Solid solution F-MnxCo3-xO4 ultrathin nanosheets: Highly active and selective catalyst for oxidation of 5-hydroxymethyl furfural

Abstract

Ultrathin nanosheets (F-MnCo) with a thickness of ∼1.7 nm are synthesized by incubation of NaF, Co(CH3COO)2, and KMnO4 in aqueous solution at room temperature. F-MnCo is comprised of the self-assembled CoOOH and Co(OH)F nanocrystals and highly dispersed MnO2. Through the calcination at 230 °C, CoOOH and Co(OH)F are pyrolyzed to form F-Co3O4, with manganese being concomitantly embedded in the lattice of F-Co3O4. The synthesized F-MnxCo3-xO4 is a solid solution, exhibiting a structure of ultrathin nanosheets with a thickness of ∼1.1 nm. F-MnxCo3-xO4 has been applied as catalyst for the oxidations of 5-hydroxymethyl furfural (HMF) and alcohols, exhibiting an excellent catalytic activity and a high aldehyde selectivity. The ultrathin nanosheets can facilitate mass transfer of reactants and provide more open active sites. High proportion of surface lattice oxygen, abundant oxygen vacancy, excellent oxygen mobility, and uniformly embedded manganese in the lattice also contribute to F-MnxCo3-xO4 exhibiting the excellent catalytic activity.