The Nature of Molecular Hybridizations in Nanodiamonds for Boosted Fe(III)/Fe(II) Circulation
Kunsheng Hu, Peng Zhou, Yangyang Yang, Shuang Zhong, Xiaoguang Duan, Shaobin Wang
Abstract
Reducing agents have been frequently utilized as electron donors for Fe(II) generation to resolve the sluggish Fe(III) reduction in Fenton-like reactions, while their irreversible consumption necessitates a robust catalytic system that utilizes green electron donors such as H 2 O 2 . In this study, we used annealed nanodiamonds (NDs) as a collection of model catalysts with different sp 2 /sp 3 ratios to investigate the roles of the molecular structure in boosting the Fenton-like reactions. The annealed NDs acted as an electron mediator to transfer electrons from H 2 O 2 to surface-adsorbed Fe(III) for Fe(II) generation as well as an electron donor for direct Fe(III) reduction, driving Fe(II)-catalyzed H 2 O 2 decomposition to produce massive hydroxyl radicals, demonstrating potential in the real-water matrixes. Galvanic cell experiments show that the contribution ratio of mediation and electron donation is 2.75:1, indicating that the majority of Fe(II) was generated through electron transfer from H 2 O 2 . Additionally, different carbon configurations (sp–sp 2 –sp 3 hybridizations) were compared to assess the molecular structure-performance relationships in Fe(III) reduction. This study unveils the distinct functions of carbon molecular structures in driving Fe(III)/Fe(II) circulation and provides insights into sustainable Fenton oxidation driven by metal-free catalysis.