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Carbon-coated Si/carbon nanotube/graphene oxide (C-Si/CNT/GO) microspheres with a robust core–shell composite structure were successfully fabricated by efficient and scalable spray-drying and chemical vapor deposition (CVD) for application as a lithium-ion battery (LIB) anode. The amphiphilic GO nanoparticles facilitated the uniform dispersion of Si nanoparticles by suppressing the CNT aggregation in the Si/CNT/GO microspheres, efficiently forming a robust Si/CNT/GO microsphere composite structure. The surface of the Si/CNT/GO microsphere composite was coated with carbon using CH4 via CVD to enhance its cycling performance. The four building block components, namely, Si nanoparticles, CNTs, and GO nanoparticles as the core and the carbon-coating layers as the shell, provided high electrochemical capacity, excellent electrical conductivity, efficient buffer space for the volume expansion of the Si nanoparticles, and high structural stability during lithiation/delithiation. The C-Si/CNT/GO composite anode also exhibited excellent electrochemical performance with high specific capacity (2921 mAh g–1 at 100 mA g–1), long cycle life (1542 mAh g–1 at 200 mA g–1 after 100 cycles), and high charge/discharge rate (1506 mAh g–1 at 6 A g–1). This approach for fabricating core–shell structured Si-based composite anodes with excellent electrochemical performance will provide a significant breakthrough for developing next-generation LIBs.

A systematic study considering the microstructural effect of carbon materials on the electrochemical or electrocatalytic performance is essential for developing carbon electrode materials of electric vehicles and smart grids that require durable and robust energy supply. In this study, the edge sites within activated carbons (ACs) were physically modified via thermal treatment to clarify the relationship between the edge density and hydrogen evolution reaction (HER). Moreover, their dominant contribution to the electrochemical performance of lead-carbon batteries was demonstrated. The ACs exhibited decreased defect density and enhanced crystallinity due to the merger of micro-domains during a high-temperature thermal treatment (HTT). In contrast to the specific surface area, the edge area of the ACs, which was quantified via temperature programmed desorption up to 1800 °C, decreased significantly with increasing HTT temperature. We have confirmed a close relationship between the edge densities and HER parameters. The lead-carbon battery unit cell employing HTT1600 with the lowest edge ratio (0.81%) exhibited a higher charging efficiency, higher cycling stability, and lower water loss than the cell employing pristine AC with a high edge ratio (8.42%). The edge ratio of carbon materials can be considered an important parameter in designing electrode materials for electrochemical energy storage.

Investigating the surface properties of heteroatom-doped carbon materials is essential because these versatile materials have found use in a variety of energy and environmental applications; an understanding of these properties would also lead to an improved appreciation of the direct interaction between the reactant and the functionalized surface. Herein, we explore the effect of boron (B) doping on the surface properties of activated carbon (AC) materials based on their water adsorption behavior and oxygen reduction reaction. In the high-temperature B doping process, B-doped AC materials at 1400 °C exhibit an open pore structure with B-O bonds, whereas at a temperature of 1600 °C, a nonporous structure containing a large amount of B-C bonds prevails. The B-O species act as active sites for water adsorption on the carbon surface. On the basis of the isothermal adsorption heat, we suggest that B atoms are present at the pore openings and on the surfaces. The B-O moieties at the open edges improve the electrocatalytic activity, whereas the B-C bonds at the closed edges decrease the electrocatalytic activity because of the stable structure of these bonds. Our findings provide new evidence for the electrocatalytic properties associated with the structure of B-doped edges.

Y.A.K. acknowledges the financial support from the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2021R1I1A305628711). A.B. gratefully acknowledges the Centre National de la Recherche Scientifique (CNRS) and the International Center for Frontier Research in Chemistry (icFRC) (Strasbourg, France). J.M.D.T. acknowledges joint partial funding from Gobierno del Principado de Asturias and European Regional Development Fund (ERDF/FEDER) (grant IDI/2021/000037). Y.C. acknowledges the financial support from the Australian Research Council under the ARC research hub for safe and reliable energy (IH200100035).

Microgels are three-dimensional (3D) colloidal hydrogel particles with outstanding features such as biocompatibility, good mechanical properties, tunable sizes from submicrometer to tens of nanometers, and large surface areas. Because of these unique qualities, microgels have been widely used in various applications. Carbon-based materials (CMs) with various dimensions (0-3D) have recently been investigated as promising candidates for the design and fabrication of microgels because of their large surface area, excellent conductivity, unique chemical stability, and low cost. Here, we provide a critical review of the specific characteristics of CMs that are being incorporated into microgels, as well as the state-of-the art applications of CM-microgels in pollutant adsorption and photodegradation, H

The conceptual, bottom-up design of functional carbon materials from microporous organic polymers was investigated. Owing to their structural rigidity and synthetic flexibility, the porous polymers streamlined the thermal carbonization process while excluding the need for exogenous additives or extra synthesis procedures and allowed for simultaneous elemental engineering of the resultant carbonaceous materials. As designed, heteroatoms such as nitrogen and sulfur could be uniformly incorporated into the carbon matrices from the microporous polymers during thermal carbonization with a concomitant change in the macroscopic properties of the materials. In particular, doping with sulfur atoms could provide reactive sites, thereby conferring superior catalytic performance to the carbon materials. This study demonstrates expansion of the capability of microporous polymers as a functional carbon source and advances the synthetic concept for carbonaceous materials.

Despite significant improvements in the synthesis of nitrogen (N)-doped carbon nanotubes (CNTs) and their versatile applications, there has always been a large difficulty in controlling the bonding configuration of N atoms within CNTs. In the current work, we report an effective chemical strategy to synthesize single-walled carbon nanotubes (SWNTs) with 100% of quaternary N via a chlorosulfonic acid(CSA) treatment. In this process, the pyridinic and pyrrolic groups were selectively and completely removed while retaining the quaternary N atoms. The presence of 2.04 at. % of quaternary N atoms within SWNTs was directly identified from a single sharp peak in the N 1s spectra of XPS, and indirectly supported by the downshift of C 1s peak in XPS, the upshift of G'-band in Raman spectroscopy, and the decrease of the work function from 5.46 to 4.59 eV. The doping effect of the quaternary N atoms on the macroscopic properties of SWNT fibers was verified by a large increase in the electrical conductivity from 0.63 to 2.17 MS/m. In perspective, our chemical approach can now be applied to synthesize carbon materials with controlled N functionalities for different applications.

The aim of this study is to develop the templateless fabrication of hierarchical porous carbon nanofiber (CNF)/MnO2 composites (PMnCD) derived from polyacrylonitrile (PAN)/cyclodextrin (CD) and investigate their morphological and electrochemical properties to determine the different capabilities of inclusion complexes (ICs) formed by α-CD, β-CD and γ-CD. Among the three CD phases, the PMnCD(β) composite using β-CD exhibits a hierarchical porous structure with large specific surface area of 499 m2g-1, and total pore volume of 0.32 cm3g-1, which helps with adsorption efficiency and accumulation of hydrated molecules for double-layer formation. In addition, the numerous mesopores and nitrogen functionalities of the PMnCD(β) composite provide fast diffusion channels for electrolyte ions and higher attractive interactions with electrolyte ions through the pseudocapacitive character. As a result, the PMnCD(β) electrode has a high specific capacitance of 228 Fg-1 at 1 mAcm−2, maximum energy density of 25.3–16.0 Whkg−1 in the power density range of 400-10,000 Wkg-1, and excellent cycling stability of more than 94% after 10000 cycles in aqueous solution, thereby offering potential applications for supercapacitors.

To understand the effect of microstructural characteristics of carbon materials on their electrochemical or electrocatalytic performance, an in-depth study of the edges in carbon materials should be carried out. In this study, catalytically grown platelet-type carbon nanofibers (CNFs) with fully exposed edges were physically and chemically passivated to clarify the relationship between the edge density and the hydrogen evolution reaction (HER) activity. Due to the aligned structure along the fiber axis, the edges on the outer surface of the CNFs were easily modified without using a complex process. The edges on the surface of the CNFs were inactivated by sequentially forming single, double, and multiple loops as the heat treatment temperatures increased. The number of edges within the CNFs was quantitatively measured using temperature-programmed desorption (TPD) up to 1800 °C. The surviving edges on the surface of thermally treated CNFs were identified by chemical functionalization via an amination reaction. We identified a close relationship between the HER activity and the edge density. When evaluating the electrochemical and electrocatalytic activity of carbon materials, it is important to know the portion of the edge surface area with respect to the total surface area and edge ratio.

We demonstrate the synthesis of double-walled carbon nanotubes (DWNTs) with a selectively boron-doped outer tube via the thermal diffusion method. Such selective boron-doping in the outer tubes alt...

The unitized regenerative fuel cell (URFC) system has attracted significant attention and interests because of its round-trip energy conversion with high energy density. However, the identification of low-cost bipolar (BP) plate with higher corrosion resistance is required to produce a sustainable system. In this work, we investigated the possibilities of using cost-effective lead (Pb) metal-based plate as a BP plate material for URFC system. To further enhance the advantageous properties of Pb plate, silver (Ag) was coated onto the Pb plate. Different types of structural and microstructural analyses (XRD, XPS, SEM, EDAX, and mapping) were conducted to characterize the properties of Pb-based plate and the presence of Ag-coated layer on the surface of Pb plate. When compared with the Pb plate, the Ag-coated Pb plate exhibited a higher water contact angle. The obtained water contact angles of Pb and Ag-coated Pb plates were 77.83° and 92.21°, respectively. The obtained water contact angle of the Ag-coated Pb plate is quite acceptable in the URFC system because it offers exceptional advantages during the URFC operation. Furthermore, the interaction between Pb plate and Ag coated layer resulted in an efficient electrochemical performance. Based on these results, we could conclude that the Pb-based BP plate can be possibly considered for the URFC applications.

In the literature, fine structuring and mixing of the radial breathing mode frequencies ( ω RBM ) due to intertube interactions ( Ω int ) for specific inner tubes in free-standing isolated double-walled nanotubes (DWNTs) have been addressed. Questions and arguments related to the Ω int nature and its dependence with the nanotube’s growth processes have also been addressed. Later, studies involving bundled (innermost tubes) and isolated (innermost and middle tubes) of triple-walled nanotubes (TWNTs) for diameters between 0.5 and 1.7 nm found no ω RBM fine structuring or mixing but suggested that the Ω int depends on the tube’s metallicity. Here, Raman Spectroscopy is combined with transmission electron microscopy (TEM) to show that for bundled DWNTs and TWNTs measured in a broad diameter range ( 0.5 ≤ d t ≤ 2.8 nm) three effects seem to be fundamental to explain the ω RBM behavior of their constituent tubes: interactions with the external environment, metallicity-independent Ω int and curvature effects due to σ-π bonds re-hybridization. Our results display no evidence of ω RBM mixing but show that Ω int has no apparent dependence with the growth process and that Ω int has the same nature of the tube interactions with the environment. The manuscript also discusses the thus far elusive TWNT outermost tubes ω RBM .

We examined the effects of different energies of electromagnetic irradiation on the molecular size increase in the low-molecular-weight fraction of fluidized catalytic cracking decant oil (LMFD), which was fractionated from the original fluidized catalytic cracking decant oil. Microwave (MW) radiation was employed as a relatively low-energy source, and an electron beam (EB) was employed as a high-energy source. Variations in viscosity, color, molecular weight, and functional groups of the LMFD were examined before and after irradiation to illuminate the LMFD reaction mechanism. The viscosity increased from 43.17 cP for LMFD to 3978 cP after 3 h of MW irradiation (MW3h) and to 1136 cP after 1000 kGy EB irradiation (EB1000). The reddish-brown color of the LMFD changed to black for the MW3h sample, whereas the EB1000 sample changed to a dark brown. As evaluated by matrix-assisted laser desorption ionization time-of-flight mass spectrometry, the molecular weights of the MW-irradiated samples increased more than those of the EB samples. The results can be related to the activation energies for radical formation and recombination. MW irradiation is considered to have an effective energy source for both radical formation and recombination, whereas EB irradiation exhibits an energy too high for radical recombination.

Free-standing hybridized electrode consisting of double-walled carbon nanotubes (DWNTs) and activated carbon have been fabricated for flexible supercapacitor applications. The xanthan-gum, used in our methodology, showed high ability in dispersing the strongly bundled DWNTs, and was then effectively converted to activated carbon with large surface area via chemical activation. The homogeneously dispersed DWNTs within xanthan-gum derived activated carbon acted as both electrical path and mechanical support of electrode material. The hybridized film from highly dispersed DWNTs and activated carbon was mechanically strong, has high electrical conductivity, and exhibited high specific capacitance of 141.5 F/g at the current density of 100 mV/s. Our hybridized film is highly promising as electrode material for flexible supercapacitors in wearable device.

Loading level, active material content of the cathode, and the thickness of composite solid electrolyte (CSE) sheets were optimized as 13 mg cm−2, 88 wt%, and 60 μm, respectively, for the development of all-solid lithium batteries (ASLBs) with high energy density. Thin CSE sheets were fabricated by adding PVDF binder with Al-LLZO powder and PEO-Li salt solution. PVDF had effects on the ionic conductivity, strength, and electrochemical stability of the CSE sheet. When the PVDF content was increased to 7 wt%, CSE sheet strength increased from 1.4 to 2.83 MPa, while the electrochemical stability has significantly improved at the range of oxidation and reduction potential. However, the ionic conductivity decreased from 3.7 × 10−4 to 1.73 × 10−4 S cm−1 at 70 °C. Moreover, the surface layer of the composite cathode was smoother than that of normal composition, and the interfacial resistance between the cathode compound layer and Al current collector has also decreased by adding PVDF. As a result of the test, the initial discharge capacity of the coin cell showed 207 mAh g−1 and 2.3 mAh cm−2 at 70 °C.

The functionalization of nanocarbon materials such as graphene has attracted considerable attention over the past decades. In this work, we designed and synthesized a unique N-heterocyclic carbene compound with a pyrene tail group (NHCp) to investigate how carbene species can be used for the functionalization of graphene. Although the carbene moiety of NHCp has the ability to covalently bond to graphene, the pyrene tail can noncovalently interact with graphene and allows monitoring its surrounding microenvironment. The major characteristics of the resulting nanohybrids were highly dependent on the type of graphene and the NHCp-to-graphene weight ratio. Importantly, despite the covalent functionalization of graphene, an anomalous decrease in the intensity of the Raman D peak and improved conductivity were observed for the nanohybrids. It was found that the covalent bond of NHCp to the graphene edge may allow the hybridization of their orbitals, which affects electronic energy levels and alters the double resonance process that originates the D peak at the edge defect. Importantly, the NHCp compound can act as a π acceptor (not just as a σ donor) via the NHCp-graphene covalent bridge. This is the first report showing that the concept of π-backdonation can be realized in two-dimensional materials, such as graphene, and rationally designed carbene molecules can functionalize graphene without losing their beneficial sp2 hybridization characteristics.

When cancer metastasizes to bone, the resulting pain and functional disorders due to bone destruction adversely affect the patient's quality of life. We have developed a new cancer metastasis control system consisting of anticancer agents conjugated to carbon fibers (CFs), which are nonbiodegradable, carriers of a wide variety of molecules with extremely high affinity for bone. In the evaluation of cancer suppression effects on Walker 256 cancer cells, cisplatin (CDDP)-conjugated CFs (CF-CDDP) were found to be as effective in cancer suppression as CDDP. In the evaluation of the cancer suppression effects of local injection in the rat model of tibial cancer bone metastasis, similar cancer suppression was noted in the CF-CDDP group and CDDP group; however, blood Pt concentrations were significantly lower in the CF-CDDP group. Experiments with CDDP and CF-CDDP injected into bone actually destroyed by cancer metastases revealed the presence of significantly more newly formed bone tissue with the administration of CF-CDDP. Local administration of CF-CDDP is expected to become the first therapy to suppress cancer growth with low prevalence of adverse reactions, and to repair bone damaged by metastasis.

Nitrogen (N)-doped nanostructured carbons have been actively examined as promising alternatives for precious-metal catalysts in various electrochemical energy generation systems. Herein, an effective approach for synthesizing N-doped single-walled carbon nanohorns (SWNHs) with highly electrocatalytic active sites via controlled oxidation followed by N2 plasma is presented. Nanosized holes were created on the conical tips and sidewalls of SWNHs under mild oxidation, and subsequently, the edges of the holes were easily decorated with N atoms. The N atoms were present preferentially in a pyridinic configuration along the edges of the nanosized holes without significant structural change of the SWNHs. The enriched edges decorated with the pyridinic-N atoms at the atomic scale increased the number of active sites for the oxygen reduction reaction, and the inherent spherical three-dimensional feature of the SWNHs provided good electrical conductivity and excellent mass transport. We demonstrated an effective method for promoting the electrocatalytic active sites within N-doped SWNHs by combining defect engineering with the preferential formation of N atoms having a specific configuration.

This paper demonstrates the hierarchical design of functional, fibrous polymer monoliths. The monoliths are composed of conjugated microporous polymers that not only are embedded with heteroatoms but also feature fibrous yet compressible structures due to the in situ self-assembly process that occurs during the polymerization process. Therefore, the doped nitrogen atoms can allow the growth of zeolitic imidazolate framework (ZIF) nanocrystals, which causes the homogeneous encapsulation of individual fibers. The resulting hybrid monoliths exhibit enhanced physical properties as well as catalytic activity, allowing the formation of an additional coating layer via a thiol-epoxy reaction. The deliberate inclusion of template molecules during the reaction forms molecularly imprinted sites on the fibers to afford functional monoliths. As a proof of concept, the hierarchically designed materials are able to show effective recognition properties toward diethylstilbestrol, an endocrine disruptor, taking advantage of the binding sites that selectively capture the analyte molecules and the fibrous morphology that increases the accessibility of these binding sites. We envisage that the incorporation of various heteroatoms or nanocrystals will bring about the bespoke design of advanced monoliths with autonomous functions, leading to smart textile systems.