Regulation of Cobalt-Nickel LDHs' Structure and Components for Optimizing the Performance of an Electrochemical Sensor

Sensitivity, line range, and response time are key indices to evaluate the performance of an electrochemical sensor. The approach commonly used to improve electrochemical performance is to search for active materials with chemical components and structures. Herein, starting with Co-based zeolitic imidazolate framework (ZIF-67), we demonstrated a sacrifice template strategy to synthesize layered double hydroxides (Co_xNi_1-x-LDHs) with various microstructures and components. The structures of the obtained Co_xNi_1-x-LDHs were transformed gradually from yolk-shell to hollow via regulating the molar ratio of cobalt and nickel. The yolk-shell and hollow products were composed of ZIF-67/LDHs (Co_xNi_1-x-YSLDHs, x = 0.74, 0.52) and LDHs (Co_xNi_1-x-HLDHs, x = 0.33, 0.21), respectively. When products were further applied to the electrochemical glucose sensor, LDHs with hollow structure have better performance than yolk-shell structure because hollow structure own a shorter electron transfer pathway than yolk-shell structure. Meanwhile, for hollow structure LDHs, Co_0.33Ni_0.67-HLDH exhibited relatively higher responsive current than Co_0.21Ni_0.79-HLDH, probably due to its delicate structural and rational compositional merits. This work exhibits the potential of MOF derivative for designed formation of delicate structure and composition that can enhance the electrochemical performance of the sensor.