Novel (CH 6 N 3 + , NH 3 + )-functionalized and nitrogen doped Co 3 O 4 thin film electrochemical sensor for nanomolar detection of nitrite in neutral pH

Abstract

The present work provides a soft chemical route for simultaneous nitrogen doping and (CH 6 N 3 + , NH 3 + )- functionalization of pre-deposited Co 3 O 4 thin film. The Co 3 O 4 thin film was prepared by metal-organic decomposition (MOD) on fluorine-doped tin oxide (FTO) substrate and hydrothermally treated in the presence of amino acid, L-Arginine. The L-Arginine-treated Co 3 O 4 thin film (L-Arginine/Co 3 O 4 /FTO) was used for the electrochemical detection of nitrite under neutral pH condition. Various physical (i.e. XRD, XPS, SEM, and Raman spectroscopy) and electrochemical characterization (i.e. CV, CA, EIS, and Tafel slope) was conducted to elucidate the role and effect of L-Arginine on Co 3 O 4 film and determine the sensor per- formance characteristics. L-Arginine/Co 3 O 4 /FTO electrode exhibited a low limit of detection of 1.95 nM, an ultrafast response time of < 2 s, and a wide linear range of up to 16 mM in neutral pH. The sensor was nitrite selective in the presence of common interferants and showed chemical stability and reproducibil- ity. The practical application of the proposed sensor was demonstrated using real samples for nitrite detection.