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

Herein, Co-MOF arrays were used as 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 (SEM) image reveals three-dimensional hierarchical micro-nano sheet arrays, the energy dispersive X-ray spectrum (EDS) and XRD analysis indicate pure Co(OH)2 phase with high crystallinity. Their glucose sensing performance is systematically explored by cyclic voltametric 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 (R2=0.999) and 0.05~5.8 mM (R2=0.999), their corresponding sensitivities are 1040 μA mM-1 cm-2 and 884 μA 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.