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Sustainable and green manufacturing of hard carbon (HC) material in a low-cost way is the key issue in promoting its industrial applications in Na-ion batteries (SIB). Nowadays, most synthesis ways to prepare HC need the help of chemical reagents to improve its Na-ion storage performance. Herein, we firstly developed a completely green biological fermentation technology to prepare HCs on a large scale using cheap and renewable carbon sources of various biomass starch. Pre-treatment by bio-fermentation can effectively modify the carbon precursor for facile pyrolysis to fabricate starch-based HCs, and make its internal microstructure with larger interlayer spacing, more disordered structure and abundant closed micropores. Finally, a case of cornstarch-based hard carbon exhibits a high reversible capacity of 335 mA h g−1 at a current density of 30 mA h g−1 and high rate performance with a reversible capacity of 140.6 mA h g−1 even at a high current of 5 A g−1 as well as long cycling stability. In-situ Raman spectra, ex-situ SAXS and ex-situ XPS tests during discharge and charge process reveal the pore filling mechanism of quasi-metallic Na in hard carbon anode. Such a "bread-making"strategy is a facile and scalable route to fabricate various starch-based hard carbons with improved performance, demonstrating a very practically promising application for industrial manufacture. • A green biological fermentation technology to prepare HCs is firstly developed. • Renewable carbon sources of various biomass starch derived HCs are achieved. • Bio-fermentation effectively improve interlayer spacing with abundant closed micropores. • HC with a reversible capacity of 335 mA h g−1 and long cycling stability is demonstrated. • Such a "bread-making" strategy is a scalable route to fabricate hard carbons at a kilogram. [ABSTRACT FROM AUTHOR]

Design and synthesis of non-precious-metal catalyst for efficient electrochemical transformation of water to molecular hydrogen in acid environments is of paramount importance in reducing energy losses during the water splitting process. Here, the hybrid material of MoS 2 -coated Cu loaded on the multi-walled carbon nanotubes (MWCNTs@Cu@MoS 2 ) was synthesized using chemical process and hydrothermal method. It was found that the participation of MWCNTs and Cu nanoparticles not only improved the electrical conductivity of the catalyst, but also further enhanced the catalytic activity by synergistic effect with edge-exposed MoS 2 -coating. Electrochemical experiments demonstrated that the catalyst exhibited excellent hydrogen evolution reaction (HER) activity with large cathode currents (small overpotential of 184 mV for 10 mA cm −2 current density) and a Tafel slope as small as 62 mV per decade. Furthermore, it was discovered that the current density of this composite catalyst had a little decrease after the continual 1000 cycling, which showed the catalyst had a high stability in the recycling process. These findings confirmed that this catalyst was a useful and earth-abundant material for water splitting. [ABSTRACT FROM AUTHOR]

The process of water splitting by using efficient non-precious-metal catalyst to make the process economically viable has brought forward an extensive research. In this study, the composite of Cu and MoS 2 on the reduced graphene oxide (rGO) (Cu–MoS 2 /rGO) with high catalytic activity toward hydrogen evolution reaction (HER) was easily synthesized using hydrothermal method and chemical process. It was found that the participation of rGO improved the electrical conductivity of the catalyst, and the MoS 2 nanoflowers (NFs) with a higher number of exposed edges exhibited higher HER activity. In addition, the addition of Cu particles could not only enhance the electrical conductivity of the catalyst, but also further improved the catalytic activity by synergistic effect with MoS 2 NFs. Electrochemical experiments demonstrated that the catalyst exhibited excellent HER activity with large cathode currents and a Tafel slope as small as 90 mV decade −1 . Furthermore, it was discovered that the current density of this composite catalyst had a little decrease after the continual 700 cycling, which showed the catalyst had a high stability in the recycling process. These findings confirmed that this catalyst was a useful and earth-abundant material for water splitting. [ABSTRACT FROM AUTHOR]

Abstract: A series of La–M–Cu–Zn–O (M = Y, Ce, Mg, Zr) based perovskite-type catalysts are prepared by sol–gel method and characterized by XRD, BET, TPR, N2O-adsorption, XPS and TPD techniques. The results indicate that all the catalysts exhibit La2CuO4 perovskite structure. The addition of Ce, Mg and Zr lead to smaller particles, lower reduction temperature, higher Cu dispersion, larger amount of hydrogen desorption at low temperature and more amount of basic sites. However, Y has less affects on the physicochemical properties. The catalysts derived from perovskite-type precursors show high selectivity for methanol, which is correlated with the Cuα+ species that exists in the reduced catalysts. More exposed Cu surface area is favorable for high CO2 conversion. [Copyright &y& Elsevier]

Abstract: In this paper, monodispersed LiFePO4 nanopillows have been successfully synthesized via solvothermal route with ethylene glycol (EG) as reaction medium. Subsequently, with the basis of the solvothermally synthesized monodispersed LiFePO4 nanopillows, monodispersed LiFePO4@C core–shell nanostructures are facilely prepared in high yield. Based on the experimental results, the formation mechanism of the monodispersed LiFePO4 nanopillows has been discussed simply. The monodispersed LiFePO4@C core–shell nanostructures exhibit nice capacity retention and high rate capacity due to the full carbon-coating and the well-crystallized nanosized particles. [Copyright &y& Elsevier]

Abstract: Asymmetric supercapacitor is constructed using hierarchical porous electrode materials of nickel oxide and carbon with the aim to facilitate ion transport. Hierarchical porous nickel oxide and carbon are prepared by template-directed synthesis. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charging–discharging are used to test the asymmetric supercapacitor and investigate the electrode processes at different supercapacitor voltages. The capacitance, energy density and power density of the asymmetric supercapacitor can be improved by elevating the supercapacitor voltage, and its cycling stability decays at high voltage, but the columbic efficiency stays close to 100%. [Copyright &y& Elsevier]

Abstract: A new type of CoO nanoparticles encapsulated by graphitable hollow carbon sphere (GHCS) composite material was synthesized. The core–shell structure CoO/GHCS composite shows the improved cyclability as an anodic material in Li-ion battery. The core–shell composite containing 50wt% CoO exhibits a reversible capacity of 584mAhg−1 at a constant current density of 100mAg−1 between 0 and 3.0V (vs. Li+/Li), and remains a capacity retention of 95% after 50th cycle. The improvement could be attributed to that the GHCS with a good electronic conductivity and high surface severs as dispersing medium to prevent CoO nanoparticles from aggregating, and provide the enough space to buffer the volume change during the Li-ion insertion and extraction reactions in CoO nanoparticles. [Copyright &y& Elsevier]

Mesoporous Ni(OH)2 is synthesized using sodium dodecyl sulfate as a template and urea as a hydrolysis-controlling agent. Mesoporous NiO with a centralized pore-size distribution is obtained by calcining Ni(OH)2 at different temperatures. The BET specific surface area reaches 477.7 m2 g-1 for NiO calcined at 250 °C. Structure characterizations indicate a good mesoporous structure for the nickel oxide samples. Cyclic voltammetry shows the NiO to have good capacitive behaviour due to its unique mesoporous structure when using a large amount of NiO to fabricate the electrode. Compared with NiO prepared by dip-coating and cathodic precipitation methods, mesoporous NiO with a controlled pore structure can be used in much larger amounts to fabricate electrodes and still maintain a high specific capacitance and good capacitive behaviour. [Copyright &y& Elsevier]

Hematite can be used as an efficient photoanode for solar water oxidation, but its oxygen evolution kinetics are quite slow. Herein, we developed an efficient hole transport photoanode via the in situ growth of ultrathin Fe-doped NiOOH on fluorine-doped hematite arrays using a natural growth strategy. The resulting FeNiOOH/F–Fe 2 O 3 photoanode showed a high charge separation and injection efficiency. It achieved a stable photocurrent density of 2.52 mA cm−2 at 1.23 V vs. RHE, which was approximately 4.1-fold higher than that of pristine α-Fe 2 O 3. Systematic studies revealed that the excellent photoelectrochemical activity was due to heteroatom doping and interactions between the co-catalyst (FeNiOOH) and F–Fe 2 O 3. Fe doping primarily changed the lattice strain of the co-catalyst, while F doping decreased surface charge recombination and enhanced the intrinsic conductivity of hematite by increasing the carrier density. An ultrathin, amorphous layer of FeNiOOH further accelerated photogenerated hole extraction and the water oxidation kinetics. This work provides a method to produce new, cost-effective photoanodes for clean hydrogen production. Image 1 • The photoanode is successfully prepared by a facile "natural growth" strategy. • The F-doped process can effectively reduce the surface electron trapping sites. • FeNiOOH plays a dual role to improve the PEC performance. • The novel photoanode presents fast charge transfer kinetics and stability. [ABSTRACT FROM AUTHOR]

Tin (Sn)-based materials are potential alternatives to the commercial graphite anode for next-generation Li-ion batteries (LIBs) due to their high theoretical capacity. However, the poor cyclic stability, originating from the large volumetric changes during charge/discharge process, hinder their practical utilization. Herein, we have successfully prepared a Sn-based metal-organic framework (MOF, Sn-PMA), and explored as potential anode materials in LIBs. Benefiting from its layered structure and efficient electron transport channels, Sn-PMA electrodes deliver a high initial capacity of 1567 mAh g−1, at 100 mA g−1, and maintained a reversible capacity of 707 mAh g−1, at 800 mA g−1, after 400 cycles. Furthermore, the detailed post-electrochemical structural, morphological and compositional analysis is carried out to unveil the structural changes and Li-ion storage mechanism of electrodes. Ex-situ XRD and XPS results revealed that, in Sn-PMA electrode, O atom, coordinated to the Sn atom, exhibited higher electronegativity, served as major Li-ion storage site and rendered excellent cyclic stability due to a stable structure. Kinetic analyses reveal that the excellent performance of the Sn-PMA is typical attributed to the pseudocapacitive contribution induced by the special porous structure. A Sn-based MOF has successfully prepared by hydrothermal reaction, which shows outstanding lithium storage properties. Image 1 • Sn-based MOF was fabricated through a simple hydrothermal reaction. • Sn-PMA exhibits excellent electrochemical performance with typical pseudocapacitive contribution. • Ex-situ XRD and XPS reveal the lithium storage mechanism of Sn-PMA. [ABSTRACT FROM AUTHOR]

Metal organic frameworks (MOF) derived carbonaceous materials have emerged as promising bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts for electrochemical energy conversion and storage. But previous attempts to overcome the poor electrical conductivity of MOFs hybrids involve a harsh high-template pyrolytic process to in situ form carbon, which suffer from extremely complex operation and inevitable carbon corrosion at high positive potentials when OER is operated. Herein, a self-assembly approach is presented to synthesize a non-precious metal-based, high active and strong durable Co-MOF@CNTs bifunctional catalyst for OER and ORR. CNTs not only improve the transportation of the electrons but also can sustain the harsh oxidative environment of OER without carbon corrosion. Meanwhile, the unique 3D hierarchical structure offers a large surface area and stable anchoring sites for active centers and CNTs, which enables the superior durability of hybrid. Moreover, a synergistic catalysis of Co(II), organic ligands and CNTs will enhance the bifunctional electrocatalytic performance. Impressively, the hybrid exhibits comparable OER and ORR catalytic activity to RuO 2 and 20 wt% Pt/C catalysts and superior stability. This facile and versatile strategy to fabricating MOF-based hybrids may be extended to other electrode materials for fuel cell and water splitting applications. [ABSTRACT FROM AUTHOR]

The catalytic activity of noble-metal nanoparticles (NPs) often has closely connection with their sizes and geometric shape. In the work, polyhedral NPs of palladium (Pd) with controlled sizes, shapes, and different proportions of {100} to {111} facets on the surface were prepared by a seed-mediated approach. Electrochemical experiment demonstrates that the catalytic performance of the Pd nanocubes (NCs) enclosed by {100} facets is more active than Pd octahedrons enclosed by {111} facets for the hydrogen evolution reaction (HER), which is consistent with density functional theory (DFT) calculation results. Meanwhile, with the assistance of a polyethyleneimine–reduced graphene oxide (PEI–rGO) support, the examined Pd cube/PEI–rGO 50:1 (10 wt. %) electrocatalyst presents outstanding HER activity comparable with that of commercial Pt/C catalyst. This correlation between the HER catalytic activity and surface structure will contribute to the reasonable design of Pd catalysts for HER with high efficiency and low metal loading. [ABSTRACT FROM AUTHOR]

Abstract: We report a simple strategy to prepare a hybrid of lithium titanate (Li4Ti5O12, LTO) nanoparticles well-dispersed on electrical conductive graphene nanosheets as an anode material for high rate lithium ion batteries. Lithium ion transport is facilitated by making pure phase Li4Ti5O12 particles in a nanosize to shorten the ion transport path. Electron transport is improved by forming a conductive graphene network throughout the insulating Li4Ti5O12 nanoparticles. The charge transfer resistance at the particle/electrolyte interface is reduced from 53.9Ω to 36.2Ω and the peak currents measured by a cyclic voltammogram are increased at each scan rate. The difference between charge and discharge plateau potentials becomes much smaller at all discharge rates because of lowered polarization. With 5wt.% graphene, the hybrid materials deliver a specific capacity of 122mAhg−1 even at a very high charge/discharge rate of 30C and exhibit an excellent cycling performance, with the first discharge capacity of 132.2mAhg−1 and less than 6% discharge capacity loss over 300 cycles at 20C. The outstanding electrochemical performance and acceptable initial columbic efficiency of the nano-Li4Ti5O12/graphene hybrid with 5wt.% graphene make it a promising anode material for high rate lithium ion batteries. [Copyright &y& Elsevier]

Abstract: An electrochemical process for modifying the pore-size distribution (PSD) of single-walled carbon nanotubes (SWNTs) is developed. The effect of electrochemical treatment time on the PSD of SWNTs is investigated, and the results show that such treatment provides an effective and controllable method for changing the PSD of SWNTs. In particular, a remarkable volume of the small mesopores in the 3.0–5.0nm diameter range is increased. The SWNTs treated for 24h at 1.5V have a higher specific surface-area (109.4m2 g−1) and larger volume of small mesopores (0.048cm3 g−1 in 3.0–5.0nm diameter range), compared with the as-grown SWNTs (46.8m2 g−1 and 0.026cm3 g−1, respectively). The as-grown SWNTs and the electrochemically-treated SWNTs are investigated as electrochemical capacitor electrodes, and it is found that the specific capacitance is increased three-fold after electrochemical treatment. [Copyright &y& Elsevier]

In this article, we propose a trilayer graphene/polypropylene/Al 2 O 3 (GPA) separator with dual function for high performance lithium–sulfur (Li–S) batteries. Graphene is coated on one side of polypropylene (PP) separator, which functions as a conductive layer and an electrolyte reservoir that allows for rapid electron and ion transport. Then Al 2 O 3 particles are coated on the other side to further enhance thermal stability and safety of the graphene coated polypropylene (GCP) separator, which are touched with lithium metal anode in the Li–S battery. The GPA separator shows good thermal stability after heating at 157 °C for 10 min while both GCP and PP separators showing an obvious shrinkage about 10%. The initial discharge specific capacity of Li–S coin cell with a GPA separator could reach 1067.7 mAh g −1 at 0.2C. After 100 discharge/charge cycles, it can still deliver a reversible capacity of as high as 804.4 mAh g −1 with 75% capacity retention. The pouch cells further confirm that the trilayer design has great promise towards practical applications. [ABSTRACT FROM AUTHOR]

Efficient and simple operation electrocatalysts for the oxygen evolution reaction (OER) are essential components of renewable energy technologies. Here, a novel, simple, and efficient routine is presented for the first time by constructing a high-efficiency anode catalyst for OER. With the aid of high intensity ultrasound, a uniformly loading, conductive multiwalled carbon nanotubes/metal/transition metal-oxide (CNTs-Au@Co 3 O 4 ) tubular hybrids is synthesized. In alkaline media, the materials catalyze OER with an onset potential of 1.56 V vs. reversible hydrogen electrode (RHE) and overpotential only of 350 mV to achieve a stable current density of 10 mA cm −2 for at least 25 h. The unusual catalytic activity and stability is due to the following elements. Firstly, the tubular architecture not only provides sufficient active centers for OER, but also improves rapid mass/charge transport. Secondly, Co 3 O 4 layer protects Au nanoparticles (NPs) against detachment. In addition, we also prove that the highest electronegativity metal Au accelerate the formation of catalytic active sites of Co IV species for OER. It is believed that this simple preparation method paves a way to fabricate a range of CNTs/metal/metal-oxide based composites as superior OER catalysts. [ABSTRACT FROM AUTHOR]

Abstract: One of the most attractive research areas in lithium-ion batteries (LIBs) is to design elaborate nanostructure of the electrode, which has been considered as keys to solve the problems such as the low energy density, slow lithium ion and electron transport, and the large volume change of electrode materials during cycling processes. Here, mesoporous Co3O4 with controllable structures was directly grown on a graphene membrane by hydrothermal reaction followed by annealing treatment, and used as an integrated anode in LIBs without using metallic current collector, binder and conductive additive. The light graphene membrane as current collector with high electrical conductivity and stability contributes to the high energy density of LIBs. A mesoporous structure with enough space is beneficial to lithium ion diffusion and strain buffer of Co3O4 during discharge/charge processes, rendering the electrodes high performance. The integrated electrode shows good rate capability and impressive cycling stability without capacity loss over 500 cycles under a high current density of 500 mA g−1. [Copyright &y& Elsevier]

Abstract: Nanocomposites of Mn3O4 nanoparticles and graphene (GR) nanosheets – Mn3O4@GR can be made by growing Mn3O4 nanoparticles directly on the surfaces of GR in solvothermal reactions. The asymmetric supercapacitors constructed with Mn3O4@GR as positive and activated carbon (AC) as negative electrodes, respectively, show highly enhanced performances in energy storage. It was found that the electrolytes employed in constructing electrodes of the devices can influence the performances of Mn3O4@GR supercapacitors dramatically. Compared to their energy density in KOH electrolyte, the devices exhibit improved charge storage performances in Na2SO4 electrolyte. Furthermore, the charge storage abilities of the devices are closely related to the amount of Mn3O4 nanoparticles loaded onto the surface of GR nanosheets. The performances of Mn3O4@GR//AC asymmetric supercapacitors can be optimized by carefully tailoring the composition of electrode materials and adjusting the electrolytes for making the devices. [Copyright &y& Elsevier]

Abstract: Free-standing and porous hierarchical nanoarchitectures constructed with cobalt cobaltite (Co3O4) nanowalls have been successfully synthesized in large scale by calcining three dimensional (3D) hierarchical nanostructures consisting of single crystalline cobalt carbonate hydroxide hydrate – Co(CO3)0.5(OH)·0.11H2O nanowalls prepared with a solvothermal method. The step-by-step decomposition of the precursor can generate porous Co3O4 nanowalls with BET surface area of 88.34 m2 g−1. The as-prepared Co3O4 nanoarchitectures show superior specific capacitance to the most Co3O4 supercapacitor electrode materials to date. After continuously cycled for 1000 times of charge–discharge at 4 A g−1, the supercapacitors can retain ca 92.3% of their original specific capacitances. The excellent performances of the devices can be attributed to the porous and hierarchical 3D nanostructure of the materials. [Copyright &y& Elsevier]

Abstract: Nanoporous copper (NPC), as a new kind of porous metal prepared by dealloying, is introduced into the lithium-ion battery as both the current collector and substrate of active material. The nanoporous copper has three-dimensional structure composed of large channels (hundreds of nanometers) and small pores (tens of nanometers) on the channel walls. Anodes were prepared by electroless depositing of a thin layer of tin on NPC and copper foil. By comparing the electrochemical performance of both electrodes, the nanostructured electrode exhibits much higher areal capacity and better Coulombic efficiency than planar electrode. [Copyright &y& Elsevier]

By designing the morphology and architecture of employed electrocatalysts, the development of high-performance hydrogen evolution reaction (HER) electrocatalysts for electrolytes with a wide pH range is practical significance for future energy conversion technologies. Herein, we synthesize an electrocatalyst composing of two-dimensional (2D) ultrathin ternary pyrite-type cobalt phosphosulfide nanosheets and conductive carbon black (CoPS NSs/C) by the one-step phosphosulfide process. Thanks to the introduction of the C, the composite not only presents a unique three-dimensional (3D) interconnected reticulum structure but also effectively reduces the thickness of nanosheets. The as-synthesized electrocatalyst exhibits remarkable small overpotential toward HER in wide pH range. Meanwhile, the electrocatalyst owns higher charge transfer rate and excellent stability. The good performance is mainly attributed to the combination of the advantages of both 2D nanosheets and 3D interconnected reticulum structure, which offers larger surface area, sufficient active sites and more contaction with electrolytes. This work provides a new method for preparing ultrathin ternary transition-metal phosphosulfide (TMPS) nanosheets, and offers a facile route for improving electrocatalytic activity by designing synergistic morphology of 2D and 3D. Image 1 • The electrocatalyst design strategy of synergistic 2D and 3D morphology is provided. • Synergistic 2D and 3D morphology engineering build novel interconnected network structure. • CoPS NSs/C with 3D structure constructed by 2D CoPS nanosheets is successfully prepared. • CoPS NSs/C electrocatalyst owns an intriguing HER activity over wide pH range. [ABSTRACT FROM AUTHOR]

Inspired by the successful application of spinel LiMn 2 O 4 cathode in Li-ion batteries, analogous spinel ZnMn 2 O 4 (ZMO) is regarded as a promising cathode for rechargeable aqueous Zn-ion batteries (ZIBs). Nevertheless, clear Zn2+ storage mechanism and phase transition of spinel ZMO is still scarce. Herein, in the first time, we report an in-situ Raman study in dynamically probing the phase and structure evolution of a spinel ZMO-based cathode during charging-discharging process, in which spinel ZMO nanoparticles are anchored on porous carbon polyhedrons (PCPs). By in-situ investigation, it is demonstrated that the electrochemical mechanism can be attributed to the highly reversible phase transformation between spinel ZMO and λ-type MnO 2 upon Zn2+ insertion/extraction, which is driven by stepwise oxidation and reduction reactions of Mn3+/Mn4+ along with efficient charge carriers. Furthermore, the resultant ZMO@PCPs composite as cathode delivers a large reversible capacity of 125.6 mAh g−1 at a high current density of 1 A g−1 after 2000 cycles, representing superior long-term cyclic stability (capacity retention of 90.3%) and remarkable rate capability in aqueous ZIBs. As a proof of concept, high-performance flexible aqueous ZIBs are fabricated and represent stable electrochemical performance under various deformation states, indicating their potential applications in portable and wearable electronics. • A 3D-confined spinel ZnMn 2 O 4 cathode is proposed for aqueous Zn-ion batteries (ZIBs). • Zn2+ storage mechanism is explored by in-situ Raman investigation in the first time. • Reversible phase change between ZnMn 2 O 4 and λ-MnO 2 upon Zn2+ insertion/extraction. • The resultant cathode represents superior electrochemical behaviors in aqueous ZIBs. • Flexible aqueous ZIBs show stable electrochemical performance at deformation states. [ABSTRACT FROM AUTHOR]