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Hybrid ion capacitors (HIC) are receiving a lot of attention due to their potential to achieve high energy and power densities, but they remain insufficient. It is imperative to explore outstanding and environmentally benign electrode materials to achieve high-performing HIC systems. Here, a unique boron carbon nitride (BCN)-based HIC system that comprises a microporous BCN structure and Fe1-xS nanoparticle incorporated BCN nanosheets (BNF) as cathode and anode, respectively is reported. The BNF is prepared through a facile one-pot calcination process using dithiooxamide (DTO), boric acid, and iron source. In situ, crystal growth of Fe1-xS facilitates the formation of BCN structure through the creation of holes/defects in the polymeric structure. The first principle density functional (DFT) theory simulations demonstrate the structural and electronic properties of the hybrid of BCN and Fe1-xS as compelling anode materials for HIC applications. The DFT calculations reveal that both BCN and BNF structures have excellent metallic characters with Li+ storage capacities of 128.4 and 1021.38 mAh g-1 respectively. These findings are confirmed experimentally where the BCN-based HIC system delivers exceptional energy and power densities of 267.5 Wh kg-1/749.5 W kg-1 toward Li+ storage, which outweighs previous HIC performances and demonstrates favorable performance for Li+ and Na+ storages.
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Sodium-ion batteries (SIBs) have received tremendous attention owing to their low cost, high working voltages, and energy density. However, the design and development of highly efficient SIBs represent a great challenge. Here, a unique and reliable approach is reported to prepare carbon nitride (CN) hybridized with nickel iron sulfide (NFCN) using simple reaction between Ni-Fe layered double hydroxide and dithiooxamide. The characterization results demonstrate that the hybridization with optimal amount of CN induces local distortion in the crystal structure of the hybrid, which would benefit SIB performance. Systematic electrochemical studies with a half-cell configuration show that the present hybrid structure exhibits a promising reversible specific capacity of 348 mAh g-1 at 0.1 A g-1 after 100 cycles with good rate capability. Simulation result reveals that the iron atoms in nickel iron sulfide act as a primary active site to accommodate Na+ ions. At last, with a full cell configuration using NFCN and Na3 V2 (PO4 )2 O2 F as the anode and cathode, respectively, the specific capacity appears to be ≈95 mAh g-1 after 50 cycles at 0.1 A g-1 condition. This excellent performance of these hybrids can be attributed to the synergistic effect of the incorporated CN species and the high conductivity of nickel-iron sulfide.
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Designing unique nanomaterials for the selective sensing of biomolecules is of significant interest in the field of nanobiotechnology. In this work, we demonstrated the synthesis of ordered Cu nanoparticle-functionalised mesoporous C3 N5 that has unique peroxidase-like nanozymatic activity for the ultrasensitive and selective detection of glucose and glutathione. A nano hard-templating technique together with the in-situ polymerisation and self-assembly of Cu and high N-containing CN precursor was adopted to introduce mesoporosity as well as high N and Cu content in mesoporous C3 N5 . Due to the ordered structure and highly dispersed Cu in the mesoporous C3 N5 , a large enhancement of the peroxidase mimetic activity in the oxidation of a redox dye in the presence of hydrogen peroxide could be obtained. Additionally, the optimised Cu-functionalised mesoporous C3 N5 exhibited excellent sensitivity to glutathione with a low detection limit of 2.0â ppm. The strong peroxidase activity of the Cu-functionalised mesoporous C3 N5 was also effectively used for the sensing of glucose with a detection limit of 0.4â mM through glucose oxidation with glucose oxidase. This unique Cu-functionalised mesoporous C3 N5 has the potential for detecting various molecules in the environment as well as for next-generation glucose and glutathione diagnostic devices.
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Cobre , Nanopartículas , Cobre/química , Glucose/química , Nanopartículas/química , Peróxido de Hidrogênio/química , Peroxidases , Glutationa , ColorimetriaRESUMO
An effective chemical way to optimize the oxygen electrocatalyst and Li-O2 electrode functionalities of metal oxide can be developed by the control of chemical bond nature with the surface anchoring of highly oxidized selenate (SeO4 2- ) clusters. The bond competition between (Se6+ -O) and (Mn-O) bonds is quite effective in stabilizing Jahn-Teller-active Mn3+ state and in increasing oxygen electron density of α-MnO2 nanowire (NW). The selenate-anchored α-MnO2 NW shows excellent oxygen electrocatalytic activity and electrode performance for Li-O2 batteries, which is due to the improved charge transfer kinetics and reversible formation/decomposition of Li2 O2 . The present study underscores that the surface anchoring of highly oxidized cluster can provide a facile, effective way of improving the oxygen electrocatalyst and electrochemical performances of nanostructured metal oxide in Li-O2 cells.
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A universal methodology to efficiently improve the photocatalyst performance of semiconductors was developed by employing exfoliated RuO2 two-dimensional nanosheets as a conducting hybridization matrix. The hybridization with a RuO2 nanosheet is easily achieved by crystal growth or electrostatically derived anchoring of semiconductor nanocrystals on the RuO2 nanosheet. An enhanced chemical interaction of inorganic semiconductor with hydrophilic RuO2 nanosheet is fairly effective in optimizing their photocatalytic activity and photostability by the enhancement of charge separation and charge mobility. The RuO2 -containing nanohybrids show much better photocatalyst functionalities than do the graphene-containing ones. The present study clearly demonstrates that hydrophilic RuO2 nanosheets are superior hybridization matrices, over the widely used hydrophobic graphene nanosheets, for exploring new efficient hybrid-type photocatalysts.
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Mesoporous hybrid network of reduced graphene oxide (rG-O) and layered MnO(2) nanosheets could act as an efficient immobilization matrix for improving the electrochemical activity of layered double hydroxide (LDH). The control of MnO(2) /rG-O ratio is crucial in optimizing the porous structure and electrical conductivity of the resulting hybrid structure. The immobilization of Co-Al-LDH on hybrid MnO(2) /rG-O network is more effective in enhancing its electrode activity compared with that of on pure rG-O network. The Co-Al-LDH-rG-O-MnO(2) nanohybrid deliveres a greater specific capacitance than does MnO(2) -free Co-Al-LDH-rG-O nanohybrid. The beneficial effect of MnO(2) incorporation on the electrode performance of nanohybrid is more prominent for higher current density and faster scan rate, underscoring the significant enhancement of the electron transport of Co-Al-LDH-rG-O. This is supported by electrochemical impedance spectroscopy. The present study clearly demonstrates the usefulness of the porously assembled hybrid network of graphene and metal oxide nanosheets as an effective platform for exploring efficient LDH-based functional materials.
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The photocatalytic activity and photostability of CdS quantum dot (QD) can be remarkably enhanced by hybridization with Rh-substituted layered titanate nanosheet even at very low Rh substitution rate (<1%). Mesoporous CdS-Ti(5.2-x)/6 Rhx/2O2 nanohybrids are synthesized by a self-assembly of exfoliated Ti(5.2-x)/6 Rhx/2O2 nanosheets with CdS QDs. The partial substitution of Rh(3+)/Rh(4+) ions for Ti(4+) ions in layered titanate is quite effective in enhancing an electronic coupling between hybridized CdS and titanate components via the formation of interband Rh 4d states. A crucial role of Rh substituent ion in the internal electron transfer is obviously evidenced from in situ X-ray absorption spectroscopy showing the elongation of (RhO) bond under visible light irradiation. This is the first spectroscopic evidence for the important role of substituent ion in the photoinduced electron transfer of hybrid-type photocatalyst. The CdS-Ti(5.2-x)/6 Rhx/2O2 nanohybrids show much higher photocatalytic activity for H2 production and better photostability than do CdS and unsubstituted CdS-TiO2 nanohybrid. This result is ascribable to the enhancement of visible light absorptivity, the depression of electron-hole recombination, and the enhanced hole curing of CdS upon Rh substitution. The present study underscores that the hybridization with composition-controlled inorganic nanosheet provides a novel efficient methodology to optimize the photo-related functionalities of semiconductor nanocrystal.
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The electrostatically derived self-assembly of cationic Zn-Cr-layered double hydroxide (LDH) nanosheets and cationic CdS quantum dots (QDs) with anionic linkers leads to the formation of strongly coupled Zn-Cr-LDH-CdS nanohybrids. The hybridization with Zn-Cr-LDH leads to significant enhancement of the photocatalytic activity of CdS for visible-light-induced H2 generation, a property that is attributed to the depression of electron-hole recombination. In comparison with a direct hybridization method between oppositely charged species, this linker-mediated method provides greater flexibility in controlling the chemical composition and electronic coupling of the nanohybrids. The present hybridization strategy provides a useful method not only to couple two kinds of isocharged nanostructured materials, but also to explore efficient hybrid-type photocatalysts.
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In comparison with the hybridization with 0D TiO2 nanoparticle, 2D layered TiO2 nanosheets are much more effective in the improvement of the photocatalytic activity and photostability of semiconducting compounds. The 2D TiO2-Ag3PO4 nanohybrid described in this paper shows a greater decrease in the electron-hole recombination upon hybridization and a stronger chemical interaction between the components than the 0D homologue. This result confirms the benefits of 2D layered TiO2 nanosheets as a building block for efficient hybrid-type photocatalyst materials.
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Carbon-based nanomaterials, including graphene, fullerenes, and carbon nanotubes, are attracting significant attention as promising materials for next-generation energy storage and conversion applications. They possess unique physicochemical properties, such as structural stability and flexibility, high porosity, and tunable physicochemical features, which render them well suited in these hot research fields. Technological advances at atomic and electronic levels are crucial for developing more efficient and durable devices. This comprehensive review provides a state-of-the-art overview of these advanced carbon-based nanomaterials for various energy storage and conversion applications, focusing on supercapacitors, lithium as well as sodium-ion batteries, and hydrogen evolution reactions. Particular emphasis is placed on the strategies employed to enhance performance through nonmetallic elemental doping of N, B, S, and P in either individual doping or codoping, as well as structural modifications such as the creation of defect sites, edge functionalization, and inter-layer distance manipulation, aiming to provide the general guidelines for designing these devices by the above approaches to achieve optimal performance. Furthermore, this review delves into the challenges and future prospects for the advancement of carbon-based electrodes in energy storage and conversion.
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Fontes de Energia Elétrica , Carbono/química , Eletrodos , Transferência de Energia , Nanotubos de Carbono/química , Pontos Quânticos , Grafite/química , Condutividade Elétrica , Lítio/química , Técnicas Eletroquímicas , Sódio/química , CatáliseRESUMO
Strongly coupled nanocomposites of layered titanate and reduced graphene oxide (RGO) are synthesized by electrostatically derived self-assembly between negatively charged RGO nanosheets and positively charged TiO(2) nanosols, which is then followed by a phase transition of the anatase TiO(2) component into layered titanate. The resulting nanocomposite consists of thin 2D nanoplates of lepidocrocite-type layered titanate immobilized on the surface of RGO nanosheets. The composite formation with RGO nanosheets is effective not only in promoting the phase transition of anatase TiO(2) nanosols, but also in improving the thermal stability of the layered titanate, indicating the role of RGO nanosheets as an agent for directing and stabilizing layered structures. The layered-titanate-RGO nanocomposites exhibit remarkably expanded surface area with the formation of micropores and mesopores. The composite formation with RGO nanosheets gives rise to the disappearance of the reflectance edge of layered titanate in the diffuse reflectance UV-vis spectra, indicating a strong electronic coupling between the RGO and layered titanate. The strong electronic correlation between the two components is further evidenced by the visible-light-induced generation of photocurrents after the hybridization with RGO. The layered-titanate-RGO nanocomposite shows a higher activity for the photodegradation of organic molecules than uncomposited layered titanate, underscoring the usefulness of graphene hybridization in improving the photocatalyst performance of layered titanate. The experimental findings presented here clearly demonstrate that the self-assembly of metal oxide nanoparticles with RGO 2D nanosheets is quite effective not only in synthesizing porous metal-oxide-graphene nanocomposites with improved photo-induced functionality, but also in achieving strong electronic coupling between RGO and metal oxides.
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Grafite/química , Nanocompostos/química , Nanotecnologia/métodos , Fotoquímica/métodos , Catálise , PorosidadeRESUMO
Graphene nanosheets are successfully applied as an effective platform for the 2D ordering of metal oxide nanoparticles. Mesoporous 2D aggregates of anatase TiO(2) nanoparticles are synthesized by the heat treatment of the uniformly hybridized nanocomposite of layered titanate-reduced graphene oxide (RGO) at elevated temperatures. The precursor layered titanate-RGO nanocomposite is prepared by self-assembly of anionic RGO nanosheets and cationic TiO(2) nanosols. The calcination of the as-prepared layered titanate-RGO nanocomposite at 500 °C induces a structural and morphological change of layered titanate nanoplates into anatase TiO(2) nanoparticles without significant modification of the RGO nanosheet. Increasing the heating temperature to 600 °C gives rise to elimination of the RGO component, leading to the formation of sheetlike porous aggregates of RGO-free TiO(2) nanoparticles. The nanocomposites calcined at 500-700 °C display promising functionality as negative electrodes for lithium ion batteries. Among the present calcined derivatives, the 2D sheet-shaped aggregate of TiO(2) nanoparticles obtained from calcination at 600 °C delivers the greatest specific discharge capacity with good capacity retention for all current density conditions applied. Such superior electrode performance of the nanocomposite calcined at 600 °C is attributable both to the improved stability of the crystal structure and crystal morphology of titania and to the enhancement of Li(+) ion transport through the enlargement of mesopores. The present findings clearly demonstrate the usefulness of RGO nanosheets as a platform for 2D-ordered superstructures of metal oxide nanoparticles with improved electrode performance.
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Homogeneously mixed colloidal suspensions of reduced graphene oxide, or RGO, and layered manganate nanosheets have been synthesized by a simple addition of the exfoliated colloid of RGO into that of layered MnO(2). The obtained mixed colloidal suspensions with the RGO/MnO(2) ratio of ≤0.3 show good colloidal stability without any phase separation and a negatively charged state with a zeta (ζ) potential of -30 to -40â mV. The flocculation of these mixed colloidal suspensions with lithium cations yields porous nanocomposites of Li/RGO-layered MnO(2) with high electrochemical activity and a markedly expanded surface area of around 70-100â m(2) g(-1). Relative to the Li/RGO and Li/layered MnO(2) nanocomposites (≈116 and ≈167â F g(-1)), the obtained Li/RGO-layered MnO(2) nanocomposites deliver a larger capacitance of approximately 210â F g(-1) with good cyclability of around 95-97 % up to the 1000th cycle, thus indicating the positive effect of hybridization on the electrode performances of RGO and lithium manganate. Also, an electrophoretic deposition of the mixed colloidal suspensions makes it possible to easily fabricate uniform hybrid films composed of graphene and manganese oxide. The obtained films show a distinct electrochemical activity and a homogeneous distribution of RGO and MnO(2). The present experimental findings clearly demonstrate that the utilization of the mixed colloidal suspensions as precursors provides a facile and universal methodology to synthesize various types of graphene/metal oxide hybrid materials.
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Grafite/química , Grafite/síntese química , Lítio/química , Compostos de Manganês/química , Metais/química , Nanocompostos/química , Óxidos/química , Eletroquímica , SuspensõesRESUMO
The harvesting of photosynthetic electrons (PEs) directly from photosynthetic complexes has been demonstrated over the past decade. However, their limited efficiency and stability have hampered further practical development. For example, despite its importance, the interfacial electron transfer between the photosynthetic apparatus and the electrode has received little attention. In this study, we modified electrodes with RuO2 nanosheets to enhance the extraction of PEs from thylakoids, and the PE transfer was promoted by proton adsorption and surface polarity characteristics. The adsorbed protons maintained the potential of an electrode more positive, and the surface polarity enhanced thylakoid attachment to the electrode in addition to promoting ensemble docking between the redox species and the electrode. The RuO2 bioanode exhibited a five times larger current density and a four times larger power density than the Au bioanode. Last, the electric calculators were successfully powered by photosynthetic energy using a RuO2 bioanode.
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We report on the synthesis of 3D mesoporous fullerene/carbon hybrid materials with ordered porous structure and high surface area by mixing the solution of fullerene and sucrose molecules in the nanochannels of 3D mesoporous silica, KIT-6 via nanotemplating approach. The addition of sucrose molecules in the synthesis offers a thin layer of carbon between the fullerene molecules which enhances not only the specific surface area and the specific pore volume but also the conductivity of the hybrid materials. The prepared hybrids exhibit 3D mesoporous structure and show a much higher specific surface area than that of the pure mesoporous fullerene. The hybrids materials are used as the electrodes for supercapacitor and Li-ion battery applications. The optimised hybrid sample shows an excellent rate capability and a high specific capacitance of 254 F/g at the current density of 0.5 A/g, which is much higher than that of the pure mesoporous fullerene, mesoporous carbon, activated carbon and multiwalled carbon nanotubes. When used as the electrode for Li-ion battery, the sample delivers the largest specific capacity of 1067 mAh/g upon 50 cycles at the current density of 0.1 A/g with stability. These results reveal that the addition of carbon in the mesoporous fullerene with 3D structure makes a significant impact on the electrochemical properties of the hybrid samples, demonstrating their potential for applications in Li-ion battery and supercapacitor devices.
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Borophene, a 2D allotrope of boron and the lightest elemental Dirac material, is the latest very promising 2D material owing to its unique structural and electronic characteristics of the X3 and ß12 phases. The high atomic density on ridgelines of the ß12 phase of borophene provides a substantial orbital overlap, which leads to an excellent electron density in the conduction level and thus to a highly metallic behavior. These unique structural characteristics and electronic properties of borophene attract significant scientific interest. Herein, approaches for crystal growth/synthesis of these unique nanostructures and their potential technological applications are discussed. Various substrate-supported ultrahigh-vacuum growth techniques for borophene, such as molecular beam epitaxy, atomic layer deposition, and chemical vapor deposition, along with their challenges, are also summarized. The sonochemical exfoliation and modified Hummer's technique for the synthesis of free-standing borophene are also discussed. Solution-phase exfoliation seems to address the scalability issues and expands the applications of these unique materials to various fields, including renewable energy devices and ultrafast sensors. Furthermore, the electronic, optical, thermal, and elastic properties of borophene are thoroughly discussed and are compared with those of graphene and its "cousins." Numerous frontline applications are envisaged and an outlook is presented.
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A scalable organic intercalant-free liquid exfoliation route to 2D nanosheets (NSs) of layered transition-metal oxides (TMOs) is developed by employing hydronium-intercalated derivatives as precursors. The replacement of interlayer alkali metal ions with larger hydronium ions via acid treatment makes possible the efficient liquid exfoliation of TMOs without any assistance of organic intercalant cations. Not only a weakening of interlayer electrostatic interaction upon hydronium intercalation but also an efficient solvation of deintercalated hydronium ions via hydrogen bonding with polar solvents is mainly responsible for the high efficacy of hydronium-intercalated TMOs as precursors for liquid exfoliation. The nature of the solvent employed also has a profound effect on the exfoliation yield of these TMO NSs; viscosity, surface tension, density, and Hansen solubility parameter as well as the capability to solvate the exfoliated NSs and hydronium ions are crucial factors for determining the exfoliation efficiency of the hydronium-intercalated precursor. All the obtained Ti1- xO2, MnO2, and RuO2 NSs show highly anisotropic 2D morphologies and distinct negative surface charges with a zeta potential of -30 to -50 mV. Such distinct surface charges of these NSs render them versatile hybridization matrices for the synthesis of novel nanohybrids with enhanced functionalities. The hybridization with the liquid-exfoliated TMO NSs is quite effective in improving the photocatalytic activity of CdS and the electrode functionalities of graphene and graphene-layered double hydroxide nanohybrids. The present study underscores the usefulness of the present liquid exfoliation method in synthesizing organic-free TMO NSs and their nanohybrids as well as in widening the application field of exfoliated TMO NSs.
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Mesoporous carbon nitride (MCN) with well-ordered porous structures is a promising anode material for secondary ion batteries owing to their unique physico- and electrochemical properties. However, the practical application of these MCNs in sodium-ion batteries (SIBs) is still limited because of their confined interlayer distance, which results in restricted accommodation of Na ions inside the lattice. Here, we report on the synthesis of highly ordered sulfur-doped MCN (S-MCN) through a hard template approach by employing dithiooxamide (DTO) as a single molecular precursor containing carbon, nitrogen, and sulfur elements. The interlayer distance of carbon nitride is significantly expanded upon the introduction of larger S ions on the MCN lattice, which enables high capability of Na ion accommodation. We also demonstrate through the first-principles density functional theory calculation that the present S-MCN is highly optimized not only for the chemical structure but also for uptaking abundant Na ions with high adsorption energy. The specific discharge capacity of SIBs appears to be remarkably enhanced for S-MCN (304.2 mA h g-1) compared to the nonporous S-CN (167.9 mA h g-1) and g-C3N4 (5.4 mA h g-1), highlighting the pivotal roles of the highly ordered mesoporous structure and S-doping in enhancing the electrochemical functionality of carbon nitride as an anode material for SIBs.
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Efficient visible light active hybrid photocatalysts for H2 production can be synthesized by the intercalative hybridization of Zn-Cr-layered double hydroxide (Zn-Cr-LDH) with a mesoporous g-C3N4 lattice. Small Zn-Cr-LDH nanocrystals with a size of â¼6 nm are immobilized in the mesopores of g-C3N4. Beyond an optimal LDH/g-C3N4 molar ratio of 0.3, a further increase in the LDH content leads to the surface deposition of LDH crystals on the g-C3N4 material as well as the intercalative immobilization of LDH into its mesopores, indicating the controllability of the LDH deposition site. The Zn-Cr-LDH-g-C3N4 nanohybrids exhibit smaller surface areas than the pristine g-C3N4, confirming the intercalative stabilization of Zn-Cr-LDH nanocrystals in the mesopore of g-C3N4. The hybridization between Zn-Cr-LDH and g-C3N4 is effective in enhancing visible light absorptivity and also in depressing electron-hole recombination, which is attributable to an efficient electronic coupling between both the hybridized components. The present Zn-Cr-LDH-g-C3N4 nanohybrid exhibits promising photocatalytic activities for visible light-induced H2 production at a rate of 155.7 µmol g-1 h-1, which is much superior to that of the pristine g-C3N4 (21.7 µmol g-1 h-1). The present study underscores that the intercalative immobilization of Zn-Cr-LDH crystals in the limited space of a mesopore is quite useful in improving the visible light active photocatalyst functionality of mesoporous carbon nitride.
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[This corrects the article DOI: 10.1039/C6RA24140A.].