# ZIF-9-Derived Cobalt and Nitrogen-Doped Carbon Nanocomposites for Sensitive Electrochemical Nitrite Determination

## TL;DR

Researchers created a highly sensitive sensor for detecting nitrite using a carbon material derived from ZIF-9, which offers excellent performance and stability.

## Contribution

A novel electrochemical sensor using ZIF-9-derived cobalt and nitrogen-doped carbon with optimized calcination temperature for nitrite detection.

## Key findings

- The sensor achieved a detection range of 0.2–7000 μM with a sensitivity of 848.6 μA mM−1 cm−2.
- It had a low detection limit of 50 nM and retained over 80% of its initial response after extended storage.
- The material's performance is attributed to its graphitization degree, surface area, and active cobalt sites.

## Abstract

The accurate monitoring of nitrite levels is critically important for safeguarding public health and ensuring food safety, as excessive intake presents severe risks. In this study, we developed a highly sensitive electrochemical sensor for nitrite detection utilizing a cobalt-embedded porous carbon material derived from zeolitic imidazolate frameworks (ZIFs) of ZIF-9. The precursor was subjected to pyrolysis at various temperatures, revealing that the sample carbonized at 800 °C (ZIF-9-800) exhibited superior electrocatalytic performance. This enhancement is attributed to its optimized graphitization degree, high specific surface area, and the well-dispersed active sites resulting from the in situ generated cobalt nanoparticles. The ZIF-9-800-based sensor demonstrated outstanding electrochemical performance, achieving a broad linear detection range of 0.2–7000 μM, high sensitivity (848.6 μA mM−1 cm−2), and an impressively low detection limit of 50 nM. Furthermore, the sensor exhibited excellent selectivity in the presence of common interfering ions and remarkable long-term stability, maintaining more than 80% of its initial response after extended storage. This work underscores the effectiveness of MOF-derived carbon-based catalysts, tailored through calcination temperature optimization, for constructing advanced electrochemical sensing platforms.