Needle-like Co3O4 nanoarrays as a dual-responsive amperometric sensor for enzyme-free detection of glucose and phosphate anion

The high cost and easy denaturation of natural enzymes under environmental conditions largely hinder their practical usefulness in sensing devices. Currently, great efforts have been focused on exploring of novel functional nanomaterials to replace natural enzymatic systems. In this study, we developed a hydrothermal growth of free-standing cobalt oxide (Co3O4) nanoneedle arrays on a flexible carbon cloth (CC) substrate and used them as electrode materials with a high catalytic activity for nonenzymatic glucose sensing. Benefiting from the densely arrayed and free-standing Co3O4 nanoneedles with a large surface area, the resulting Co3O4/CC electrode exhibits an excellent sensing performance for glucose with a broad linear range and low detection limit (0.23 μM). More importantly, the Co3O4/CC electrode also exhibited a good performance for determining phosphate ions in a glucose containing alkaline solution. Under optimal condition, the resulted electrode exhibits a linear range of 0.1–1.0 mM and 1.0–30.0 mM with a detection limit of 10 μM for phosphate anion. The as-proposed electrode was further used for the determination of glucose and phosphate ions in human blood serum and urine samples with satisfactory recoveries, verifying the feasibility and great potential as a sensitive, selective, potable, and low-cost electrochemical electrode in sensing application.