Interface Stabilization of Undercoordinated Iron Centers on Manganese Oxides for Nature-Inspired Peroxide Activation
By Yu, Li; Zhang, Gong; Liu, Chunlei; Lan, Huachun; Liu, Huijuan; Qu, Jiuhui
Published in ACS Catalysis
2018
Abstract
Coordinatively unsaturated metal centers constitute a key element in natural catalytic cycles. Construction of analogues of these ensembles on heterogeneous supports may aid in the innovative development of artificial catalysts showing efficient and stable reaction patterns. We herein stabilized naturally prevalent undercoordinated iron (UCI) centers on manganese oxides via the interface confinement effect between transition-metal oxides. The created heterostructure showed efficient activation of peroxy-bonds containing peroxymonosulfate (PMS) molecules, with aqueous organic contaminant oxidation efficacy several times that of reference metal oxides. The combined spectroscopic, electrochemical, and in situ measurement results revealed that these interfacial oxygen-deficient UCI sites not only benefited thermodynamically favored PMS accumulation but also facilitated surface-to-surface electronic communication across atomic interface-bonding channels, thus providing a feasible platform to give rise to highly oxidizing (Fe, Mn)-oxo intermediates. Such PMS-activating metal centers in transitional states were sequentially reduced via either direct oxidation of organic substrates or electrophilic attack of other PMS molecules, with reactive singlet oxygen (1O2) generation. This reaction pattern guaranteed preservation of the catalyst structure after the reversible redox cycle, enabling a stable, kinetics-enhanced catalytic process.