Open AccessMetalloenzyme-Inspired Ce-MOF Catalyst for Oxidative Halogenation Reactions
Author(s) -
Sergio RojasBuzo,
Patricia Concepción,
José Luis OlloquiSariego,
Manuel Moliner,
Avelino Corma
Publication year - 2021
Publication title -
acs applied materials and interfaces
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 2.535
H-Index - 228
eISSN - 1944-8252
pISSN - 1944-8244
DOI - 10.1021/acsami.1c07496
Subject(s) - catalysis , terephthalic acid , halogenation , redox , fourier transform infrared spectroscopy , x ray photoelectron spectroscopy , metal organic framework , materials science , nanoclusters , chemistry , inorganic chemistry , photochemistry , adsorption , chemical engineering , organic chemistry , nanotechnology , polyester , engineering
The structure of UiO-66(Ce) is formed by CeO 2- x defective nanoclusters connected by terephthalate ligands. The initial presence of accessible Ce 3+ sites in the as-synthesized UiO-66(Ce) has been determined by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR)-CO analyses. Moreover, linear scan voltammetric measurements reveal a reversible Ce 4+ /Ce 3+ interconversion within the UiO-66(Ce) material, while nanocrystalline ceria shows an irreversible voltammetric response. This suggests that terephthalic acid ligands facilitate charge transfer between subnanometric metallic nodes, explaining the higher oxidase-like activity of UiO-66(Ce) compared to nanoceria for the mild oxidation of organic dyes under aerobic conditions. Based on these results, we propose the use of Ce-based metal-organic frameworks (MOFs) as efficient catalysts for the halogenation of activated arenes, as 1,3,5-trimethoxybenzene (TMB), using oxygen as a green oxidant. Kinetic studies demonstrate that UiO-66(Ce) is at least three times more active than nanoceria under the same reaction conditions. In addition, the UiO-66(Ce) catalyst shows an excellent stability and can be reused after proper washing treatments. Finally, a general mechanism for the oxidative halogenation reaction is proposed when using Ce-MOF as a catalyst, which mimics the mechanistic pathway described for metalloenzymes. The superb control in the generation of subnanometric CeO 2- x defective clusters connected by adequate organic ligands in MOFs offers exciting opportunities in the design of Ce-based redox catalysts.