Ag-AgO decorated multi-walled carbon nanotubes/NiCoAl hydrotalcite sensor for trace nitrite quantification.

Ag-AgO-decorated multiwall carbon nanotube/NiCoAl-hydrotalcite (CNT/LDH-Ag) composites were designed and synthesized for nitrite quantification. The materials were characterized by various techniques, and their electrochemical NO detection performances investigated using amperometric and differential pulse voltammetry (DPV) techniques. The Ag-AgO nanoparticles (NPs) were anchored on the surface of the CNT/LDH-Ag composites. At a suitable amount of the Ag-AgO loading, the Ag-AgO NPs with small particle size were distributed evenly on the CNT/LDH surface, increasing the surface area of the composites. The optimal CNT/LDH-Ag composite exhibited a high electrochemical activity for NO oxidation in pH 7.0. Furthermore, the optimal CNT/LDH-Ag composite was fabricated for trace NO quantification. The proposed sensor displayed a high sensitivity (0.0960 μA·μM·cm) and fast response (< 3 s) toward NO in a wide linear range from 0.250 μmol·L to 4.00 mmol·L with a low detection limit of 0.0590 μmol·L(S/N = 3). The sensor provided an outstanding analytical performance with a desirable recovery (95.3 ~ 107%, RSD < 1.05%) in real sample. As a result, the proposed sensor can be used for the real-time quantification of trace NO in the biological, food, and environmental fields.