Nitrogen-doped graphene (N-graphene) is obtained by exposing graphene to nitrogen plasma. N-graphene exhibits much higher electrocatalytic activity toward oxygen reduction and H₂O₂ reduction than graphene, and much higher durability and selectivity than the widely-used expensive Pt for oxygen reduction. The excellent electrochemical performance of N-graphene is attributed to nitrogen functional groups and the specific properties of graphene. This indicates that N-graphene is promising for applications in electrochemical energy devices (fuel cells, metal–air batteries) and biosensors.

Redox flow batteries are receiving wide attention for electrochemical energy storage due to their unique architecture and advantages, but progress has so far been limited by their low energy density (~25 Wh l⁻¹). Here we report a high-energy density aqueous zinc-polyiodide flow battery. Using the highly soluble iodide/triiodide redox couple, a discharge energy density of 167 Wh l⁻¹ is demonstrated with a near-neutral 5.0 M ZnI₂ electrolyte. Nuclear magnetic resonance study and density functional theory-based simulation along with flow test data indicate that the addition of an alcohol (ethanol) induces ligand formation between oxygen on the hydroxyl group and the zinc ions, which expands the stable electrolyte temperature window to from −20 to 50 °C, while ameliorating the zinc dendrite. With the high-energy density and its benign nature free from strong acids and corrosive components, zinc-polyiodide flow battery is a promising candidate for various energy storage applications.

Nano-structured vanadium oxide (V₂O₅) is fabricated via a facile thermal-decomposition of vanadium precursor, vanadyl oxalate, which is produced by reacting micro-sized V₂O₅ with oxalic acid. The V₂O₅ nanoparticles produced by this method exhibit much better electrochemical performance than commercial micro-sized V₂O₅. The optimized-nanorod electrodes give the best specific discharge capacities of 270 mAh g⁻¹ at C/2 (147 mA g⁻¹) coupled with good cycle stability with only 0.32% fading per cycle. Even at a high rate of 4C (1176 mA g⁻¹), the nanorod electrode still delivers 198 mAh g⁻¹. These results suggest that the well-separated V₂O₅ nanorod is a good cathode material for high-rate lithium battery applications.