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The structural stability and reaction kinetics of anodes are essential factors for high-performance battery systems. Herein, the molybdenum sulfide selenide (MoSSe) nanosheets anchored on carbon tubes (MoSSe@CTs) are synthesized by a facile hydrothermal method combining with further selenization/calcination treatment. The unique tubular carbon skeletons expose abundant active sites for the well-dispersed growth of MoS

It is important to develop novel energy to solve energy shortage and environmental problems. Hydrogen evolution reaction (HER) is envisaged as a viable technology that can be used to develop sustainable clean energy. Herein, we report a catalyst with CoSe2-MoSe2 heterostructure grown on reduced graphene oxide with an optimum Co/Mo proportion of 1:1 (CoSe2-MoSe2(1–1)/rGO). It exhibits good HER activities in both acidic and alkaline conditions. The CoSe2-MoSe2(1–1)/rGO shows an overpotential of 107 mV at 10 mA cm−2 with a Tafel slope of 56 mV dec−1 under acidic condition. Meanwhile, CoSe2-MoSe2(1–1)/rGO also presents an overpotential of 182 mV at 10 mA cm−2 and with a Tafel slope of 89 mV dec−1 under alkaline condition. These impressive performances of the catalyst are mainly due to the excellent electronic transmission capability of rGO and the abundant active sites of CoSe2-MoSe2 heterostructure as well as the optimized hydrogen adsorption energy of CoSe2-MoSe2 interface. The design of CoSe2-MoSe2(1–1)/rGO provides a meaningful guide for manufacturing electrode in energy storage and conversion.

Electrochemical water splitting is one of the promising way to enhance energy with less outflow. In this regard different electrocatalysts have been reported for Oxygen evolution reaction (OER) to get alternative of noble metal based electrocatalysts. In this work, we have introduced Cadmium-oxide/Cobalt-oxide (CdO/Co3O4) nanocomposite by co-precipitation chemical strategy with impressive OER performance in alkaline medium. Almost 310 mV overpotential value is required to achieve 10 mA/cm2 current density with Tafel slope value of 62 mV/Dec. The as synthesized nanocomposite has stability of 6h as its longer electrochemical performance

MoS2 is regarded as an attractive anode material for lithium-ion batteries due to its layered structure and high theoretical specific capacity. Its unsatisfied conductivity and the considerable volume change during the charge and discharge process, however, limits its rate performance and cycling stability. Herein, 3D tremella-like nitrogen-doped carbon encapsulated few-layer MoS2 (MoS2@NC) hybrid is obtained via a unique strategy with simultaneously poly-dopamine carbonization, and molybdenum oxide specifies sulfurization. The three-dimensional porous nitrogen-doped carbon served both as a mechanical supporting structure for stabilization of few-layers MoS2 and a good electron conductor. The MoS2@NC exhibits enhanced high rate performance with a specific capacity of 208.7 mAh g−1 at a current density of 10 A g−1 and stable cycling performance with a capacity retention rate of 85.7% after 1000 cycles at 2 A g−1.

Exploring capable and universal electrode materials could promote the development of alkalis (Li, Na, K) ion batteries. 2D MXene material is an ideal host for the alkalis (Li, Na, K) ion storage, but its electrochemical performance is limited by serious re-stacking and aggregation problems. Herein, we cleverly combined electrostatic self-assembly with gas-phase vulcanization method to successfully combine Ti

Binary metal niobium oxides can offer a higher specific capacity compared to niobium pentoxide (Nb2O5) and thus are ideal anode candidates for lithium ion capacitors (LICs). However, their lower electronic conductivity limits their ability to achieve high energy and power densities. In this paper, one-dimensional (1D) copper niobate (CuNb2O6) nanowires are successfully prepared by electrospinning technology and then immobilized on two-dimensional (2D) reduced graphene oxide (rGO) nanosheets to form a unique 1D nanowire/2D nanosheet CuNb2O6/rGO structure. The 1D/2D CuNb2O6/rGO electrode exhibits a high specific capacity of 312.2 mAh g−1 at 100 mA g−1 as the anode of LICs. The proposed Li+ storage mechanism of the CuNb2O6 anode involves CuNb2O6 decomposition into lithium niobate (Li3NbO4) and copper (Cu) during the initial lithium insertion process. The intercalation-type Li3NbO4 will further serve as the host to Li+ and the inactive Cu phase will act as a conductive network for electron transportation. Furthermore, the energy density of the assembled CuNb2O6/rGO//activated carbon (CuNb2O6/rGO//AC) device could achieve a value as high as 92.1 Wh kg−1 and could thus be considered as a possible alternative electrode material for high energy and power LICs.

Polymer materials containing C

Lithium‐sulfur batteries attract lots of attention due to their high specific capacity, low cost, and environmental friendliness. However, the low sulfur utilization and short cycle life extremely hinder their application. Herein, we design and fabricate a three‐dimensional electrode by a simple filtration method to achieve a high‐sulfur loading. Biomass porous carbon is employed as a current collector, which not only enhances the electronic transport but also effectively limits the volume expansion of the active material. Meanwhile, an optimized carboxymethyl cellulose binder is chosen. The chemical bonding restricts the shuttle effect, leading to improved electrochemical performance. Under the ultrahigh sulfur load of 28 mg/cm2, the high capacity of 18 mAh/cm2 is still maintained, and stable cycling performance is obtained. This study demonstrates a viable strategy to develop promising lithium‐sulfur batteries with a three‐dimensional electrode, which promotes sulfur loading and electrochemical performance.

Cobalt manganese hydroxides with well-defined nanowire morphology (CoMn-HW) is scalable fabricated by adjusting solution contents, Mn/Co ratio and alkaline species. To further improve the conductivity of CoMn-HW, GO is introduced during fabrication process and reduced to rGO according to the high temperature and alkali atmosphere. By optimizing the adding mass of rGO, CoMn-HW/rGO with sandwiched like structure is successfully synthesized for supercapacitor electrode. The composite delivers a high specific capacitance of 784 F g−1 at current density of 0.5 A g−1, good rate capability (84.2% capacitance retention after current density increase 10 times). Moreover, an asymmetric supercapacitor with CoMn-HW/rGO10 as the positive electrode and active carbon as the negative electrode, is assembled and delivers a maximum energy density of 38.3 Wh kg−1 and power density of 8000 W kg−1, representing its potential in energy storage and conversion systems.

Herein, we choose the waste walnut shell as the carbon source, and ammonium heptamolybdate as the molybdenum source to prepare the β-Mo2C catalyst supported on carbon matrix (Mo2C@C) by the calcination method for hydrogen evolution reaction (HER). The open pores in the porous Mo2C nanoparticle clusters can facilitate electrolyte permeation and hydrogen molecules release as well as the carbon matrix can enhance the conductivity. As a result, the optimal Mo2C exhibits an efficient HER performance, with an overpotential of 140 mV at 10 mA cm−2 and a Tafel slope of 63 mV dec−1 as well as excellent electrochemical stability. The strategy changing waste walnut shell into the effective catalysts sets an example for the searching and designing rational energy materials.

The room temperature abrasive wear behavior of three selected MAX phases, Ti3SiC2, solution strengthened Ti2.7Zr0.3SiC2 and Cr2AlC, is investigated by low velocity scratch testing using a diamond conical indentor with a final radius of 100 μm and a cone angle of 120° and applied loads of up to 20 N. All three materials showed a relatively low wear resistance in comparison to most engineering ceramics such as Al2O3, Si3N4 and SiC. For all three materials, the wear rate scaled more or less linearly with the applied load. The softer Ti3SiC2 with a hardness of 2.8 GPa showed the lowest wear resistance with extensive ploughing and grain breakout damage, both within and outside the direct wear track, in particular at the highest load. The hardest material, Ti2.7Zr0.3SiC2, with a hardness of 7.3 GPa, showed a 5 times better wear resistance. The Cr2AlC with a hardness of 4.8 GPa showed a wear resistance equal to or even better than that of the Ti2.7Zr0.3SiC2. The wear mechanism depends on the applied load and the microstructure of the MAX phase materials tested. For the Ti3SiC2 sample, a quasi-plastic deformation behavior occurs below a point load of 10 N, resulting in grain bending, kink band formation and delamination, grain de-cohesion, as well as trans-and intra-granular fracture near the scratch groove. At this load, the Ti2.7Zr0.3SiC2 and Cr2AlC MAX samples display plastic ploughing, grain boundary cracks and material dislodgments.

Rechargeable metal batteries such as non-aqueous Li metal batteries and aqueous Zn metal batteries have received increasing attention due to the benefits of the high-energy metal anode. However, the dendric growth on the metal anode extremely leads to restricted cycling performance and potential safety issues. Herein, the MXene-modified conductive framework (MCF) is designed and fabricated as a universal current collector of anode for non-aqueous Li metal batteries and aqueous Zn metal batteries to suppress the dendric Li and Zn growth. The MCF exhibits the merits of good lithiophilicity and zincophilicity, enables an easy Li/Zn nucleation process, and possesses high plating/stripping reversibility. After plating Li/Zn, MCF@Li and MCF@Zn realize a dendrite-free surface, facilitating Li/Zn plating/stripping kinetics. The MCF@Li and MCF@Zn symmetric cell shows a low overpotential of 13 mV at 1 mA cm

In order to alleviate the energy crisis and propel a low-carbon economy, hydrogen (H2) plays an important role as a renewable cleaning resource. To break the hydrogen evolution reaction (HER) bottleneck, we need high-efficiency electrocatalysts. Based on the synergistic effect between bimetallic oxides, hierarchical mesoporous CoNiO2 nanosheets can be fabricated. Combining physical representations with electrochemical measurements, the resultant CoNiO2 catalysts present the hierarchical microflowers morphology assembled by mesoporous nanosheets. The ultrathin two-dimensional nanosheets and porous surface characteristics provide the vast channels for electrolyte injection, thus endowing CoNiO2 the outstanding HER performance. The excellent performance with a fewer onset potential of 94 mV, a smaller overpotential at 10 mA cm−2, a lower Tafel slope of 109 mV dec−1 and better stability after 1000 cycles makes CoNiO2 better than that of metallic Co and metallic Ni.

The development of efficient catalysts for hydrogen evolution reaction (HER) from water splitting is one of the most promising strategies to achieve the goal of peak carbon dioxide emissions and carbon neutrality. Herein, Ru nanoclusters decorated MoSe

The development of efficient bifunctional catalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential for reducing the cost of hydrogen production by water splitting. Herein, hollow microtubes composed of RuNi

It is important to develop novel energy to solve energy shortage and environmental problems. Hydrogen evolution reaction (HER) is envisaged as a viable technology that can be used to develop sustainable clean energy. Herein, we report a catalyst with CoSe

In this article, ZnCo 2 O 4 nanowires deposited with two kinds of typical layered double hydroxides (Ni–Al,Co–Al LDH) are developed via scalable method. Two materials all display core–shell hierarchical structure. High specific capacitance of 2041 F g −1 and 1586 F g −1 are obtained for ZnCo 2 O 4 @Co–Al LDH and ZnCo 2 O 4 @Ni–Al LDH,respectively. Combining with active surface and synergistic effect, the role of hierarchical structure in enhancing performance is revealed. Moreover, two all solid state supercapacitors based on fabricated materials as positive electrodes, activated carbon as negative electrodes and PVA–KOH as polymer electrolyte are assembled. The maximum power and energy densities of ZnCo 2 O 4 @Co–Al LDH//AC are 6200 W kg −1 and 50.1 Wh kg −1 , respectively. While the power and energy densities of ZnCo 2 O 4 @Ni–Al LDH//AC are 3400 W kg −1 and 27.8 Wh kg −1 . At last, an energy storage–conversion system, based on solar cell as input device and assembled asymmetric supercapacitor ZnCo 2 O 4 @Co–Al LDH//AC as output device, is integrated as a self–sustaining power device, indicating its potential in practical applications.

A 3D NiCo2S4 nanowire arrays directly grown on Ni foam electrode (NiCo2S4/NF) is prepared by two-step simple hydrothermal process. The morphology and phase composition of NiCo2S4/NF are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). As expected, in the following electrocatalytic measurement, the binder-free, self-made NiCo2S4/NF electrode exhibits much higher catalytic activity, lower onset potential, better stability and greater tolerance towards urea electrooxidation compared with the Ni3S2/NF electrode synthesized under the same reaction conditions. The NiCo2S4/NF electrode delivers a current density of 720 mA cm−2 at 0.18 V (vs. Ag/AgCl) in a solution containing 5 mol L−1 KOH and 0.33 mol L−1 urea. The impressive electrocatalytic activity of the NiCo2S4/NF catalyst is largely ascribed to its distinctive structure, which exposes more electrochemical active sites at the electrode–electrolyte interface. Besides, the high intrinsic electronic conductivity also largely boosts the charge transfer rates for urea electrooxidation. The results demonstrate that the NiCo2S4/NF electrode showing a beneficial application prospect in the wastewater treatment and direct urea fuel cells.

A high working voltage and specific capacitance are vital for flexible solid-state symmetric supercapacitor (FSSC) devices to achieve decent energy densities with high power. In this paper, we report a 1.8 V FSSC based on NiFe2O4 nanocubes anchored on reduced graphene oxide (rGO) cryogel electrode. Through surface protection by a free-standing three-dimensional cross-linked network structure, NiFe2O4 converted from Ni3[Fe(CN)6]2 inhibits the original nanocube structure. Benefiting from the synergistic effects between NiFe2O4 nanocubes and graphene nanosheets, the newly synthesized NiFe2O4@rGO hybrid electrode delivers a high charge storage capacity (488 F g−1 at a constant current density of 1 A g−1), excellent rate ability and cycling performance (89.8% of the initial capacitance value after 10,000 cycles). In addition, NiFe2O4@rGO FSSC has been assembled and exhibits stable behavior at bend state, as well as high energy density of 62.5 Wh kg−1, and long cycle life (93.2% of the initial capacitance value after 6000 cycles). The proposed strategy for controlling the design and synthesis of NiFe2O4@rGO nanostructures provides promise for the development of high performance electrode in advanced energy storage devices.

NiCo2O4 nanowire arrays grown on Ni foam (NiCo2O4/NF) are synthesized by a simple template-free hydrothermal route followed by a thermal treatment in the air at 400 °C. The as-prepared Ni foam substrate exhibits homogeneous and porous nanowire arrays, which providing a number of active sites and electronic transmission channels for urea electrooxidation. The electroactivity of NiCo2O4/NF electrode toward the oxidation of urea in alkaline solution is evaluated using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) measurements. Results show that the as-obtained electrode delivers an outstanding electrocatalytic activity and stability for urea electrooxidation. The NiCo2O4/NF electrode delivers a low open potential at 0.19 V versus Ag/AgCl with a corresponding current density of 570 mA cm−2 in 5 mol L−1 KOH and 0.33 mol L−1 urea electrolytes. Meanwhile, detailed investigation is made for the electrocatalytic oxidation of urea by varying several reaction parameters, such as scan rate, urea and KOH concentrations. Benefiting from the unique structure and synergistic effects of Ni and Co, the NiCo2O4/NF electrode exhibit superior electrocatalyst activity and is considered to be a promising candidate catalysis material for direct urea fuel cell.

Unique nanostructure, high electrical conductivity, satisfactory energy density, and extraordinary cycling stability are important evaluation criteria for high-efficient energy storage devices. Herein, Fe3O4 nanospheres are successfully in situ decorated on graphene nanosheets through an environmentally benign and facile solvothermal procedure. When utilized as an electrode for supercapacitor, the graphene/Fe3O4 nanocomposite exhibits a notably enhanced specific capacity (268 F·g−1 at 2 mV·s−1) and remarkable cycling performance with 98.9% capacity retention after 10,000 cycles. Furthermore, the fabricated graphene/MnO2//graphene/Fe3O4 asymmetric supercapacitor device displays a desirable energy density (87.6 Wh·kg−1) and superior cycling stability (93.1% capacity retention after 10,000 cycles).

Almost pure (Ti1-xZrx)3SiC2 MAX phase solid solutions with x ranging up to 0.17 were synthesized at temperatures in the range of 1450–1750 °C with reactive Spark Plasma Sintering (SPS). The zirconium partially replaces the M-element titanium of the Ti3SiC2 MAX phase up to x equals 0.17. The lattice parameters of the hexagonal (Ti1-xZrx)3SiC2 MAX phase are determined with X-ray diffraction using Rietveld refinement and show an anisotropic lattice expansion upon Zr insertion into Ti3SiC2. This observation is in very good agreement with density functional theory calculations where the deviation between the measured and calculated lattice parameter is less than 1%. The predicted elastic modulus reduction is only 4%. This behavior can be rationalized by considering the electronic structure, where only minute changes are observable as Zr is incorporated into Ti3SiC2. The measured nanohardness of the synthesized (Ti1-xZrx)3SiC2 MAX phase increases from 12.7 ± 1 GPa for Ti3SiC2 to 16.3 ± 1.1 GPa when x is raised from 0 to 0.17 due to an increasing amount of accompanying Ti1-yZryC. The elastic moduli of (Ti1-xZrx)3SiC2 solid solutions measured by an ultrasonic pulse-echo method (325–354 GPa) are in good agreement with the predicted elastic moduli (357–342 GPa).

Recently, it has been shown that silver nanoparticles (AgNPs) exhibit great potential for different applications, including food storage, cosmetic products, electronic components, biosensor materials, cryogenics, dental materials and especially for drug-delivery activities. In this study, we synthesized AgNPs with neem extract (NE) alone and mixed plant extracts of neem, onion and tomato (NOT) as a combined reducing and stabilizing agent by a green synthesis method at different pHs. The synthesized products were characterized by ultraviolet-visible spectroscopy (UV-vis), X-ray diffraction (XRD), dynamic light scattering (DLS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The antibacterial effects of the synthesized products were studied by the Kirby disk diffusion method. It was confirmed that the AgNPs work effectively as a drug material against Gram-positive bacteria Staphylococcus aureus in nutrient agar. In addition, it was seen that the reducing and stabilizing agent NOT could work effectively with six medicines with a different nature at the maximum addition of 15 μg. However, the synthesized product with NE alone only worked for four of the medicines. Therefore, it was evident that the AgNPs synthesized with NOT extract were more susceptible to the Gram-positive bacteria Staphylococcus aureus. We believe that this new route for synthesizing AgNPs with NOT extract could be more beneficial in comparison to NE alone for improved antibacterial properties in drug-delivery applications.

MoS

It is of great significance to develop inexpensive and high-efficiency electrocatalysts for the hydrogen evolution reaction (HER). In this work, we synthesized iron molybdenum selenide (FeSe2-MoSe2) loaded on reduced graphene oxide (FeSe2-MoSe2/rGO) by a one-step hydrothermal method. We further optimized the Fe/Mo ratio and determined the best ratio to be 1-1. In acidic (or alkaline) solution, the optimized FeSe2-MoSe2(1-1)/rGO has a small Tafel slope of 55 (or 80) mV dec−1 and needs an overpotential of 101 (or 178) mV to achieve 10 mA cm−2. These good properties are mainly due to the structure of bimetallic selenides combining rGO. Moreover, rGO enhances the electrical conductivity. Furthermore, the synergistic effect between FeSe2-MoSe2(1-1) and rGO results in better HER performance. Density functional theory (DFT) calculation proves that FeSe2-MoSe2(1-1)/rGO has a small work function. Based on our reasonable design and analysis, FeSe2-MoSe2(1-1)/rGO is expected to be an efficient and robust catalyst for large-scale applications.

Electrocatalytic water splitting used for generating clean and sustainable hydrogen (H2) can be very promising to address current energy shortage and associated environmental issues. However, this methodology is severely impeded by the tardy oxygen evolution reaction (OER). Hence, designing a preferable kinetics and thermodynamics oxidation reaction that supersede OER is very significant for the energy-saving production of H2. Herein, hollow needle-like copper cobalt sulfide was constructed on carbon cloth (CuCo2S4/CC) as a bifunctional electrocatalyst to accelerate H2 generation and simultaneously convert ethanol into value-added acetic acid. Thanks to the synergistic effect and unique structure of Cu and Co, CuCo2S4/CC displays superior catalytic activity and durability in ethanol oxidation reaction (EOR) with a low potential of 1.38 V vs. RHE (@10 mA cm−2). Meanwhile, it exhibits excellent hydrogen evolution reaction (HER) performance. The homemade CuCo2S4/CC//CuCo2S4/CC ethanol–water electrolyser only demands a voltage of 1.59 V to deliver 10 mA cm−2, 150 mV less than that used for ordinary water splitting. This shows that the ethanol–water electrolyser elaborated here holds encouraging potential in the energy-saving production of H2 and oxidation of ethanol into value-added acetic acid. This present work may open the way for the rational design of other electrocatalysts for efficient biomass oxidation reaction and relevant H2 production applications.

Sodium ion batteries and capacitors have demonstrated their potential applications for next-generation low-cost energy storage devices. These devices's rate ability is determined by the fast sodium ion storage behavior in electrode materials. Herein, a defective TiO2@reduced graphene oxide (M-TiO2@rGO) self-supporting foam electrode is constructed via a facile MXene decomposition and graphene oxide self-assembling process. The employment of the MXene parent phase exhibits distinctive advantages, enabling defect engineering, nanoengineering, and fluorine-doped metal oxides. As a result, the M-TiO2@rGO electrode shows a pseudocapacitance-dominated hybrid sodium storage mechanism. The pseudocapacitance-dominated process leads to high capacity, remarkable rate ability, and superior cycling performance. Significantly, an M-TiO2@rGO//Na3V2(PO4)3 sodium full cell and an M-TiO2@rGO//HPAC sodium ion capacitor are fabricated to demonstrate the promising application of M-TiO2@rGO. The sodium ion battery presents a capacity of 177.1 mAh g−1 at 500 mA g−1 and capacity retention of 74% after 200 cycles. The sodium ion capacitor delivers a maximum energy density of 101.2 Wh kg−1 and a maximum power density of 10,103.7 W kg−1. At 1.0 A g−1, it displays an energy retention of 84.7% after 10,000 cycles.

Iron oxides have been recognized as a potential electrode material for lithium-ion and sodium-ion batteries owing to their relatively ultrahigh theoretical capacity, low-cost and earth-rich resources. Nevertheless, the rapid capacity degradation and sluggish kinetics seriously limit their practical applications. Herein, the kinetics enhanced ultrafine Fe2O3 nanocrystals (~5 nm) well anchored on graphene are prepared for high-rate lithium and sodium storage. The unique structure could provide abundant electrochemical active edge sites, short ion/electron diffusion pathways, and excellent electrical conductivity, allowing for enhanced electron/ion transport/diffusion kinetics. The fabricated Fe2O3/reduced graphene oxide nanocomposite shows impressive discharge capacity (1175 mAh g−1 at 0.2 A g−1), significant rate performance (822 mAh g−1 at 5 A g−1) and stable long-term cycle durability (993 mAh g−1 after 500 cycles at 1 A g−1) as a lithium-ion battery anode. As for sodium-ion storage, it also shows high discharge capacity of 701 mAh g−1 at 0.1 A g−1 and remarkable rate performance (253 mAh g−1 at 2 A g−1). These above intriguing electrochemical performances outperform most of the so-far recorded Fe2O3 based electrodes. Such material design strategy may pave a new way for the development of outstanding performance anode materials based on earth-rich materials for energy storage application.