A highly sensitive electrochemical sensor for the detection of chloramphenicol based on Ni/Co bimetallic metal-organic frameworks/reduced graphene oxide composites

A highly and simply sensitive electrochemical sensor has been developed for the detection of trace chloramphenicol (CAP) in water based on Ni/Co bimetallic metal–organic framework-reduced graphene oxide composites [rGO/NiCo-BTC MOFs (BTC = 1,3,5-benzenetricarboxylicacid)] modified glassy carbon electrode (GCE/rGO/NiCo-BTC MOFs). The bare glassy carbon electrode was initially coated with graphene oxide (GO). Subsequently, the GO was electrochemically reduced to obtain reduced graphene oxide (rGO). NiCo-BTC MOFs was grown on the surface of rGO modified electrode by in-situ electrochemical synthesis method to construct GCE/rGO/NiCo-BTC MOFs. The as-made composites films have been characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Further, different electrochemical techniques are utilized for investigating the electrochemical reduction behaviors of CAP at GCE/rGO/NiCo-BTC MOFs. This composites film modified electrode combines the large surface area and excellent electrical properties of rGO with the good catalytic activity of NiCo-BTC MOFs, resulting in a significant enhancement of the electrochemical signal during the electroreduction of CAP. Under the optimized experimental conditions, the sensor exhibits excellent sensing performance for CAP, with a wider linear dynamic range (0.1 − 100 μM), a lower limit of detection (0.235 μM) (S/N = 3) and a ultra-high sensitivity (33.12 μA·μM−1·cm−2). The tap water spiked with different concentrations of CAP were considered. The recoveries ranges from 97.79 % to 100.07 %, with relative standard deviations ranging from 3.45 % to 5.40 %. The method has been successfully applied for the determination of CAP in real samples, yielding satisfactory results. With further research and development, electrochemical in-situ synthesis of MOFs composites have the potential to revolutionize the design and performance of electrochemical sensors, holding great promise in the field of electrochemical sensing.