In-situ growth of iron-based metal-organic framework crystal on ordered mesoporous carbon for efficient electrocatalysis of p-nitrotoluene and hydrazine.

In this paper, HN-Fe-MIL-88B@OMC composites were fabricated by the simple hydrothermal method through in-situ growth iron-based metal-organic frameworks (HN-Fe-MIL-88B) on ordered mesoporous carbon (OMC). Compared with pure HN-Fe-MIL-88B crystals, the introduction of OMC can shrink the size of HN-Fe-MIL-88B, increase the specific surface area, decrease the electron transfer resistance and drastically improve the electrochemical performance of HN-Fe-MIL-88B@OMC. The composite exhibits remarkable electrocatalytic activity for p-nitrotoluene (p-NT) reduction and hydrazine (NH) oxidation. Therefore, a novel electrochemical sensor based on HN-Fe-MIL-88B@OMC was constructed for the efficient detection of these two environmental pollutants, respectively. Under the optimal experimental conditions, the proposed sensor displays a wide linearity range for p-NT that is composed by two line segments (20-225 μM and 225-2600 μM) and the limit of detection (LOD) is 8 μM (S/N = 3). Meanwhile, the sensor also shows a linear response to NH in the range of 0.006-0.061 μM and 0.061-611.111 μM with a high sensitivity of 20.1 μA/μM·cm in low concentration range as well as a very low LOD as 5.3 nM (S/N = 3). And the response time of the sensor for NH detection is about 1 s. In addition, the proposed sensor shows satisfactory electrochemical stability, reproducibility, selectivity and practicability. HN-Fe-MIL-88B@OMC may be a splendid candidate for developing electrochemical sensors to detect environmental pollutants.