Solvent-exfoliated Cu-TCPP nanosheets: Electrochemistry and sensing application in simultaneous determination of 4-aminophenol and acetaminophen

The design and preparation of 2D metal-organic frameworks (MOFs) can effectively improve the performance of electrochemical sensing. In this work, a series of Cu-TCPP nanosheets (TCPP: Tetrakis(4-carboxyphenyl)porphyrin) are prepared through ultrasonic exfoliation of bulk Cu-TCPP in different solvents, including ethanol absolute (EtOH), N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), and ultrapure water (H2O). The exfoliation ability of DMF is higher than EtOH, H2O, and NMP, and the exfoliated Cu-TCPP nanosheets in DMF (Cu-TCPP-DMF) are more uniform and thinner due to their approximate surface energy. Then, the electrochemistry of different Cu-TCPP nanosheets is studied. Cu-TCPP-DMF modified glassy carbon electrode (Cu-TCPP-DMF/GCE) features higher redox activity, larger electrochemical response area, faster electron transfer ability, and higher enhancement effects toward the oxidation of 4-aminophenol (4-AP) and acetaminophen (AC). The corresponding electrochemical reaction mechanisms are explored. Using Cu-TCPP-DMF as sensing material, a platform for simultaneous measurement of 4-AP and AC is successfully developed with the determination limit of 2.6 and 1.9 nM. The wonderful recoveries are also obtained when the sensor is used to determine 4-AP and AC in urine, river water and commercial paracetamol tablet. This work is in favor of constructing a novel 2D MOFs based electrochemical sensing system with superior performance.