Nanoporous nickel hydroxide (Ni(OH)2) thin film was grown on the surface of ultrathin-graphite foam (UGF) via a hydrothermal reaction. The resulting free-standing Ni(OH)2/UGF composite was used as the electrode in a supercapacitor without the need for addition of either binder or metal-based current collector. The highly conductive 3D UGF network facilitates electron transport and the porous Ni(OH)2 thin film structure shortens ion diffusion paths and facilitates the rapid migration of electrolyte ions. An asymmetric supercapacitor was also made and studied with Ni(OH)2/UGF as the positive electrode and activated microwave exfoliated graphite oxide ('a-MEGO') as the negative electrode. The highest power density of the fully packaged asymmetric cell (44.0 kW/kg) was much higher (2-27 times higher), while the energy density was comparable to or higher, than high-end commercially available supercapacitors. This asymmetric supercapacitor had a capacitance retention of 63.2% after 10,000 cycles.

In this report, NiCo2O4 nanostructures with different morphologies were directly grown on conductive substrates (stainless steel and ITO) by a facile electrodeposition method in addition to a post-annealing process. The morphology changes on different conductive substrates are discussed in detail. The NiCo2O4 on stainless steel (SS) had a high surface area (119 m(2) g(-1)) and was successfully used in the electrocatalytic oxidation of methanol. The electrocatalytic performance was investigated by cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS) measurements. Impressively, the NiCo2O4 showed much higher electrocatalytic activity, lower overpotential and greater stability compared to that of only NiO or Co3O4 synthesized by the same method. The higher electrocatalytic activity is due to the high electron conductivity, large surface area of NiCo2O4 and the fast ion/electron transport in the electrode and at the electrolyte-electrode interface. This is important for further development of high performance non-platinum electrocatalysts for application in direct methanol fuel cells.

Graphene has been successfully modified with palladium nanoparticles in a facile manner by reducing palladium acetate [Pd(OAc) 2 ] in the present of sodium dodecyl sulfate (SDS), which is used as both surfactant and the reducing agent. The palladium nanoparticle-graphene hybrids (Pd-graphene hybrids) are characterized by highresolution transmission electron microscopy, atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and energy dispersive X-ray spectroscopy. We demonstrate that the Pd-graphene hybrids can act as an efficient catalyst for the Suzuki reaction under aqueous and aerobic conditions, with the reaction reaching completion in as little as 5 min. The influence of the preparation conditions on the catalytic activities of the hybrids is also investigated.

Single and binary metal oxides based on conversion reactions for Li-ion batteries are discussed in this review.

Cathode materials mainly include transition metal oxide compounds, [11][12][13][14][15] polyanionic compounds, [16][17][18][19][20][21][22][23] Prussian blue analogues, and organic materials. [24][25][26][27][28] Among the various cathode materials for SIBs, polyanion-based cathode materials possess stable 3D host framework structure due to strong covalent bonding of oxygen atom in the polyanion polyhedra, resulting in their excellent thermal stability and long cycle life. [29] More importantly, this open 3D framework could provide enough interstitial channels for Na + transit and buffer severe volume change during Na + insertion/extraction. Particularly, NaVPO 4 F has attracted a great deal of interests owing to the low-cost raw materials, safe application, and high working potential. NaVPO 4 F was first proposed by Barker et al., [30] which possesses a tetragonal symmetry structure (space group I4/mmm). The crystal structure is consistent with the sodium aluminum fluorophosphate (Na 3 Al 2 (PO 4 ) 2 F 3 ). When used as cathode for Na-ion batteries, it delivered a discharge capacity of 82 mA h g −1 . However, the capacity faded more than 50% after 30 cycles. To improve the cyclability and rate performance, many strategies, including coating with conductive materials, fabricating pores, and doping alien ions have been attempted. [31][32][33] Although these attempts improve the electrochemical property of NaVPO 4 F in a certain degree, the capacity of the reported NaVPO 4 F materials is far below its theoretical specific capacity and still could not meet the application requirements in Na-storage. The root problem is traditional technology for preparing NaVPO 4 F mainly based on the high-temperature solid-state reaction, sol-gel method, and hydrothermal method, which often produce bulk or micrometer-sized NaVPO 4 F particles with insufficient carbon coating, leading to rapid capacity fading since this structure is unfavorable to electron transfer and the permeation of electrolyte. [31,32,34] Hence, it is significant to enhance the kinetics of Na-ion transfer in NaVPO 4 F. In order to achieve this goal, strategies mainly include decreasing the crystallite size and altering morphology of the material. [7,22,35,36] As far as we know, electrospinning is a versatile technique to prepare various 1D carbon-containing composites and produce flexible membrane, [6,8,[37][38][39] which encourages us to fabricate NaVPO 4 F with novel morphology combined the method of electrospinning to improve its electrochemical performance.Herein, we first synthesized 1D NaVPO 4 F/C nanostructure via an electrospinning method. Such a structure combines a variety of advantages for battery electrodes: (I) the small nanoparticles (≈6 nm) shorten the length of Na-ion transport; (II) NaVPO 4 F has received a great deal of attention as cathode material for Na-ion batteries due to its high theoretical capacity (143 mA h g −1 ), high voltage platform, and structural stability. Novel NaVPO 4 F/C nanofibers are successfully prepared via a feasible el...