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

Herein, Co-MOF arrays were used as a precursor to fabricate hierarchical catalysts. Heterostructure Co-MOF/Co(OH)₂and Co(OH)₂micro-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)₂phase with high crystallinity. Their glucose sensing performance is systematically explored by cyclic voltammetric and amperometrici-tcurves. The linear ranges of Co-MOF/Co(OH)₂and Co(OH)₂micro-nano sheet arrays are 0.05-2.2 mM (R²= 0.999) and 0.05-5.8 mM (R²= 0.999), their corresponding sensitivities are 1040μA mM^-1cm^-2and 884μA mM^-1cm^-2, respectively. Good glucose sensing performance of Co(OH)₂micro-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)₂electrode possesses good selectivity, stability, repeatability and practical detection ability.