A colorimetric sensing platform based on MOF-derived hollow Co, N co-doped C with dual-enzyme mimetic activity for the highly sensitive detection of hexavalent chromium

Hexavalent chromium (Cr(VI)) poses serious risks to human health and ecological environment due to its high toxicity and non-biodegradability. Therefore, developing highly sensitive detection methods for Cr(VI) is of significant importance. Here, a colorimetric sensing platform based on hollow cobalt and nitrogen co-doped porous carbon (H-Co, NPC) was proposed for the sensitive detection of Cr(VI). H-Co, NPC was synthesized by high-temperature calcination of a ZIF-8@ZIF-67 precursor, and it exhibited excellent peroxidase-like and oxidase-like activities. The hollow structure significantly enhances the accessibility of active sites and facilitates mass transport, while the co-doping of Co and N effectively improves electron transfer capability and substrate affinity. These synergistic effects make H-Co, NPC a promising candidate for colorimetric sensing applications. The sensing platform demonstrated excellent detection capabilities toward Cr(VI), including low detection limit (5 nM), wide linear range (0.015-1.5 µM), outstanding reproducibility and anti-interference ability. Moreover, it exhibited satisfactory detection performance of Cr(VI) in real samples. This work would provide new insights into the development of highly sensitive colorimetric sensing platforms.