Nanomolar level electrochemical sensing of explosive material sodium azide by a hexagonal boron nitride modified glassy carbon electrode

Abstract

In this work, for the first time, a solvent-exfoliated hexagonal boron nitride nanosheet (h-BNNS) has been employed for the electrochemical (EC) sensing of a hazardous primary azide (sodium azide, SA). Besides, this is the first time that a modified glassy carbon electrode (GCE) platform has been demonstrated for the EC sensing of SA. The h-BNNS made by exfoliating bulk h-BN in dilute NaOH, which exhibited stability for more than one year with a few layers of thickness, was utilized to drop cast on a GCE for the electrode. The h-BNNS/GCE showed a ∼25- and 20-fold increase in peak current compared to those of the corresponding controls: unmodified GCE and bulk h-BN/GCE for SA. The detection limit is in parts per trillion (0.1 nM, i.e., 6.5 ppt), is the lowest so far reported, and satisfactorily meets the sensitivity requirement for SA based on the U.S. Environmental Protection Agency prescribed safe limit. The sensing performance was successfully extended to environmental water samples such as ground-, tap-, and contaminated river water spiked with SA. Our results suggest that highly stable h-BNNS could open the way to a range of important applications of h-BN-based materials.