Anion-tuning in cobalt chalcogenides for a comparative study on electro-oxidation of glucose

Electronic structure modulation is of great important to enhance the electrocatalytic ability for glucose oxidation and follow up the electrochemical sensing performance. In this work, Co3X4 (X = O, S, Se) synthesized by oxidation, sulfurization and selenylation of ZIF-67 precursor, respectively, are served as electrocatalysts and then modified on conductive indium tin oxide (ITO) to construct sensing electrodes. The Co3S4/ITO electrode shows a highest sensitivity of 1109.9 μA−1 mM−1 cm−2 when compared with those of the Co3Se4/ITO electrode (515.9 μA−1 mM−1 cm−2), Co3O4/ITO electrode (227.7 μA−1 mM−1 cm−2), and even the relative reported sensing electrodes, enabling more efficient electro-oxidation of glucose by S substitution in Co3X4. The experimental characterization and theoretical calculation elucidate that tuning the anion components in cobalt chalcogenides can modulate their electrochemical active surface area, hydrophilicity, electrical conductivity and binding energies for glucose adsorption, in turn, the electrocatalytic ability. This work provides not only an effective strategy for performance improvement but also a significant understanding of how the anion component of electrocatalyst affect their glucose oxidation ability.