Preparation of hexagonal BN whiskers synthesized at low temperature and their application in fabricating an electrochemical nitrite sensor

Hexagonal boron nitride (h-BN) whiskers were synthesized via the polymeric precursor method using boric acid (H3BO3) and melamine (C3H6N6) as raw materials at 1073-1273 K in flowing nitrogen/hydrogen (5% hydrogen). The phase and morphology of the obtained products were characterized using XRD, FTIR, SEM, TEM and BET techniques. The results show that h-BN wishers can be successfully fabricated at 1073-1273 K with 0.5-3 mm diameters and 50-200 mu m lengths. They possess micropores and mesopores. Moreover, the as-prepared BN whiskers can be used as a sensing electrode for detection of nitrite (NO2-). Compared with other electrodes for nitrite detection, the h-BN wishers electrode shows a much higher sensitivity in the wider range from 10 to 1000 mu M, with a detection limit of 0.089 mu M (10-400 mu M) and 0.412 mu M (400-6300 mu M) (S/N = 3), respectively. The oxidation process of NO2 on the h-BN whiskers electrode is controlled by a diffusion process.