Facile synthesis of Ni nanofoam for flexible and low-cost non-enzymatic glucose sensing

• We present a novel nanostructure, called Ni nanofoam.
• The Ni nanofoam is grown using aqueous solutions at room temperature.
• By employing Ni nanofoam we fabricated a non-enzymatic glucose sensor with excellent performances.
• Flexible and highly sensitive glucose sensors have been produced with Ni nanofoam on a plastic substrate.

A novel Ni nanofoam electrode has been fabricated by low-cost methods and applied for non-enzymatic glucose sensing. Ni(OH)2 nanowalls, prepared by room-temperature chemical bath deposition, were transformed into an ensemble of Ni nanoparticles (20–30 nm in size) upon annealing in forming gas at 350 °C, and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), temperature programmed reduction with hydrogen (H2-TPR) and surface area measurements. The Ni nanofoam was converted to the catalytic Ni(OH)2/NiOOH – necessary for non-enzymatic glucose oxidation – by cyclic voltammetry (CV) in NaOH electrolyte. The electrode fabricated on conducting glass substrate showed a glucose sensitivity of 2.37 mA/cm2 mM, a linear range of 0.01–0.7 mM, a limit of detection (LOD) of 5 μM, a fast response time (1 s), and resistance to chloride poisoning. The glucose sensor also exhibited an excellent long-term stability (4% decrease in sensitivity after 64 days) and selectivity in the presence of common interfering species. The versatility of the preparation method was demonstrated in the fabrication of a flexible (plastic substrate) sensor with a sensitivity of 1.43 mA/cm2 mM. The ease of fabrication and the excellent properties of Ni nanofoam in glucose sensing make it promising for low-cost and wearable sensing applications.