Ionic liquid-assisted synthesis of copper oxalate nanowires and their conversion to copper oxide nanowires

Copper oxalate nanowires were synthesized via the reaction of Cu(CH3COO)2·4H2O and oxalic acid in ethanol solution with the aid of 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4) ionic liquid under solvothermal conditions at 180 °C. The as-synthesized nanowires were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), thermogravimetric analysis and differential scanning calorimetric analysis (TG-DSC). The length of the nanowires reaches ∼10 μm, and the width ∼30 nm, giving an aspect ratio of a few hundreds. The formation of the nanowires follows a novel mechanism based on the reorganization of a copper oxalate solid phase. The copper oxalate nanowires can further transform from a dense structure (enclosed by a smooth surface) into highly porous CuO nanowires consisting of interconnected nanocrystallites.