Skillfully manipulating electron transitions of Au nanoparticles for the modulation of nanozyme functions

Nowadays, great progress has been achieved in improving the activity of nanozymes, nevertheless there are still huge challenges to skillfully modulate the catalytic functions of nanozymes. Herein, a nanozyme (CZIF/Au) is synthesized by chemically depositing Au nanoparticles (NPs) on a pyrolyzed zeolitic imidazolate framework-8 (CZIF). Surprisingly, the CZIF/Au presents enhanced peroxidase-like activity when irradiated with a 655 nm laser and improved catalase-like properties under 808 nm laser irradiation. The catalytic mechanisms of the CZIF/Au were investigated. Energy levels reveal that the 655 nm laser triggers the collective oscillation of the electrons in the 6sp band of Au NPs, called the intraband transition, whereas the 808 nm laser excites the valence electrons in the 5d band of the Au NPs into the 6sp band, named the interband transition, associated with a photothermal effect. The different electron transitions result in the two different photocatalytic functions. CZIF/Au with peroxidase-like performance to detect hydrogen peroxide (H2O2) exhibits an excellent detection limit (0.35 μM) and a wide detection range (2.5–500 μM). The molecular-level insights into the photocatalytic reactions provide a strategy to regulate the properties of nanozymes and prospects for the multi-faceted use of nanozymes in the future.