The phase transformation from MOF to hierarchical catalysts and their non-enzymatic glucose sensing performance

Abstract Herein, Co-MOF arrays were used as a precursor to fabricate hierarchical catalysts. Heterostructure Co-MOF/Co(OH) ₂ and Co(OH) ₂ micro–nano sheet arrays were fabricated by etching treatment in ultrapure water for different time. When treated for 60 min, infrared spectrum and x-ray diffraction (XRD) pattern indicate that there is the co-existence of Co-MOF and Co(OH) ₂ . After etching for 120 min, the scanning electron microscopy image reveals three-dimensional hierarchical micro–nano sheet arrays, the energy dispersive x-ray spectrum and XRD analysis indicate pure Co(OH) ₂ phase with high crystallinity. Their glucose sensing performance is systematically explored by cyclic voltammetric and amperometric i – t curves. The linear ranges of Co-MOF/Co(OH) ₂ and Co(OH) ₂ micro–nano sheet arrays are 0.05–2.2 mM ( R ² = 0.999) and 0.05–5.8 mM ( R ² = 0.999), their corresponding sensitivities are 1040 μ A mM ⁻¹ cm ⁻² and 884 μ A mM ⁻¹ cm ⁻² , respectively. Good glucose sensing performance of Co(OH) ₂ micro–nano sheet arrays is attributed to its unique three-dimensional array structure which guarantees the sufficient diffusion of electrolyte and effective contact between glucose molecule and active sites. Further, the obtained hierarchical Co(OH) ₂ electrode possesses good selectivity, stability, repeatability and practical detection ability.