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 O-2. 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 multi-enzyme systems, an exquisite nanozyme-modified alpha-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, similar to 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 center dot OH (similar to 96.84 mu mol.L-1), thus mimicking an enzyme cascade pathway. alpha-FeOOH nanocrystals, attached by C-O-Fe bondings, are encapsulated into the mesoporous PC frameworks, facilitating the electron transfer between alpha-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 center dot OH production.