Exquisite Enzyme-Fenton Biomimetic Catalysts for Hydroxyl Radical Production by Mimicking an Enzyme Cascade.

Hydrogen peroxide (H2O2) is a key reactant in the Fenton process. As a byproduct of enzymatic reaction, H2O2 can be obtained via catalytical oxidation of glucose using glucose oxidase in the presence of O2. Another oxidation product (gluconic acid) can suitably adjust the microenvironmental pH contributing to the Fe3+/Fe2+ cycle in the Fenton reaction. Enzymes are extremely efficient at catalyzing a variety of reactions with high catalytic activity, substrate specificity, and yields in living organisms. Inspired by the multiple functions of natural multienzyme systems, an exquisite nanozyme-modified α-FeOOH/porous carbon (PC) biomimetic catalyst constructed by in situ growth of glucose oxidase-mimicking Au nanoparticles and crystallization of adsorbed ferric ions within carboxyl into hierarchically PC is developed as an efficient enzyme-Fenton catalyst. The products (H2O2, ∼4.07 mmol·L-1) of the first enzymatic reaction are immediately used as substrates for the second Fenton-like reaction to generate the valuable •OH (∼96.84 μmol·L-1), thus mimicking an enzyme cascade pathway. α-FeOOH nanocrystals, attached by C-O-Fe bondings, are encapsulated into the mesoporous PC frameworks, facilitating the electron transfer between α-FeOOH and the PC support and greatly suppressing iron leaching. This study paves a new avenue for designing biomimetic enzyme-based Fenton catalysts mimicking a natural system for •OH production.