Synergistically enhanced electrochemical sensor based on a covalent organic framework/carbon nanotube composite for 4-nitrophenol detection

An electrochemical sensor was developed for the sensitive voltammetric determination of 4-nitrophenol (4-NP) by integrating an in situ grown nanocomposite of amino-functionalized carbon nanotubes (NH 2 -CNTs) and a zinc porphyrin-tetrathiafulvalene covalent organic framework (TTCOF-Zn). This hybrid design strategically couples the electron donor–acceptor (D-A) architecture of TTCOF-Zn, featuring pre-engineered electron transport channels, with the exceptional electrical conductivity of NH 2 -CNTs via covalent bonding, synergistically enhancing charge transfer efficiency. Leveraging the high conductivity, abundant active sites, and hierarchical porosity of the TTCOF-Zn/NH 2 -CNTs nanocomposite, the modified electrode achieves an exceptional detection limit of 17 nM (linear range, 50 nM–1 mM) using differential pulse voltammetry, surpassing most reported sensors. The sensor also demonstrates excellent reproducibility, long-term stability, and strong anti-interference capability against common co-existing species. Its practical applicability was demonstrated through quantitative analysis of 4-NP in real lake water samples, with results validated by the HPLC method, underscoring the potential of D-A COF/CNT covalent hybrids for high-performance environmental monitoring. Graphic