Ultrathin porous Pd metallene as highly efficient oxidase mimics for colorimetric analysis

Pd-based nanomaterials have shown great promise as promising mimic enzymes, but traditional catalysts can only expose only part of the active sites, resulting in low atomic utilization. Herein, we demonstrated that ultrathin Pd metallene with abundant accessible active sites could be served as highly efficient oxidase mimics. Due to their ultrathin porous structure, nearly all the Pd atoms of the Pd metallenezymes could be efficiently utilized during the catalytic process. By using the 3,3',5,5'-tetramethyl benzidine (TMB) as a typical chromogenic substrate, the Pd metallenezymes with excellent oxidase-like activity are successfully applied for some colorimetric-based analysis applications. Benefiting from the sensitive Pd metallene/TMB detection system, the TAC of some commercial beverages and vitamin C chewable pieces are proved to meet the description and the activity of alkaline phosphatase (ALP) was successfully detected in 0-20 U/L range, achieving a lowest detect limit of 0.41 U/L. This work provides not only one kind of novel nanozymes, but also an effective strategy to maximize the atom utilization as enzyme mimics.