Search

Three dimensional (3D) honeycomb-like NiS 2 /NiO nano-multiple materials were successfully prepared by fabricating cribrate NiS 2 on the surface of NiO nanosheets through simple hydrothermal process on nickel foam. The morphology and phase structure of the NiS 2 /NiO are characterized by scanning electron microscopy equipped with energy dispersive X-ray spectrometer, transmission electron microscope, X-ray diffractometer and the electrochemical properties are tested by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The NiS 2 /NiO electrode owns lower electrochemical impedance compared with bare NiO substrate and exhibits exceptional capacitance performance with a high specific capacitance of 2251 F g −1 delivered at current density of 1 A g −1 , while 1192 F g −1 retained at 20 A g −1 . What's more, after 2000 cycles, the specific capacitance remains 1275 F g −1 (at 5 A g −1 ) with a capacitance retention of 78%. Therefore, the NiS 2 /NiO electrode shows remarkable electrochemical performance and has a promising future for electrochemical supercapacitors. [ABSTRACT FROM AUTHOR]

The unique Au nanosheets (Au NSs) are electrodeposited uniformly on Ni foam substrate via a one-step potentiostatic electrodeposition technique. The electrode is characterized by scanning electron microscopy equipped with energy dispersive X-ray spectrometer and X-ray diffractometer. It shows a unique open structure allowing the full utilization of Au surface active sites. NaBH 4 electrooxidation in KOH solution on the Au NSs/Ni foam electrode are studied by linear sweep voltammetry and chronoamperometry. The electrode exhibits a high catalytic performance outperforming the Au particles made by the same method. At the oxidation potential of 0 V, the current density of 827 mA cm −2 can be achieved on Au NSs/Ni foam electrode, and only 219 mA cm −2 was obtained on Au NPs/Ni foam electrode, indicating that the catalytic activity is increased by 278%, which is attributed to the porous 3D structure, ensuring the full utilization of Au surfaces. Besides, H 2 generated by NaBH 4 hydrolysis can quickly diffuse away from the electrode, preventing surface active sites of Au from blocking by adsorbed gas bubbles. [ABSTRACT FROM AUTHOR]

In this work, Co(OH) 2 buds direct growth on Ni foam (Co(OH) 2 buds/Ni foam) is prepared via a hydrothermal method. Their structure and morphologies are characterized by using X-ray diffraction analysis, scanning electron microscopy and transmission electron microscopy. Result shows that the Co(OH) 2 buds are assembled by several nanorods and uniformly covered on the surface of Ni foam. Due to its unique structure, the Co(OH) 2 buds/Ni foam electrode shows high capacitive performance and long cycle life. The specific capacitance of Co(OH) 2 buds/Ni foam is as high as 2041 F g −1 at a current density of 3 mA cm −2 in 6 M KOH electrolyte, and 811 F g −1 even at a high current density of 60 mA cm −2 . The capacitance of the Co(OH) 2 buds/Ni foam electrode remained 72.4% after 1000 cycles at 18 mA cm −2 . An asymmetric supercapacitor was successfully assembled, in which Co(OH) 2 buds/Ni foam and AC used as positive and negative electrode, respectively. The energy density of the AC//Co(OH) 2 buds/Ni foam supercapacitor reaches to 20.3 W h kg −1 at a power density of 90.6 W kg −1 . Our result shows that the Co(OH) 2 materials are promising candidate for electrochemical energy applications. [ABSTRACT FROM AUTHOR]

A high-performance capacitor battery AC/ λ -MnO 2 based on Na-ion insertion-deinsertion into λ -MnO 2 in 1 mol dm −3 Na 2 SO 4 solution is successfully demonstrated. A simple acid leaching technique is used to produce λ -MnO 2 by treating LiMn 2 O 4 with H 2 SO 4 . X-ray power diffraction and inductively coupled plasma analysis provide supporting evidences for the extraction of Li + from the LiMn 2 O 4 , and the particle morphology of λ -MnO 2 is studied by scanning and transmission electron microscopy. A high specific capacity of 390.7 mAh g −1 is obtained for the λ -MnO 2 electrode at a current density of 13.6 mA g −1 with a nearly 100% efficiency. The capacitor battery AC/ λ -MnO 2 can operate at a cell voltage as high as 2.2 V, and it exhibits a specific energy of 19.7 Wh Kg −1 at a high power density of 3500 W Kg −1 and a high energy density of 71.7 Wh Kg −1 at a low power density of 403 W Kg −1 . It has potentials to be used as an energy storage device for the integration of solar and wind power into the electrical power grid. [ABSTRACT FROM AUTHOR]

Ni foam supported-NiCo 2 O 4 nanostructures with various morphologies are successfully prepared by a facile template-free method. The synthesis involves the electrodeposition of the bimetallic (Ni, Co) film on Ni foam support. The NiCo 2 O 4 nanostructures are formed by immersing the bimetallic film in an oxalic acid solution, followed by a calcination progress. The control over NiCo 2 O 4 nanostructures with different morphologies is achieved by adjusting the electrodeposition time and immersing time. The electrode is characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. H 2 O 2 electrooxidation and electroreduction in KOH solution on the NiCo 2 O 4 nanostructures are studied by cyclic voltammetry and chronoamperometry. Results show that NiCo 2 O 4 nanostructures exhibit high performance and superior stability for both H 2 O 2 electrooxidation and electroreduction, resulting from hierarchical porous structure inside their architectures. [ABSTRACT FROM AUTHOR]

Abstract: A facile and green method is developed to fabricate Fe3O4–Fe nanowires with a large amount of nanoholes directly grown on highly conductive nanofiber arrays. By electrodeposition of Fe clusters on C/TiC nanofiber array, followed by in-situ chemical conversion of Fe to FeC2O4–Fe nanowires and the thermal decomposition of FeC2O4–Fe to Fe3O4–Fe, a Fe3O4–Fe nanocomposite electrode with unique architecture is successfully prepared. The electrode is characterized by means of X-ray diffractometer, scanning electron microscope and transmission electron microscope. Electrochemical properties of the nanowire arrays electrode as the anode of lithium-ion batteries are examined by cyclic voltammetry and galvanostatic charge/discharge test. The electrode displayed remarkably high capacity, excellent high rate performance and superior cycling stability. The reversible capacity of the electrode reached 1012 mAh g−1 at 1C and retained to be 500 and 255 mAh g−1 at 10 and 20C, respectively. It can still deliver a specific capacity of 100 mAh g−1 even at 50C (72 s charge–discharge). The electrode also has a satisfactory cycling performance with capacity retention of 93.9% after 100 cycles at 1C. The magnificent performance can be attributed to the distinct configuration resulting from the novel fabrication process. [Copyright &y& Elsevier]

Abstract: Non-noble metal film electrode (Co/Ni foam) modified with noble metals (Au and Pd) has been reported. Highly porous Co film is firstly prepared electrochemically on the commercial Ni foam substrate and in turn serves as a hard template and a redox inducer for modification by spontaneous deposition of Au or Pd. The electrodes (Au-modified Co/Ni foam and Pd-modified Co/Ni foam) are characterized by scanning electron microscopy equipped with energy dispersive X-ray spectrometer, and X-ray diffractometer. The catalytic performance of the 3D porous electrodes is evaluated by voltammetry and chronoamperometry. Results reveal that Au- and Pd-modified Co/Ni foam exhibit excellent catalytic performance and good stability for H2O2 electroreduction compared with Au and Pd particles supported on Ni foam, benefitting from the unique 3D structure which can ensure high utilization of catalyst and quick releases of gas bubbles produced by H2O2 decomposition from the electrode. [Copyright &y& Elsevier]

Abstract: Flexible and wearable cobalt electrode with a unique three-dimensional hierarchical-network structure is prepared by electrodeposition of spherical Co particles onto multiwalled carbon nanotubes (MWNTs) which are assembled on the skeleton of cosmetic cotton (CC). The morphology and phase structure of the cobalt–multiwalled carbon nanotubes–cosmetic cotton (Co–MWNTs–CC) electrode are characterized by scanning electron microscope, transmission electron microscope and X-ray diffraction spectrometer. The NaBH4 electrooxidation performance on the Co–MWNTs–CC electrode is investigated by means of cyclic voltammetry and chronoamperometry. Results show that the Co–MWNTs–CC electrode exhibits remarkably high catalytic activity and good stability for NaBH4 electrooxidation. The oxidation current density reaches as high as 170 mA cm−2 at −0.7 V in 1.0 mol dm−3 NaOH and 0.1 mol dm−3 NaBH4, which is higher than the most-related previous results. [Copyright &y& Elsevier]

Highlights: [•] MnO2/C/TiO2 shell/shell/core arrays electrode has been prepared by simple thermal reaction and electrodeposition method. [•] The unique shell/shell/core structure has easy access of electrolyte ions, large surface to volume and high electrochemical activity. [•] The MnO2/C/TiO2 shell/shell/core arrays exhibits high specific capacitance of 639 F g−1 at a charge/discharge current density of 1 A g−1. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fe2O3 sheets have been synthesized on nickel foam by a simple template-free growth process and heat treatment. [•] The Fe2O3 electrode exhibits a specific capacitance of 147Fg−1 at 0.36Ag−1 and 98Fg−1 at 3.6Ag−1. [•] The as-prepared Fe2O3 electrode presents a wider potential window of 1.0V. [Copyright &y& Elsevier]

Highlights: [•] λ-MnO2 is prepared by treating LiMn2O4 with H2SO4. [•] λ-MnO2 has ideal battery behavior for polyvalent cations (Mg2+, Zn2+) to intercalate/deintercalate in aqueous electrolyte. [•] λ-MnO2 electrode exhibits a high specific capacity of 545.6 mAh g−1 at 13.6mAg−1 in 0.5mol dm−3 MgCl2 electrolyte. [ABSTRACT FROM AUTHOR]

Highlights: [•] Electrodeposition of Au nanoflowers supported on CFC for ethanol oxidation is reported. [•] Many thorn-like Au nanostructures have a common basis to form a single flower. [•] The as-prepared electrode exhibits good catalytic performance for ethanol electrooxidation. [Copyright &y& Elsevier]

Highlights: [•] MgFe2O4 nanoparticles are prepared by a sol–gel method. [•] The initial discharge specific capacity under the current density of 180mAg−1 reaches 1404mAhg−1. [•] The high specific capacities and good stability were due to its small particle size and the good electrochemical activity. [ABSTRACT FROM AUTHOR]

Abstract: Nanostructured Co x Ni1−x (OH)2 (x = 0, 0.053, 0.068, 0.116, 0.192) composites are synthesized via a simple template-free growth process onto nickel foam by using a mixed aqueous solution of nickel nitrate, cobalt nitrate and ammonia. Their structure and surface morphology are characterized by X-ray diffraction, energy dispersive X-ray spectroscopy and scanning electron microscopy. The SEM images show changes in the microstructure of β-Ni(OH)2 by the doping of cobalt. The effects of cobalt content on the electrochemical behaviors of β-Ni(OH)2 are investigated by cyclic voltammetries, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The results show that the Co0.116Ni0.884(OH)2 composite electrode exhibits a drastic improvement in the capacitive characteristics of β-Ni(OH)2 with a specific capacitance increase from 386.4 to 1082.6 F g−1 at a high discharging current density of 6 A g−1. This work suggests that the as-prepared Co0.116Ni0.884(OH)2 composite electrode has a promising future as higher charging/discharging rate materials for pseudo-supercapacitors. [Copyright &y& Elsevier]

Abstract: Co3O4 nanowire arrays freely standing on Ti foil (Co3O4/Ti) are prepared via a template-free growth method. Pd nanoparticles are electrochemically deposited by cyclic voltammetry method on Co3O4 nanowires to obtain a nanocomposite electrode (Pd@Co3O4/Ti). The morphology and phase structure of the Pd@Co3O4/Ti electrode are characterized by scanning electron microscope and X-ray diffraction spectrometer. The catalytic activity of H2O2 electroreduction on the Pd@Co3O4/Ti electrode in alkaline medium is evaluated by means of linear scan voltammetry and chronoamperometry. The Pd@Co3O4/Ti electrode exhibits high performance and good stability to H2O2 electroreduction with a current density of 145.8 mA cm−2 at −0.4 V in 3.0 mol dm−3 KOH and 0.4 mol dm−3 H2O2 electrolyte, which outperforms the bare Co3O4 nanowire arrays without Pd doping. [Copyright &y& Elsevier]

Highlights: [•] A 3D porous Ni film is electrodeposited on Ni foam via electrodeposition. [•] Ni/Ni-foam electrode shows high catalytic activity for H2O2 electrooxidation. [•] DPPFC with Ni/Ni foam anode and Pd/CFC cathode has been demonstrated. [ABSTRACT FROM AUTHOR]

• α-MnSe Nanosheets are prepared via a facile hydrothermal method. • The effect of reaction time on electrochemical performance is investigated. • The α-MnSe electrode delivers a high capacity of 88.3 mAh g−1 at 1 A g−1. • The asymmetric supercapacitor exhibits a high energy density of 39.3 Wh kg−1. Transition metal selenides are regarded as emerging materials for energy storage devices because of their good electrical conductivity and electrochemical activity. Here, a binder-free ultrathin α-MnSe nanosheets electrode is prepared and the supercapacitor performance is comprehensively explored. Due to the increased active sites, enlarged contact area for electrolyte, as well as shorten ions diffusion pathway, the prepared electrode delivers high capacity of 88.3 mAh g−1 at 1 A g−1, good rate capability, and long-term durability (91% remain after 5000 cycles). Moreover, the asymmetric supercapacitor, fabricated by α-MnSe anode and active carbon cathode, displays a high energy density of 39.3 Wh kg−1 at a power density of 0.92 kW kg−1 and satisfying cycle performance. This study demonstrates that the binder-free α-MnSe electrode holds great promise for supercapacitor. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pd nanofilm supported on carbon coating TiO2 nanocone arrays (C@TiO2) is reported. [•] Pd NF-C@TiO2 electrode shows an open structure allowing the full utilization of Pd. [•] Pd NF-C@TiO2 electrode exhibits high catalytic activity for H2O2 reduction. [Copyright &y& Elsevier]

Abstract: A novel synthesis of Au–Pd alloy nanoparticles supported on carbon fiber cloth (Au–Pd NPs/CFC) via a potential pulse technique is presented. Different composition stoichiometry of Au–Pd nanoparticles are deposited from the aqueous solutions of HAuCl4/PdCl2 mixtures in molar ratios of 5:1, 2:1, 1:1, 1:2 and 1:5. The electrode is characterized by scanning electron microscopy coupled to energy dispersive X-ray analysis (SEM–EDX), transmission electron microscopy (TEM) and X-ray diffractometer (XRD). H2O2 electroreduction in H2SO4 solution on Au–Pd nanoparticles is studied by linear sweep voltammetry and chronoamperometry. The catalytic performance on different composition stoichiometry of Au–Pd nanoparticles increases with the increase of Pd content. Additionally, the flower-like Au–Pd NPs/CFC electrode exhibits the excellent catalytic properties and good stability to H2O2 electroreduction in acid solution, and it outperforms pure Au or Pd catalyst supported on carbon fiber cloth. [Copyright &y& Elsevier]

Abstract: Al-doped β-Ni(OH)2 nanosheets are prepared by a simple hydrothermal process onto nickel foam by using a mixed aqueous solution of nickel nitrate, aluminum nitrate and ammonia. Their structure and surface morphology are studied by using X-ray diffraction analysis, energy-dispersive X-ray spectroscopy and scanning electron microscopy. The SEM images show changes in the microstructure of β-Ni(OH)2 by the addition of Al. The XRD results show that the α-phase Ni(OH)2 appeared by the addition of Al. The effects of Al content on the electrochemical behaviors of β-Ni(OH)2 are investigated by cyclic voltammetrys, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The results show a drastic improvement in the capacitive characteristics of β-Ni(OH)2 with a specific capacitance increase from 941.7 to 2122.6 F g−1 by the addition of just 3.4 mol% Al. This work suggests that the as-prepared Al0.034Ni0.966LDH electrode has a promising future as higher charging/discharging rate materials for pseudo-supercapacitors. [Copyright &y& Elsevier]

Highlights: [•] Dendritic Pd supported on CFC is decorated with Au via potential pulse technique. [•] Au@Pd/CFC electrode shows high catalytic activity for H2O2 reduction and oxidation. [•] DPPFC obtains a much higher performance based on the Au@Pd/CFC electrodes. [ABSTRACT FROM AUTHOR]

Abstract: Carbon fiber cloth supported micro- and nano-structured Co electrode is prepared by a facile and fast square-wave electrodeposition method. The electrode is characterized by scanning electron microscope and X-ray diffractometer. Its electrocatalytic performance for hydrazine oxidation in alkaline media is investigated by means of cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Co is uniformly deposited on the carbon fiber surface and presents as nano-sheets and micro-particles intersected mutually. The nano-sheets have a thickness of around 250nm and the size of the micro-particles is up to around 10μm. Hydrazine electrooxidation on the electrode occurs via both direct and indirect pathways. The activation energy of the direct electrooxidation of hydrazine is 16.6kJmol−1 which is higher than that of the electrooxidation of hydrogen in the indirect pathway (9.9kJmol−1). [Copyright &y& Elsevier]

Abstract: Composites of Li4Ti5O12–Ketjen Black (Li4Ti5O12–KB) and Li4Ti5O12–Ketjen Black–multi-walled carbon nanotubes (Li4Ti5O12–KB–MWCNTs) are prepared by a simple solution method. Their morphologies and structures are characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. Their electrochemical properties are investigated by galvanostatic charge–discharge test. Li4Ti5O12 particles in Li4Ti5O12–KB and Li4Ti5O12–KB–MWCNT composite have a diameter of ca. 40–60nm. The discharge specific capacity is 157 (0.1C), 110 (20C) and 93 (30C) mAhg−1 for Li4Ti5O12–KB composite, and 157 (0.1C), 133 (20C) and 105 (30C) mAhg−1 for Li4Ti5O12–KB–MWCNT composite. After 100cycles at 5C, the discharge capacity retention of Li4Ti5O12–KB and Li4Ti5O12–KB–MWCNTs is 94% and 96%, respectively. Li4Ti5O12 shows asymmetric behavior between charge and discharge. The excellent high rate performance of Li4Ti5O12–KB and Li4Ti5O12–KB–MWCNT composites can be attributed to the reduction of Li4Ti5O12 particle size and the improvement of electronic conductivity due to the uniform distribution of Li4Ti5O12 particles within the carbon matrix conductive network. [Copyright &y& Elsevier]

Abstract: Sr-doped Li4Ti5O12 composites are prepared by a solid-state reaction method and characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and transmission electron microscopy. Their electrochemical properties as the anode material of lithium ion batteries are investigated by galvanostatic charge and discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that Sr2+ doping increases the lattice parameter, reduces the particle size, decreases the charge transfer resistance, and significantly enhances the rate capability of Li4Ti5O12. The Sr-doped Li4Ti5O12 exhibits a specific discharge capacity of about 1.62 times that of pristine Li4Ti5O12 at 5C charge/discharge rate. Sr doping introduces a small amount of SrLi2Ti6O14 to the composites, which also makes a contribution to the specific capacity of Li4Ti5O12 at low charge/discharge potentials. [Copyright &y& Elsevier]

Abstract: The electrochemical behavior of the aluminum current collector with a fresh surface (the scratched aluminum foil) in three kinds of Grignard reagents/THF electrolytic solutions has been studied by cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS) analysis methods. The experimental results show that the passivating film on aluminum foils after five cycles of CV tests is mainly composed of Al2O3. The pitting potentials of scratched aluminum foils in three kinds of Grignard reagents/THF electrolytic solutions increase in the order of EtMgCl/THF

Abstract: Nanostructured CuO with diverse morphology was directly grown on copper foam. Their supercapacitance performance was investigated and correlated with the morphology. CuO nanowires, nanosheets, and flower-like nanostructures were formed on copper foam which acts as both the substrate of CuO formation and the current collector of the electrode. Their morphology was examined by scanning and transmission electron microscopy and their phase structure was analyzed by X-ray diffraction spectroscopy. The supercapacitance of the nanostructured CuO on copper foam was investigated by cyclic voltammetry, galvanostatic charge/discharge measurements and electrochemical impedance spectroscopy. Results showed that the specific capacitance of the nanostructured CuO strongly depends on its morphology and dimension. CuO nanosheets exhibited higher specific capacitance than nanowires and flower-like nanostructure. The specific capacitance of the CuO nanosheets reached 212Fg−1 at a current density of 0.41mAmg−1 in 6.0moldm−3 KOH electrolyte. The capacitance loss is around 15% after 850 charge/discharge cycles at 0.41mAmg−1 and the majority of capacitance loss occurred in the initial 50 cycles (8.1%). [Copyright &y& Elsevier]

Abstract: Running of direct 2-propanol fuel cell generates liquid acetone as the main product in the anode compartment. Its concentration continuously increases during cell operation. Its effect on the electrooxidation of 2-propanol at the anode catalyst deserves to be addressed. In this study, the influence of acetone concentration and reaction temperature on the electrooxidation of 2-propanol at Pt and Au electrode in alkaline electrolyte is investigated by cyclic voltammetry and chronoamperometry. The results show that the rate of 2-propanol electrooxidation at Pt and Au electrode is remarkably diminished with the increase of acetone concentration. When the concentration of acetone reaches 0.1molL−1, the oxidation current of 2-propanol at Pt and Au electrode decreases by around 50% and 30%, respectively. The effect of acetone can be attributed to its competitive adsorption with 2-propanol on electrodes surface, leading to the poison of electrodes. Increase of reaction temperature decreases the oxidation current of 2-propanol at Au electrode. Au electrode is more tolerant to acetone than Pt electrode at low acetone concentration. Results of this study suggest that new acetone insensitive electrocatalysts are needed for 2-propanol electrooxidation in alkaline electrolytes. [Copyright &y& Elsevier]

Abstract: Co3O4 nanowires have been successfully synthesized on nickel foam by a hydrothermal method. The morphology of Co3O4 is examined by scanning and transmission electron microscopy and the phase structure of Co3O4 nanowires is confirmed by X-ray diffraction. The electrochemical capacitance behavior of the Co3O4 nanowires electrode is investigated by cyclic voltammetry, galvanostatic charge/discharge test and electrochemical impedance spectroscopy in 6moldm−3 KOH solution. The results show that the Co3O4 nanowires have diameters of around 100nm and the lengths up to 1–2μm. The specific capacitance of Co3O4 nanowires is 1019.58Fg−1 at 3.38Ag−1 and 466.06Fg−1 at 33.80Ag−1. The capacitance loss is less than 5% after 1000 charge/discharge cycles at 3.38Ag−1 and with columbic efficiency higher than 98%. The enhancement of pseudocapacitive properties at a higher charging/discharging rate is due to the porous nanostructure and the high utilization of active material. [Copyright &y& Elsevier]

Abstract: Perovskite-type series of compounds La1−x Sr x MnO3 are synthesized by a sol–gel method using Chitosan as the gelling agent. Their catalytic activity for hydrogen peroxide electroreduction in 3.0moldm−3 KOH at room temperature is evaluated by means of cyclic voltammetry and chronoamperometry. Effects of annealing temperature and the ratio of La to Sr of La1−x Sr x MnO3 on their catalytic performance are investigated. Among this series of compounds, La0.4Sr0.6MnO3 calcined at 650°C exhibits the highest activity, which is comparable with Co3O4. An aluminum–hydrogen peroxide semi-fuel cell using La0.4Sr0.6MnO3 as cathode catalyst achieves a peak power density of 170mWcm−2 at 170mAcm−2 and 1.0V running on 0.6moldm−3 H2O2. [Copyright &y& Elsevier]

Abstract: Activation of the MmNi4.03Co0.42Mn0.31Al0.24 hydrogen storage alloy electrode is performed by immersing the electrode in a solution containing 6.0moldm−3 NaOH and 0.1 mol dm−3 NaBH4. The effects of activation on the electrocatalytic activity of the electrode for NaBH4 oxidation are investigated by cyclic voltammetry and chronoamperometry. Immersion activation greatly improves the electrocatalytic activity of the alloy electrode. Hydrogen was absorbed in the alloy during the immersion activation treatment and its electrooxidation is responsible for the high initial oxidation current. The stabilized current mainly results from the direct oxidation starting from the borohydride species. The effects of activation on structure and surface chemistry of the alloy are also discussed. [Copyright &y& Elsevier]

Abstract: A novel anticorrosion pigment for AZ31 Mg alloy protection, molybdate pillared hydrotalcite (HT-MoO4 2−), was successfully fabricated via a simple one-step process. The physicochemical properties of the samples were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectra, and inductively coupled plasma (ICP) method, respectively. The results indicated that the material showed typical characteristics of molybdate intercalated hydrotalcite. Additionally, it was found that the sample exhibited nano-sized lamellar morphology with the particle size of 35–60nm. Moreover, the coating on AZ31 Mg alloy containing HT-MoO4 2 − pigment showed obviously higher corrosion protection performance in comparison with the strontium chromate (SC) pigment by Electrochemical impedance spectroscopy (EIS) measurements. The mechanism of corrosion protection was proposed to be that the HT-MoO4 2 − pigment in the coating would cause the pigment to undergo amphoteric ion exchange with aggressive NaCl solution, leading to the release of molybdate and Zn2+ inhibitors. [Copyright &y& Elsevier]

Developing efficient hydrogen evolution reaction (HER) electrocatalysts is extremely important for large-scale hydrogen production from water splitting. In this work, ultra-small MoS 2 nanosheets with 5% Ni doping grown on both sides of hollow carbon microtubes (5%-Ni-MoS 2 /aCMT) are prepared by a hydrothermal method. The vertically oriented Ni-doped MoS 2 nanosheets provide more active sites for HER, while open porous structure promotes ions transport, and hollow carbon microtube substrate accelerates electrons transport as well as hydrogen release. Density functional theory (DFT) analysis proves that the optimal amount of Ni doping can effectively adjust the electronic structure of MoS 2. As a result, 5%-Ni-MoS 2 /aCMT electrode exhibits enhanced kinetics for HER in both acidic and alkaline conditions. To deliver the current density of 10 mA cm−2, it requires overpotentials of 140 and 88 mV in 1 M KOH and 0.5 M H 2 SO 4. 5%-Ni-MoS 2 /aCMT exhibits better stability than commercial Pt/C at a high current density of 200 mA cm−2. Moreover, 5%-Ni-MoS 2 /aCMT/NF (nickel foam) || RuO 2 /NF electrolyzer exhibits ultra-long stability of 30 h at the current density of 100 mA cm−2 and excellent overall water splitting performance with requiring low cell voltages of 1.52 and 1.71 V to generate current densities of 10 and 50 mA cm−2. [Display omitted] • The Ni doping with an optimized content adjusted the electronic structure of MoS 2 , and improved the intrinsic activity. • The ultra-small vertically oriented and defect-rich Ni-doped MoS 2 nanosheets provide more active sites for HER. • The natural N-doped aCMT substrate promotes electron transport during the HER process. • 5%-Ni-MoS 2 /aCMT behaves an enhanced kinetics process based on EIS and DFT analysis. [ABSTRACT FROM AUTHOR]

• Three F-doped biomass carbon were prepared by combining PTFE, DAST, HF and hemp. • The fluorinated products showed unexpected morphology and structure. • Products (by PTFE) exhibit the best capacity, rate capability, and lifetime in PIBs. • A lot of defects and high heteroatom content are key merits. Heteroatom doping can effectively improve the electrochemical activity of carbon materials. In this paper, three kinds of fluorine-doped biomass carbon are synthesized using industrial hemp core as the precursor and Poly tetra fluoroethylene (PTFE), Diethylaminosulphur trifluoride (DAST) and Hydrofluoric acid (HF) as fluorinating agents, respectively. Among them, the PTFE-treated biomass carbon (PTFE-CHEMP) is wrapped by fluorine-containing nanotubes, which has the most defects, the most F doping amount and the optimum pore size, and is beneficial to the adsorption of K +. When used as the anode of potassium ion batteries (PIBs), the PTFE-CHEMP electrode can provide an average reversible capacity of 369.6 mAh g−1 (200 mA g−1) in 500 cycles. Even at a high current of 2000 mA g−1, it can still provide an excellent rate capability of 229.3 mAh g−1. Kinetic analysis verify that its excellent rate performance comes from the K + storage mechanism dominated by surface-driven behavior. In addition, the constant current intermittent titration technique (GITT) shows that it still has the storage capacity for K + at high potentials. This work not only provides a reference for subsequent research on fluorine-doped biomass carbon, but also provides a potential solution for the production of low-cost, high-capacity PIBs anodes. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The electrochemical performance of Ni/Al-CO3 hydrotalcite supported on porous nickel electrode in hexacyanoferrate(III) media was investigated. The structure and morphology of Ni/Al hydrotalcite were characterized by XRD, FT-IR, SEM and TEM. The XRD and FT-IR results indicated that the intercalation of hexacyanoferrate into Ni/Al hydrotalcite was caused by potential scan. In addition, the conductive mechanism was studied by voltammetric methods. The result demonstrated that the [Fe(CN)6]3− anion significantly affected the electrochemical behavior of the electrode and the electrode reaction was controlled by the diffusion of [Fe(CN)6]3−. The electrochemical impedance spectra of Ni/Al-CO3 hydrotalcite electrodes were recorded at different potentials in order to study the electronic and ionic conduction, both inside and on the surface of the material. [Copyright &y& Elsevier]

• Sulfur-doped hemp-derived carbon is used in PIBs high-performance anodes. • It exhibits a higher capacity and better rate capability at 60 °C than at 25 °C. • Bonded sulfur is awakened at high temperature to enhance the adsorption of K +. • High temp promotes the decomposition of electrolyte is the main cause of danger. • The full cell composed of PTCDA exhibits excellent capacity at 60 °C. Potassium-ion batteries (PIBs) have huge advantages in terms of price and resource abundance, and are ideal substitutes for lithium-ion batteries (LIBs), but there is currently little research on their high-temperature fields. In this work, the sulfur-doped biomass carbon (CHP/S) is synthesized from biomass hemp stalks as the carbon source and sulfur powder as the sulfur source, with a high sulfur content of 18.6%. Sulfur mainly exist in the form of bonded sulfur (S-C, S-O) and have quite favorable stability. As a PIBs anode, it exhibits a specific capacity of 589 mAh g−1 (30 mA g−1) at 60 °C, which is 1.5 times the capacity at 25 °C. Electrochemical analysis and kinetic analysis indicate that the increased capacity mainly comes from the "arousal effect" of sulfur under high temperature conditions, and an increased temperature has a positive effect on the absorption and desorption performance of the material. In addition, the full cell assembled with Perylene-3, 4, 9, 10-tetracarboxylic dianhydride (PTCDA) cathode shows greater capacity (~80 mAh g−1) at 60 °C than at 25 °C. Unfortunately, the electrolyte decomposition problem caused by high temperature is easily dangerous. The result is of great significance to the research of high-temperature PIBs. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract: The catalytic activity of a homogeneous molten salt consisting of (Li,Na,K)2CO3 with dissolved additions of CsVO3–MoO3 for graphite electrooxidation is investigated. This electrolyte forms a eutectic mixture with low melting point, high stability in the presence of CO2, and catalytic activity for graphite electrooxidation. The current density of graphite electrooxidation in this novel electrolyte reaches 125mAcm−2 at −0.4V and 750°C, which is much higher than that obtained in the conventional molten carbonate electrolyte (47mAcm−2). More importantly, the addition of CsVO3–MoO3 significantly improves the electrooxidation activity of graphite at low temperature. The onset potential for graphite electrooxidation at 550°C is negatively shifted by −0.3V and the current density at −0.4V is increased by 6.7 times by introducing CsVO3–MoO3 into the molten (Li,Na,K)2CO3. The catalytic mechanism of CsVO3–MoO3 is briefly discussed. [Copyright &y& Elsevier]

Bimetallic metal selenides have gained increasing attention as potential electrode materials for energy storage systems owing to good electrical conductivity and superior electrochemical activity. Herein, the Ni x Co y Se 2 (x+y=1) electrodes are prepared by a facile and rapid electrodeposition process. The electrochemical performance is optimized via adjusting the ratio of Co and Ni. It is turned out that equivalent Co and Ni in the composite (Ni 1/2 Co 1/2 Se 2) shows the best supercapacitor performance, including high specific capacity (166.1 mAh g−1) and long-term stability. Moreover, Density Functional Theory (DFT) calculation confirms the covalent interaction between nickel and cobalt, implying the existence of synergistic effect. To assess the practical value of the rationally designed Ni 1/2 Co 1/2 Se 2 electrode material, an asymmetric supercapacitor device is fabricated (Ni 1/2 Co 1/2 Se 2 //AC), which delivers a high energy density of 46.0 Wh kg−1 at 1141 W kg−1, coupled with 9.8% capacity loss after 10000 cycles. Notably, the low-voltage setups (LED and electric fan) can be easily activated by two devices in series, further demonstrating the great potential for practical application of Ni 1/2 Co 1/2 Se 2 electrode. [ABSTRACT FROM AUTHOR]

• Carbon-coated SnS nanosheets and reduced graphene oxide composites are designed and synthesized. • Dual-carbon modification enhances the rate performance of SnS. • Potassiation stage adjustment results in stable cycling performance. Potassium ion batteries (PIBs) have attracted lots of attention due to its abundant resources. Exploring capable anode materials becomes one of the critical issues to achieve high-performance PIBs. Herein, carbon-coated SnS nanosheets and reduced graphene oxide (SnS@C/rGO) composite are designed and synthesized by a solvothermal reaction and heat treatment. The strategy of double carbon modification enhances the rate performance of SnS. Meanwhile, the cycling stability of SnS@C/rGO can be further improved by optimizing the voltage window, which can achieve the potassiation stage adjustment. K ions storage mechanism of SnS@C/rGO is investigated under different voltage windows. The deep alloying reaction occurs under low potential and is harmful to cycling performance. Moreover, the electrochemical kinetics of K ions storage is investigated by quantitative kinetics analysis. This work highlights the important effect of dual-carbon modification and adjusting the potassiation stage on the K ion storage. [ABSTRACT FROM AUTHOR]

This work presents a novel method for loading phosphorus nanoparticles by gas deposition. A large amount of nano phosphorus is loaded on the carbon matrix by the reaction of phosphine gas heating. The carbon is obtained by carbonization of hemp and has a natural porous structure. The combination of phosphorus and carbon in the form of C–O–P has better stability. The product obtained a stable capacity of 463 mAh/g at 0.04 A/g. There was still a reversible capacity of 270 mAh/g after continuous operation for 6 months at a high current density of 1 A/g, and the capacity retention rate was 96.7%. The excellent cyclic stability is due to new methods of phosphorus deposition. It can reach 10 times the running time of the same type of battery, which provides a new idea for preparing phosphor-doped electrode materials. Assembled into a potassium ion capacitor, an energy density of 294.2 Wh/kg can be obtained. [ABSTRACT FROM AUTHOR]

• NiNb 2 O 6 @NC-2 hollow nanoparticles is used as rate capability anode for LICs. • The NiNb 2 O 6 @NC-2 exhibits a high specific capacity of 435.8 mAh g−1 at 50 mA g−1. • NiNb 2 O 6 decomposes into Ni metal and Li x Nb 2 O 6 in the 1st charge/discharge process. • The NiNb 2 O 6 @NC//AC LICs has a maximum energy density of 123.9 Wh kg−1. Searching for anode materials with fast Li+ intercalation kinetics to mitigate the dynamic imbalance with the rapid capacitive cathode is the fundamental strategy to achieve high energy-power density of Li-ion capacitors (LICs). Hence, NiNb 2 O 6 hollow nanoparticles are first synthesized by hydrothermal method and then sealed with a protective N-doped carbon shell to achieve the target NiNb 2 O 6 @NC composite. As the anode of LICs, the NiNb 2 O 6 @NC sample exhibits a high capacity of 435.8 mAh g−1 at 50 mA g−1 and excellent rate performance of 47.8% capacity retention with the current density increased to 2 A g−1. The lithium storage mechanism of NiNb 2 O 6 is proposed as a combined conversion reaction and an intercalation reaction, which the NiNb 2 O 6 decomposes into Ni metal and Li x Nb 2 O 5 during the 1st discharge/charge process. The irreversible Ni would not contribute to the reversible capacity and will improve the electric conductivity for fast transport of electrons and the Li x Nb 2 O 5 will act as the host for lithium ions by means of the intercalation mechanism. Furthermore, the assembled NiNb 2 O 6 @NC//activated carbon LICs exhibit a maximum energy density of 123.9 Wh kg−1 and the capacity retention reaches 86.1% after 5000 cycles. The superior electrochemical performances indicate that the rationally-designed NiNb 2 O 6 @NC is expected to be a potential anode material for LICs. [ABSTRACT FROM AUTHOR]

As a mainstream energy storage device, lithium-ion batteries have always been the focus of scientific researchers. As the most promising anode material, lithium metal has the advantages of high capacity and low reduction potential. Unfortunately, lithium dendrites can cause serious safety hazards during cycling. In this study, biomass carbon with a large number of straight holes was embedded with nickel particles as the anode framework. Nickel induces lithium to complete nucleation and growth in the pores and inhibits dendrite growth. Solid electrolyte interface (SEI) film growth, dead lithium, and electrode breakage all occur within the holes to a limited extent. Benefited from this internal reaction, the electrode obtains better electrochemical and cycling performances. The nickel-modified electrode was stably cycled for 1370 h at a current density of 5 mA/cm2 with a capacity of 2 mAh/cm2. Moreover, more massive capacity lithium storage (5 mAh/cm2) was tried, and the cycle was stable for 630 h. Using the same biomass carbon matrix, the pores were filled with sulfur powder as the positive electrode. After 100 periods of the full cell operation, the capacity retention rate is 85%. [ABSTRACT FROM AUTHOR]

K-ion batteries (KIBs) are widely considered as a promising alternative to Li-ion batteries (LIBs) due to the cost effective and earth abundant features of K. However, identifying a potential anode for KIBs showing good capacity and stability is still challenging. Because traditional graphite suffers from poor stability owing to the large volume expansion during the insertion/extraction of K ions. Non-graphite carbon is a good candidate because of the disordered nature. A facile high temperature pyrolysis method was adopted to obtain bio-derived carbon materials. Among different kinds of biomass precursors, the porous dandelion seed with nitrogen doping shows the best electrochemical performance with a specific capacity of 168 mAh g−1. The nitrogen-doped carbon presents good K ion adsorption capability and enhanced wettability, which is demonstrated in Fig.S1. Moreover, after introducing activation agent (KOH) in the carbonization process, the capacity in improved to 243 mAh g−1. Meanwhile, the as-prepared carbon material delivers good capacity retention of 91% after 100 cycles. Therefore, the hierarchically porous doped carbon derived from renewable biomass precursor shows great economical potential as KIBs anode. Unlabelled Image • The bio-derived carbon activated by KOH maintain maintain an integrated porous microstructure. • The heteroatoms-doped bio-derived carbon exhibits high specific capacity as K ions anode. • The abundant bio-mass precursor enables large scale preparation of the carbon materials. [ABSTRACT FROM AUTHOR]

High-quality F-doped graphene as rate capability anode for Li-ion battery is prepared by a one-step arc-discharge method. The in-situ formation of LiF nano-particles in the first lithium insertion process enhance the interlayer spacing of graphene, thus provid enough void for rapid ion diffusion, which is capable to deliver much high reversible capacity, outstanding rate performance, and excellent cycling stability. • A high-quality F-modified graphene as rate capability anode for Li-ion battery is reported. • The structural evolution of F-modified graphene electrode during the Li+ insertion/extraction is investigated. • The F-modified graphene delivers a high reversible capacity, outstanding rate performance, and excellent cycling stability. The application of lithium ion battery (LIB) in portable electronics and electric vehicle has received tremendous attention, however, challenges remain in seeking suitable high-capacity anode materials with excellent rate performance and thus potentially to boost the energy/power density. Here we report an arc-discharge production of high-quality F-modified graphene as anode for LIB with high-rate capability. As a result of F-modified, the acquired graphene exhibits high atomic ratio of C/O, excellent electric conductivity and more crumpled and wrinkled surface. Interestingly, the in-situ formation of LiF nanoparticles during the first Li+ insertion process not only act as barriers to effectively prevent the agglomeration and re-stacking of graphene sheets but also enhance the interlayer spacing, thus providing enough void for rapid Li+ ion insertion/extraction. These optimized features enable the resultant F-modified graphene delivers a high reversible capacity (783.2 mAh g−1 at 100 mA g−1), outstanding rate performance (298.5 mAh g−1 at 10 A g−1), and excellent cycling stability (>91% capacity retention after 1000 cycles), providing great application prospect in high-enegy-power LIB. [ABSTRACT FROM AUTHOR]

• Low-cost MgFe x Mn 2-x O 4 nanoparticles were prepared via a facile so-gel route. • MgFe 1.33 Mn 0.67 O 4 exhibited good rate ability and cycling stability. • MgFe 1.33 Mn 0.67 O 4 displays Mg-ions diffusion coefficients of 2.55 × 10−7 cm2 s−1. Aqueous Mg-ion batteries attract lots of attention due to its high safety, low cost and potential application for large scale energy storage system. Although spinel-type metal oxides display their capable Mg ions storage behavior, low diffusion ability extremely hinder their practical application. Herein, low-cost MgFe x Mn 2-x O 4 (x = 0.67, 1, 1.33, 1.6) nanomaterials are prepared by a facile sol–gel method. Their electrochemical performance is affected by molar ratio of iron to manganese. The optimized MgFe 1.33 Mn 0.67 O 4 exhibits excellent electrochemical cycling performance and rate capability. Even at high current density of 1000 mA g−1, a specific capacity 88.3 mAh g−1 is obtained after 1000 charge–discharge cycles. The stable structure of MgFe 1.33 Mn 0.67 O 4 promise a cycling stability. Moreover, hydrogen evolution and oxygen evolution of the electrode material during charging-discharging process can be effectively suppressed by regulating the atom ratio of iron to manganese. In addition, it presents a high magnesium diffusion coefficient at two oxidation peaks, leading to a good rate ability. [ABSTRACT FROM AUTHOR]

Strengthening electrical conductivity and multiple atomic interaction are benefit for improving activity of oxygen evolution reaction (OER). Herein, we synthesized Fe-Doped NiSe 2 nanospheres distribute on reduced graphene oxide sheets (Ni 0.7 Fe 0.3 Se 2 /rGO). The optimum ratio (30%) of rGO was ascertained by comparing the properties of catalysts with different rGO amounts. In alkaline electrolyte, the Ni 0.7 Fe 0.3 Se 2 /rGO-30% owns the better OER performance than those of Ni 0.7 Fe 0.3 Se 2 and NiSe 2 , ascribed to the unique architecture that Ni 0.7 Fe 0.3 Se 2 nanospheres decorate rGO. In the architecture, the rGO matrix increases conductivity, enlarges transfer rate of ions and electrons and promotes dispersion of Ni 0.7 Fe 0.3 Se 2. In addition, multiple atomic interaction of Ni/Fe atoms and the synergistic effect between the Ni 0.7 Fe 0.3 Se 2 and rGO enable the compound to be an efficient OER catalyst. Through the rational analysis, Ni 0.7 Fe 0.3 Se 2 /rGO-30% hybrid is promising as an effective non-noble metal catalyst for OER application. • The Ni 0.7 Fe 0.3 Se 2 nanospheres uniformly decorate the rGO. • Multiple atomic interaction contributes to better OER activities. • The rGO increases conductivity of composite and accelerates charge transfer rate. • The content of rGO in composites affects the OER performance. [ABSTRACT FROM AUTHOR]

• A PPy-rGO Janus-faced film is prepared through a facile and scalable method. • The PPy-rGO electrode reveals a ultra-high specific capacitances of 1380 mF cm−2. • The assembled PPy-rGO//PPy-rGO device delivers a high energy density of 31.95 Wh L−1. The flexible supercapacitors have attracted tremendous attention, but challenges still remain in seeking suitable electrode materials to enhance the energy density and other aspects. To this end, a unique Polypyrrole (PPy)-reduced graphene oxide (rGO) Janus-faced film is prepared through a facile and scalable method consisting of the deposition of graphene film on the surface of copper foil via a Cu||GO electrochemical cell followed by the self-assembly of PPy at the heterogeneous interface. Such a distinctive structure, in which the PPy layer acts as the source of high pseudo-capacitance, while the graphene layer is employed as the "high way" for rapid electron transport and as well as the strong π-π coupling effect between graphene and polymer nanosheets, endows the resultant electrode ultra-high specific capacitances (1380 mF cm−2 at 1 mA cm−2) and excellent rate capability (65.1% capacitance retention with the current density increases to 20 mA cm−2). Furthermore, the assembled PPy-rGO//PPy-rGO symmetric supercapacitors deliver a maximum energy density of 31.95 Wh L−1, remarkable cyclic stability (89.7% capacitance retention after 10,000 cycles) and superior mechanical property (82% capacitance retention after 8000 cycles under different bending conditions). [ABSTRACT FROM AUTHOR]

• The human hair with high elasticity capable can serve as a promising flexible supporter for the electrode. • The reduced graphene oxide nanosheets can effectively improve the electrical conductivity of the electrode. • The Ni(OH) 2 nanoribbon-intercalated rGO nanosheets shows an interconnected porous structure. • The solid-state flexible supercapacitor delivers high energy density and good cycling stability. The demands for wearable energy storage devices keep growing and novel flexible electrode materials and facile prepared methods for these devices are crucial and attractive. In this work, human hair fiber is employed as the flexible fiber-based material due to the high utilization values of low cost, controllable length and high elasticity capable. Herein, an effective and hazard-free microwave-assisted method is reported to develop superelastic reduced graphene oxide coating human hair (rGO@Hh) to achieve conductive and high-strength fibrous electrode. With the braided rGO@Hh fibers, nickel hydroxide nanoribbon-intercalated rGO nanosheets (Ni(OH) 2 /rGO@Hh) are further prepared through microwave radiation treatment, which shows an interconnected porous structure with outstanding electrochemical performances of high specific capacitance (316 F g−1 at 1 A g−1) and good cycling performance. Moreover, a solid-state fiber-based asymmetric supercapacitor (FASC) is assembled with rGO@Hh fibers and Ni(OH) 2 /rGO@Hh fibers as negative and positive electrodes, which demonstrates a high energy of 27.6 Wh kg−1 and a power density of 699 W kg−1, respectively. The FASC also can be further used for numerous electronic products, presenting its prospect for portable wearable devices with high tensile strength and excellent performances. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous aluminum ion batteries (RAAB) have gained increasing attentions for large scale energy storage system due to their high safety, nontoxicity and low cost. However, lack of capable anode materials extremely hinders their potential application. As we all know, the anodic material of aluminum ion battery was limited, we report poly (3,4,9,10-perylentetracarboxylic diimide) (PPTCDI) under the different synthesis conditions as organic anode material for aqueous RAAB. The aluminum ions intercalation/deintercalation storage mechanism is affected by the different electrolyte concentrations. Upon their high capacity and cycling stability, our work would highlight potential application of conjugated polymer organic electrode materials for aqueous aluminum ion batteries. Unlabelled Image • The PPTCDI as anode in aqueous Al-ion battery was reported for the first time. • The Al-ion battery delivers excellent electrochemical cycling stability. • The aluminum ions intercalation/deintercalation storage mechanism is affected by the different concentrations of electrolyte. [ABSTRACT FROM AUTHOR]

In this work, one-pot hydrothermal method is used to prepare a novel electrode material of nanosheet-like Fe 2 O 3 in-situ grown on Ni foam. The performance of the as-prepared material toward H 2 O 2 oxidation is investigated systematically. The crossed nanosheet-like structure allows a full contact between the electrode surface and electrolyte which is highly beneficial to the sufficient use of H 2 O 2. The catalytic activity of Fe 2 O 3 grown on Ni foam(Fe 2 O 3 /Ni foam) electrode in alkaline medium for H 2 O 2 oxidation is researched by methods of cyclic voltammetry and chronoamperometry. According to the results of cyclic voltammetry in solutions with different H 2 O 2 concentrations, we proposes a possible reaction mechanism that the good ability of Fe3+ to break the oxygen-hydrogen bond in H 2 O 2 leads to the oxidation of H 2 O 2 on the electrode. Meanwhile, Ni foam also has a positive effect on the process of H 2 O 2 oxidation. In a solution of 4 mol L−1 NaOH and 0.4 mol L−1 H 2 O 2 , the current density of H 2 O 2 oxidation on the Fe 2 O 3 /Ni foam electrode is 800 mA cm−2 revealing a desirable catalytic activity toward H 2 O 2 oxidation. Besides, the activation energy of H 2 O 2 oxidation on the Fe 2 O 3 /Ni foam electrode is calculated to be 9.17 kJ mol−1 by studying the influence of temperature on the electrode performance. All the results show that the as-prepared electrode exhibits vast prospect in application. Image 1 • One-pot hydrothermal method was applied to prepare nanosheet-like Fe 2 O 3. • Fe 2 O 3 /Ni foam electrode exhibits good catalytic activity toward H 2 O 2 oxidation. • A possible mechanism of H 2 O 2 oxidation on Fe 2 O 3 /Ni foam electrode was proposed. [ABSTRACT FROM AUTHOR]

NiS 2 is a promising anode material for sodium-ion batteries (SIBs) and capacitors (SICs). However, the sluggish Na+ diffusion and large volume change of bulk NiS 2 during sodiation/de-sodiation lead to poor rate capability and fast capacity decay, limiting its practical application. Herein, we design and prepare well-oriented NiS 2 nanosheets on porous carbon microtubes (denoted as NiS 2 /pCMT) as a novel anode material for SIBs/SHCs. The unique porous hollow carbon tubes and NiS 2 nanosheets can well relieve the repeated stress/strain and maintain the structural integrity of the composite anode during long-term charging/discharging. As a confirmation, a modelled SHC is constructed by using the NiS 2 /pCMT composite as anode and coupling with an activated carbon cathode, delivering a high energy density of 136 Wh kg−1 and good cycling stability. The first-principles density functional theory (DFT) calculations confirm that the NiS 2 nanosheets surface has a high chemical affinity towards Na+ ions, promising the concentration of Na+ ion on/nearby the surface for fast redox reactions during sodiation/de-sodiation of NiS 2. This work provides some new insights for the design and fabrication novel composite electrode materials for applications in beyond lithium-ion batteries/capacitors. • The carbon microtubes have unique tubular structure and good conductivity. • NiS 2 nanosheets uniformly grow on both sides of the carbon microtubes. • The layered NiS 2 nanosheets facilitate the intercalation of the Na+ ions. • The sodium-ion hybrid capacitor delivers high energy and power densities. [ABSTRACT FROM AUTHOR]