Realizing highly sensitive electrochemical determination of 2,4,6-trichlorophenol by tailoring the electronic state of a palladium‒carbon cocatalyst.

Chlorophenols (CPs) have been identified as priority pollutants due to their ecological persistence, mutagenic, and carcinogenic properties. Among CPs, 2,4,6-trichlorophenol (2,4,6-TCP) is one of the most toxic chlorinated organic compounds. Owing to the detrimental impacts of 2,4,6-TCP, the development of a sensing platform for real-time and on-site monitoring is essential for effective management and pollution control. In this study, a palladium-carbon cocatalyst was utilized to determine 2,4,6-TCP. These results indicate that the anodic current response of 2,4,6-TCP was regulated by the electronic state and dispersity of Pd loaded on two-dimensional reduced graphene oxide (rGO) nanosheets. The resulting Pd with a more electron-deficient nature (i.e., higher-valent Pd) promoted charge polarization of the ring structure of 2,4,6-TCP and facilitated the subsequent nucleophilic attack, leading to superior electrochemical oxidation of 2,4,6-TCP. 2,4,6-TCP is dechlorinated into chlorophenol species at lower voltages, which subsequently oxidize at peak anodic voltages, thereby providing voltage-dependent selectivity. The palladium‒carbon cocatalyst‒modified electrode exhibited a wide sensing concentration range (0.1 to 100 μM) for 2,4,6-TCP, with a low LOD of 16.5 nM and excellent anti-interference ability. Overall, the constructed sensing platform demonstrated high sensitivity, stability, and resistance to interference, which is promising for the on-site determination of 2,4,6-TCP in aqueous environments.