In this work, we report a facile top-down approach to fabricate uniform single-crystal α-Fe(2)O(3) nanodiscs via selective oxalic acid etching. Phosphate ions are employed as a capping agent to control the etching to along the [001] direction. We also show that α-Fe(2)O(3) melon-like microparticles with contrasting textural properties can be generated using the same approach. The etched particles exhibit a much larger total pore volume and average pore size compared to the pristine ones, thus serving as the possible origin for their greatly enhanced capacity retention when tested as potential anode materials for lithium-ion batteries.

We report an environment-friendly approach to synthesize transition metal oxide nanoparticles (NPs)/reduced graphene oxide (rGO) sheets hybrids by combining the reduction of graphene oxide (GO) with the growth of metal oxide NPs in one step. Either Fe2O3 or CoO NPs were grown onto rGO sheets in ethanol solution through a solvothermal process, during which GOs were reduced to rGO without the addition of any strong reducing agent, e.g. hydrazine, or requiring any post-high-temperature annealing process. The GO or rGO during the precipitation of metal oxide NPs may act as heterogeneous nucleation seeds to facilitate the formation of small crystal grains. This may allow more efficient diffusion of Li ions and lead to high specific capacities. These metal oxide NPs-rGO hybrids were used as anodes for Li-ion batteries, which showed high capacities and excellent charge-discharge cycling stability in the voltage window between 0.01 and 3.0 V. For example, Fe2O3 NPs/rGO hybrids showed specific capacity of 881 mA h g(-1) in the 90th cycle at a discharge current density of 302 mA g(-1) (0.3 C), while CoO NPs/rGO hybrids showed a lower capacity of 600 mA h g(-1) in the 90th cycle at a discharge current density of 215 mA g(-1) (0.3 C). These nanohybrids also show excellent capacities at high C rate currents, e.g. 611 mA h g(-1) for Fe2O3/rGO sample in the 300th cycle at 2014 mA g(-1) (2 C). Such synthesis technique can be a promising route to produce advanced electrode materials for Li-ion batteries.

Hierarchical NiS hollow spheres assembled from ultrathin nanosheets are synthesized by an efficient template-engaged conversion method. Silica nanospheres were used as templates, and SiO 2 @nickel silicate core-shell nanostructures were first prepared. In the presence of Na 2 S, the nickel silicate shell completely transformed into NiS nanosheets via a hydrothermal treatment, accompanied by the total dissolution of the inner SiO 2 core. This gives rise to uniform hollow nanospheres whose shells are assembled from ultrathin NiS nanosheets. In virtue of the large surface area and enhanced structural stability, the asprepared NiS hollow spheres exhibit excellent electrochemical performance as electrode materials for supercapacitors.

In this work, we report a facile approach for the shape-controlled synthesis of cobalt carbonate/ hydroxide intermediates. Three different structures, viz., one-dimensional (1D) needle-like nanorods, two-dimensional (2D) leaf-like nanosheets, and three-dimensional (3D) oval-shaped microparticles, have been synthesized through varying experimental parameters such as precursor (cobalt acetate) concentrations and volume ratio of polyethylene glycol to water. Phase-pure tricobalt tetroxide (Co 3 O 4 ) has been obtained by annealing these as-prepared intermediates without significant alterations in morphology. With relatively high specific surface areas of 86.1-121.5 m 2 g À1 , these products with distinct nanostructures were tested for their potential application in supercapacitors. The results show that these porous Co 3 O 4 structures exhibit promising capacitive properties with high capacitance and good retention. The needle-like nanorods show the highest capacitance of 111 F g À1 , and 88.2% of which can still be maintained after 1000 charge-discharge cycles.

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One‐dimensional (1D) hierarchical structures composed of Ni3S2 nanosheets grown on carbon nanotube (CNT) backbone (denoted as CNT@Ni3S2) are fabricated by a rational multi‐step transformation route. The first step involves coating the CNT backbone with a layer of silica to form CNT@SiO2, which serves as the substrate for the growth of nickel silicate (NiSilicate) nanosheets in the second step to form CNT@SiO2@NiSilicate core‐double shell 1D structures. Finally the as‐formed CNT@SiO2@NiSilicate 1D structures are converted into CNT‐supported Ni3S2 nanosheets via hydrothermal treatment in the presence of Na2S. Simultaneously the intermediate silica layer is eliminated during the hydrothermal treatment, leading to the formation of CNT@Ni3S2 nanostructures. Because of the unique hybrid nano‐architecture, the as‐prepared 1D hierarchical structure is shown to exhibit excellent performance in both supercapacitors and photocatalytic H2 production.

Uniform carbon-coated MoO(2) nanospheres assembled from small primary nanocrystals have been synthesized by a one-pot hydrothermal method followed by thermal annealing. Because of the desirable structural features, these core-shell MoO(2)@carbon nanospheres exhibit significantly improved electrochemical performance for high-rate reversible lithium storage.