Simultaneous detection of 4-chlorophenol and 4-nitrophenol using a Ti₃C₂T MXene based electrochemical sensor

Developing a sensitive and rapid detection method for 4-chlorophenol (4-CP) and 4-nitrophenol (4-NP) is very important due to their high toxicity. In this work, bulk Ti₃AlC₂ powder was etched to Ti₃C₂T for the first time through a hydrothermal reaction in NaF/HCl solution. After ultrasonication in N-methylpyrrolidone (NMP), Ti₃C₂T powder was successfully exfoliated into multilayered Ti₃C₂T nanosheets (i.e. Ti₃C₂T MXene). The prepared Ti₃C₂T MXene not only has a large electrochemical surface area for the oxidation of 4-CP and 4-NP, but also lowers their electron transfer resistance. As a result, the oxidation signals of 4-CP and 4-NP are significantly improved on the surface of the Ti₃C₂T MXene. Based on the remarkable signal amplification of the Ti₃C₂T MXene, a sensitive and rapid method was developed for the simultaneous detection of 4-CP and 4-NP. The linear range is from 0.1 to 20.0 μM for 4-CP, and from 0.5 to 25.0 μM for 4-NP, with detection limits of 0.062 μM (4-CP) and 0.11 μM (4-NP). This method was used in wastewater samples, and the accuracy was confirmed to be good by high-performance liquid chromatography.