Electrocatalytic behavior of pillared montmorillonite-supported cobalt oxide doped with Cu, Zn, Fe, and Ni for glucose sensing

Abstract

Aluminum pillared montmorillonite-supported cobalt (Co/AP) has proven to be a suitable non-enzymatic sensing material (Mudrinić, 2019). Beside low cost, Co/AP exhibited adequate electrocatalytic performance toward glucose. However, further improvements of electrocatalytic performances are needed, especially regarding increasing sensitivity and widening the linear range of glucose detection. In this regard, in addition to the monometallic cobalt oxide catalyst, a series of bimetallic catalysts supported on AP (Co+Cu/AP, Co+Zn/AP, Co+Fe/AP, and Co+Ni/AP) have been synthesized by the incipient wetness impregnation method (Pinna, 1998). The total amount of supported metal was fixed at 4 mass%, while cobalt:dopant molar ratio was 9:1 for all samples. The synthesized materials were prepared in the form of carbon paste electrode (Co+dopant/AP-CPE) with the same mass ratio of Co+dopant/AP to carbon black (CB) and applied as a working electrode. All the electrochemical measurements of each Co+dopant/AP-CPE were conducted using an Autolab PGSTAT302N potentiostat with Nova 2.1 software. The experiments were carried out in a three-electrode cell with prepared electrodes as working, Ag/AgCl (3 M KCl) as a reference electrode, and platinum rod as a counter electrode. Electrochemical behavior of the working electrodes for glucose detection was studied by the cyclic voltammetry and chronoamperometry in alkaline solution, with and without glucose. Among investigated electrodes for glucose electrooxidation, the Co+Fe/AP-CPE exhibited the highest current response with the best sensitivity. These very first results indicated a vital role of Fe in enhancing the glucose-sensing performance of aluminum pillared montmorillonite-supported cobalt. The physical chemical characterization of all Co+dopant/AP materials is ongoing.