From Mn‐Triazine Crystalline Framework to <scp>MnO_<i>x</i></scp>@<scp>NC</scp>: Biomimetic Double‐Enzyme Activity and Labeling of Ascorbic Acid as Well as Application in Pharmaceuticals

Comprehensive Summary Imbalance in the levels of ascorbic acid (AA) can pose a risk to human health. Therefore, it's essential to establish an accurate method for the detection of AA. In this work, a novel N‐doped carbon composite (MnO x @NC) with dual enzyme‐like activities to detect AA was prepared by calcination of Mn‐MOF containing H 3 TTPCA ligand. Interestingly, the •O 2 − that leads to its oxidase‐like activity was not formed by dissolved oxygen, but came from the synergistic effect of lattice oxygen generated by calcination and the transformation of Mn II /Mn III /Mn IV , and the presence of H 2 O 2 provided much •OH, which caused its peroxidase‐like activity. Meanwhile, the residual N element came from H 3 TTPCA ligand assisted the catalytic process. Accordingly, a dual‐signal sensing platform and smartphone‐assisted recognition for detection of AA was developed and a colorimetric sensor array was established to distinguish three antioxidants. This work also demonstrates considerable promise for the detection of AA in authentic pharmaceuticals.