Electrochemical approach to the surface characterization of mechanochemically synthesized alumina-supported cobalt applicable in glucose sensing

Abstract

The main goals of this study are: i) employ the electrochemical methods as alternative methods for alumina-supported cobalt (Co-A) surface characterization; ii) investigate the electro-catalytic activity of different cobalt phases toward glucose, and iii) implement the mechanochemical approach for the synthesis of the fourth generation of glucose sensing materials. Co3O4 and alumina were either manual grinded (Co3O4-A) or ball-milled (CoAl2O4-A) with different amounts of cobalt in CoAl2O4-A. The final products were characterized by XRF, LDPSA, XRD and TPR. The electrodes were prepared in the form of the carbon paste electrode and tested in supporting electrolyte (1 M NaOH) as well as in a glucose-containing solution. The CV, EIS, and chronoamperometry were used for electrochemical measurements. TPR revealed the formation of CoAl2O4 during the ball milling process. Different cobalt phases significantly affected the electrochemical responses. Higher activity of CoAl2O4-A toward glucose oxidation in comparison with Co3O4-A was ascribed to tetrahedral Co2+ ion acting as the active site in glucose oxidation. In addition, results convinced employing the scarcely employed mechanochemical synthesis protocols for obtaining glucose-sensing materials. Finally, it was proven that electrochemical techniques can be harnessed as alternative, new, powerful methods for Co-A surface characterization.