High Performance Electrocatalyst Based on MIL-101(Cr)/Reduced Graphene Oxide Composite: Facile Synthesis and Electrochemical Detections

Graphical With a sense of selectivity : the metal-organic framework/reduced graphene oxide composite MIL-101(Cr)/rGO is prepared via a simple hydrothermal method. The electrochemical sensor based on the composite shows low detection limits and wide linearity ranges for the determination of metronidazole, Cd 2+ and Pb 2+ , and shows excellent selectivity, reproducibility and stability. In this work, a Cr-based MOF (MIL-101(Cr))/reduced grapheme oxide(rGO) electrocatalyst was prepared through a one-pot hydrothermal method. The obtained composite was characterized via scanning electron microscopy, transmission electron microscopy, X-ray diffraction and other standard techniques. Electrochemical methods were adopted to study the electrocatalytic ability of the composite. The results imply that, compared to the single components, it exhibits higher electrocatalytic activity for the reduction of metronidazole and stripping of Cd 2+ and Pb 2+ . Optimizing the ratio of MIL-101(Cr) and rGO, an electrochemical sensor was prepared using MIL-101(Cr)/rGO-20 and used for detection of metronidazole, Cd 2+ and Pb 2+ , respectively. The linear range for metronidazole can be divided in two parts, i. e. from 0.5 to 200 μM and from 200 to 900 μM. The limit of detection is 0.24 μM (S/N=3, n=10). Likewise, it also exhibits a wide linear range from 0.05 to 6.0 μM for the detection of Cd 2+ and Pb 2+ . The corresponding detection limits are found to be 5.2 nM and 3.0 nM (S/N=3, n=10), respectively. The proposed sensor also possesses superb selectivity, reproducibility, stability and can be applied to detect real samples with desired recovery rates. In addition, the possible reduction mechanism of metronidazole and adsorption mechanism of Cd 2+ and Pb 2+ were further discussed simply in this work.