Silver Ion-Facilitated Singular Poulos–Kraut Mechanism of O–O Heterolysis to Enhance the Light Activation of H₂O₂ over Peroxidase-Mimicking Photonanozymes

Abstract

The Poulos–Kraut heterolytic O–O cleavage mechanism is essential for natural peroxidases to activate H2O2. Current existing peroxidase-mimicking nanozymes, including photonanozymes (PNZs), however, are generally believed to prefer the Fenton-type mechanism of O–O homolysis, which produces •OH radicals. Here, Ag+ ions are introduced into TiO2 PNZs to boost the hot hole-driven O–O heterolysis for the expedited H2O2 activation in the peroxidase-like photonanozymatic reaction while inhibiting the Fenton-type O–O homolysis. The Ag+-facilitated Poulos–Kraut heterolytic O–O cleavage mechanism for H2O2 activation is explicated in terms of the speedy capture and exhaustion of photogenerated electrons by Ag+ and the dissociation of the peroxo-oxygen bridge in Ti–O–OH promoted by accumulated hot holes. Moreover, the enhanced photonanozymatic activity of TiO2 PNZs enables the construction of a rapid colorimetric sensing platform for Ag+ determination. This work provides valuable insights into the mechanism of H2O2 activation and exemplifies a novel photoregulation strategy for controlling reaction pathways in nanozymes.

Bioinspired Surface Ligand Engineering Regulates Electron Transfers in Gold Clusterzymes to Enhance the Catalytic Activity for Improving Sensing Performance

“…In this structure, electrons can move from the metal core to the catalytic center of Fe-N 4 , enabling an effective ET process from AuSG-Fe-TCPP to H 2 O 2 . This ET process of AuSG-Fe-TCPP results in a higher H 2 O 2 reduction ability and promotes the O–O homolysis of H 2 O 2 to generate more •OH for the oxidation of ABTS. , …”