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Highlights: We developed an efficient and extensible strategy to produce the single-phase ternary NbSSe nanohybrids with defect-enrich microstructure. The anionic-Se doping play a key role in effectively modulating the electronic structure and surface chemistry of NbS2 phase, including the increased interlayers distance (0.65 nm), the enhanced intrinsic electrical conductivity (3.23 × 103 S m-1) and extra electroactive defect sites. The NbSSe/NC composite as anode exhibits rapid Na+ diffusion kinetics and increased capacitance behavior for Na+ storage, resulting in high reversible capacity and excellent cycling stability. Sodium-based dual-ion batteries (SDIBs) have gained tremendous attention due to their virtues of high operating voltage and low cost, yet it remains a tough challenge for the development of ideal anode material of SDIBs featuring with high kinetics and long durability. Herein, we report the design and fabrication of N-doped carbon film-modified niobium sulfur–selenium (NbSSe/NC) nanosheets architecture, which holds favorable merits for Na+ storage of enlarged interlayer space, improved electrical conductivity, as well as enhanced reaction reversibility, endowing it with high capacity, high-rate capability and high cycling stability. The combined electrochemical studies with density functional theory calculation reveal that the enriched defects in such nanosheets architecture can benefit for facilitating charge transfer and Na+ adsorption to speed the electrochemical kinetics. The NbSSe/NC composites are studied as the anode of a full SDIBs by pairing the expanded graphite as cathode, which shows an impressively cyclic durability with negligible capacity attenuation over 1000 cycles at 0.5 A g−1, as well as an outstanding energy density of 230.6 Wh kg−1 based on the total mass of anode and cathode. [ABSTRACT FROM AUTHOR]

Electrochemical carbon dioxide (CO2) reduction to fuels or chemicals is a promising route to offset the over discharged CO2, where efficient electrocatalysts are desirable. In this study, we synthesized SnO nanosheets with thickness of around 2 nm for electrochemical CO2 reduction (ECO2R) by one-pot hydrothermal method. Such fabricated SnO nanosheets favors to advance formation of carbon monoxide (CO) and formate, exhibiting good stability and high Faradaic efficiency (FE) above 90% towards CO2 reduction and a FEformate of 71.7% at –1.08 V vs. RHE with a total current density of more than 20 mA cm–2. The remarkable performance for electrochemical CO2 reduction over the SnO nanosheets can be assigned to its nanosheets structure with rich catalytic active sites. This work provides a simple strategy for preparing nano electrocatalysts for efficient CO2 reduction. [ABSTRACT FROM AUTHOR]

Sodium-based dual-ion batteries have received increased attention owing to their appealing cell voltage (i.e., >3 V) and cost-effective features. However, the development of high-performance anode materials is one of the key elements for exploiting this electrochemical energy storage system at practical levels. Here, we report a source-template synthetic strategy for fabricating a variety of nanowire-in-nanotube MSxTey@C (M = Mo, W, Re) structures with an in situ-grown carbon film coating, termed as nanocables. Among the various materials prepared, the MoS1.5Te0.5@C nanocables are investigated as negative electrode active material in combination with expanded graphite at the positive electrode and NaPF6-based non-aqueous electrolyte solutions for dual-ion storage in coin cell configuration. As a result, the dual-ion lab-scale cells demonstrate a prolonged cycling lifespan with 97% capacity retention over 1500 cycles and a reversible capacity of about 101 mAh g−1 at specific capacities (based on the mass of the anode) of 1.0 A g−1 and 5.0 A g−1, respectively. Sodium-based dual-ion batteries are promising electrochemical energy storage devices. Here, the authors report a source-template synthetic strategy to prepare carbon-coated MoS1.5Te0.5 nanocables and their use as anode active materials in Na-based dual ion cells. [ABSTRACT FROM AUTHOR]

Highlights: A newly versatile self-sacrifice method to fabricate selenium and nitrogen co-doped 3D macroporous carbon was developed. The K+ storage mechanism of Se and N active sites was deeply studied by systematic electrochemical characterization combined with theoretical calculations. The assembled K-ion hybrid capacitor possesses high energy/power densities and excellent cycling stability for practical applications.Potassium-ion hybrid capacitors (PIHCs) tactfully combining capacitor-type cathode with battery-type anode have recently attracted increasing attentions due to their advantages of decent energy density, high power density, and low cost; the mismatches of capacity and kinetics between capacitor-type cathode and battery-type anode in PIHCs yet hinder their overall performance output. Herein, based on prediction of density functional theory calculations, we find Se/N co-doped porous carbon is a promising candidate for K+ storage and thus develop a simple and universal self-sacrifice template method to fabricate Se and N co-doped three-dimensional (3D) macroporous carbon (Se/N-3DMpC), which features favorable properties of connective hierarchical pores, expanded interlayer structure, and rich activity site for boosting pseudocapacitive activity and kinetics toward K+ storage anode and enhancing capacitance performance for the reversible anion adsorption/desorption cathode. As expected, the as-assembled PIHCs full cell with a working voltage as high as 4.0 V delivers a high energy density of 186 Wh kg−1 and a power output of 8100 W kg−1 as well as excellent long service life. The proof-of-concept PIHCs with excellent performance open a new avenue for the development and application of high-performance hybrid capacitors. [ABSTRACT FROM AUTHOR]

Organofluorine compounds have shown their great value in many aspects. Moreover, allenes are also a class of important compounds. Fluorinated or fluoroalkylated allenes might provide an option as candidates for drug and material developments, as allenes allow a great number of valuable transformations. Herein, we report a metal-free synthesis of difluoromethylated allenes via regioselective trifunctionalization of 1,3-enynes. This method proceeds through double C–F bond formation with concomitant introduction of an amino group to the allene. Synthetic applications are conducted and preliminary mechanistic studies suggest that a two-step pathway is involved. DFT calculations revealed an unusual dibenzenesulfonimide-assisted fluorination/fluoroamination with NFSI. In addition, kinetic reaction study revealed the induction period of both major and side products to support the proposed reaction mechanism. This work offers a convenient approach for the synthesis of a range of difluoromethylated allenes and is also a rare example of trifunctionalization of 1,3-enynes. Fluorinated or fluoroalkylated allenes are versatile building blocks for medicinal and material chemistry. Here, the authors show a regioselective trifunctionalization of 1,3-enynes proceeding through double C-F bond formation and concomitant installation of a -NSO2Ph group to the allene moiety. [ABSTRACT FROM AUTHOR]

Renewable biomass-derived carbon materials have attracted increasing research attention as promising electrode materials for electrochemical energy storage devices, such as sodium-ion batteries (SIBs), due to their outstanding electrical conductivity, hierarchical porous structure, intrinsic heteroatom doping, and environmental friendliness. Here, we investigate the potential of hierarchical N-doped porous carbon (NPC) derived from jackfruit rags through a facile pyrolysis as an anode material for SIBs. The cycling performance of NPC at 1 A/g for 2000 cycles featured a stable reversible capacity of 122.3 mA·h/g with an outstanding capacity retention of 99.1%. These excellent electrochemical properties can be attributed to the unique structure of NPC; it features hierarchical porosity with abundant carbon edge defects and large specific surface areas. These results illuminate the potential application of jackfruit rags-derived porous carbon in SIBs. [ABSTRACT FROM AUTHOR]

We report a relatively low-temperature molten salt strategy to prepare hollow structured N-doped noble carbon (h-NNC) with highly desirable features of ultra-large surface area (1957 m2 g−1) and high graphitization, endowing the h-NNC with high activity toward catalysis of oxygen reduction reaction in acidic medium. The h-NNC is applied as cathode catalyst of an asymmetrical-electrolyte Zn-air battery, which exhibits an open circuit voltage of 2.11 V, a power density up to 270 mW cm−2, and an energy density of 1279 W h kg−1, behaving advantages over the conventional Zn-air batteries. [ABSTRACT FROM AUTHOR]

Recent theoretical studies revealed that two-dimensional (2D) antimonene has attractive characteristics, such as superior photothermal conductivity, absorption over a wide range, high mobility, and good spintronic properties. Herein, we report a reliable liquid phase exfoliation (LPE) route for the preparation of high-quality high-stability atomically thin (AT) antimonene via high ultrasonic power. The AT antimonene delivers a high specific capacity of up to 860 mA·h·g-1, with high rate capability and good cycling stability as an anode of a sodium ion battery (SIB). The good conductivity and 2D structure endow AT antimonene with more active sites for sodium storage, a facilitated pathway for electron transfer and mass transport, and the capability to reduce the volume expansion during the discharge-charge process. [ABSTRACT FROM AUTHOR]

A strategy was developed to fabricate a set of MnO@C nanohybrids with MnO nanoparticles (NPs) embedded in an ultrathin three-dimensional (3D) carbon framework for use as anode materials for lithium-ion batteries (LIBs). The 3D carbon frameworks provide MnO NPs with electrical pathways and mechanical robustness, which efficiently improved the reaction kinetics, prevented the MnO from fracturing and agglomerating, and limited the formation of a solid electrolyte interface (SEI) at the MnO-electrolyte interface. Benefitting from the unique 3D framework structure, the MnO/C nanohybrids carbonized at 500 °C exhibited a highly reversible specific capacity of 1,420 mAh·g at 0.2 A·g, excellent cycling stability with 98% capacity retention, and enhanced rate performance of 680 mAh·g at 2 A·g. The feasibility of the large-scale production of such MnO/C nanohybrids, associated with their outstanding Li-ion storage properties, opens a promising avenue for the development of high-performance anodes for nextgeneration LIBs. [ABSTRACT FROM AUTHOR]

This work describes a potential anode material for lithium-ion batteries (LIBs), namely, anatase TiO 2 nanoparticle-decorated carbon nanotubes (CNTs@TiO 2). The electrochemical properties of CNTs@TiO 2 were thoroughly investigated using various electrochemical techniques, including cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic cycling, and rate experiments. It was revealed that compared with pure TiO 2 nanoparticles and CNTs alone, the CNT@TiO 2 nanohybrids offered superior rate capability and achieved better cycling performance when used as anodes of LIBs. The CNT@TiO 2 nanohybrids exhibited a cycling stability with high reversible capacity of about 190 mAh g -1 after 120 cycles at a current density of 100 mA g -1 and an excellent rate capability (up to 100 mAh g -1 at a current density of 1,000 mA g -1). [ABSTRACT FROM AUTHOR]

It is of great significance in exploring alternative catalysts to platinum (Pt)-based materials for oxygen reduction reaction (ORR), because this reaction is invariably involved in various fuel cells and metal-air batteries. We herein reported the nitrogen doped graphene nanosheets (NGNSs) with pore volume of as high as 3.42 m/g and investigated their potential application as ORR catalysts, it was demonstrated the NGNSs featured high activity, improved kinetics and excellent long-term stability for ORR. The NGNSs were successfully used as cathode catalysts of microbial fuel cells (MFCs) and performed even better than the commercial Pt/C (Pt 10%) catalysts at the maximum power output. [ABSTRACT FROM AUTHOR]

Nickel oxide-decorated graphene nanosheet (NiO/GNS), as a novel non-enzymatic electrocatalyst for glucose oxidation reaction (GOR), was synthesized through a facile hydrothermal route followed by the heat treatment. The successful synthesis of NiO/GNS was characterized by a series of techniques including XRD, BET, SEM and TEM. Significantly, the NiO/GNS catalyst show excellent catalytic activity toward GOR, and was employed to develop a sensitive non-enzymatic glucose sensor. The developed glucose sensor could response to glucose in a wide range from 5 μM-4.2 mM with a low detection limit (LOD) of 5.0 μM (S/N = 3). Importantly, compared with bare NiO, the catalytic activity of NiO/GNS was much higher. The reason might be that the 2D structure of graphene could prevent the aggregation of NiO and facilitate the electron transfer at electrode interface. Moreover, the outstanding catalytic activity of NiO/GNS was further demonstrated by applying it to construct a biofuel cell using glucose as fuel, which exhibited high stability and current density. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) layered materials have attracted significant attention for device applications because of their unique structures and outstanding properties. Here, a field-effect transistor (FET) sensor device is fabricated based on 2D phosphorene nanosheets (PNSs). The PNS sensor exhibits an ultrahigh sensitivity to NO2 in dry air and the sensitivity is dependent on its thickness. A maximum response is observed for 4.8-nm-thick PNS, with a sensitivity up to 190% at 20 parts per billion (p.p.b.) at room temperature. First-principles calculations combined with the statistical thermodynamics modelling predict that the adsorption density is ∼1015 cm−2 for the 4.8-nm-thick PNS when exposed to 20 p.p.b. NO2 at 300 K. Our sensitivity modelling further suggests that the dependence of sensitivity on the PNS thickness is dictated by the band gap for thinner sheets (<10 nm) and by the effective thickness on gas adsorption for thicker sheets (>10 nm). [ABSTRACT FROM AUTHOR]

We propose a 'weaving' evolution mechanism, by systematically investigating the products obtained in controlled experiments, to demonstrate the formation of Ni-based 'microflowers' which consists of multiple characteristic dimensions, in which the three dimensional (3D) NiO 'microflower' is constructed by a two-dimensional (2D) nanosheet framework that is derived from weaving one-dimensional (1D) nanowires. We found such unique nanostructures are conducive for the generation of an electrically conductive Ni-network on the nanosheet surface after being exposed to a reducing atmosphere. Our study offers a promising strategy to address the intrinsic issue of poor electrical conductivity for NiO-based materials with significant enhancement of utilization of NiO active materials, leading to a remarkable improvement in the performance of the Ni-NiO microflower based supercapacitor. The optimized Ni-NiO microflower material showed a mass specific capacitance of 1,828 F g−1, and an energy density of 15.9 Wh kg−1 at a current density of 0.5 A g−1. This research not only contributes to understanding the formation mechanism of such 'microflower' structures but also offers a promising route to advance NiO based supercapacitor given their ease of synthesis, low cost, and long-term stability. [ABSTRACT FROM AUTHOR]

Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti3+-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti4+ on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti3+-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity. [ABSTRACT FROM AUTHOR]

Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti3+-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti4+ on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti3+-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity. [ABSTRACT FROM AUTHOR]