Large-scale in situ synthesis and characterization of ternary single-crystal NaV6O15 nanoneedles

Ternary single-crystalline NaV6O15 nanoneedles were synthesized on a large scale by a novel in situ reaction–crystallization–etching process using bulk V2O5 powders and poly(styrene-alt-maleic acid) sodium salt (PSMA-Na) as raw materials and HF as a catalyst under hydrothermal treatment at 180 °C for 24 h. HF not only catalyzes the formation of NaV6O15 nanowires but also promotes the transition of nanowires to nanoneedles. The synthesized nanostructures appeared needle-shaped, with sharp tips about 3–50 nm in diameter and wide butts of tens to 250 nm at the other end, while the lengths of the nanoneedles normally ranged from 5 to ∼20 μm.