Tunable Synthesis of CoP and CoP2 Decorated 3D Carbon Nanohybrids and the Application of CoP2 Decorated One in Electrochemical Detection of Chloramphenicol in Milk and Honey

Cobalt phosphides embedded in electrocatalysts with low Co/P ratio have recently garnered a great deal of attention due to their high catalytic activities. However, compared to the studies on Co2P and CoP based catalysts, the studies on facile and controllable synthesis of CoP2 based catalysts are few. Herein, two types of cobalt phosphides embedded in 3D carbon nanohybrids (CoPx-N-C) with controllable Co/P ratio were developed via a facile one-step phosphidation-carbonization using a cobalt centered metal-organic framework, ZIF-67, as building block. Based on the high affinity between chloramphenicol (CAP) and cobalt phosphide, the as-prepared CoPx-N-C hybrids were further utilized as electrode components in electrocatalytic determination of CAP in milk and honey. The abundant cobalt phosphide component exhibits high affinity to CAP thus favors its adsorption and facilitates the followed redox reaction. The P-rich CoP2-N-C shows better performance than the metal-rich CoP-N-C in CAP detection, owing to its better electro-activity. The developed CoP2-N-C based sensor exhibits good analytical performance with low detection limit of 0.044 μM (signal-to-noise ratio, S/N = 3) and wide linear range (0.2∼40 μM and 40∼200 μM). The proposed sensor was also applied in the analyses of spiked milk and honey samples, demonstrating its feasibility in CAP analysis.