Layered 2D MOF nanosheets grown on CNTs substrates for efficient nitrite sensing

In this work, we report a ligand-deficient layered cerium-based metal-organic framework (MOF) nanosheets grown on carbon nanotube (CNT) substrates and its application in electrochemical sensors. The construction of layered MOF nanosheet materials is based on CNTs as the backbone and relies on the low ligand-metal ratios which is controlled by the loaded organic ligands on the surface of CNTs, providing a new approach for the application of 2D MOFs in the field of electrochemical sensing. The obtained 2D MOFs possess unique layered structure and hierarchical connectivity channels, providing highly efficient and stable pathways for electron, ion, and mass transport. The synthesized layered 2D CNTs@Ce-MOF nanosheet hybrid material uses Ce as the center ion and electrocatalytic active material for nitrite sensing. This material exhibits excellent nitrite detection performance within two wider linear ranges of 0.65–3.25 μM and 3.25–7000 μM with the sensitivity of 87.65 ± 0.6 μA·μM−1·cm2 and 0.35 ± 0.03 μA·μM−1·cm−2, respectively. The detection limit is estimated to be 0.12 μM according to signal to noise ratio (S/N) = 3. As the result, the prepared sensors possess advantages in aspects of reproducibility, stability, selectivity and responsiveness in comparison to the reported ones.