Agaric-like anodes of porous carbon decorated with MoO2 nanoparticles for stable ultralong cycling lifespan and high-rate lithium/sodium storage

Co-assisted strategy of sacrificial salt-template and nitrogen-doping to promote lithium storage performance of NiO-Ni/N-C frameworks

Tailoring the omnidirectional conductivity networks in nickel oxide-based electrodes is important for ensuring their long lifespan, stability, high capacity, and high-rate capability. In this study, nickel metal nanoparticles and a three-dimensional nitrogen-doped carbon matrix were used to embellish the nickel oxide composite NiO-Ni/N-C via simplified hard templating. When a porous nitrogen-doped carbon matrix is present, a rapid pathway would be established for charging and discharging the electrons and lithium ions in a lithium-ion battery, thereby alleviating the volumetric expansion of the NiO nanoparticles during the operation of the battery. Moreover, the Ni0 ions added to serve as active sites to improve the capacity of the NiO-based electrodes and strengthen their conductivities. The multielement-effects of the optimal NiO-Ni/N-C electrode leads it to exhibit a capacity of 1310.8 mAh g-1 at 0.1 A g-1 for 120 loops and a rate capability of 441.5 mAh g-1 at 20.0 A g-1. Kinetic analysis of the prepared electrodes proved their ultrafast ionic and electronic conductivities. This strategy of hard templating reduces the number of routes required for preparing different types of electrodes, including NiO-based electrodes, and improves their electrochemical performance to enable their use in energy storage applications.

Redox-active NiS@bacterial cellulose nanofiber composite separators with superior rate capability for lithium-ion batteries

Separator is an essential component of lithium-ion batteries (LIBs), which is placed between the electrodes to impede their electrical contact and provide the transport channels for lithium ions. Traditionally, the separator contributes the overall mass of LIBs, thereby reducing the gravimetric capacity of the devices. Herein, a dual-layer redox-active cellulose separator is designed and fabricated to enhance the electrochemical performances of LIBs by introducing NiS. The presented separator is composed of an insulating bacterial cellulose (BC) nanofiber layer and a conductive, and redox-active NiS@BC/carbon nanotubes layer. By using the NiS@BC separator, the discharge capacity of the LiFePO4//Li half battery is enhanced to 117 mAh g-1 at a current of 2C owing to the redox-activity of NiS. Moreover, the functional separator-electrode interface can facilitate the homogenous Li stripping/plating and depress the polarization upon the repeated stripping/plating process. Consequently, the battery containing the redox-active separator exhibits outstanding cycle stability and rate capability. The present study contributes a novel strategy for the developments of functional separators to improve the electrochemical properties of LIBs.

Hollow Bowl NiS2 @polyaniline Conductive Linker/Graphene Conductive Network: A Triple Composite for High-Performance Supercapacitor Applications

The achievement of the outstanding theoretical capacitance of nickel sulfide (NiS2 ) is challenging due to its low conductivity, slow electrochemical kinetics, and poor structural stability. In this study, we utilize polyaniline (PANI) as a linker to anchor the NiS2 with a hollow bowl-like structure, uniformly dispersed at the surface of graphene oxide (GO)(NiS2 @15PG). The presence of PANI provides growth sites, resulting in a uniform and dense arrangement of NiS2 . This morphological modulation of NiS2 increases the contact area between the active material to electrolyte. Additionally, PANI effectively connects NiS2 with the conductive network of GO, which advances the electrical conductivity and ion diffusion properties. As a result, the Rct (charge transfer resistance) and Zw (Warburg impedance) of NiS2 @15PG decrease by 82.61 % and 66.76 % respectively. This unique structure confers NiS2 @15PG with high specific capacitance (536.13 C g-1 at 1 A g-1 ) and excellent multiplicative property of 60.93 % at 20 A g-1 . The assembled NiS2 @15PG//YP-50 supercapacitors (HSC) demonstrates an energy density (13.09 Wh kg-1 ) at a high-power density (16 kW kg-1 ). The capacity retention after 10,000 cycles at 5 A g-1 is 86.59 %, indicating its significant potential for practical applications.

Restricted growth of molybdenum carbide nanoparticles in hierarchically porous nitrogen-doped carbon matrix for boosting electromagnetic wave absorption performance

With the development of electronic science and technology, electromagnetic pollution is becoming increasingly serious, which urgent people to develop wave-absorbing materials with the features of "thin, light, strong and wide". In this paper, restricted growth of molybdenum carbide nanoparticles in hierarchically porous nitrogen-doped carbon matrix (Mo2C/NC) was designed and prepared via a salt-assisted template route and carbonization process, whose morphology and the wave-absorbing properties are regulated by changing the content of Mo2C/NC nanoparticles. The honeycomb porous Mo2C/NC composites with large specific surface area and smooth surface can optimize the impedance matching and allow the entrance, multiple reflections and scattering of incident electromagnetic waves (EMW), which effective enhance the electromagnetic wave consumption. Meanwhile, the honeycomb cross-linked carbon matrix facilitates the construction of the conductive network and enhances its conductive loss. Furthermore, numerous Mo2C/NC nanoparticles dispersed restricted growth in carbon matrix induces interfacial polarization. In addition, the heteroatom nitrogen doping acts as dipole centers to induce dipole polarization under electromagnetic field. The uniquely designed Mo2C/NC absorbers show satisfactory EMW absorption behaviors of a minimum reflection loss (RLmin) of -61.53 dB at 1.5 mm and an effective absorption bandwidth (EAB) of 9.6 GHz at 3.5 mm. This work enriches the variety of EMW absorbers and offers the route to promote the EMW absorption performance, especially large effective absorption bandwidth.

Initiating Binary Metal Oxides Microcubes Electrsomagnetic Wave Absorber Toward Ultrabroad Absorption Bandwidth Through Interfacial and Defects Modulation

Cobalt nickel bimetallic oxides (NiCo2O4) have received numerous attentions in terms of their controllable morphology, high temperature, corrosion resistance and strong electromagnetic wave (EMW) absorption capability. However, broadening the absorption bandwidth is still a huge challenge for NiCo2O4-based absorbers. Herein, the unique NiCo2O4@C core-shell microcubes with hollow structures were fabricated via a facile sacrificial template strategy. The concentration of oxygen vacancies and morphologies of the three-dimensional (3D) cubic hollow core-shell NiCo2O4@C framework were effectively optimized by adjusting the calcination temperature. The specially designed 3D framework structure facilitated the multiple reflections of incident electromagnetic waves and provided rich interfaces between multiple components, generating significant interfacial polarization losses. Dipole polarizations induced by oxygen vacancies could further enhance the attenuation ability for the incident EM waves. The optimized NiCo2O4@C hollow microcubes exhibit superior EMW absorption capability with minimum RL (RLmin) of -84.45 dB at 8.4 GHz for the thickness of 3.0 mm. Moreover, ultrabroad effective absorption bandwidth (EAB) as large as 12.48 GHz (5.52-18 GHz) is obtained. This work is believed to illuminate the path to synthesis of high-performance cobalt nickel bimetallic oxides for EMW absorbers with excellent EMW absorption capability, especially in broadening effective absorption bandwidth.

Electrochemical activated molybdenum oxides based multiphase heterostructures with high hydrogen evolution activity in alkaline condition

Electrochemical activation is an effective method for synthesizing economically feasible heterogeneous hydrogen evolution reaction (HER) electrocatalysts. Herein, we first synthesized MoO2-Co2Mo3O8precatalyst, which was electrochemically activated to produce K2Mo3O10within the original phase to form the heterogeneous structure. The electrochemically activated samples demonstrate exceptional HER activity in alkaline medium, which exhibit a low overpotential of 31 mV at current density of 10 mA cm-2(135 mV at 100 mA cm-2), as well as a small Tafel slope of 34 mV dec-1. This is due to the creation of multiphase heterostructures that prompt interfacial interactions and accelerate charge transfer. Simultaneously, the creation of additional active sites increases their intrinsic activities. The combined effects collectively enhance the HER performance. The application of this method in the preparation of HER catalysts is still relatively unexplored, thus rendering our work a pioneering contribution to the field.

Ga2O3 Quantum Dots with N-Doped Amorphous Carbon Fixed for Efficient Storage and Transfer of Lithium Ions by Introduction of Dopamine Hydrochloride

The Ga₂O₃ anode has great potential due to its self-healing and high theoretical capacity in lithium-ion batteries. Like anodes with other transition metal oxides, the Ga₂O₃ anode has the problems of structural change and low electrical conductivity. The electrochemical performance of the Ga₂O₃ anode still needs to be improved. In this work, we synthesized a Ga₂O₃ quantum dots@N-doped carbon (Ga₂O₃-QD@NC) composite by hydrothermal reaction with a carbon source of dopamine hydrochloride, in which Ga₂O₃ quantum dots were dispersed in the interior of the amorphous carbon. Such a special structure is conducive to the high-speed migration of lithium ions and electrons and effectively inhibits volume expansion and agglomeration. Smaller and more uniform quantum dots facilitate efficient repair of the structure. Due to these advantages, the Ga₂O₃-QD@NC electrode has great electrochemical performance. The Ga₂O₃-QD@NC electrode has an initial discharge capacity of 1580 mAh g^-1 with a high first Coulombic efficiency of 62.8% and a cycling capacity of 953 mAh g^-1 under 0.1 A g^-1. It even has a capacity of 460 mAh g^-1 at 1 A g^-1 after 300 cycles. This strategy can provide a new direction for the Ga₂O₃ anode in lithium-ion batteries with high capacity.

In-situ synthesis of FeS/N, S co-doped carbon composite with electrolyte-electrode synergy for rapid sodium storage

Pyrrhotite (FeS) is extensively investigated as the anode for low-cost sodium-ion batteries (SIBs) due to their natural abundance and high theoretical capacity. However, it suffers from significant volume expansion and poor conductivity. These problems can be alleviated by promoting sodium-ion transport and introducing carbonaceous materials. Here, FeS decorated on N, S co-doped carbon (FeS/NC) is constructed through a facile and scalable strategy, which is the best of both worlds. Moreover, to give full play to the role of the optimized electrode, ether-based and ester-based electrolytes are used for matching. Reassuringly, the FeS/NC composite displays a reversible specific capacity of 387 mAh g^-1 after 1000 cycles at 5A g^-1 in dimethyl ether electrolyte. The even distribution of FeS nanoparticles on the ordered framework of carbon guarantees a fast electron/Na-ion transport channel, and the reaction kinetics can be further accelerated in the dimethyl ether (DME) electrolyte, ensuring the excellent rate capability and cycling performance of FeS/NC electrodes for sodium-ion storage. This finding not only provides a reference for the introduction of carbon via in-situ growth protocol, but also demonstrates the necessity for electrolyte-electrode synergy in realizing efficient sodium-ion storage.

Ceria-doped SnO2 nanocubes for solar light-driven photocatalytic hydrogen production

The photocatalytic generation of hydrogen via solar energy using metal oxide semiconductor catalysts is a clean and renewable process which has the potential of solving the current energy nexus. SnO₂ is one such well-studied and established photocatalyst currently in practice but is only ultraviolet-light active which accounts for only 4% of the total incoming solar energy. The current study focuses on bringing this SnO₂ into the visible range using ceria as a dopant. Sol-gel and combustion methods were employed for synthesis and the as-synthesized catalysts were characterized using XRD, BET, UV diffuse reflectance spectra, PL spectra, and SEM micrographs. A unique cuboid type morphology was observed in 6% ceria-doped SnO₂ which provided more active sites for light absorption and thus reported a remarkable hydrogen production rate of 1.978 mmol/h under sunlight which was almost 346 times that of pure SnO₂ (5.71 µmol/h). Photoluminescence spectra of ceria-doped SnO₂ showed lower peak positions as compared to the pure SnO₂ indicating a reduction in charge recombination and an increase in the life time of the active species which explains the enhanced hydrogen production rates. The recyclability study of the catalysts showed that the hydrogen amount produced in the fifth recycle was nearly 80% as the first cycle showing that the catalyst can be used very effectively for more than five cycles without compromising on the yield.

In situ preparation of molybdenum-dioxide-incorporated carbonized silk fiber and its application in supercapacitors

A previous study found that the capacitive behavior of nanoparticles fed to the silkworm can be delivered to carbonized silk fibers, which can be used to fabricate electrodes for the construction of flexible supercapacitors. However, the tendency of nanoparticles to aggregate decreases the quantity of nanoparticles that enter the silk and therefore reduces the capacitance performance of the prepared carbonized silk. Here, we sprayed ammonium molybdate tetrahydrate (AMT) on the surface of mulberry leaves used for feeding silkworms and investigated the effect of feeding AMT on the growth of silkworms and the properties of spun silk. The precursor incorporated into the silk was converted into scattered MoO2 NPs, which were embedded within the carbonized silk fiber (CSF) via carbothermal reduction. The specific capacitance of CSF obtained from silkworms fed with an aqueous solution of AMT-treated mulberry leaves reached up to 298 F/g at 0.2 g/A, which is much higher than that of the control group (102 F/g). Since AMT is highly water-soluble, and its concentration can be easily modulated, we believe that the proposed strategy is feasible for the large-scale fabrication of CSF with enhanced capacitive performance.

Hard Carbons as Anodes in Sodium-Ion Batteries: Sodium Storage Mechanism and Optimization Strategies

Sodium-ion batteries (SIBs) are regarded as promising alternatives to lithium-ion batteries (LIBs) in the field of energy, especially in large-scale energy storage systems. Tremendous effort has been put into the electrode research of SIBs, and hard carbon (HC) stands out among the anode materials due to its advantages in cost, resource, industrial processes, and safety. However, different from the application of graphite in LIBs, HC, as a disordered carbon material, leaves more to be completely comprehended about its sodium storage mechanism, and there is still plenty of room for improvement in its capacity, rate performance and cycling performance. This paper reviews the research reports on HC materials in recent years, especially the research process of the sodium storage mechanism and the modification and optimization of HC materials. Finally, the review summarizes the sterling achievements and the challenges on the basis of recent progress, as well as the prospects on the development of HC anode materials in SIBs.

Manipulation of the MoO2/MoSe2 Heterointerface Boosting High Rate and Durability for Sodium/Potassium Storage

The main challenge for sodium/potassium ion storage is to find the suitable host materials to accommodate the larger-sized Na⁺/K⁺ and conquer the sluggish chemical kinetics. Herein, by selenation of polyoxometalate in electrospinning fiber, a novel MoO₂/MoSe₂ heterostructure embedded in one-dimensional (1D) N,P-doped carbon nanofiber (MoO₂/MoSe₂@NPC) is rationally constructed to show distinct enhancement of rate performance and cycle life for sodium ion batteries (SIBs) and potassium ion batteries (PIBs). The 1D skeleton of MoO₂/MoSe₂@NPC decreases the diffusion pathway of Na⁺/K⁺, and the doping of N/P heteroatoms in carbon fiber creates abundant active sites and provides good reachability for Na⁺/K⁺ transportation. MoSe₂ nanosheets grow in the bulk phase of MoO₂ via in situ local phase transformation to achieve effective and firm heterointerfaces. Especially, the exposure extent of heterointerfaces can be controlled by treatment temperature during the preparation process, and the optimized heterointerfaces result in an ideal synergic effect between MoO₂ and MoSe₂. DFT calculations confirm that the internal electric field in the heterogeneous interface guides the electron transfer from MoO₂ to MoSe₂, combined with strong adsorption capacity toward sodium/potassium, facilitating ion/electron transfer kinetics. It is confirmed that the MoO₂/MoSe₂@NPC anode for SIBs delivers 382 mA h g^-1 under 0.1 A g^-1 upon 200 cycles; meanwhile, a reversible capacity of 266 mA h g^-1 is maintained even under 2 A g^-1 after 2000 cycles. For PIBs, it can reach up to 216 mA h g^-1 in the 200th cycle and still retain 125 mA h g^-1 after 2000 cycles under 1 A g^-1. This study opens up a new interface manipulation strategy for the design of anode materials to boost fast Na⁺/K⁺ storage kinetics.

Insights into the enhanced electrochemical performance of MnV2O6 nanoflakes as an anode material for advanced lithium storage

Binary transition metal oxides (BTMOs) are regarded as potential anode materials for lithium-ion batteries (LIBs) owing to their low cost, high specific capacities, and environmental friendliness. In this work, MnV₂O₆ nanoflakes are successfully synthesized by a facile hydrothermal method. When evaluated as an anode material for LIBs, benefiting from the activation process, the as-prepared MnV₂O₆ nanoflake electrode delivers a high reversible specific capacity of 1439 mA h g^-1 after 300 cycles at a current density of 200 mA g^-1, and especially presents a specific capacity of 1010 mA h g^-1 after 700 cycles at a higher current density of 1 A g^-1. Furthermore, MnV₂O₆ shows a pleasurable rate capability; a reversible specific capacity of 867 mA h g^-1 can be obtained at a current density of 2000 mA g^-1, and when the current density is returned to 200 mA g^-1 and continues for another 80 cycles, the specific capacity can still reach 1499 mA h g^-1. Meanwhile, the morphology variation and electrochemical kinetic behavior of the MnV₂O₆ electrode during cycling are scrutinized in detail. After that, the electrochemical reaction mechanism of MnV₂O₆ during the discharge/charge process is corroborated by in situ X-ray diffraction (XRD), which involves the coexistence of a conversion reaction and solid solution behavior. The practical application of MnV₂O₆ nanoflakes as an anode material is examined as well. Sure enough, the NCM811//MnV₂O₆ full-cell exhibits excellent lithium-storage performance.

Cotton-Derived Fe/Fe3C-Encapsulated Carbon Nanotubes for High-Performance Lithium-Sulfur Batteries

Fabrication processes of fossil fuel-derived carbon nanomaterials are of high carbon emissions. Deriving carbon materials from low-cost and sustainable biomass is eco-friendly. Cotton, one of the most abundant biomass materials, naturally holds a hierarchically porous structure, making the activated cotton textile (ACT) an ideal scaffold for loading active materials. Here, we report a low-cost approach to massively producing multiwalled carbon nanotubes (MWCNTs) via a combination process of vapor-liquid-solid (VLS) and solid-liquid-solid (SLS) where cotton decomposed into carbon-containing gases and amorphous carbons that then dissolved into Fe nanoparticles, forming Fe/Fe₃C-encapsulated MWCNTs. The lithium-sulfur (Li-S) battery constructed by the Fe/Fe₃C-MWCNT@ACT/S composite (as the cathode) and the Fe/Fe₃C-MWCNT@ACT (as the interlayer) exhibited a superlative cycling stability (over 1000 cycles at 1.0 C), an ultralow capacity decay rate (0.0496% per cycle) and a remarkable specific capacity (1273 mAh g^-1 at 0.1 C). The Fe/Fe₃C-MWCNTs enhanced electrode stability and suppressed polysulfide dissolution during cycling.

Constructing zigzag-like hollow mesoporous nanospheres MoO2/C with superior lithium storage performance

Hollow mesoporous nanospheres MoO₂/C are successfully constructed through metal chelating reaction between molybdenum acetylacetone and glycerol as well as the Kirkendall effect induced by diammonium hydrogen phosphate. MoO₂nanoparticles coupled by amorphous carbon are assembled to unique zigzag-like hollow mesoporous nanosphere with large specific surface area of 147.7 m²g^-1and main pore size of 8.7 nm. The content of carbon is 9.1%. As anode material for lithium-ion batteries, the composite shows high specific capacity and excellent cycling performance. At 0.2 A g^-1, average discharge capacity stabilizes at 1092 mAh g^-1. At 1 A g^-1after 700 cycles, the discharge capacity still reaches 512 mAh g^-1. Impressively, the composite preserves intact after 700 cycles. Even at 5 A g^-1, the discharge capacity can reach 321 mAh g^-1, exhibiting superior rate capability. Various kinetics analyses demonstrate that in electrochemical reaction, the proportion of the surface capacitive effect is higher, and the composite has relatively high diffusion coefficient of Li ions and fast faradic reaction kinetics. Excellent lithium storge performance is attributed to the synergistic effect of zigzag-like hollow mesoporous nanosphere and amorphous carbon, which improves reaction kinetics, structure stability and electronic conductivity of MoO₂. The present work provides a new useful structure design strategy for advanced energy storage application of MoO₂.

N-Doped celery-based biomass carbon with tunable Co3O4 loading for enhanced-performance of solid-state supercapacitors

N-doped celery-based biomass carbon with tunable Co3O4 loading is prepared and shows enhanced specific capacitance.

Toughening Shape-Memory Epoxy Resins via Sacrificial Hydrogen Bond

The long fatigue life and stable performance in extreme environment of composites have been putting forward requirements for both high strength and toughness of epoxy matrix. However, for thermosets, promoting...

Co3O4 Nanoparticles Dotted Hierarchical-Assembled Carbon Nanosheet Frameworks Catalysts with Formation/Decomposition Mechanisms of Li2O2 for Smart Lithium-Oxygen Batteries

The Li-O2 batteries (LOB) have been regarded as a promising candidate for the next generation of electric vehicles owing to their excellent energy density. Nevertheless, the practical application of LOB...

Regulating the electronic structure of MoO2/Mo2C/C by heterostructure and oxygen vacancies for boosting lithium storage kinetics

The electronic structure regulation of the electrode materials can improve the ion/electron kinetics, which are beneficial to the cyclic performance and rate capability for lithium ion batteries (LIBs). Herein, we...

Facile construction of lamellar-like phosphorus-based triazole-zinc complex for high-performance epoxy resins

Epoxy resins (EP) possessing superior flame retardancy, mechanical properties and glass transition temperature are urgently needed to meet the ever-increasing requirement of high performance for the practical application of EP. Herein, lamellar-like phosphorus-based triazole-zinc complex (Zn-PT) was firstly constructed through coordination reaction in a facile condition to address the above issue. The results revealed that Zn-PT was well dispersed in epoxy matrix, and with 3 wt% Zn-PT, the tensile strength, flexural strength and modulus of epoxy composites were remarkably increased from 71, 112 and 2982 MPa of neat epoxy resin (EP) to 80, 162 and 3482 MPa respectively. The glass transition temperature was higher than EP. Besides, the limiting oxygen index (LOI) increased to 28.3%, and UL-94V-1 level was available. Meanwhile, the cone calorimeter test (CCT) results showed that epoxy composites displayed less heat release and smoke production. Generally, this work provides a feasible strategy to prepare high-performance epoxy composites, which has the potential to satisfy the requirement of epoxy in the practical application.

Multiple reflection and scattering effects of the lotus seedpod-based activated carbon decorated with Co3O4 microwave absorbent

The lotus seedpod-based activated carbon (LSAC) is derived from pyrolysis of lotus seedpod as biomass carbon precursor, and Co₃O₄ is then deposited to LSAC by oxidation-precipitation and crystallization process of Co ions from Co(NO₃)₂ solution. The Co₃O₄ particles uniformly decorate on the surface and/or the inner channels of LSAC. The optimal reflection loss (RL) value of LSAC/Co₃O₄-paraffin wax (PW) composite reaches -39.8 dB, and the bandwidth for RL below -10 dB and -20 dB are 10.3 and 3.0 GHz, respectively, much better than that of LSAC-PW composite for the higher magnetic loss. The addition of Co₃O₄ particles in LSAC-PW composite significantly enhance the RL values in various thicknesses. The channels of the LSAC and decorated Co₃O₄ can improve the abilities of multiple scattering, dipole polarization, interface polarization and magnetic loss. This composite provides a promising method to construct high performance absorbers by using biomass carbon to tune the dielectric properties of the ferromagnetic materials.

Flexible Diodes/Transistors Based on Tunable p-n-Type Semiconductivity in Graphene/Mn-Co-Ni-O Nanocomposites

We report a novel Mn-Co-Ni-O (MCN) nanocomposite in which the p-type semiconductivity of Mn-Co-Ni-O can be manipulated by addition of graphene. With an increase of graphene content, the semiconductivity of the nanocomposite can be tuned from p-type through electrically neutral to n-type. The very low effective mass of electrons in graphene facilitates electron tunneling into the MCN, neutralizing holes in the MCN nanoparticles. XPS analysis shows that the multivalent manganese ions in the MCN nanoparticles are chemically reduced by the graphene electrons to lower-valent states. Unlike traditional semiconductor devices, electrons are excited from the filled graphite band into the empty band at the Dirac points from where they move freely in the graphene and tunnel into the MCN. The new composite film demonstrates inherent flexibility, high mobility, short carrier lifetime, and high carrier concentration. This work is useful not only in manufacturing flexible transistors, FETs, and thermosensitive and thermoelectric devices with unique properties but also in providing a new method for future development of 2D-based semiconductors.

T-Nb2O5 nanoparticles confined in carbon nanotubes with fast ion diffusion rates for lithium storage

A T-Nb₂O₅/CNT nanohybrid with short transmission paths, many active sites, and favorable mechanical flexibility can achieve the fast transportation of ions/electrons. The obtained nanohybrid with continuous conductive networks exhibited better lithium storage performance than sodium storage performance, due to lower resistance to the diffusion of Li⁺ ions crossing the carbon matrix.

A novel rose-with-thorn ternary MoS2@carbon@polyaniline nanocomposite as a rechargeable magnesium battery cathode displaying stable capacity and low-temperature performance

Developing high-performance cathode materials for magnesium (Mg) batteries is of great significance. Here, a novel rose-with-thorn ternary MoS₂@C@polyaniline (PANI) nanocomposite composed of carbon and PANI nanoneedles co-coated on rose-like MoS₂ is developed. The conductive PANI needles on the surface of MoS₂ improve the conductivity, and the inner MoS₂ is wrapped by a carbon layer which is beneficial for the aniline coating. The MoS₂@C@PANI-based Mg battery cathode displays a good capacity of 114 mA h g^-1 after 100 cycles, and a recoverable rate-performance after repeated measurements. In addition, a stable capacity of 105 mA h g^-1 when cycled at a low temperature of -5 °C is also achieved, indicating good potential for applications.

Highly Efficient Oxygen Evolution Reaction Enabled by Phosphorus Doping of the Fe Electronic Structure in Iron-Nickel Selenide Nanosheets

The electronic structure of active sites is critically important for electrochemical reactions. Here, the authors report a facile approach to independently regulate the electronic structure of Fe in Ni0.75 Fe0.25 Se2 by P doping. The resulting electrode exhibits superior catalytic performance for the oxygen evolution reaction (OER) showing a low overpotential (238 mV at 100 mA cm-2 , 185 mV at 10 mA cm-2 ) and an impressive durability in an alkaline medium. Additionally, the mass activity of 328.19 A g-1 and turnover frequency (TOF) of 0.18 s-1 at an overpotential of 500 mV are obtained for P─Ni0.75 Fe0.25 Se2 which is much higher than that of Ni0.75 Fe0.25 Se2 and RuO2 . This work presents a new strategy for the rational design of efficient electrocatalysts for OER.

Cobalt-Nickel Phosphate Composites for the All-Phosphate Asymmetric Supercapacitor and Oxygen Evolution Reaction

Recently, design of cost-effective multifunctional electromaterials for supercapacitors and oxygen evolution reaction (OER) and enhancing their functionalities have become an emphasis in energy storage and conversion. Herein, a series of cheap and functional phosphate composites with different ratios of cobalt and nickel are synthesized using a simple polyalcohol refluxing method, and their excellent capacity and OER properties are systematically studied. Notably, owing to the different major role of Co and Ni elements in the phosphate composites for capacity and OER, the optimal electroconductibility, structural adjustment, electrochemical active sites, and activities for capacity and OER are obtained from the composites with the different ratios of Co/Ni. In addition, using high-capacity BiPO₄ (BPO) as the negative electrodes, the new type of all-phosphate asymmetric supercapacitor (CNPO-40//BPO) shows a high energy density and reaches 36.84 W h kg^-1 at a power density of 254.52 W kg^-1. Its cyclic stability is also more excellent than that of the CNPO-40//AC device using commercial activated carbon as the negative electrodes. This study is beneficial to the more in-depth research on efficient dual-function electromaterials in capacity and OER and provides a high-efficient way to improve the practicality of asymmetric supercapacitors using the high-capacity Bi-based electromaterials as the negative electrodes.