High-loading Cu single-atom nanozymes supported by carbon nitride with peroxidase-like activity for the colorimetric detection of tannic acid

The design of nanozymes with high metal atom loading is of great significance to improve enzyme activity and is also the key to furthering the construction of highly sensitive colorimetric sensors. In this work, a colorimetric sensor for the quantitative analysis of tannic acid (TA) was developed based on two-dimensional carbon nano -sheet carbon nitride (CN)-supported Cu single-atom nanozymes (Cu/CN). Cu/CN was synthesized by supramo-lecular preorganization and calcination, with an ultrathin nanosheet structure and a high density of Cu active sites, with a Cu loading of up to 14.3 wt%. Benefiting from the above characteristics, Cu/CN exhibits peroxidase-mimicking activity and excellent catalytic performance. Therefore, a colorimetric sensor was constructed for the fast and sensitive quantitative analysis of TA with good linearity in the range of 0.09-3.2 mu M and a low detection limit of 30 nM. Furthermore, the sensor was successfully applied to the analysis of TA in tea samples of different varieties. This work sheds new light on the design of nanozymes with a high density of active sites and the analysis of TA in real environments.

Automated summary

This study developed a colorimetric sensor based on two-dimensional carbon nitride (CN)-supported Cu single-atom nanozymes (Cu/CN) for the quantitative analysis of tannic acid (TA). Cu/CN, synthesized by supramolecular preorganization and calcination, exhibited peroxidase-mimicking activity and excellent catalytic performance due to its ultrathin nanosheet structure and high density of Cu active sites (up to 14.3 wt%). The sensor demonstrated fast and sensitive quantification of TA in the range of 0.09-3.2 μM with a low detection limit of 30 nM. Furthermore, it was successfully applied to analyze TA in different varieties of tea samples. This work is of great importance for the design of nanozymes with high active site density and the analysis of TA in real environments.