Two-dimensional conductive MOFs toward electrochemical sensors for environmental pollutants

Environmental pollution has become a global public safety issue, and precise analytical methods capable of detecting environmental pollutants are of immense scientific importance and practical value. Electrochemical sensors are ideal for tracking analytes due to their high sensitivity and specificity, rapid response, miniaturization, convenience, cost-effectiveness, real-time feedback, and robust customizability. To achieve optimal performance of an electrochemical sensor, the modified nanomaterial with characteristics conducive to rapid electron transfer, sizable surface areas, outstanding electrocatalytic activity, and ample sites available for bioconjugation are crucially required. Two-dimensional conductive metal-organic frameworks (2D c-MOFs) are composed of metal ions or clusters linked by organic ligands, forming a 2D layered nanostructure. These modified materials exhibit both electrical conductivity and porous structure due to their unique configurations, providing all the criteria needed as the sensing material for electrochemical biosensor applications. This review summarizes the recent progress in the development of 2D c-MOFs, with emphasis on conductive mechanisms and synthetic methods. Then, 2D c-MOFs based electrochemical sensors for environmental pollutants detection, including heavy metal ions, phenolic compounds, pesticides, N-containing compounds, and volatile organic compounds, are further discussed. In the last, the current challenges, key findings, and outlook of 2D c-MOFs with respect to their preparation and electrochemical biosensor for environmental pollutants monitoring are addressed.