Scalable synthesis and characterization of cobalt sodium tartrate nanowires with adjustable diameters

Cobalt sodium tartrate nanowires are synthesized by a simple hydrothermal method using ethanol–water mixed solvents. The smooth wires are on average 30 μm long. Their diameters are narrowly size distributed with a controllable average in the range from 80 to 250 nm. Interestingly, after the initial two hours, the diameter decreases with further reaction time. The tartrate anions act as coordination ligands with all six oxygen atoms participating in the coordination. The Co2+ and Na+ ions chelate with the O atoms from the carboxylate and hydroxyl groups in the tartrate ligands. The ethanol participates in the formation of pi bonds. The cobalt is divalent while the sodium is monovalent in their tartrates. The respective crystal structures of these metal tartrates are incompatible, and the wires are therefore amorphous. The influence of the reaction time, sodium tartrate concentration, pH value, and the ethanol water ratio are studied in detail.