One-step synthesis of three-dimensional Co(OH)2/rGO nano-flowers as enzyme-mimic sensors for glucose detection

Highlights: • A flower-like Co(OH)₂/rGO nano-composite film was in-situ prepared by a facile hydrothermal method. • This architecture can effectively capture OH⁻ to mimic the function of glucose oxidase under a very low alkali environment. • The as-prepared biosensor shows ultrahigh sensitivity at a very wide range of alkali concentration from 5 × 10⁻³ M to 1 M. Currently, most metal oxides- or hydroxides-based and non-enzymatic sensors require a high alkali concentration in the working environment. Here, we designed a novel non-enzymatic sensor based on a 3D nanostructured Co(OH)₂/rGO film to address this issue. The architecture of the hybrid film was in-situ constructed by the dense assembly of 200 nm flower-like Co(OH)₂ crystals bridged by rGO nanosheets. This structure possessed an extremely large specific surface area and an excellent conductivity which were beneficial for adsorbing OH to produce oxidative CoOOH or CoO₂, even in a low alkaline condition. This material was able to mimic the functionality of glucose oxidase to oxidize glucose to gluconolactone and exhibited a good sensitivity at a wide alkaline range from 5 × 10⁻³ to 1 mol L⁻¹ NaOH solution. Moreover, this sensor showed a wide linear range, excellent selectivity, reproducibility and stability for real blood analysis.