Facile fabrication of carbon-loaded covalent-organic framework composites with enhanced electrochemical performance for dopamine determination

In this work, a crystalline electroactive triphenylamine-based covalent-organic framework (TPA-COF) was composited with carbon black (CB) using a facile one-pot solvothermal method. It is shown that the loaded amount of CB significantly affects the electrochemical performance of the composites. On one hand, CB dispersed in the COF matrix can improve the conductivity of the composite. On the other hand, the π-π interactions between COF layers and carbon particles may affect the accumulation of COF layers, resulting in the increasement of the surface area and the exposure of active sites. These structural advantages promote the performance of the composite toward dopamine (DA) detection. When 30 wt% CB was loaded, the composite modified electrode demonstrates best activity with a wide linear range of 20 μM–1000 μM and a low detection limit of 0.17 μM (S/N = 3). Moreover, due to its high selectivity, satisfying stability, and good repeatability, the constructed electrochemical sensor was successfully used to detect the DA concentration in real medical injection with satisfactory recovery results, that is in the range of 98.7–111.0%. Further studies show that the good performance of the constructed sensor is attributed to its good conductivity, high specific surface area and effective host guest interaction between DA molecules and COF framework. This work provides a simple method to utilize COFs for quantitative detection of DA, as well as a new way to extend the applications of COFs in sensing.