Chain-mail NCNT encapsulated CoCu NPs coupled with 3D wrinkled graphitized carbon: a high-efficiency platform for electrochemical nitrite detection

Hierarchical CoCu/CoO carbon matrix is formed via ion-impregnation-pyrolysis method. • NCNTs-encapsulated CoCu and GC-anchored CoO form rich electrochemical catalytic sites. • CoCuNCNT/CoO-GC shows high sensitivity and 0.8 s fast response for nitrite sensing. • The sensor exhibits excellent anti-interference capability and long-term stability. • The sensor quantifies nitrite precisely in real samples via standard addition method. This work proposed a hierarchical hybrid metal/carbon material fabricated via metal ion wet impregnation using a MOF precursor, followed by high-temperature pyrolysis. The resulting architecture features intertwined, chain-mail-like network of intertwined nitrogen-doped carbon nanotubes (NCNTs) encapsulating CoCu nanoparticles (NPs), which is integrated into three-dimensionally (3D) wrinkled graphitized carbon (GC) layers decorated with crosslink CoO NPs. Due to the synergistic effect between CoCu/CoO active sites, porous structures and conductive carbon matrix, the resultant CoCuNCNT/CoO-GC-2 composite modified glassy carbon electrode (GCE) sensor exhibits a high electrochemical sensitivity of 1445 µA·cm −2 ·mM −1 and a rapid response time of 0.8 s toward nitrite ion. It also demonstrates a remarkably low limit of detection (LOD) of 1.56 µM, wide linear ranges of 10–1000 µM and 1000–4000 µM, as well as excellent anti-interference and long-term stability. Moreover, the practical applicability of the sensor was demonstrated by determining nitrite in drinking water, lemon tea, tap water, and lake water using the standard addition method. This work provides valuable insights into designing high-performance nitrite-oxidizing electrochemical sensors with multi-functional catalytic sites. Download: Download high-res image (133KB) Download: Download full-size image