Ternary composite material based on copper-metal organic frameworks, Mxene and carbon nanotubes as a sensitive electrochemical platform for determination of dopamine in aquatic environments

Dopamine (DA) is a crucial neurotransmitter, however, its excessive use can lead to its accumulation as a micropollutant in aquatic ecosystems, thereby presenting various health risks to humans. Consequently, the accurate determination of dopamine levels is of paramount importance and has attracted considerable attention within scientific and regulatory communities. In this work, a ternary composite material (Cu-MOF/MXene/CNTs, MMC) based on copper-metal organic framework (Cu-MOF), the MXene and carbon nanotubes (CNTs) was developed using the hydrothermal method for sensitive electrochemical detection of DA. The prepared MMC possessed a stable structure derived from Cu-MOF, an extensive surface area attributed to MXenes, and numerous conductive channels formed by CNTs. Consequently, the modified MMC demonstrated high performance in DA detection. The electrochemical sensing capabilities of the MMC were assessed utilizing cyclic voltammetry (CV), and differential pulse voltammetry (DPV) methodologies. Under the optimal conditions, a strong linear relationship was observed between peak current and DA concentration within the range of 0.1–50 µM, achieving a detection limit (LOD) as low as 0.035 µM. The modified MMC sensor was utilized to quantify trace concentrations of DA in actual water samples, with recovery rates ranging from 97.3 % to 103 %, indicating satisfactory performance. Experiments were conducted to demonstrate that this composite material exhibited significant selectivity for metal ions and met related objectives. It was also shown acceptable stability over a period of 30 days and a commendable reproducibility, with a relative standard deviation (RSD) of 0.3 % across different production batches. Moreover, a comprehensive investigation was undertaken into the kinetics and underlying mechanisms of the electrochemical reaction. The transfer of electrons and hydrogen ions facilitated the transformation of DA into dopaminoquinones (DQ), a process that was accelerated by the increased availability of active sites in the designed sensor. This work introduces a method for the precise detection of DA utilizing the active sites and conductive pathways offered by the synergistic effect of MOF, CNTs and MXene, which have excellent performance in both laboratory and real environment, indicating that the proposed sensor is highly effective for detecting DA in water samples.