Biomimetic design of graphdiyne supported hemin for enhanced peroxidase-like activity

摘要

Effective electronic interactions between molecular catalysts and supports are critical for heterogeneous enzyme mimics, yet they are frequently neglected in most catalyst designs. Taking the enzyme mimics of hemin immobilized on graphdiyne (Hemin-GDY) as an example, we explicate for the first time the underlying role of GDY as a co-catalyst. Based on the robust conjugation between GDY and hemin, the delocalized pi-electrons in GDY act as a ligand for Fe ions so that the orbital interactions including electron transport from GDY -> Fe can induce the formation of an electron-rich Fe center and an electrondeficient pi-electron conjugated system. This mechanism was validated by electron paramagnetic resonance (EPR), Raman spectroscopy, and DFT calculations. Moreover, both EPR spetra and Lineweaver-Burk plots revealed that Hemin-GDY could efficiently catalyze the decomposition of hydrogen peroxide (H2O2) to produce hydroxyl radical (center dot OH) and superoxide anion (O-2(center dot-)) by a ping-pong type catalytic mechanism, and particularly, the catalytic activity was increased by 2.3-fold comparing to that of hemin immobilized on graphene (Hemin-GR). In addition, Hemin-GDY with the exceptional activity and stability was demonstrated for efficient catalytic degradation of organic pollutants under acidic conditions. Collectively, this work provides a theoretical basis for the design of GDY supported catalysts and renders great promises of the GDY based enzyme mimics. (C) 2021 Elsevier Inc. All rights reserved.