Dual-confinement regulating ternary metal-oxide activity sites derived from Co-MOF for enhanced electrocatalytic activity for glucose oxidation

Based on a dual-confinement strategy on a cobalt-metal-organic framework (Co-MOF), a series of trimetallic-oxide catalysts of Cux-O-Niy-O-Co3-x-y (x/y = 1/1, 1/3, 1/5 and 1/7) were developed for glucose oxidation. By chemical confinement regulation of ion exchange, diverse metal catalytic sites of Cu2+ and Ni2+ were introduced into Co-MOF, respectively; Then by spatial confinement synthesis of pyrolysis, trimetallic MOF of CuxNiyCo3-x-y-MOF was transformed into trimetallic-oxide of Cux-O-Niy-O-Co3-x-y, which maintained the regular morphology and highly ordered lattice structure of Co-MOF. The Cux-O-Niy-O-Co3-x-y composite modified glassy carbon electrode (Cux-O-Niy-O-Co3-x-y/GCE) exhibited enhanced electrocatalytic activity towards glucose oxidation when compared with Co-MOF/GCE, bimetallic MOFs of CuCo-MOF/GCE and NiCo-MOF/GCE, trimetallic MOF of CuxNiyCo3-x-y-MOF/GCE, as well as monometallic oxide Co3O4/GCE, bimetallic oxide of CuCo2O4/GCE and NiCo2O4/GCE, which was mainly due to the synergistic catalysis of electrocatalytically active Co-O-Cu-O-Ni bridges. With Cu2+/Ni2+ molar ratio of 1/3, Cux-O-Niy-O-Co3-x-y/GCE (x/y = 1/3) displayed excellent sensing behaviours on glucose detection. This work not only designed well-performed electrocatalysts for enhancing catalytic activity towards glucose oxidation, but also provided a new perspective to realize the controlled preparation of high-performance electrocatalysts.