 7 nm with specific surface areas of 135.9 m² g^?1. The MoS₂@C nanofibers are treated at 450 °C in H₂ and comparison samples annealed at 800 °C in N₂. The heat treatments are designed to achieve good crystallinity and desired mesoporous microstructure, resulting in enhanced electrochemical performance. The small amount of oxygen in the nanofibers annealed in H₂ contributes to obtaining a lower internal resistance, and thus, improving the conductivity. The results show that the nanofibers obtained at 450 °C in H₂ deliver an extraordinary capacity of 1022 mA h g^?1 and improved cyclic stability, with only 2.3 % capacity loss after 165 cycles at a current density of 100 mA g^?1, as well as an outstanding rate capability. The greatly improved kinetics and cycling stability of the mesoporous MoS₂@C nanofibers can be attributed to the crosslinked conductive carbon nanofibers, the large specific surface area, the good crystallinity of MoS₂, and the robust mesoporous microstructure. The resulting nanofiber electrodes, with short mass‐ and charge‐transport pathways, improved electrical conductivity, and large contact area exposed to electrolyte, permitting fast diffusional flux of Li ions, explains the improved kinetics of the interfacial charge‐transfer reaction and the diffusivity of the MoS₂@C mesoporous nanofibers. It is believed that the integration of MoS₂ nanocrystals and mesoporous carbon nanofibers may have a synergistic effect, giving a promising anode, and widening the applicability range into high performance and mass production in the Li‐ion battery market.     

有序介孔碳的简易模板法制备与电化学电容性能研究

0引言电化学电容器(Electrochemical Capacitors),又称为超级电容器(supercapacitors)是介于传统电容器和二次电池之间的一种新型储能装置,它具有循环寿命长、比容量高、能快速充放电等优点[1,2]。近年来随着电子、电气设备的日趋小型化以及电动汽车工业的不断发展,作为后备电源和记忆候补装置的超级电容器日益引起了人们的广泛关注。碳材料由于具有成本低、比表面积大、导电性优良、制备电极工艺简单等特点,一直是超级电容器电极材料的首选。其中,活性炭是最早采用的多孔电极材料,其比表面积可高达2500￣3000m·2g-1[3]。然而,活性炭材料…     

Recent Advances in Porous Carbon Materials for Electrochemical Energy Storage

Climate change and the energy crisis have promoted the rapid development of electrochemical energy‐storage devices. Owing to many intriguing physicochemical properties, such as excellent chemical stability, high electronic conductivity, and a large specific surface area, porous carbon materials have always been considering as a promising candidate for electrochemical energy storage. To date, a wide variety of porous carbon materials based upon molecular design, pore control, and compositional tailoring have been proposed for energy‐storage applications. This focus review summarizes recent advances in the synthesis of various porous carbon materials from the view of energy storage, particularly in the past three years. Their applications in representative electrochemical energy‐storage devices, such as lithium‐ion batteries, supercapacitors, and lithium‐ion hybrid capacitors, are discussed in this review, with a look forward to offer some inspiration and guidelines for the exploitation of advanced carbon‐based energy‐storage materials.     

Nitrogen‐Doped Ordered Mesoporous Carbon Supported Bimetallic PtCo Nanoparticles for Upgrading of Biophenolics

Hydrodeoxygenation (HDO) is an attractive route for the upgrading of bio‐oils produced from lignocellulose. Current catalysts require harsh conditions to effect HDO, decreasing the process efficiency in terms of energy and carbon balance. Herein we report a novel and facile method for synthesizing bimetallic PtCo nanoparticle catalysts (ca. 1.5 nm) highly dispersed in the framework of nitrogen‐doped ordered mesoporous carbon (NOMC) for this reaction. We demonstrate that NOMC with either 2D hexagonal (p6m) or 3D cubic (Im m) structure can be easily synthesized by simply adjusting the polymerization temperature. We also demonstrate that PtCo/NOMC (metal loading: Pt 9.90 wt %; Co 3.31 wt %) is a highly effective catalyst for HDO of phenolic compounds and “real‐world” biomass‐derived phenolic streams. In the presence of PtCo/NOMC, full deoxygenation of phenolic compounds and a biomass‐derived phenolic stream is achieved under conditions of low severity.