Highly efficient ˙OH generation in Fenton-like reactions over a bioinspired manganese single-atom site

Abstract

Enhancing the catalytic activity of a Fenton-like process is of great significance in the field of hydroxyl radical (˙OH) induced oxidation reactions. The isolated Mn center in natural enzymes, including Mn superoxide dismutase and Mn peroxidase, can effectively trigger the electron transfer process for oxygen-containing species activation. In this work, via anchoring Mn single-atom sites on a nanodiamond (ND) surface, a bioinspired Mn₁/ND single-atom catalyst has been successfully prepared. Multiple state-of-the-art characterization results indicated that the Mn₁/ND catalyst possessed enzyme-like Mn₁–N₄ sites on the onion-like ND surface. In the meantime, the electronic structure of Mn species over Mn₁–N₄ sites was revealed with a +2 oxidation state. Kinetic experiment and DFT calculation results demonstrated that hydrogen peroxide (H₂O₂) can be strongly adsorbed over the above-mentioned Mn₁(II)–N₄ site and can be easily activated to produce ˙OH. On this basis, the Mn₁/ND catalyst achieved superior activities in ˙OH-induced 3,3′,5,5′-tetramethylbenzidine oxidation and pollutant degradation. This work provides a bionic approach over supported metal-based catalysts to achieve highly efficient ˙OH generation in Fenton-like reactions.