A sensitive electrochemical sensor with Hf-MOF@activated Ketjen black/calix[4]arene composite for the detection of 2,2′-methylenebis(4-chlorophenol) in environmental water

Abstract

The high toxicity and persistence of 2,2′-methylenebis(4-chlorophenol) (Dcp) necessitate its sensitive detection in aquatic environments. However, its accurate detection at low concentrations remains challenging. This study proposes a novel electrochemical sensor based on hafnium-based metal–organic frameworks@activated Ketjen black/calix[4]arenes composite (Hf-MOF@a-KB/Calix). Hf-MOFs are promising sensing materials owing to their high surface area and high porosity, along with low toxicity in aqueous environments. However, their practical application is hindered by poor electrical conductivity and limited active sites. To address these issues, activated Ketjen black (a-KB) was introduced to substantially improve electrical conductivity. Leveraging the strong molecular recognition capability of calix[4]arenes (Calix), a ternary composite Hf-MOF@a-KB/Calix was developed. This composite material features improved electrical conductivity and moderate host–guest recognition performance, which enables the fabrication of an electrochemical platform with favorable sensitivity and selectivity for DCP detection. The as-prepared sensor shows a stable linear response over the concentration range of 5.0 nM to 100 μM, accompanied by good reproducibility, long-term stability and effective anti-interference ability. Compared to previously reported work, the sensor developed in this study exhibits superior performance. Real water sample tests yield spiked recovery rates of 95.2%–103.6%, further confirming the acceptable practicability and reliability of the sensor. This work offers a promising electrochemical analysis strategy for the rapid and sensitive detection of environmental contaminants.