Construction of a bimetallic MOF-derived nanozymes with enhanced peroxidase-like activity for colorimetric detection of hydroquinone.

Hydroquinone (HQ) is a typical toxic phenolic pollutant that can severely disrupt the ecological balance of aquatic ecosystems and threaten human health. Therefore, it is imperative to develop simple and portable analytical techniques for the rapid on-site monitoring of HQ in aquatic environments. Here, the carbon-supported cobalt-nickel oxide nanozymes (CoNiOx@C) with enhanced peroxidase-like activity was synthesized using a CoNi bimetallic metal-organic framework (CoNi-MOF) as a precursor followed by annealing process. The significantly enhanced peroxidase-like activity of CoNiOx@C was derived from the synergistic effect of highly exposed Co/Ni-O-C bimetallic active sites and the in situ constructed carbon layer network, which effectively overcomes the inherent performance limitations of conventional nanozymes. Meanwhile, a catalytic signal amplification strategy was proposed based on the peroxidase-like mimetic mechanism of CoNiOx@C and the reducibility of the phenolic hydroxyl group, enabling the colorimetric detection of HQ. The colorimetric sensor developed showed good linearity in the range of 0-200 μM, with a detection limit as low as 0.068 μM. Interestingly, a portable visual detection platform was developed by integrating paper-based chips with smartphone, which achieves the sensitive the detection of HQ in real water samples. This study not only provides a facile synthetic route for MOF-derived bimetallic nanozymes but also offers a new approach for the development of low-cost, easy-to-operate visual on-site detection strategies.