Electrocatalytic study of low-cost bimetallic cobalt/iron catalyst on carbon for non-enzymatic glucose sensor in human urine

Abstract

This study investigated an electrocatalytic behavior of non-enzymatic glucose detection in urine by using low-cost non-precious metal CoFe catalyst on carbon (C) supported. The bimetal catalyst was prepared by the reduction of oleic acid and loaded 10% wt. metal onto the activated carbon. Due to the synergistic effect, CoFe exhibited its intrinsic electrocatalytic property, suitable for the chemisorption of glucose molecule and the d-electron of metal. For morphology and elemental composition, CoFe/C was characterized by Transmission Electron Microscopy (TEM), and X-ray Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD), exhibiting Co(111) and Fe2O3(104) with the nanocluster average diameter of 25 nm. More importantly, electrocatalytic behaviors of CoFe/C were assessed by cyclic voltammetry (CV) and Differential Pulse Voltammetry (DPV) on the glassy carbon rotating disk electrode for glucose detection (0-3 mM) in modified artificial urine (mAUM), and human urine specimens. In particular, excellent sensitivities from the lower range of glucose level (< 1 mM) and the higher level by DPV in mAUM were estimated to be 318.42 and 82.20 µA.cm-2.mM-1 with the correlation coefficient (R2 ) values of 0.90 and 0.94, respectively. Furthermore, the as-prepared CoFe/C biosensor also demonstrated practical measurement in human urine sample with the sensitivity of 59.72 µA.cm-2.mM-1 (R2 = 0.99) without any electron facilitators (e.g. sodium hydroxide), thereby providing a promising cost-effective catalyst design for future technology of non-enzymatic glucose sensing applications in urine.