In this work, we have successfully grown single-crystalline nanoneedle arrays of NiCo₂O₄ on conductive substrates such as Ni foam and Ti foil through a simple solution method together with a post-annealing treatment. Remarkably, the NiCo₂O₄–Ni foam binder-free electrode exhibits greatly improved electrochemical performance with very high capacitance and excellent cycling stability.

Hollow hierarchical spheres self-organized from the ultrathin nanosheets of α-Fe₂O₃ were prepared by a simple process. These ultrathin nanosheet subunits possess an average thickness of around 3.5 nm and show preferential exposure of (110) facets. Their Li ion storage and visible-light photocatalytic water oxidation performance are tested. Such hierarchical nanostructures show high Li storage properties with good cycling stability and excellent rate capabilities. The water oxidation catalytic activity is 70 μmol h⁻¹ g⁻¹ for O₂ evolution under visible light irradiation and can be maintained for 15 hours. The structural features of these α-Fe₂O₃ nanocrystals are considered to be important to lead to the attractive properties in both Li storage and photocatalytic water oxidation, e.g. hollow interior, ultrathin thickness and largely exposed active facets.

Nanomaterials as anode for lithium-ion batteries (LIB) have gained widespread interest in the research community. However, scaling up and processibility are bottlenecks to further commercialization of these materials. Here, we report that bulk antimony sulfide with a size of 10-20[emsp14][mgr]m exhibits a high capacity and stable cycling of 800[emsp14]mAh g-1. Mechanical and chemical stabilities of the electrodes are ensured by an optimal electrode-electrolyte system design, with a polyimide-based binder together with fluoroethylene carbonate in the electrolyte. The polyimide binder accommodates the volume expansion during alloying process and fluoroethylene carbonate suppresses the increase in charge transfer resistance of the electrodes. We observed that particle size is not a major factor affecting the charge-discharge capacities, rate capability and stability of the material. Despite the large particle size, bulk antimony sulfide shows excellent rate performance with a capacity of 580[emsp14]mAh g-1 at a rate of 2000[emsp14]mA g-1.