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Encapsulation of various materials inside nanotubes has emerged as an effective method in nanotechnology that facilitates the formation of novel one-dimensional (1D) structures and enhances their functionality. Because of the effects of geometrical confinement and electronic interactions with host nanotubes, encapsulated materials often exhibit low-dimensional polymorphic structures that differ from their bulk forms. These polymorphs exhibit unique properties, including altered electrical, optical, and magnetic behaviors, making them promising candidates for applications in electronics, energy storage, spintronics, and quantum devices. This review explores recent advancements in the encapsulation of a wide range of materials such as organic molecules, elemental substances, metal halides, metal chalcogenides, and other complex compounds. In particular, we focus on novel polymorphs formed through the geometrical confinement effect within the nanotubes. The atomic structure, other key properties, and potential applications of these encapsulated materials are discussed, highlighting the impact of nanotube encapsulation on their functionalities. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI), an emerging and promising new method, is being utilized to remove ionic and polarizable species from water. The development of effective electrode materials has been the main driving force behind the increased interest in the CDI system for water purification because it is simple to use, affordable, and environmentally friendly compared to other traditional methods. Carbon electrodes made from biomass are often considered as low-cost, high-performance energy storage materials due to their abundance, simple synthesis methods, and high specific surface area. Herein, we developed materials from biowastes of banana plant leaves (B) and java black (J) that were hydrothermally carbonized. These materials were then chemically treated with KOH at a 1:4 ratio to produce extremely porous activated carbon from the biowastes of banana plant leaves (AC-B) and java black (AC-J). The surface areas of AC-B and AC-J were 84.155 and 295.517 m2 g−1 respectively, with high mesoporous properties. Poly(vinyl alcohol) (PVA) was employed as a binder to bind the synthetic activated carbons like AC-B and AC-J together in order to make electrodes. Despite the fact that PVA is hydrophilic by nature, the hydrophobic glutaraldehyde (GA) was used to cross-link the PVA molecules in order to increase the durability of the carbon material and produced AC-B-PVA-GA and AC-J-PVA-GA electrodes. X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, Brunauer-Emmett-Teller, and cyclic voltammetry were used to characterize the synthesized carbon materials. The newly developed CDI electrodes, which demonstrated a variety of electrosorption capacities at different applied potentials, were used to investigate the effectiveness of the desalination process. The developed electrodes showed good stability under shear conditions, and the CDI process was repeatable and stable after around 10 electrosorption cycles. For example, the specific capacities of the AC-B-PVA-GA and AC-J-PVA-GA electrodes were 31.01 and 40.78 F/g, respectively in a 0.5 M NaCl aqueous solution. At 1.2 V, it was found that the AC-B-PVA-GA and AC-J-PVA-GA electrodes removed 2.41 and 3.64 mg g−1 of salt, respectively. The findings obtained encourage the development of CDI systems for desalination and water treatment and provide essential information on ion electrosorption. It also demonstrates an effective method for environmental cleanup utilizing a basic CDI system. [ABSTRACT FROM AUTHOR]

The exploration of renewable energy in the twenty-first century emerged as the world-leading movement to support energy sustainability, leading to the paramount necessity for energy storage systems (ESSs). The porous carbon-derived electrode has been a long-pursued aim in supercapacitor applications, which feature their availability, renewability, environmental friendliness, rapid ion transport, and tunable surface chemistry. In this regard, chemical activation is one of the most highly praised and compatible strategies for synthesizing porous carbon in energy storage applications. Nevertheless, the most challenging issue to reconcile has been using environmentally hazardous, unsustainable activators. NaNH2 emerges as a greener solution to the synthesis of porous carbon. Additionally, it presents as a dual-function activator, serving as a nitridation and activating agent. This dual role promotes the development of micropores and mesopores in the pore architecture and active sites for effective ion transport, highlighting the critical facets in the fabrication of supercapacitor electrode materials. Herein, this paper discussed the promising use of NaNH2-activated porous carbon in electrochemical applications that covered the synthesis of porous carbon to the proposed activation mechanism, the impact of variations in design parameters, and the electrochemical properties of the resultant porous carbon. Ultimately, the recent challenges and future outlooks were comprehensively highlighted. [ABSTRACT FROM AUTHOR]

Owing to the intrinsic excellent mechanical, electrical, and thermal properties of carbon nanotubes (CNTs), carbon nanotube fibers (CNTFs) have been expected to become promising candidates for the next-generation of high-performance fibers. They have received considerable interest for cutting-edge applications, such as ultra-light electric wire, aerospace craft, military equipment, and space elevators. Wet-spinning is a broadly utilized commercial technique for high-performance fiber manufacturing. Thus, compared with array spinning from drawable CNTs vertical array and direct dry spinning from floating catalyst chemical vapor deposition (FCCVD), the wet-spinning technique is considered to be a promising strategy to realize the production of CNTFs on a large scale. In this tutorial review, we begin with a summative description of CNTFs wet-spinning process. Then, we discuss the high-concentration CNTs wet-spinning dope preparation strategies and corresponding non-covalent adsorption/charge transfer mechanisms. The filament solidification during the coagulation process is another critical procedure for determining the configurations and properties for derived CNTFs. Next, we discuss post-treatment, including continuous drafting and thermal annealing, to further optimize the CNTs orientation and compact configuration. Finally, we summarize the physical property-structure relationship to give insights for further performance promotion in order to satisfy the prerequisite for detailed application. Insights into propelling high-performance CNTFs production from lab-scale to industry-scale are proposed, in anticipation of this novel fiber having an impact on our lives in the near future. [ABSTRACT FROM AUTHOR]

The application of Li metal anodes in rechargeable batteries is impeded by safety issues arising from the severe volume changes and formation of dendritic Li deposits. Three‐dimensional hollow carbon is receiving increasing attention as a host material capable of accommodating Li metal inside its cavity; however, uncontrollable and nonuniform deposition of Li remains a challenge. In this study, we synthesize metal–organic framework‐derived carbon microcapsules with heteroatom clusters (Zn and Ag) on the capsule walls and it is demonstrated that Ag‐assisted nucleation of Li metal alters the outward‐to‐inward growth in the microcapsule host. Zn‐incorporated microcapsules are prepared via chemical etching of zeolitic imidazole framework‐8 polyhedra and are subsequently decorated with Ag by a galvanic displacement reaction between Ag+ and metallic Zn. Galvanically introduced Ag significantly reduces the energy barrier and increases the reaction rate for Li nucleation in the microcapsule host upon Li plating. Through combined electrochemical, microstructural, and computational studies, we verify the beneficial role of Ag‐assisted Li nucleation in facilitating inward growth inside the cavity of the microcapsule host and, in turn, enhancing electrochemical performance. This study provides new insights into the design of reversible host materials for practical Li metal batteries. [ABSTRACT FROM AUTHOR]

Density functional theory calculations are carried out to investigate the adsorption properties of Li+ and Li on twenty-four adsorbents obtained by replacement of C atoms of coronene (C24H12) and circumcoronene (C54H18) by Si/N/BN/AlN units. The molecular electrostatic potential (MESP) analysis show that such replacements lead to an increase of the electron-rich environments in the molecules. Li+ is relatively strongly adsorbed on all adsorbents. The adsorption energy of Li+ (Eads-1) on all adsorbents is in the range of − 42.47 (B12H12N12) to − 66.26 kcal/mol (m-C22H12BN). Our results indicate a stronger interaction between Li+ and the nanoflakes as the deepest MESP minimum of the nanoflakes becomes more negative. A stronger interaction between Li+ and the nanoflakes pushes more electron density toward Li+. Li is weakly adsorbed on all adsorbents when compared to Li+. The adsorption energy of Li (Eads-2) on all adsorbents is in the range of − 3.07 (B27H18N27) to − 47.79 kcal/mol (C53H18Si). Assuming the nanoflakes to be an anode for the lithium-ion batteries, the cell voltage (Vcell) is predicted to be relatively high (> 1.54 V) for C24H12, C12H12Si12, B12H12N12, C27H18Si27, and B27H18N27. The Eads-1 data show only a small variation compared to Eads-2, and therefore, Eads-2 has a strong effect on the changes in Vcell. [ABSTRACT FROM AUTHOR]

Fluorinated graphene, a two-dimensional nanomaterial composed of three atomic layers, a central carbon layer sandwiched between two layers of fluorine atoms, has attracted considerable attention across various fields, particularly for its potential use in biomedical applications. Nonetheless, scant effort has been devoted to assessing the potential toxicological implications of this nanomaterial. In this study, we scrutinize the potential impact of fluorinated graphene on a protein model, HP35 by utilizing extensive molecular dynamics (MD) simulation methods. Our MD results elucidate that upon adsorption to the nanomaterial, HP35 undergoes a denaturation process initiated by the unraveling of the second helix of the protein and the loss of the proteins hydrophobic core. In detail, substantial alterations in various structural features of HP35 ensue, including alterations in hydrogen bonding, Q value, and RMSD. Subsequent analyses underscore that hydrophobic and van der Waals interactions (predominant), alongside electrostatic energy (subordinate), exert influence over the adsorption of HP35 on the fluorinated graphene surface. Mechanistic scrutiny attests that the unrestrained lateral mobility of HP35 on the fluorinated graphene nanomaterial primarily causes the exposure of HP35's hydrophobic core, resulting in the eventual structural denaturation of HP35. A trend in the features of 2D nanostructures is proposed that may facilitate the denaturation process. Our findings not only substantiate the potential toxicity of fluorinated graphene but also unveil the underlying molecular mechanism, which thereby holds significance for the prospective utilization of such nanomaterials in the field of biomedicine. [ABSTRACT FROM AUTHOR]

Electromagnetic absorbing composites modified by ceramic- ferromagnetic-graphite (CFG) fillers were first received. Ceramic-ferromagnetic-graphite polymer composites impact strength characteristics were researched and compositions with a higher silicon carbide SiC-10 % wt. content were studied, while chromium oxide Cr2O3 and graphite content in 5-15% wt. range was optimized. It is shown, that chromium oxide Cr2O3 and graphite introduction in polyamide 6-SiC 10 % wt. system increases their impact strength and breaking stress during bending. As a result of statistical data processing, the approximating curves equation were obtained, which allow to calculate ceramic-ferromagnetic-graphite polymer composites strength characteristics. It is shown that the nature of modification effect for CFG fillers on ceramic- ferromagnetic-graphite polymer composites complex spectral characteristics for absorbing electromagnetic radiation indicates the advantage in using complex system in order to receive effective materials. [ABSTRACT FROM AUTHOR]

Here, we have prepared carbon-coated cadmium sulfide nanowires with sulfur defect (Vs-CdS NWs@C) anode by a polyvinylpyrrolidone (PVP)-assisted solvothermal method. Vs-CdS NWs@C anode not only increases the wettability of the electrode material and the electrolyte but also exposes more active sites, which can effectively alleviate the volume expansion during the charging and discharging process, accelerate the reaction kinetics, and maintain the stability of the electrode structure. At the same time, the surface defects engineered to construct unsaturated active sites on the surface contribute to the conductivity and introduce active sites for binding lithium ions. Finally, the conductivity of the carbon layer can effectively improve the electrode conductivity. Therefore, the synergistic regulation strategy of nanostructures, sulfur defect engineering, and carbon coating is expected to construct new and efficient anode materials for LIBs. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanomaterials have greater capacity and better cycling stability for Li-ion batteries as compared to undoped carbon materials. In situ near-edge X-ray absorption fine structure (NEXAFS) spectroscopy in combination with quantum chemical modeling has been applied to determine the chemical states of the incorporated nitrogen after interaction with lithium. NEXAFS N K-edge spectra of nitrogen-doped porous carbon were measured before and after thermal deposition of Li vapors. The simulation and interpretation of NEXAFS data were carried out based on density functional theory calculations of initial and lithiated graphene fragments that contained different nitrogen species. The preferable interactions of Li with pyridinic and hydrogenated pyridinic nitrogen which are located at edges of atomic vacancies and graphene planes were revealed. [ABSTRACT FROM AUTHOR]

In this paper, we present a comparative analysis of the Raman spectra of two heterostructures: Si/SiO2/HfO2/Graphene and Si/SiO2/Graphene/HfO2. In the former configuration, the Graphene layer is transferred onto the 5 nm-thick HfO2 layer, while the latter configuration involves the growth of à 5 nm-thick HfO2 layer by atomic layer deposition (ALD) on the Graphene layer. The analysis of the Raman spectra has demonstrated significant differences between the interfaces Graphene/HfO2 and HfO2/Graphene. The distinct Raman signatures observed emphasize the critical role played by the specific order and arrangement of the Graphene and HfO2 layers within the heterostructure, which impacts the charge transfer between these two materials and the presence or absence of strains. The Raman spectra corresponding to different thickness of the HfO2 layer (5, 10, 15, and 20 nm) in Si/SiO2/Graphene/HfO2 heterostructure shows the appearance of a small shoulder on the low-frequency side of the G band around 1523 cm-1. Furthermore, it was observed that the intensity of this shoulder diminishes as the thickness of the HfO2 layer increases. The observed discrepancies between spectra, related to the experimental conditions employed for sample preparation, are attributed to the interplay of two phenomena: the transfer of charges among Graphene, HfO2, and SiO2, as well as the emergence of constraints. [ABSTRACT FROM AUTHOR]

Amorphous silicon carbide (a-SiC) films hold promise for microelectronic and MEMS devices. Prior to their use in microfabricated devices, these films undergo plasma etching. This study investigates reactive ion etching (RIE) of sputtered a-SiC films on Si (100) substrates using sulfur hexafluoride (SF6) gas. The focus is on the impact of RF power on the thickness, structure, chemistry, and morphology of the SiC film. Grazing Incidence X-ray Diffraction (GIXRD) analysis of the etched samples indicates crystalline SiC formation at low temperatures. Surface morphology analysis using Field Emission Scanning Electron Microscopy (FESEM) confirms the GIXRD results. The RIE process unintentionally induces crystallization of a-SiC films, but adjusting etching process parameters allows control over film crystallinity. [ABSTRACT FROM AUTHOR]

Hydrophobic carbon nanotubes are hardly to disperse in water and prone to agglomerate when poured with Copper Tailing-Based Cementitious Material (CTCM). Multi-walled carbon nanotubes (MWCNTs) + Arabic Gum (GA) dispersions were prepared by a novel method of synergistic optimization of concentration, controlling low-frequency ultrasonic time and setting the ambient temperature with non-toxic anionic surfactant GA as surfactant. The results of UV–Vis spectroscopy showed that the high stability MWCNTs + GA dispersion with low aggregation area (< 1.2%) and low aggregation beam size (< 219 nm) have been prepared by using 1.7 mmol/l GA. The effects of highly stable MWCNTs dispersion on the mechanical properties, microstructure and durability of CTCM were studied. The 28 days compressive strength increased by 21.5%, and the flexural strength increased by 20.5%, almost reaching the mechanical level of the control group. The results of SEM, XRD and EDS showed that GA significantly enhanced the dispersion of MWCNT in aqueous solution at a suitable concentration (mass ratio of GA:CNTs = 1:1). The microstructure of the prepared CTCM by high stability MWCNTs dispersion was optimized obviously, and the mechanical properties and durability were improved significantly. This method solves the dual problem of MWCNTs not being fully dispersed in aqueous solution and being easily re-agglomerated in cementitious materials, as well as finding a breakthrough for the low cost and industrialization of tailings cement-based composite cementitious materials. [ABSTRACT FROM AUTHOR]

Supported metal clusters comprising of well-tailored low-nuclearity heteroatoms have great potentials in catalysis owing to the maximized exposure of active sites and metal synergy. However, atomically precise design of these architectures is still challenging for the lack of practical approaches. Here, we report a defect-driven nanostructuring strategy through combining defect engineering of nitrogen-doped carbons and sequential metal depositions to prepare a series of Pt and Mo ensembles ranging from single atoms to sub-nanoclusters. When applied in continuous gas-phase decomposition of formic acid, the low-nuclearity ensembles with unique Pt3Mo1N3 configuration deliver high-purity hydrogen at full conversion with unexpected high activity of 0.62 molHCOOH molPt−1 s−1 and remarkable stability, significantly outperforming the previously reported catalysts. The remarkable performance is rationalized by a joint operando dual-beam Fourier transformed infrared spectroscopy and density functional theory modeling study, pointing to the Pt-Mo synergy in creating a new reaction path for consecutive HCOOH dissociations. Precise design of bimetallic low-nuclearity catalysts is challenging. Here, the authors report a defect-driven nanostructuring strategy combining defect engineering of nitrogen-doped carbons and sequential metal depositions, yielding a series of platinum and molybdenum ensembles in the sub-nano regime. [ABSTRACT FROM AUTHOR]

Graphene is a 2D material with promising commercial applications due to its physicochemical properties. Producing high-quality graphene economically and at large scales is currently of great interest and demand. Here, the potential of producing high-quality graphene at a large scale via water-phase exfoliation methods is investigated. By altering exfoliation parameters, the production yield of graphene and flake size are evaluated. Pretreatment of the precursor graphite powder using acidic solutions of H2SO4 at different concentrations is found to increase further the yield and structural quality of the exfoliated graphene flakes. These findings are confirmed through various spectroscopy and surface characterization techniques. Controlling flake size, thickness, and yield are demonstrated via optimization of the sonication process, centrifuge time, and H2SO4 pretreatment. [ABSTRACT FROM AUTHOR]

Graphene materials including porous few-layered graphenes are under focus of scientific community today. The great attention towards them is caused by their remarkable properties. Here, we use two different fluorinated graphite intercalation compounds with different fluorine content in their matrices to prepare thermally exfoliated fluorinated graphites and to investigate them in terms of their structural, spectroscopic and electrochemical properties as materials for use in supercapacitors. A higher temperature of low-fluorinated graphenes preparation resulted in higher exfoliation degree and higher gravimetric capacitance in supercapacitor appliances. More dramatic leap of gravimetric capacitance was observed after a treatment in a concentrated acid mixture of graphene material samples prepared at the highest temperature of thermolysis with highest exposition time. [ABSTRACT FROM AUTHOR]

In this work, we report that hydrogen (H2) doped in n-type a-Si:H thin films strongly influences the electronic correlation in increasing the conversion output power of solar cells. Type n a-Si:H thin films were grown using PECVD on ITO substrates with various H2-doping, to obtain various thin films for solar-cell applications. N-type a-Si:H thin films were prepared, and then characterized using ellipsometric spectroscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. The addition of doped-H2 to the thin layer shows a decrease in optical conductivity, while the energy gap in the thin layer shows a significant increase in the a-Si:H-type thin layer. Our results show that H2 doping plays a very important role in the electronic structure, which is indicated by the significant energy gap difference. On the other hand, the bond structure of each H2-doped thin film showed a change from amorphous to nanocrystalline structures which were evenly distributed in each H2-doped bonding. Overall, we believe that the addition of doped-H2 to our findings could help increase the power conversion output of the solar cell due to the modification of the electronic structure. [ABSTRACT FROM AUTHOR]

The pretilt angles of LC molecules can be controlled by tetrafluoromethane (CF4) plasma treatment. For conventional polyimide layers, the homogeneous alignment turns homeotropic owing to the invasion of fluoride atoms, which leads to the wettability transition from being hydrophilic to hydrophobic. The different treatment times generate variable pretilt angles such that the values of pretilt angles can be changed from 7.21ο to 79.53ο, and the polar anchoring energy can be tuned continuously. This technique can provide a reversible alignment layer that can be controlled by applying different plasmas of CF4 and O2. Moreover, a hybrid-aligned LC cell with patterned displays based on different pretilt angles, was proposed herein. [ABSTRACT FROM AUTHOR]

A new strategy to prepare copper (Cu) nanoparticles anchored in nitrogen-doped carbon nanosheets (Cu@CN) has been designed and the nanomaterial applied to the determination of paraquat (PQ). The nanocomposite materials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and several other techniques. We found that the Cu nanoparticles are uniformly distributed on the carbon materials, providing abundant active sites for electrochemical detection. The electrochemical behavior of the Cu@CN-based PQ sensor was investigated by square-wave voltammetry (SWV). Cu@CN exhibited excellent electrochemical activity and PQ detection performance. The Cu@CN-modified glassy carbon electrode (Cu@CN/GCE) exhibited excellent stability, favorable sensitivity, and high selectivity under optimized conditions (enrichment voltage −0.1 V and enrichment time 400 s) of the SWV test. The detection range reached 0.50 nM to 12.00 μM, and the limit of detection was 0.43 nM with high sensitivity of 18 μA·μM−1·cm−2. The detection limit is 9 times better than that of the high-performance liquid chromatography method. The Cu@CN electrochemical sensor demonstrated excellent sensitivity and selectivity also in environmental water and fruit samples enabling its use in practical, rapid trace-level detection of PQ in environmental samples. [ABSTRACT FROM AUTHOR]

A well-defined controlled selective edge functionalization of graphene oxide (GO) is of high interest because it allows tuning the chemical and physical properties of graphene oxide with minimal damage to the carbon at the basal plane. The present work reports a rapid one-step synthesis of edge fluorinated graphene oxide (FGO) from GO in an aqueous medium. A selective fluorination of the tertiary carbon at the edge of GO was achieved by chemoselective substitution of the carboxylic acid with fluorine in one hour following a decarboxylative fluorination technique using 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (SELECTFLUOR) and silver ion catalyst. The structure and composition of FGO were characterized by multiple analytical techniques, such as TEM, SEM, XRD, EDS, FTIR, XPS, Raman spectroscopy, etc. As observed in XPS and NMR analysis, the decarboxylative fluorination of GO resulted in the formation of covalent C–F bonds at the edge. The absence of the peak associated with the C–F group on the basal plane in 19F NMR clearly indicates the fluorination at the edge of GO. Most importantly, similar linewidth and spectral patterns in proton-decoupled 19F{1H} and proton-coupled 19F NMR spectra of FGO suggest that the fluorine atoms are bonded to the tertiary carbon atom. The selective functionalization of the tertiary carbon at the edges of GO achieved here, is unprecedented. The fluorine group at the edge of GO can act as a new reaction center for subsequent chemical modification. This simple edge-controlled fabrication method described here provides a facile pathway to fabricate multifunctional GO and expand their potential applications. [ABSTRACT FROM AUTHOR]

A facile strategy to improve the electrochemical performance of graphene and SnO2 hybrid (SnO2/GNSs) as anode for lithium-ion batteries through adding and removing of Al2O3 from the composite was introduced. Benefiting from the vacancy formed during the soaking in sodium hydroxide solution, the volume expansion of SnO2 was remitted. Meanwhile, the agglomeration of SnO2 was effectively alleviated. Therefore, a much better cyclic performance was achieved as compared to pristine composite. The modified composite (M-SnO2/GNSs) exhibited reversible capacities of 611 mAh g−1 for the first charge and 436 mAh g−1 after 50 cycles at 50 mA g−1, respectively. The high capacity and good retention can be attributed to the synergistic effect between SnO2 and GNSs, including excellent conductivity of graphene and the vacancy formed after removing Al2O3, which could buffer the volume changes of SnO2 during cycling. This modification approach presented a promising route to design better anodes for high-performance Li-ion batteries. [ABSTRACT FROM AUTHOR]

Here, the possibility of the existence of nitro-graphene derivatives with undisturbed graphene backbone is considered. Based on the first-principles calculation, it is shown that while NO 2 is unable to form a covalent bond with bare graphene, it becomes possible in some structures of hydrogenated graphane, fluorographene, and graphene oxide. This paper presents, among others, an analysis of the surrounding influence on the C-NO 2 bond strength. The author believes that the potential prospects of these materials and discussion about possible synthesizing routes may help further research on graphene-based materials. [ABSTRACT FROM AUTHOR]

Self-organizing catalytic systems are promising for synthesis of carbon nanomaterials via catalytic chemical vapor deposition. The precursors of catalysts, 100Ni and 96Ni–4Mo, were synthesized by reductive thermolysis at 800 °C and tested in the H2-assisted catalytic pyrolysis of C2HCl3 to produce carbon nanofibers. The reaction temperature was varied in a range of 475–675 °C. The kinetics of carbon accumulation over the prepared catalysts was studied to reveal the effect of Mo on the catalytic performance of nickel. It was shown that the process is characterized by the presence of induction period, and the addition of molybdenum to nickel leads to a shortening of this period in ~ 70% along with an increase in the C2HCl3 decomposition rate and boosting the carbon yield. The maximum yield of the carbon nanomaterial obtained after 2 h of the C2HCl3 decomposition over 96Ni–4Mo alloy at 600 °C was as high as 89 g/gcat. The presence of Mo in the catalyst's composition also leads to a decrease in activation energy value from 79 to 55 kJ/mol. The longevity tests performed at 600 °C for 7 h showed that the bimetallic 96Ni–4Mo alloy provides productivity of 259 g/gcat, which is 2.2 times higher than for the monometallic 100Ni catalyst. According to transmission and scanning electron microscopies, the obtained carbon nanomaterial is predominantly represented by long filaments attached to submicron-sized catalytic particles. The carbon nanofibers are characterized by a defective and non-uniform segmented secondary structure and possess high specific surface area (up to 385 m2/g). [ABSTRACT FROM AUTHOR]

The purpose of this study was to achieve a specific unlocking of the butterfly effect: nanointerface-based electrochemical biosensing of adenosine triphosphate (ATP) and alkaline phosphatase (ALP). Based on the Faraday-cage concept reported first by our group, we built a new outer Helmholtz plane (OHP)-based electrochemical biosensor by using an unique nanocomposite involving three-dimensional graphene-Au nanoparticles (3D-GO-AuNPs), tetrahedral DNA nanostructures (TDNs), and separated ATP aptamers, in which methylene blue (MB) was employed as the electrochemical signal output. In this process, the prepared nanocomposites were attached favorably onto the TDN substrate electrode surface due to the interaction of ATP and its aptamer, creating a better OHP of the electrode owing to its large enough specific surface area; then a detection limit of 0.25 pM was calculated by 3δ/slope. Whereas, the hydrolysis for ATP of ALP can hinder this binding process, therefore, the biosensor could be indirectly applied for ALP analysis with a detection limit of 0.21 mU/L (3δ/slope). Since some small changes of the two targets will set off a whole series of changes in system, the OHP-extended biosensor provides a superior electrochemical platform for complex biological processes with causal relationships in clinical diagnosis and drug development, similar to the butterfly effect. [ABSTRACT FROM AUTHOR]

The scalable preparation of high‐quality and low‐cost two‐dimensional (2D) materials is critical to achieving their potential applications in various fields. Chemical vapor deposition (CVD) method is considered the most promising method for producing ultrathin 2D materials and has continued to develop in recent years. First‐principles calculations have provided important theoretical guidance for the CVD synthesis of 2D materials, and have played an increasingly important role in the field of material synthesis in recent years. In this review, we present recent advances in the growth mechanism of 2D materials, focusing on the theoretical research progress of four typical 2D materials: graphene, hexagonal boron nitride (hBN), transition metal dichalcogenide (TMDC), and phosphorene. Several aspects of the growth process are discussed in detail, including the decomposition of precursors, nucleation, growth kinetics, domain shape, and epitaxial and alignment of 2D crystals. Based on the understanding of these atomic‐scale growth processes, strategies toward the wafer‐scale growth of continuous and homogeneous 2D thin films are proposed and confirmed by experiments. In the final section, we summarize future challenges and opportunities in the computational studies of the growth mechanism of 2D materials. This article is categorized under:Structure and Mechanism > Computational Materials ScienceElectronic Structure Theory > Density Functional TheoryTheoretical and Physical Chemistry > Reaction Dynamics and Kinetics [ABSTRACT FROM AUTHOR]

It is very important to develop electrode materials with good mechanical flexibility and excellent electrochemical performance to adapt to the development of flexible electronic devices, and the preparation of non-binder flexible electrode is a good strategy. In this work, nitrogen-doped carbon nanotubes (N-CNT) were grown in situ on the surface of carbon cloth (CC) by a simple method and directly used as binder-free electrodes for supercapacitors. The electrochemical tests show that the electrode can achieve an areal capacitance of 4081.6 mF/cm2 when the ampere density is set at 2mA/cm2, and when the ampere density is promoted 10 times to 20mA/cm2, this electrode can still retain 72.8% of the areal capacitance at 2mA/cm2. The flexible electrode can also retain 90.3% of an areal capacitance after 5000 recharge/discharge cycles at a set ampere density of 10 mA/cm2 and 97.6% of its areal capacitance after 50 bending cycles. The electrode was assembled into a symmetrical supercapacitor for electrochemical performance testing, and an areal capacitance of 572.6 mF/cm2 can be maintained when the ampere density is set at 2 mA/cm2, and an energy density of 79.53 and 40.28 µWh/cm2 at a power density of 1000 and 10,000µW/cm2, separately. The excellent electrochemical performance is mainly attributed to the following three points: (1) No binder is used to avoid the problems that affect the conductivity and utilization rate of active substances caused by the binder. (2) The electrode material has a large specific surface area and has more active sites for electrochemical reaction. (3) The presence of N and O is of great help to improve the electrochemical performance of the electrode material. [ABSTRACT FROM AUTHOR]

Relative humidity (RH) is one of the most important factors that deserve intensive study because of its impact on many aspects of life. In this work humidity sensor based on carbon nitride / graphene quantum dots (g-C3N4/GQDs) nanocomposites have been developed. The structure, morphology and composition properties of the g-C3N4/GQDs were investigated and analyzed by XRD, HR-TEM, FTIR, UV–Vis, Raman, XPS and BET surface area. The average particle size of GQDs was estimated from XRD to be 5 nm and confirmed using HRTEM. The HRTEM images prove that the GQDs are attached to the external surface of the g-C3N4. The measured BET surface area was found to be 216 m2/g, 313 m2/g, and 545 m2/g for GQDs, g-C3N4, and g-C3N4/GQDs respectively. The d-spacing and crystallite size were estimated from XRD and HRTEM and found in a good matching. The humidity sensing behavior of g-C3N4/GQDs was measured in a wide span of humidity from 7% up to 97% RH under different testing frequencies. The obtained results demonstrate good reversibility and fast response/recovery time. The implemented sensor exhibits a great application prospect in humidity alarm devices, automatic diaper alarms, and breath analysis, which have advantages such as strong anti-interference capability, low cost, and easy to use. [ABSTRACT FROM AUTHOR]

Highly defective carbon nanotubes (HD-CNTs) are fabricated by template carbonization of polydopamine nanofilm coated on mesoporous titanium nitride nanotube arrays. With introduction of mesoporous holes on the side walls from the template, HD-CNTs exhibit much improved electrochemical properties. An ideal Nernst behavior toward [Fe(CN)6]3−/4− redox couple was observed on the HD-CNTs, with a heterogeneous charge transfer rate constant k0 greater than 0.5 cm/s that is among the fastest kinetics of electrode materials. Sensitive determination of dopamine has been demonstrated in the presence of ascorbic acid and uric acid, with a linear range of 0.1–180 μM, a detection limit of 0.074 μM (S/N = 3) and a sensitivity of 555 µA mM−1 cm−2. The excellent electrochemical activity should be attributed to the large number of exposed edge planes on the carbon nanofilm, the free-standing highly conductive titanium nitride architecture that is beneficial for electron transfer, mesoporous morphology that promotes the mass transfer between the nanotubes, and effective ion-accessible surface area. [ABSTRACT FROM AUTHOR]

Selecting a suitable catalyst for implementing the simultaneous production of hydrogen-rich syngas and multi-walled carbon nanotubes through the integration of dry reforming and methane decomposition reactions has recently gained great interests. In this study, a series of bimetallic (NiMo/MgO) and trimetallic (CoNiMo/MgO, FeNiMo/MgO, CoFeMo/MgO) catalysts was prepared and evaluated for a catalytic activity of CH4 and CO2 conversions of biogas in a fixed bed reactor at 800 °C and atmospheric pressure. Among the investigated catalysts, the bimetallic NiMo/MgO catalyst showed the outstanding catalytic performance with 86.4% CH4 conversion and 95.6% CO2 conversion as well as producing the highest syngas purity of 90.0% with H2/CO ratio = 1.1. Moreover, the characterization of the synthesized solid products proved that the well-aligned structured morphology, high purity, and excellent textural properties of CNTs were obtained by using NiMo/MgO catalyst. On the other hand, using trimetallic catalysts which have the composition of Co and Fe leads to the severe deactivation. This could be attributed the catalyst oxidation with CO2 in biogas, resulting in the transformation of metals into large metal oxides. The integrative process with NiMo/MgO catalyst is regarded as a promising pathway, which has a high potential for directly converting biogas into the high value-added products and providing a green approach for managing the enormous amounts of wastes. [ABSTRACT FROM AUTHOR]

As a type of energy storage device between traditional capacitors and batteries, the supercapacitor has the advantages of energy saving and environmental protection, high power density, fast charging and discharging speed, long cycle life, and so forth. One of the key factors affecting the performance of supercapacitor is the electrode material. Carbon materials, such as carbon nanotube, graphene, activated carbon, and carbon nanocage, are most widely concerned in the application of supercapacitors. The synergistic effect of composites can often obtain excellent results, which is one of the common strategies to increase the electrochemical performance of supercapacitors. To further improve the performance of binary composites, it is a relatively simple method to increase the components as the "bridge" between the two materials to form the ternary composites. The review mainly introduces the current research progress of supercapacitors with pure carbon nanomaterials and multistage carbon nanostructures (composites) as electrodes. The characteristics and application directions of different pure carbon nanomaterials are introduced in detail. Different ways of multilevel structure (material) composite have their own effects on the development of high‐performance supercapacitors. We also highlight the recent advances related to these fields and provide our insight into high‐energy supercapacitors. Highlight: The characteristics and application directions of different pure carbon nanomaterials and the structure construction of multilevel structures (composites) are introduced.It is analyzed that different multilayer structures (materials) have different effects on the development of high‐performance supercapacitors.The application and development direction of carbon nanomaterials in supercapacitors are prospected, which provides some guidance for the research of carbon nanomaterials for supercapacitors. [ABSTRACT FROM AUTHOR]

Graphene-porphyrin hybrid materials with direct assembly between the fluorinated graphene (FG) nanosheets and the pre-formed 5,10,15,20-tetrakis(p-hydroxyphenyl)porphyrin (THPP) units have been successfully synthesized. The structure–property, binding, and assembly of THPP over FG nanosheets were methodically analyzed by spectroscopic, microscopic, and solvent wetting techniques. The solvent wetting characteristics and surface free energy of the supportless THPP and FG-supported THPP were investigated. The decoration of porphyrin over FG ensued in a surface free energy of 28.7 mJ m−2 directing to hydrophobic (WCA ~ 130 ± 2°) networks. Photo-physical studies demonstrated considerable non-covalent interactions between the THPP with FG multi-layers. The emission responses of THPP and FG-THPP with ferric complexes and its coordination with respect to the –philicity of the THPP were probed using photoluminescence spectroscopy. The functional groups blended in the FG-THPP inks were subjected to fuse with interconnected networks like cellulose paper and melamine sponge by exploiting the dispersion processability followed by morphology evaluation and water-wettability. [ABSTRACT FROM AUTHOR]

Summary: This work is aimed to synthesize hybrid nanocomposite electrode materials for supercapacitor applications. The carbon nanotubes (CNTs) are incorporated into MoS2 as well as TiO2 to form different hybrid electrode materials such as MoS2/CNTs, TiO2/CNTs, and MoS2/TiO2/CNTs in an effort to improve the electrochemical performance. The resulting hybrid electrode materials are examined by SEM, TEM, XRD, XPS, and Raman studies. Cyclic voltammetry and galvanostatic charge‐discharge tests are used to evaluate the specific capacitance and charge‐discharge stability of the synthesized MoS2/TiO2/CNTs. Among the hybrid electrode materials investigated, the MoS2/TiO2/CNTs exhibits superior electrochemical performance with specific capacitance of 1252.57 mA h/g at a scan rate 20 mV/s as compared with MoS2/CNTs (810.53 mA h/g), TiO2/CNTs (607.10 mA h/g), and CNTs (204.35 mA h/g). All electrochemical tests were carried out in a solution of 1 M KOH. The Rct and Rf for the MoS2/TiO2/CNTs electrode were found to be 1.7 Ω.cm2 and 2.1 Ω.cm2, respectively, which were significantly lower than the corresponding Rct (40.2 Ω.cm2) and Rf (51.1 Ω.cm2) for the CNTs electrode, indicating that the MoS2/TiO2/CNTs has a significantly lower overall impedance, which could be one of the key factors responsible for the improved electrochemical performance of the MoS2/TiO2/CNTs. Moreover, this MoS2/TiO2/CNTs hybrid electrode displays good cycling stability with the capacitance retention of 98.83% after 10 000 cycles of charge‐discharge at 1 A/g. The energy density and power density of MoS2/TiO2/CNTs composites are found to be 757.80 Wh/kg and 4546.80 W/kg respectively. [ABSTRACT FROM AUTHOR]

Summary: Molybdenum sulfide (MoSx)‐based materials have been extensively studied as a potential alternative of low‐capacity graphite anode, owing to their remarkable capacity through intercalation and conversion reactions. However, these materials should be electrochemically activated at a low potential in first discharge and simultaneously degrade, owing to their inert basal plane and unstable sulfur configuration, respectively, leading to unexpectedly low performance. Hence, it is necessary to apply sulfur‐enriched crystalline Mo3S13 clusters as an anode material to increase the number of active sites and energy densities. Unlike MoS2 possessing only terminal sulfur, Mo3S13 clusters have higher sulfur content with various and stable configuration in their structure, which can act as additional active sulfur sites. To realize an electrode with high energy density, we used the Mo3S13 clusters without any carbon supports as active materials. In the electrode preparation, we confirmed that employing poly(acrylic acid) and isopropyl alcohol as a binder and solvent, respectively, was appropriate for retaining the cluster crystallinity, resulting in the enhanced cycling stability. The Mo3S13 cluster‐based electrode as a carbon‐free electrode exhibited capacity of 1192 mAh g−1 at 0.1 A g−1 and good C‐rate capability. The significant capacity variation with the selective removal of sulfur configuration in Mo3S13 clusters indicates that the increased sulfur contents were provided as additional sources for (de)lithiation. [ABSTRACT FROM AUTHOR]

Ni electrochemical deposition into a matrix of various diameters (500–2000 nm) vertical vias in Si/SiO2 substrates with a barrier layer at the vias' bottom has been investigated. Morphological study of Ni deposits in the vias showed they are deposited directly on the surface of the barrier layer. Repeatability and stability in combination with a homogeneous structure and 70% filling degree of vias determine the prospects of the Si/SiO2/Ni system as a basic element for the creation of three-dimensional micro-, nanostructures, and 3D assembly of IC crystals. [ABSTRACT FROM AUTHOR]

The structural, electronic, and optical properties of hydrogenated silicene have been investigated using first-principles DFT calculations. Compared to pristine silicene, hydrogenated silicene exhibits high stability, reduced anisotropy, and less birefringence. Hydrogenated silicene shows a constant refractive index in the visible region, increasing exponentially in silicene. The elastic and optical parameters such as Young's modulus (Y), Poisson's ratio (ν), bulk modulus (B), shear modulus (G), dielectric constant ε(0), refractive index n(0), conductivity threshold (Eth), birefringence Δn(0), and plasmon energy (ħωp) were calculated for the first time for different hydrogen coverage on silicene, which is crucial in the applications of linear and non-linear optoelectronic devices. The estimated parameters agree well with the available experimental and reported values. [ABSTRACT FROM AUTHOR]

Nitrogen doping of carbon nanomaterials has emerged as a method to develop novel material properties, though limitations in the form of extended treatment times, harsh chemical usage and limited total nitrogen content exist. Here, macroscopic ribbon-like assemblies of carbon nanotubes are functionalized with nitrogen using a simple direct current-based plasma–liquid system. This system utilizes the plasma-generated species in an ethanol:water solution with ethylenediamine as a nitrogen precursor for the nitrogen functionalization of the carbon nanotube assembly. These unique, plasma-generated species and pathways enable rapid and high levels of functionalization with the atomic concentration of nitrogen reaching 22.5%, with amine groups, pyrrolic groups and graphitic nitrogen observed in the X-ray photoelectron spectra, the highest ever achieved. This nitrogen content is demonstrated to be significantly higher than a comparative electrolysis process. This demonstrates that this plasma process enhances the availability of nitrogen from the ethylenediamine precursor, facilitating greater functionalization. [ABSTRACT FROM AUTHOR]

The excellent photoresponse of semiconductors enables them as a promising photocatalyst for photocatalytic degradation of organic pollutants and antibiotics, but their practical applications are limited by photogenerated carrier recombination, instability, and fixed energy band positions. Herein, we designed and synthesized a dual Z-scheme flower-like spherical Ag3PO4/MoS2/g-C3N4 (AMN) photocatalyst loaded with different mass of g-C3N4 (3, 5 and 7 mg). Under visible light irradiation, MoS2 enhanced the light absorption range of AMN composite. The holes concentrated in the valence band of Ag3PO4 provide strong oxidation capacity, and the electrons retained in conduction band of g-C3N4 provide strong reduction ability in the photocatalytic system. It is helpful to improve the separation efficiency of photogenerated carriers and enhance the photocatalytic activity of AMN composite. The AMN photocatalyst loaded with 5 mg g-C3N4 (AMN-5) has the optimal photocatalytic activity. The photocatalytic degradation efficiency of the photocatalyst for methylene blue (MB) within 24 min is 3.98, 1.85, and 1.17 times that of g-C3N4, Ag3PO4, and Ag3PO4/MoS2, respectively. After three cycles, the degradation efficiency of AMN-5 for MB decreased from 99.44% to 90%, about 3.79 times of Ag3PO4 (23.77%). In addition, the optimal AMN-5 photocatalyst also has excellent photocatalytic degradation efficiency for Rhodamine B (RhB) and tetracycline (TC). This design and concept provide a promising insight for the photocatalytic degradation of pollutants. [ABSTRACT FROM AUTHOR]

A new method is proposed for the simultaneous introduction of fluorine and chlorine into the surface layer of nanoporous-activated carbon (NAC). The method comprises treatment with dichlorodifluoromethane at 400–800 °C. Elemental analysis, nitrogen adsorption–desorption studies, electron microscopy, X-ray photoelectron (XPS) and solid-state 19F nuclear magnetic resonance (ssNMR) spectroscopies were exploited to analyze the composition, micro-, nanostructure, and functional surface coverage. The NAC modified at 400 °C has the lowest halogen content of 0.21 mmol g–1 of fluorine and 1.11 mmol g–1 of chlorine. Increasing the halogenation temperature to 500–700 °C significantly upsurges the efficiency of both fluorination and chlorination, up to 0.82–0.96 and 2.23–2.87 mmol g–1, respectively. Fluorine and chlorine are randomly but not evenly distributed in the porous structure of NAC. The outer carbon surface is enriched in fluorine, contrasting to the inner surface of the micropores. From XPS and 19F ssNMR measurements, mainly C–F, C–Cl, CClF2, CF2, and CF3 groups were identified as attached forms of halogens. High halogenation temperatures (up to 800 °C) cause a significant increase in the amount of "semi-ionic" fluorine, which is present as C–F and CF2 groups directly bonded to the π-electron system of the carbon matrix. [ABSTRACT FROM AUTHOR]

In this work, pure and supersalt-doped graphene is evaluated by the density functional theory (DFT) to explore its optical and electronic properties. The doping of supersalt Al(BH4)3 on graphene reduces the highest occupied molecular orbital and lower unoccupied molecular orbital (HOMO–LUMO) bandgap of graphene@Al(BH4)3 and graphene@2Al(BH4)3 to 3.57 and 3.55 eV from 3.61 eV. The improvement in the optoelectronic properties of the supersalt Al(BH4)3-doped graphene is determined by the upshift of UV absorption peak and dipole moment. Polarizability (α) values of graphene@Al(BH4)3, and graphene@2Al(BH4)3 increase to 14% and 26% in the comparison of pure graphene. The first hyperpolarizability (βo) is increased from 0.44 (graphene) to 1295.4 au in graphene@2Al(BH4)3. Our findings suggest that Al(BH4)3-doped graphene could be an effective method for making graphene an efficient nonlinear optical material. [ABSTRACT FROM AUTHOR]

In this study, the HCOOH decomposition reaction on nickel (Ni)- and copper (Cu)-embedded graphene surfaces was computationally modeled using density functional theory. The charge density of both graphene surfaces was investigated by bader charge analysis and demonstrated by an electron density difference map. The results proved that HCOOH, HCOO, COOH, HCO, H2O, CO, OH and H structures chemically bonded to both graphene sheets. Moreover, the minimum energy reaction path from HCOOH to CO2 and CO on both graphene surfaces was investigated by breaking the C–O, C–H and O–H bonds. The main intermediate of HCOOH dissociation on Ni and Cu embedded graphene substrates was determined as HCOO. The main product of HCOO decomposition on both graphene surfaces was CO2. In comparison to cis-COOH and trans-COOH, CO2 recovery from HCOO on graphene substrates was less favored.The breakdown of trans-COOH on graphene surfaces was of a more minimal-energy reaction pathway than cis-COOH. In addition, the main product of HCO decomposition on both graphene surfaces was determined to be CO. Finally, it was determined that the minimum energy reaction pathway for HCOOH dissociation on both graphene surfaces was HCOOH → HCOO → CO2. [ABSTRACT FROM AUTHOR]

A dual immunosensor is reported for the simultaneous determination of two important immunity-related cytokines: BAFF (B cell activation factor) and APRIL (a proliferation-induced signal). Sandwich-type immunoassays with specific antibodies (cAbs) and a strategy for signal amplification based on labelling the detection antibodies (dAbs) with binary MoS2/MWCNTs nanostructures and using horseradish peroxidase (HRP) were implemented. Amperometric detection was carried out at screen-printed dual carbon electrodes (SPdCEs) through the hydroquinone HQ/H2O2 system. The developed dual immunosensor provided limit of detection (LOD) of 0.08 and 0.06 ng mL−1 for BAFF and APRIL, respectively, and proved to be useful for the determination of both cytokines in cancer cell lysates and serum samples from patients diagnosed with autoimmune diseases and cancer. The obtained results agreed with those found using ELISA methodologies. [ABSTRACT FROM AUTHOR]

Porous carbon is regarded as one of the most promising anode candidates for Li-ion battery and Na-ion battery, and the specific porous structure and heteroatom doping within porous carbon play a key role in the electrochemical performance. We herein demonstrate a series of nitrogen-doped porous carbon (NPC) by simply carbonizing bimetallic ZnCo-containing zeolitic imidazolate frameworks (ZnCo-ZIFs). The nitrogen content, specific surface area, and microstructure of prepared NPCs are balanced by adjusting the Zn2+/Co2+ molar ratio of ZnCo-ZIFs and carbonization process parameters. The optimized NPC derived from ZnCo-ZIFs delivers high specific capacity of 876.5 and 352.6 mA h g−1 for Li+ storage at 0.1 and 5 A g−1, respectively. After repeating 500 cycles at a high current density of 1 A g−1, it almost has no capacity loss. In addition, the electrode also shows a great promise for Na+ storage. The excellent electrochemical Li+/Na+ storage performances could be attributed to the hierarchical porous structure, large specific surface area, and relatively high N-doping content. [ABSTRACT FROM AUTHOR]

For the first time, nanosized molybdenum disulfide (MoS2) nanoparticles (NPs) were grown on the surface of poly(ethylene glycol)‐polydopamine‐modified reduction graphene oxide) nanosheets (rGO‐PDA‐PEG). The obtained rGO‐PDA‐PEG@MoS2 nanocomposites exhibits excellent dispersion in polyalkylene glycol (PAG) synthetic oil and outperforms GO and MoS2 NPs as additives in terms of friction reduction and wear resistance at elevated temperature. The superior tribological behaviour of rGO‐PDA‐PEG@MoS2 might be beneficial to the synergistic effect between MoS2 and rGO. [ABSTRACT FROM AUTHOR]

In this study, we considered changes in the surface chemistry after introducing fluorine into the surface layer of nanoporous activated carbon (BAU) produced from the birch wood. Here, we examined the BAU treated with 1,1,1,2-tetrafluoroethane at the selected temperature in the range of 400–800 °C. Diverse methods, including chemical analysis, nitrogen adsorption–desorption, SEM–EDS, XPS, and 19F solid-state NMR, were used for the characterization of the prepared materials. It was found that one can introduce from 0.17 to 0.42 mmol of F per gram of BAU using fluoroalkylation at 400–500 °C. Increasing the temperature to 600 °C increases the fluorination efficiency, and the relatively high fluorine content of 1.86 mmol of F per gram of BAU can be reached. At least three group types, namely, C–F, CF2, and CF3 groups, were found by XPS and 19F solid-state NMR after such treatment. The content of "semi-ionic" fluorine drastically increases in the surface layer after high-temperature fluoroalkylation at 700 °C and 800 °C. This "semi-ionic" fluorine, in the form of C–F and CF2 groups, is directly conjugated with the π-electron system of the carbon matrix. [ABSTRACT FROM AUTHOR]

Medium-temperature fluoroalkylation of microporous activated carbons (ACs) with 1,1,1,2-tetrafluoroethane is presented. Supercapacitor (SC) electrodes based on the fluoroalkylated ACs showed enhanced specific capacitance and high specific energy in electrolytes, either aqueous potassium hydroxide solution or tetraethylammonium tetrafluoroborate-acetonitrile solution. We found the largest increase in the specific capacitance, up to 89 F g–1, and in the specific energy, up to 7.5 Wh kg–1, at the voltage of 1.5 V. The specific capacitance of the SC electrode based on the sample prepared at 350 °C increases by a factor of ~ 2–3 × for certain scan rates in the organic electrolyte. The fluoroalkylated ACs have good electrochemical stability in the tested model systems. We associate the registered enhanced SC parameters with an increase in the total fluorine content and high specific surface areas of the carbon electrode materials. The surface "isolated fluorine" formed during fluoroalkylation at 300–400 °C ensures the production of improved electrode materials for SC applications. Fluoroalkylation is a simple and cost-effective method of improving the specific capacitance of carbon-based SC electrodes. [ABSTRACT FROM AUTHOR]

A facile and green approach was developed to in-situ prepare Ag nanoparticles (AgNPs) on the TiO2. Through the (3-mercaptopropyl)trimethoxysilane (MPTMS), mono-dispersed AgNPs were loaded on TiO2 (AgNPs@MPTMS-TiO2). In the presence of NaBH4, the AgNPs@MPTMS-TiO2 displayed an ultra-high catalytic activity for 4-nitrophenol reduction, of which the apparent kinetic rate constant (kapp) reached up to 394 × 10–3 s−1. Comparing to the best previous performance (kapp = 120 × 10–3 s−1), the obtained Ag-catalysts made a huge progress. Moreover, the catalytic activity of the AgNPs@MPTMS-TiO2 could be optimized via changing series of fabrication parameters including Ag+ precursor amount and MPTMS amount, and reaction time. Various characterization techniques including TEM, HRTEM, XPS, FT-IR and Zeta potential have been utilized to study the material morphology, valance states and surface chemistry. It revealed that the AgNPs were coordinated by MPTMS though R-S–Ag bonds, which could prohibit the AgNPs from self-aggregation. In addition, the R-S–Ag bonds favored reaction of AgNPs with BH4− and thus releasing substantial protons. Consequently, the increasing proton concentration would speed up the transformation from 4-hydroxylaminophenol to 4-aminophenol. In-situ grow Ag nanoparticles (AgNPs) on (3-mercaptopropyl)trimethoxysilane (MPTMS) modified TiO2 with characters of small size, good distribution and controllable loading. The apparent kinetic rate constant (kapp) reaches as high as 394 × 10–3 s−1. [ABSTRACT FROM AUTHOR]