Maximizing Accessible Fe-N-C Sites on Highly Curved Surfaces via Chemical Vapor Deposition for Boosting...

Single-atom nanozymes (SAzymes) have emerged as a highly promising class of next-generation nanozymes. However, their widespread application remains significantly restricted by low reaction activity, primarily attributed to inefficient site utilization and sluggish reaction kinetics. Herein, we provided a novel approach to maximize accessible Fe-N-C sites on a highly curved surface (hFeSA) through chemical vapor deposition. This innovative catalyst demonstrated superior multienzyme-like activities compared to the conventional single iron atom catalyst (FeSA) with planar Fe-N₄ sites. Specifically, for peroxidase-like activity, the hFeSA exhibited a maximal reaction velocity of 1.91 × 10^-7 M s^-1, a catalytic constant of 5.78 s^-1, and a specific activity of 177.5 U mg^-1, which were 9.67-, 2.56-, and 9.56-fold higher than those of the conventional FeSA, respectively. Similarly, for oxidase-like activity, the hFeSA achieved a maximal reaction velocity of 2.84 × 10^-7 M s^-1, a catalytic constant of 4.3 s^-1, and a specific activity of 76.27 U mg^-1, representing enhancements of 11.73-, 3.11-, and 12.01-fold over FeSA, respectively. These results underscore the significant advantages of hFeSA in dramatically enhancing multienzyme-like activities. Furthermore, theoretical calculations revealed that single iron atoms anchored on curved surfaces can effectively lower the energy barrier, thereby enhancing the intrinsic activity of the Fe-N₄ sites and accelerating reaction kinetics.