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[Display omitted] • NiM (M: Sb, Sn)/nitrogen-doped hollow carbon tubes (NiM-C) structure was constructed. • NiM-C displays exciting capacity and rate performance for lithium ion batteries. • Electrochemical analysis reveals the lithium storage behavior of NiM-C during cycling. Alloy-type materials are regarded as prospective anode replacements for lithium-ion batteries (LIBs) owing to their attractive theoretical capacity. However, the drastic volume expansion leads to structural collapse and pulverization, resulting in rapid capacity decay during cycling. Here, a simple and scalable approach to prepare NiM (M: Sb, Sn)/nitrogen-doped hollow carbon tubes (NiM C) via template and substitution reactions is proposed. The nanosized NiM particles are uniformly anchored in the robust hollow N -doped carbon tubes via Ni N C coordination bonds, which not only provides a buffer for volume expansion but also avoids agglomerating of the reactive material and ensures the integrity of the conductive network and structural framework during lithiation/delithiation. As a result, NiSb C and NiSn C exhibit high reversible capacities (1259 and 1342 mAh/g after 100 cycles at 0.1 A/g) and fascinating rate performance (627 and 721 mAh/g at 2 A/g), respectively, when employed as anodes of LIBs. The electrochemical kinetic analysis reveals that the dominant lithium storage behavior of NiM C electrodes varies from capacitive contribution to diffusion contribution during the cycling corresponding to the activation of the electrode exposing more NiM sites. Meanwhile, M (Sb, Sn) is gradually transformed into stable NiM during the de-lithium process, making the NiM C structure more stable and reversible in the electrochemical reaction. This work brings a novel thought to construct high-performance alloy-based anode materials. [ABSTRACT FROM AUTHOR]

Abstract: Cationic gemini surfactant homologues alkanediyl-α,ω-bis(dodecyldiethylammonium bromide), [C12H25(CH3CH2)2N(CH2)SN(CH2CH3)2C12H25]Br2 (where S =2, 4, 6, 8, 10, 12, 16, 20), referred to as C12CSC12(Et) were synthesized systematically. This paper focused on various properties of the above gemini surfactants in order to give a full understanding of this series of surfactants. The following points are covered: (1) surface properties, which include (i) effect of the spacer carbon number on the general properties and (ii) the effect of added NaBr on the general surface properties; (2) aggregation behavior in bulk solution, including (i) morphologies of above gemini surfactants classed as having short spacers, middle-length spacers and long spacers and (ii) superior vesicle stability against high NaBr concentration for the long spacer gemini surfactants; (3) thermodynamic properties during micellization and the effect of spacer carbon number on them; and (4) perspectives for the further use and application of these compounds. [Copyright &y& Elsevier]

Abstract: Researches on the bolaamphiphiles have attracted considerable attentions in the last three decades. Among which, the mixed systems with conventional surfactants are of special interest. This review focuses on the recent advances in the research of the bolaamphiphile/oppositely charged conventional surfactant mixed systems. The following contents are covered: (1) surface properties, which include (i) the general properties of the mixed systems, (ii) the effect of rigid group on the surface properties, and (iii) the slow adsorption process of bolaamphiphiles on solid surface; (2) aggregation behaviors in the bulk solution, including (i) the superior vesicle formation ability, (ii) superior vesicle stability, (iii) dynamic morphology of the aggregates, and (iv) tunable morphologies; (3) perspective for the future. [Copyright &y& Elsevier]

[Display omitted] As an emerging class of layered transition metal carbides/nitrides/carbon-nitrides, MXenes have been one of the most investigated anode subcategories for sodium ion batteries (SIBs), due to their unique layered structure, metal-like conductivity, large specific surface area and tunable surface groups. In particular, different MAX precursors and synthetic routes will lead to MXenes with different structural and electrochemical properties, which actually gives MXenes unlimited scope for development. In this feature article, we systematically present the recent advances in the methods and synthetic routes of MXenes, together with their impact on the properties of MXenes and also the advantages and disadvantages. Subsequently, the sodium storage mechanisms of MXenes are summarized, as well as the recent research progress and strategies to improve the sodium storage performance. Finally, the main challenges currently facing MXenes and the opportunities in improving the performance of SIBs are pointed out. [ABSTRACT FROM AUTHOR]

[Display omitted] Currently, the development of economical and effective non-noble metal electrocatalysts is vital for advancing hydrogen evolution reaction (HER) and enabling its widespread applications. The customizable pore structure and enormous surface area of metal–organic frameworks (MOFs) have made them to become promising non-noble metal electrocatalysts for HER. However, MOFs have some challenges, including low conductivity and instability, which can result in them having high overpotentials and slow reaction kinetics in electrocatalytic processes. In this work, we present an innovative approach for synthesizing cost-effective and high-efficient Zr-MOF-derived pH-universal electrocatalysts for HER. It entails creating the interfaces of the electrocatalysts with suitable proportions of phosphide nanostructures. Zr-MOF/Ni 2 P@nickel foam (NF) electrodes with interface regulated by Ni 2 P nanostructures were successfully developed for high-efficient pH-universal HER electrocatalysts. The presence of Ni 2 P nanostructures with abundant active sites at the Zr-MOFs@NF interfaces boosted the electronic conductivity and local charge density of the hybrid electrocatalysts. This helped to improve their reaction kinetics and electrocatalytic activity. By optimizing the Ni 2 P amount, Zr-MOF/Ni 2 P@NF demonstrated impressive stability and superior HER activities, with a low overpotential of 149 mV (acidic electrolytes) and 143 mV (alkaline electrolytes) at 10 mA cm−2. The proven strategy in this work can be expanded to many types of MOF-based materials for wider practical applications. [ABSTRACT FROM AUTHOR]

• V 2 O 5 · n H 2 O/rGO was synthesized via a dual electrostatic assembly strategy. • The synergistic contribution in the composite improves the energy storage ability. • The composite exhibits excellent rate capability when used as cathode for LIBs. As well-known, hydrated vanadium pentoxide (V 2 O 5 · n H 2 O) has a larger layer spacing than orthogonal V 2 O 5 , which could offer more active sites to accommodate lithium ions, ensuring a high specific capacity. However, the exploration of V 2 O 5 · n H 2 O cathode is limited by its inherently low conductivity and slow electrochemical kinetics, leading to a significant decrease in capability. Herein, we prepared V 2 O 5 · n H 2 O/reduced graphene oxide (rGO) composite with low rGO content (8 wt%) via a simple yet effective dual electrostatic assembly strategy. When used as the cathode material for lithium-ion batteries (LIBs), V 2 O 5 · n H 2 O/rGO manifests a high reversible capacity of 268 mAh g−1 at 100 mA g−1 and especially an excellent rate capability (196 mAh g−1 at 1000 mA g−1 and 129 mA h g−1 at 2000 mA g−1), surpassing those of the V 2 O 5 /carbon composites reported in the literatures. Notably, the remarkable performance should be referable to the synergetic effects between one-dimensional V 2 O 5 · n H 2 O nanobelts and two-dimensional rGO nanosheets, which provide a short transport pathway and enhanced electrical conductivity. This strategy opens a new opportunity for designing high-performance cathode material with excellent rate performance for advanced LIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] Prussian blue analogs (PBAs) have gained much attention in the capacitive deionization (CDI) field because of their rigid open structure and good energy storage capacity. However, their desalination performance is still to be improved for practical application. Herein, we reported the NiCoFe ternary-metal PBAs materials and explored their application as Na+ capturing electrode in rocking-chair capacitive deionization (RCDI) system. On the one hand, the introduction of Ni2+ into CoFe PBA can effectively reduce the lattice changes in the (dis)charging process. On the other hand, the RCDI system with symmetrical structure could avoid the performance deficiency caused by the unbalanced capacity of common HCDI system. Due to the rationalized RCDI cell configuration and ternary-metal PBAs with improved stability, the NiCoFe-PBAs-based RCDI exhibits amazing desalination performance with maximum capacity of 131.4 mg·g−1 and rate of 0.46 mg·g−1·s−1 as well as optimum stability with 90.7 % capacity retention over 300 cycles, surpassing those of PBAs based CDI system reported previously. The special strategy in this work offers inspiration via optimizing the cell structure and electrode materials for the promising development of CDI systems. [ABSTRACT FROM AUTHOR]

[Display omitted] As a typical transition-metal sulfides (TMS), nickel disulfide (NiS 2) has attracted great attention in terms of hydrogen evolution reaction (HER). Howbeit, owing to the poor conductivity, slow reaction kinetics and instability of NiS 2 , its HER activity is still necessary to be improved. In this work, we designed hybrid structures consisting of the nickel foam (NF) as a self-supporting electrode, NiS 2 derived from the sulfuration of NF and Zr-MOF grown on the surface of NiS 2 @NF (Zr-MOF/NiS 2 @NF). Due to the synergistic effect between the different constituents, the obtained Zr-MOF/NiS 2 @NF demonstrates ideal electrochemical hydrogen evolution ability in acidic and alkalescent environment, reaching a standard current density of 10 mA cm−2 at overpotentials of 110 and 72 mV in 0.5 M H 2 SO 4 and 1 M KOH electrolytes, respectively. What is more, it also maintains excellent electrocatalytic durability for 10 h in both electrolytes. This work could provide a useful guidance on effectively combining metal sulfide with MOF for high-performance HER electrocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] Ignited by the concept of bionics, hydrogel-based bionic skin sensors have received more and more attention and been widely used in health monitoring, robots, implantable prostheses and human-machine interfaces. However, there still remain some challenges to be urgently solved for hydrogel-based bionic skin sensors, such as the water evaporation and the defects of single conductive mechanism of electronic skin or ionic skin. Herein, we prepared a polyvinyl alcohol/polyacrylamide/CaCl 2 /MXene (PPCM) ionotronics hydrogel with moisture self-regenerative, highly sensitive, ultra-low temperature anti-freezing (−50 °C) and self-adhesive features and applied it as bionic skin strain sensor. The introduction of MXene and CaCl 2 endows the PPCM hydrogel with both electron and ion conductive channels, which effectively compensates for the defects of single electronic skin or ionic skin. Importantly, the addition of CaCl 2 into the PPCM hydrogel offers it the moisture self-regenerative ability, holding the long-term water retention. The water in the PPCM hydrogel can still be kept in a stable state after continuous use for 70 days at room temperature, thus ensuring the long-term stability of the hydrogel-based sensor. Such a moisture self-regenerative ability should be an important feature for intelligentizing the hydrogel-based bionic skin for practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Although widely used as hybrid capacitive deionization (HCDI) electrode material, the low intrinsic conductivity of metal hexacyanometalate (MHCF) severely hinders the fast insertion/extraction of Na+ in/from its 3D framework structure, damaging its desalination performance. Herein, we design a carbon nanotube (CNT) bridged nickel hexacyanoferrate architecture (NiHCF). The highly conductive CNT not only acts as the skeleton for the uniform growth of NiHCF to provide more ion-accessible surface and active sites but also serves as the conductive bridge to connect the NiHCF particles, which prevents the agglomeration of NiHCF particles and facilitates the charge transfer and ion diffusion during the desalination process. Therefore, the HCDI cell assembled by NiHCF/CNT cathode and AC anode exhibits an excellent desalination performance with a high desalination capacity of 29.1 mg g−1 and a superior desalination rate of 7.2 mg g−1 min−1 in 500 mg L−1 NaCl solution. This work provides a facile method for preparing high-performance MHCF-based electrodes for desalination application. [ABSTRACT FROM AUTHOR]

[Display omitted] Transition metal phosphides, especially bimetallic phosphides, are promising noble-metal-free electrocatalysts for hydrogen evolution reaction (HER). However, their inferior charge transfer ability constrains further performance improvement. In this work, a facile strategy is reported to fabricate Co 2 P/Ni 2 P/carbon nanotube (CNT) composite from a precursor Co-Ni Prussian blue analogue. The combination of Co 2 P/Ni 2 P and CNT endows Co 2 P/Ni 2 P/CNT with improved electrical conductivity and a richer electrochemically active surface area. As a result, the Co 2 P/Ni 2 P/CNT composite exhibits desirable HER activities across a wide pH range, delivering a benchmark current density of 10 mA cm−2 at overpotentials as low as 151 and 202 mV in 0.5 M H 2 SO 4 and 1 M KOH electrolytes, respectively, as well as remarkable electrocatalytic stabilities over 48 h in both electrolytes. This strategy enables the design of high-performance electrocatalysts for efficient and stable hydrogen generation. [ABSTRACT FROM AUTHOR]

[Display omitted] One prevailing method to construct excellent temperature tolerance/long-lasting moisture hydrogels is to couple the original hydrogel networks with freezing-tolerant/moisture retaining agents, including ionic liquids, inorganic salts, zwitterionic osmolytes, and polyhydric alcohols. Among them, organohydrogels have shed new light on the development of ionic skins with long-term usability and stable sensing performance at subzero temperatures due to their long-lasting water retention and anti-freezing capability. We report a dual network organohydrogel by doping conductive ZnSO 4 into the double network hydrogel of polyvinyl alcohol-polyacrylamide (PVA-PAM) with subsequent immersing in a mixed solvent of ethylene glycol (EG) and H 2 O. The anti-freezing and moisture retaining abilities of the PVA/PAM/Zn/EG (PPZE) organohydrogel were studied and the sensing performances of the PPZE organohydrogel-based ionic skin were investigated. The organohydrogel exhibits a high conductivity (0.44 S m−1), excellent fatigue resistance and exceptional moisture retaining ability with more than 99.3% of the initial weight retention after 31 days storage at ambient temperature. Importantly, the PPZE organohydrogel-based ionic skin shows an ultra-low temperature anti-freezing ability and remains flexibility and sensing capability with a high sensitivity (signal response time ∼ 0.23 s) even at -50 °C. The PPZE organohydrogel demonstrates a tremendous potential in artificial skin and health monitoring. [ABSTRACT FROM AUTHOR]

[Display omitted] Metal sulfides are recognized as potential candidates for the anode materials of lithium ion batteries (LIBs) because of their high theoretical capacity. However, the low reaction kinetics of metal sulfides leads to their poor cycle life and rate performance, which limits their practical application in the field of energy storage. In this work, we synthesized a self-assembled carbon-free vanadium sulfide (V 3 S 4) nanosheet via a facile and efficient method. The unique mesoporous nanostructure of V 3 S 4 can not only accelerate the migration of ions/electrons, but also alleviate the volume expansion during the lithium ion insertion/extraction process. When used as the anode material of LIBs, the carbon-free V 3 S 4 electrode exhibits remarkable electrochemical performance with ultra-high charge capacity (1099.3 mAh g−1 at 0.1 A g−1), superior rate capability (668.8 mAh g−1 at 2 A g−1 and 588.8 mAh g−1 at 5 A g−1) and impressive cycling ability (369.6 mAh g−1 after 200 cycles at 10 A g -1), which is very competitive compared with those of most metal sulfides-based anode materials reported so far. The strategy in this work provides inspiration for the rational design of advanced nanostructured electrode materials for energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] Rational construction of hybrid materials integrating the collective virtues of individual building blocks has spurred significant interest in electrode materials for energy storage. Herein, a smart hybrid was fabricated via in-situ assembling of the few-layered MoS 2 (f-MoS 2) coated on the multi-layered Ti 3 C 2 MXene decorated with the TiO 2 nanoparticles by the scalable hydrothermal and annealing approaches. In the unique architecture, the multi-layered Ti 3 C 2 with the expanded interspaces as the conductive backbone can facilitate the electron transport, provide adequate space to facilitate the infiltration of organic electrolyte into the interior of electrode, and inhibit the aggregation of MoS 2 nanosheets, while the f-MoS 2 with enlarged interlayer can be beneficial for the lithium-ion diffusion and prevent the multi-layered Ti 3 C 2 from restacking. Moreover, the TiO 2 decorated on the Ti 3 C 2 can effectively inhibit the instability of long-chain lithium polysulfides dissolved in organic electrolyte to improve the cycling stability. Thanks to the synergistic effect of the building blocks, the Ti 3 C 2 /TiO 2 @f-MoS 2 hybrid employed as lithium storage anode delivers an extraordinary endurable ability with a high storage capacity of 403.1 mA h g−1 after 1200 cycles at 2 A g−1. Importantly, the smart hybridization strategy in this work paves an efficient way to explore the high-performance MXene-based hybrid materials in energy storage fields. [ABSTRACT FROM AUTHOR]

[Display omitted] Aqueous zinc-ion batteries (ZIBs) have been considered to be potential energy storage devices because of their cost-effectiveness and environmental friendliness. However, most of the cathode materials reported in ZIBs exhibit poor electrochemical performances like capacity fading during cycling and inferior performance at high current densities, which significantly hinder the further development of ZIBs. Here, we reported a novel three-dimensional hydrated vanadium pentoxide (V 2 O 5 · n H 2 O)/MXene composite via a simple one-step hydrothermal method. Owing to the unique structure and high electrical conductivity of MXene, V 2 O 5 · n H 2 O/Ti 3 C 2 T x MXene shows a remarkable electrochemical performance with a reversible capacity of 323 mAh g−1 at 0.1 A g−1 and exceptional rate capability (262 mAh g−1 at 1 A g−1 and 225 mAh g−1 at 2 A g−1) when used as the cathode for aqueous ZIBs. This work offers a new insight into fabricating novel vanadium oxide-based cathode material for aqueous ZIBs. [ABSTRACT FROM AUTHOR]

• FTOC/MXene was fabricated by combining MXene, C and (Fe 2.5 Ti 0.5) 1.04 O 4. • FTOC/MXene shows a unique two-dimensional architecture. • FTOC/MXene exhibits a superior rate performance as anode for LIBs. • The effects on restricting the volume expansion during cycling have been studied. The development of battery systems with high specific capacity and power density could fuel various energy-related applications from personal electronics to grid storage. (Fe 2.5 Ti 0.5) 1.04 O 4 possessing high theoretical specific capacity has been considered as a promising high rate anode material for lithium ion batteries due to the replacement of Fe3+ (0.64 Å) by Ti4+ (0.68 Å) with a larger radius to expand the interlayer space for ion intercalation. However, its extreme volume variation upon cycling as well as poor electrical conductivity hinder its further application. To tackle the above problems, in this work, we successfully synthesized two-dimensional (2D) (Fe 2.5 Ti 0.5) 1.04 O 4 /C/MXene architecture derived from Ti 3 C 2 T x MXene via solvo-hydrothermal, ultrasound hybridizing and high temperature annealing processes. The (Fe 2.5 Ti 0.5) 1.04 O 4 /C/MXene shows a high discharge capacity of 757.2 mAh g−1 after 800 cycles at a current density of 3 A g−1 with excellent rate performance. The superior electrochemical performances are triggered primarily by the incorporation of carbon and MXene into (Fe 2.5 Ti 0.5) 1.04 O 4 moiety to construct a 2D layered structure, which can improve the ion diffusion and electron transport. In addition, the synergistic contributions from diffusion controlled and capacitive processes for (Fe 2.5 Ti 0.5) 1.04 O 4 /C/MXene improve the ion diffusion rate and offer high specific capacity at high current density. The MXene-derived synthesis strategy in this work should be a promising pathway to synthesize other anode materials with 2D layered architecture for high performance lithium storage. [ABSTRACT FROM AUTHOR]

• N, S co-doped V 2 CT x MXene was prepared and its structure was optimized. • N, S co-doped V 2 CT x MXene exhibited superior electrochemical performances for LIBs. • The lithium storage mechanism of N, S co-doped V 2 CT x MXene was investigated. As an emerging group of two-dimensional (2D) layered material, MXenes have received significant attention in the direction of energy storage. However, the restacking of MXene flakes severely hinders the ion transport within electrodes, which limits their application for lithium-ion batteries (LIBs). To address this issue, herein, we rationally designed and optimized the structure of N, S co-doped V 2 CT x MXene, which exhibits excellent electrochemical performance with a high reversible capacity of 590 mAh g−1 after 100 cycles at 0.1 A g−1 when used as anode of LIBs. Even at a high current density of 2 A g−1, a reversible capacity of 298 mAh g−1 is obtained after 300 cycles, which outperforms most of the V 2 CT x -based anode materials reported so far. The lithium-ion storage mechanism of N, S co-doped V 2 CT x MXene was studied by a series of characterizations. The results show that the significant improvement of electrochemical performance should be attributed to the facilitated charge transfer after N and S co-doping in V 2 CT x MXene, which can effectively improve the ion transfer kinetics during the lithiation-delithiation process. Furthermore, the expanded interlayer spacing of N, S co-doped V 2 CT x provides more active sites for the adsorption of lithium ions, promoting the insertion capacity of lithium ions. This work indicates that the N, S co-doped 2D V 2 CT x MXene should be a promising anode material for high-performance LIBs. [ABSTRACT FROM AUTHOR]

Co/Co 2 P@C Mott-Schottky electrocatalysts were successfully synthesized from Co-MOF and show excellent HER activity owing to the Mott-Schottky effect, synergy effect of Co and Co 2 P and porous carbon shell. Cobalt phosphides, as low cost and abundant non-noble materials for hydrogen evolution reaction (HER), are always constrained by their inferior charge transfer and sluggish intrinsic electrocatalytic kinetics. In this work, carbon-incorporated Co/Co 2 P microspheres (Co/Co 2 P@C) as a novel Mott–Schottky catalyst were synthesized successfully via carbonization and gradual phosphorization of Co based metal-organic frameworks. The unique merits, including Mott-Schottky effect at the interface formed between metal Co and semiconductor Co 2 P, the incorporated carbon-layer on the surface and the spherical structure endow Co/Co 2 P@C with favorable electrical conductivity, preferable kinetics and long-term stability when it was evaluated as electrocatalyst for HER in wide-pH range. As a result, the Co/Co 2 P@C with the optimized phosphorization degree delivers a benchmark current density of 10 mA cm−2 at the low overpotential of 192 and 158 mV in acidic and alkaline electrolytes, respectively, with a remarkable stability (CV cycling for 3000 cycles and continuous electrolysis at the overpotential of 200 mV for 48 h). Therefore, the as-designed Co/Co 2 P@C should be one of the most promising catalysts for HER application. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Covalent organic frameworks (COFs) with devisable nanostructures have exhibited extensive application prospects in energy storage and conversion. In this work, spherical COFs were successfully utilized as an ideal precursor for N, B co-doped carbon spheres (NBCs) that display hierarchical spherical architectures with rich pores. When applied as lithium ion batteries (LIBs) anode, NBCs exhibit high reversible specific capacity and outstanding long-life cycling stability (205.5 mAh g−1 at 5.0 A g−1 and 171.4 mAh g−1 at 10.0 A g−1 after 5000 cycles) owing to their hierarchical porosity, unique structure and in-situ N, B co-doping. The excellent lithium storage ability, especially satisfactory long cycling stability, enables NBCs to be a promising candidate for LIBs. [ABSTRACT FROM AUTHOR]

Recently sodium ion batteries (SIBs) as a new energy storage system have attracted enormous interests. Unfortunately, the development of high-performance electrode materials for SIBs is restricted owing to the large volume change during sodium insertion and extraction. In this work, porous CoFe 2 O 4 nanocubes (PCFO-NCs) were prepared simply by annealing metal-organic frameworks and used as anode materials for SIBs. The PCFO-NCs exhibit a high initial Coulombic efficiency of 68.8% and a maximum reversible capacity of 360 mAh g −1 after 50 cycles at the current density of 50 mA g −1 , as well as good rate capability and excellent cycling stability at high current density. The excellent electrochemical performance can be attributed the short diffusion distance of sodium ion due to the good interfacial contact between electrode and electrolyte, and the buffering of volume change during charge/discharge processes by the porous structure. [ABSTRACT FROM AUTHOR]

Currently, metal-organic frameworks (MOFs) and their derivates have attracted great interest as a new kind of electrode material for energy storage devices, mainly due to their designable framework structures, abundant pore structures, adjustable pore and particle sizes. In this work, porous CuO/reduced graphene oxide (RGO) composites were obtained through the pyrolysis of Cu-based MOFs/graphene oxide under microwave irradiation, and investigated as anode materials for sodium-ion batteries (SIBs). CuO/RGO composites exhibit a maximum specific capacity of 466.6 mA h g −1 after 50 galvanostatic charge/discharge cycles at a current density of 100 mA g −1 . Even at a high current density of 2 A g −1 , a capacity of 347.6 mA h g −1 is still maintained with stable cycling. The superior electrochemical performance, which is better than those of CuO-based electrodes reported previously, makes the CuO/RGO composites to be applied promisingly as anodes for high-performance SIBs. [ABSTRACT FROM AUTHOR]

One of the most challenging issues in developing electrochemical flow capacitor (EFC) technology is the design and synthesis of active electrode materials with high energy density and long cycle life. However, in practical cases, the energy density and cycle ability obtained currently cannot meet the practical need. In this work, we propose a new active material, nitrogen-doped carbon spheres (NCSs), as flowable electrodes for EFC application. The NCSs were prepared via one-pot hydrothermal synthesis in the presence of resorcinol/formaldehyde as carbon precursors and melamine as nitrogen precursor, followed by carbonization in nitrogen flow at various temperatures. The results of EFC experiments demonstrate that NCSs obtained at 800 °C exhibit a high energy density of 13.5 Wh kg −1 and an excellent cycle ability, indicating the superiority of NCSs for EFC application. [ABSTRACT FROM AUTHOR]

BiOBr/BiOF (BF) composites were successfully synthesized via a facile one-step hydrothermal method for the first time. The structures, morphologies and photocatalytic performances of BF composites were characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, UV–vis absorption spectroscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy and electrochemical impedance spectroscopy respectively. The results show that the BF composites exhibit enhanced photocatalytic performances in the degradation of RhB and nitrobenzene with maximum degradation rates of 100% (25 min) and 94% (300 min) under visible light irradiation, respectively. The improved photocatalytic performance is mainly ascribed to the small crystalline size and the reduced electron-hole pair recombination with the presence of BiOF in the composites. Furthermore, the photodegradation mechanism was investigated and the h + and OH radicals are suggested to be the main active species for photocatalytic degradation of RhB and nitrobenzene. [ABSTRACT FROM AUTHOR]

Nitrogen-doped graphene (NG) was fabricated via a simple thermal treatment of graphene oxide in an ammonia atmosphere. The morphology, structure and electrochemical performance of NG were characterized by scanning electron microscopy, Raman spectroscopy, nitrogen adsorption–desorption, X-ray photoelectron spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The electrosorption performance of NG in NaCl solution was studied and compared with pristine graphene (PG). The results show that due to its high specific surface area, increased specific capacitance and low charge transfer resistance, NG exhibits high electrosorption capacity of 4.81 mg g −1 when the initial solution conductivity is 100 μS cm −1 , which are much higher than those of PG (3.85 mg g −1 ). [ABSTRACT FROM AUTHOR]