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Highlights: [•] β-Ni(OH)2 was modified via a template-free method by using different nickel salt. [•] The effects on the morphology and electrochemical behaviors were investigated. [•] The β-Ni(OH)2–SO4 2−/Ni-foam electrode displays 1025.3Fg−1 at 1.0Ag−1. [ABSTRACT FROM AUTHOR]

Abstract: We report a new method of preparation of a methanol-tolerant Se/Ru cathode catalyst for the direct methanol fuel cell (DMFC) , whereby selenium is deposited on ruthenium nanoparticles by H2-reduction of SeO2 in aqueous solution at room temperature. The obtained Se/Ru(aq) was studied by electrochemical measurements and tested as a cathode catalyst in H2–air and direct methanol fuel cells. The new catalyst formulation (Se/Ru(aq)) is shown to be superior to Se/Ru synthesized from xylenes solvent and to Ru black by RRDE measurements, in terms of both activity and selectivity for complete oxygen reduction to water. Although Ru black is less active, the Tafel slopes and activation energies of Se/Ru catalysts and reduced-Ru black are similar, implying similar ORR mechanisms. In H2–air fuel cell tests, Se/Ru(aq) was more active than Se/Ru(xyl) at all voltages. Compared to Ru black, Se/Ru(aq) was superior at low current densities, but Ru black slightly exceeded the performance of Se/Ru at high current densities. To explain the RRDE and fuel cell observations, the two roles of Se as an inhibitor of Ru oxidation and as a site-blocker are discussed. [Copyright &y& Elsevier]

Abstract: The open circuit potentials (OCPs) of H2O2 at Pt, Pd, Au, and glassy carbon electrodes are measured in H2SO4 and NaOH electrolyte solutions. Effects of concentration of H+, OH− and H2O2 as well as temperature on the OCP of H2O2 are investigated. The OCP of H2O2 is much lower than its theoretical reduction potential in both acidic and basic medium. The OCP is actually a mixed potential of H2O2 electroreduction and electrooxidation simultaneously occurring at electrode surfaces and it is more close to the equilibrium potential of H2O2 electrooxidation rather than electroreduction. The OCP of H2O2 is around 0.77–0.80V at [H+]=[H2O2]=1.0moldm−3 in H2SO4 solution and is about 0–0.06V at [OH−]=[H2O2]=1.0moldm−3 in NaOH at 298K on Pt, Pd, Au and GC electrodes. The OCP of H2O2 is independent of H2O2 concentration within the range of 0.01 to 1.0moldm−3. It increases approximately linearly with the logarithm of H+ concentration from 0.02 to 2.0moldm−3, decreases with the logarithm of OH− concentration from 0.01 to 1.0moldm−3 and decreases with increase of temperature from 278K to 333K. The linear equations were presented and discussed. [Copyright &y& Elsevier]

Abstract: Pd nanoparticles were immobilized on Au disk electrode and kinetics of hydrogen peroxide electroreduction on the Pd electrode in 0.1M H2SO4 solution was investigated using a rotating disk electrode method. The phase and particle size of palladium were characterized by XRD measurements. The morphology of Pd on Au was examined using SEM. We found that the hydrogen peroxide reduction on Pd nanoparticles proceeds via a two-electron process. The reaction order is one with respect to hydrogen peroxide. An apparent activation energy of 55kJmol−1 was calculated from exchange currents at different temperature. The lower activation energy and higher exchange current density demonstrated that hydrogen peroxide reduction has a faster kinetics than oxygen reduction. Electrolyte anions significantly affect hydrogen peroxide reduction activity, and the activity decreases in the order > >Cl−, which is consistent with the increasing adsorption bond strength of the anions. [Copyright &y& Elsevier]

The organometallic precursor Ru4(μ-H)4(CO)12 (1) reacts with dihydrogen (60 atm, room temperature hexane as solvents, 3 h) over either blacked Pt gauze or Pt black powder to deposit Ru adatoms (Ruad) and CO on the Pt surface. The deposition is self-poisoned by adsorbed CO, stopping when a specific coverage of Pt by CO is reached. The results from the electrooxidation of the adsorbed CO, from base voltammograms recorded in aqueous sulfuric acid, from exhaustive anodic stripping of Ruad, and from the potentiodynamic and potentiostatic electrooxidation of MeOH, all show that the deposition self-poisons after ca. 0.05 surface equivalents (moles Ruad vs. moles Pt surface) of Ruad are deposited on blacked Pt gauze. The deposition over Pt black powder self-poisons after depositing ca. 0.10 surface equivalents of Ruad. A direct CH3OH fuel cell using the resulting black Pt–Ruad powder was constructed by hot-pressing the catalyst into a Nafion® membrane. Contrary to expectations, the Pt–Ruad catalyst did not lose significant amounts of surface Ru during either hot pressing the membrane electrode assembly, nor during operation of the fuel cell at 90 °C. [Copyright &y& Elsevier]

Abstract: The synthesis, electrochemical analysis, and hydrogen-air fuel cell testing results for a new type of Se/Ru catalyst called Se/Ru(aq) were described in Part 1. In this second report, we present methanol tolerance studies and direct methanol fuel cell testing for the same catalyst. A “methanol-tolerant” catalyst does not oxidize methanol, nor becomes depolarized by its presence, which is a desirable property for DMFC cathodes used with methanol-permeable membranes or in mixed-reactant designs. In perchloric acid electrolyte, the Se/Ru(aq) catalyst was found to be highly tolerant to 1.0M methanol. More importantly, in fuel-cell testing as a DMFC cathode, Se/Ru(aq) was shown to be highly tolerant to methanol crossing through the membrane (from the anode side) up to a feed concentration of 17M. The results were compared to those obtained using unmodified Ru black and Pt black at the DMFC cathode, in order to gain insight into the catalyst function and to compare the performance to relevant benchmarks. Compared to Pt cathodes, the performance of Se/Ru(aq) is significantly better at high methanol concentrations (e.g., 17M), suggesting their use either in DMFCs with high methanol feed concentrations or in mixed-reactant fuel cells. [Copyright &y& Elsevier]

In our work, the porous carbon nanosheets (PCNs) are successfully prepared using one-step activation and carbonization of the naturally hollow tube-like dandelion fluffs. The dandelion fluff with hollow tube structure is composed of aligned nanocellulose, enabling the facile activating agent (KOH) permeation, which can activate the dandelion fluff into porous interconnected carbon nanosheets. The obtained porous interconnected graphene-like structure of the activated carbon material contributes to the electrolyte permeation and electron transfer, which is beneficial to enhance the electrochemical performances, especially the rate capability. Manganese dioxide (MnO 2 ) modified PCNs composited with MnO 2 is prepared as the positive electrode for asymmetric supercapacitor using in-situ microwave deposition method. The conformally coated MnO 2 on PCNs can facilitate the ion diffusion and the electron transport, which contribute to the enhancement of the rate performance. Herein, the assembly asymmetric supercapacitor based on PCNs and MnO 2 /PCNs composite displays an energy density as high as 28.2 Wh kg −1 at the power density of 899.36 W kg −1 and a good capacitance retention of 89% after 10,000 cycles. These results present that the graphene-like cross-linked carbon material is a promising electrode material for high-efficiency electrochemical energy storage and conversion. [ABSTRACT FROM AUTHOR]

A new type of nanoporous carbon (NPC) was synthesized using dandelion pappus as a cost-effective carbon source through chemical activation with phosphoric acid. Notably, NPC is first considered to be used as an enhanced electrode material for the analysis of tryptophan (Trp). The high electrical conductivity of nanoporous carbon modified electrode (NPC/GCE) was better demonstrated by cyclic voltammetry using the ferricyanide system as a probe. Furthermore, the NPC/GCE exhibited an excellent electrocatalytic activity toward Trp oxidation with a decreased overpotential and improved current response, mainly due to the porous structure and large specific surface of nanoporous carbon. The electrocatalytic oxidation mechanism of Trp at the modified electrode was also investigated by cyclic voltammetry. The amperometric response of NPC-based sensor is linear in the 1 μM to 103 μM concentration range and the sensitivity is 171.43 μA mM −1  cm −2 . The proposed sensor was also successfully applied to the determination of Trp in real samples, and the satisfactory recoveries were obtained. [ABSTRACT FROM AUTHOR]

Fe 3 O 4 nanospheres are synthesized by a solvothermal method with only one step under the assistance of surfactant. Fe 3 O 4 /C nanospheres are further fabricated by modifying Fe 3 O 4 nanospheres with glucose as carbon source. The crystalline structure and surface morphology are investigated by a combination of X-ray diffraction, Roman spectroscopy, transmission electron microscopy and scanning electron microscopy. The results suggest that cubic Fe 3 O 4 nanospheres are achieved, with a diameter around 200 nm. After the coating process, uniform carbon layer ~5 nm is formed on the surface of Fe 3 O 4 spheres. The electrochemical performances of prepared Fe 3 O 4 and Fe 3 O 4 /C nanospheres as anode materials for lithium-ion batteries are conducted via galvanostatic discharge/charge measurements and cyclic voltammetry. Under a current density of 100 mA g −1 , the Fe 3 O 4 /C nanospheres exhibit a delithiation capacity of 767.2 mAh g −1 over 100 cycles with excellent capacity retention of 98.2% and improved rate capacities, both of which are better than those of Fe 3 O 4 nanospheres. This work demonstrates that the prepared Fe 3 O 4 /C nanospheres can be a promising anode material for lithium ion batteries. [ABSTRACT FROM AUTHOR]

The 1 × 1 magnesium octahedral molecular sieve (Mg-OMS-7), utilizing as cathode material in aqueous rechargeable magnesium ions batteries, is synthesized by a simple one-step hydrothermal method. Meanwhile, by changing the concentrations of H 2 SO 4 , the Mg-OMS-7 materials with controllable size and shape are obtained. To check the structure and morphology, the host materials are measured by X-ray power diffraction, scanning, transmission and high-resolution transmission electron microscopy. The electrochemical reaction mechanism is examined by cyclic voltammetry and X-ray photoelectron spectroscopy. The Mg-OMS-7 changes the morphology from micro-rugby to nano-club by controlling the concentrations of H 2 SO 4 . The nano-club Mg-OMS-7 which obtained by the 1.6 mol dm − 3 H 2 SO 4 owns a more uniformly distribution and smaller size, which provides the shorter route for magnesium ions insert/deinsert into/from the lattice of host material and exhibits the better rate ability and cycle performance. The initial discharge capacity of this electrode can obtain 283.1 mAh g − 1 at the current density of 10 mA g − 1 in the 0.2 mol dm − 3 Mg(NO 3 ) 2 aqueous electrolyte and the specific capacity retention rate is 94.1% after cycling 200 cycles at 100 mA g − 1 in the 0.5 mol dm − 3 Mg(NO 3 ) 2 electrolyte. [ABSTRACT FROM AUTHOR]

Petal shaped Co/Co 3 O 4 composite electrocatalyst with a special structure used as a cathode for H 2 O 2 electroreduction is obtained by a route of hydrothermal synthesis and in-situ chemical reduction. The phase composition and microstructure of the electrocatalyst are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Electrochemical performance of H 2 O 2 electroreduction on the Co/Co 3 O 4 petals (Ps) is explored by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectrometry (EIS). The Co/Co 3 O 4 Ps exhibits a higher conductivity than single Co 3 O 4 , which leads to a better catalytic activity and stability toward H 2 O 2 electroreduction. In a solution of 3 mol L − 1 NaOH and 0.5 mol L − 1 H 2 O 2 , the current density of H 2 O 2 electroreduction on Co/Co 3 O 4 Ps is 440 mA cm − 2 at − 0.8 V, higher than that on Co 3 O 4 , which make the obtained Co/Co 3 O 4 Ps an excellent alternative catalyst for H 2 O 2 fuel cell. [ABSTRACT FROM AUTHOR]

Designing and fabricating self-supported and binder-free MnO 2 nanostructure electrode to overcome their low conductivity for supercapacitor application with high comprehensive electrochemical performance, such as high capacitance, excellent stability, and good rate capability, is still a tremendous challenge. In this paper, carbon nanotubes are uniform covered on nickel foam (denote as CNT/Ni) by a simple dip & dry method to form a 3D skeleton for MnO 2 nanosheets deposition (denoted as MnO 2 -CNT/Ni). Results show the MnO 2 -CNT/Ni electrode exhibits a unique 3D porous interconnected network with a high specific capacitance of 402.5 F g − 1 at 1 A g − 1 and a favorable cycling performance that 83% capacitance retained after 5000 cycles at a current density of 2 A g − 1 . Meanwhile, the MnO 2 -CNT/Ni//CNT/Ni asymmetric supercapacitor exhibits an excellent energy density of 25 Wh kg − 1 at a power density of 0.9 kW kg − 1 with 85.3% capacitance retention after 5000 cycles. Therefore, such a facile and manageable method to prepare MnO 2 electrode with high supercapacitor performance is offering a promising future for practical applications. [ABSTRACT FROM AUTHOR]

Ni foam supported Co 3 O 4 nanoflakes is prepared for battery-type supercapacitor application through a simple three-step route. In briefly, Co metals are first deposited on Ni foam with a nanosheet morphology. The CoC 2 O 4 protrudes out from the surface of Co through an in-situ reaction with H 2 C 2 O 4 to form dendritic-like nanowires morphology. Finally, Co 3 O 4 are obtained through thermal decomposition of the CoC 2 O 4 precursor and the dendritic-like nanowires morphology is melting and transforming into a nanoflakes morphology. The unique architectures morphology with porosity and interconnected channels has great advantages since it can effectively increases the contact surface area with electrolyte, which could significantly not only enhances surface area but also the ion/electron diffusion. Electrochemical tests show that Co 3 O 4 nanoflakes exhibit a high specific capacity up to 576.8 C g − 1 at a current density of 1 A g − 1 and remain 283.7 C g − 1 capacity at a high current density of 50 A g − 1 , as well as 82% capacitance retained after 5000 cycles. These above results demonstrate the great potential of Co 3 O 4 nanoflakes in the development of battery-type supercapacitors. [ABSTRACT FROM AUTHOR]

Ni foam supporting flower-like Co nano-particles (Co NFs/Ni foam) are successfully synthesized by a simple electrochemical method. The electrodes are characterized by scanning electron microscopy equipped with an energy dispersive X-ray spectrometer, and X-ray diffractometer. Without any conducting carbons and polymer binders, the 3D electrode with a unique structure is directly used as the noble metal-free catalyst for hydrazine oxidation and the catalytic performance is evaluated by voltammetry and chronoamperometry. The Co NFs/Ni foam electrode exhibits excellent catalytic performance and superior stability for hydrazine electrooxidation in alkaline media. In the solution of 1.0 mol L − 1 NaOH + 30 mmol L − 1 N 2 H 4 , the oxidation current density at − 0.8 V is 140 mA cm − 2 for the Co NFs/Ni foam electrode, and it is only 42 mA cm − 2 for the Pt/Ni foam electrode. Also, the onset potential for Co NFs/Ni foam electrode can reach to − 1.06 V (only − 0.72 V for Ni foam), suggesting that the high cell voltage of DHFC with Co NFs/Ni foam anode. These merits are benefitting from the unique 3D structure which can ensure high utilization of catalysts. [ABSTRACT FROM AUTHOR]

In this work, Au nanoparticles directly grown on the surface of TiO 2 core-C shell (Au/C@TiO 2 ) has prepared by a simple electrodeposition method for the first time. The morphology is characterized by scanning electron microscope, and its structure is investigated by X-ray diffraction. Au nanoparticles are uniformly distributed on the surface of C@TiO 2 nanowire array. Its catalytic performance for NaBH 4 oxidation is evaluated by cyclic voltammetry and chronoamperometry measurement. The results indicate that Au/C@TiO 2 shows a good and stable catalytic performance. In 2 mol cm −3 NaOH and 0.2 mol cm −3 NaBH 4 the oxidation current density for the electrooxidation of BH 4 − can reach 475 mA cm −2 at 0 V. The electrons transfer number released by BH 4 − electrooxidation on Au/C@TiO 2 electrode has been found to be a 6-electron process. The high performance is mainly attributed to its 3D structure which can promote the mass transport of NaBH 4 , electronic conductivity and Au utilization. [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]

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]

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: [•] Cd(OH)2 nanowires was directly grown on nickel foam via a simple template-free method. [•] Cd(OH)2 nanowires exhibits a high specific capacitance of is 1164.8Fg−1 at 1Ag−1 in 6moldm−3 KOH solution. [•] The as-prepared Cd(OH)2 nanowires has potential applications in electrochemical capacitors. [Copyright &y& Elsevier]

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]

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]

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]

Bimetallic oxide CoMn 2 O 4 with nano-peony structure is prepared on Ni foam by a traditional hydrothermal process. Then constant-potential electrodeposition is applied to anchor Pd nanoparticles on CoMn 2 O 4 to form an electrode of Pd nanoparticles modified CoMn 2 O 4 (PCMN electrode) for H 2 O 2 electroreduction. The combination of Pd and CoMn 2 O 4 effectively reduces the dosage of noble metal. Besides, no binder is involved in the preparation which cuts the electrode cost and avoids the poor stability of traditional electrodes produced with binders. Scanning electron microscopy, X-ray diffraction and transmission electron microscopy are operated to investigate the structure and composition of the electrode. And the electrochemical behavior of the electrode is characterized by cyclic voltammetry and chronoamperometry. In 0.7 mol L−1 H 2 O 2 and 3 mol L−1 NaOH, a reduction current density of 580 mA cm−2 (normalized by geometric area) at −0.8 V on the electrode is obtained which reveals large capacity for actual application in H 2 O 2 -based fuel cell. A binder-free electrode of Pd nanoparticles anchored to nano-peony CoMn 2 O 4 was prepared and the synergy effect of Co, Mn and Pd highly improved the catalytic activity toward H 2 O 2 reduction. Unlabelled Image • Pd modified CoMn 2 O 4 electrode with special nano-peony structure was synthesized. • The special nano-peony structure provides more active sites for H 2 O 2 reduction. • The synergy effect of Co, Mn and Pd highly improved the catalytic activity. [ABSTRACT FROM AUTHOR]

Lithium-ion capacitors (LICs) by combines the virtues of lithium-ion batteries and supercapacitor have received intensive attention owing to their preeminent energy density, outstanding power density and uncompromised cycle life. However, the practical application of LICs has been greatly hampered by the lack of efficient anode materials. Herein, a facile strategy including hydrothermal reaction and subsequent thermal calcination has been carefully designed for constructing MnO porous spheres with a N-doped carbon coated layer (MnO@N-C). The resultant MnO@N-C electrode delivers a high capacity of 903 mA h g−1 and excellent cyclic performance with 96.2% capacity retention after 1000 cycles. Furthermore, the assembled MnO@N-C//AC LICs displays an excellent energy density of 125.3 Wh kg−1 and superior power density of 19.9 KW kg−1, as well as long cyclic lifetime of 5000 cycles with 83.2% capacity retention, outperforming those of recently reported metal oxide based LICs. Image 1 • MnO@N-C is obtained through a hydrothermal reaction and subsequent thermal calcination. • The MnO@N-C displays a high capacity of 903 mA h g−1 and outstanding stability with 96.2% capacity retention. • The assembled MnO@N-C//AC LICs reveals an excellent energy density of 125.3 Wh kg−1. [ABSTRACT FROM AUTHOR]

MnO 2 is regarded as an ideal material of supercapacitor since its low-cost, environment friendly and high specific capacitance but hindered by its poor electrical conductivity. Developing a composite electrode that combines nano-structure MnO 2 with a conductive skeleton such as carbon materials could make up for the shortcomings. Here, porous activated carbon (PAC) is synthesized by using low-cost wheat bran as biomass carbon precursor and a mixture of NaCl/ZnCl 2 as combined solvent-porogen. The resultant PAC sample presents a hierarchical porous structure and large specific surface area up to 1058 m2 g−1. Afterwards, MnO 2 nanosheets decorated PAC (MnO 2 @PAC) is prepared via an in-situ hydrothermal deposition. It is a key finding that the ion/electron transfer kinetics of MnO 2 @PAC could be effectively improved by the addition of hierarchical porous carbon. Thus, the MnO 2 @PAC electrode displays a high specific capacitance (258 F g−1 at 1 A g−1) and superior rate performance (82.8% capacitance retention with the current density ranging from 1 A g−1 to 20 A g−1). Furthermore, an asymmetric supercapacitor is assembled by employing the MnO 2 @PAC as the positive electrode and PAC as negative electrode, which exhibits a high energy density of 32.6 Wh kg−1 and as well as 93.6% capacity retention at over 10,000 charge/discharge cycles. • Porous activated carbon (PAC) is synthesized by a controllable molten salt method. • MnO 2 nanosheets were deposited on the PAC through a simple hydrothermal reaction. • The MnO 2 @PAC displays high specific capacitance and outstanding stability. • The PAC//MnO 2 @PAC asymmetric supercapacitor exhibits energy density of 32.6 Wh kg−1. [ABSTRACT FROM AUTHOR]