Bimetallic Ruthenium-Cobalt Catalyst Supported on Carbon Nanotubes: Synthesis, Characterization, and Application in Electrochemical Sensing of Isoleucine

In this work, a bimetallic Ru-Co catalyst based on carbon nanotubes (Ru-Co/CNT) with a Ru to Co ratio of 95:5 is developed. The catalyst, featuring a total metal loading of 3% on the CNTs, is synthesized using the NaBH₄ reduction method. Several analytical analyses are used to detect the properties of the Ru-Co/CNT catalyst. X-ray diffraction (XRD) provides information on crystal structures of the catalysts, high-resolution transmission electron microscopy (HR-TEM) reveals particle size and distribution, inductively coupled plasma mass spectrometry (ICP-MS) measures the elemental composition, and X-ray photoelectron spectroscopy (XPS) use to investigate the chemical oxidation states. In addition, thermal techniques including temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), and temperature-programmed desorption (TPD) are used to recognize the active sites on the catalyst's surface and the acidity. Then, the Ru-Co/CNT catalyst is applied as a sensor for isoleucine amino acid for the first time. It shows high performance with these parameters, sensitivity (0.002 mA cm⁻² mm), LOD – limit of detection (0.04 µm), and LOQ – limit of quantification (0.12 µm). Moreover, the interferences of common serum blood including (D-glucose, uric acid, ascorbic acid, and L-tryptophan) are studied. The findings indicated that the sensor is applicable to work in complex biological systems.