Covalent-organic framework/carbon nanotubes for electrochemical detection of o-nitrophenol

Covalent organic frameworks (COFs) have aroused much attention as candidate materials for constructing electrochemical sensors. However, their inherent low conductivities have limited their sensing applications. Here, a novel COF/carbon nanotubes (CNTs) composite is prepared via a straightforward ultrasonic method, incorporating amino-functionalized CNTs (NH2-CNTs) into COF composed of 1, 3, 5-benzenetricarboxaldehyde and 1,4-diaminobenzene. The resulting COF/NH2-CNTs composite exhibits high specific surface area, improved conductivity, fast electron transfer capability due to the high porosity of COF, the introduction of NH2-CNTs, and the conjugate interaction between CNTs and COF. The proposed COF/NH2-CNTs-based sensor offers an amplified current toward the electrochemical sensing of o-nitrophenol (o-NP). Notably, the sensor exhibits a wide linear detection range (0.1–100 and 100–1000 μM), a high sensitivity (8.66 and 1.44 μA/(μM cm2)), and a very low detection limit (0.03 μM). Moreover, it is successfully applicable in the quantitative analysis of o-NP in lake water samples with satisfactory recoveries (97.0–105.3 %). This work not only demonstrates the viability of COF-based sensors for the trace-level detection of nitrobenzene contaminants but also enriches the variety of COF-based sensing materials.