Mechanochemical approach for non-enzymatic sensing materials

Recently the focus of electrochemical glucose sensing is on the fabrication of enzyme-free electrodes based on non-precious transition metal oxides, especially cobalt oxide [1]. To our best knowledge, these materials were primarily prepared by conventional methods using solutions, while the solvent-free mechanochemical approach was scarcely reported. Therefore, in this work Co3O4 supported on alumina (Co3O4/Al2O3) were prepared by ball milling using different milling times (0.5, 1, and 2 h) and Co3O4 contents (4, 8, and 16 wt. %). Ball to powder ratio was 30:1 and the rotation speed was 300 rpm. The electrodes based on the synthesized material were prepared in the form of a carbon paste electrodes (CP-Co3O4/Al2O3). The particle size distribution, phase, and chemical composition of the obtained materials were determined using LDPSA, XRPD, and XRF, respectively. The electrochemical performance of the CP-Co3O4/A12O3 electrode was tested in an alkaline solution containing glucose using cyclovoltammetry (CV) and chronoamperometry (ChA). CV revealed that milling time affected the electrochemical response. The highest current response was obtained with material milled for 1 h. Both ChA and CV confirmed that the electrochemical performance was further improved by increasing cobalt content. The CP electrode-based mechanochemically prepared samples showed enhanced performance in comparison to hand mixed Co3O4 and alumina. The beneficial effect of ball milling was attributed to the high dispersion of cobalt oxides over alumina even for large cobalt loadings without agglomeration. The obtained experimental results proved that the solvent-free mechanochemical approach is a promising synthetic route for obtaining green and sustainable glucose-sensing material for the fourth generation.