Fabrication of carbon nanospheres functionalized Sm2O3/Co3O4 novel hybrid nanocomposites for selective and sensitive amperometric detection of hydrogen peroxide

In the present research work, we have explored amperometric sensing properties of carbon nanospheres ( Cx) (5%, 8%, and 15%) decorated over Sm2O3/Co3O4 nanocomposites (NC) that are synthesized by microwave-assisted method. The synthesized electrode materials are characterized by the techniques of X-ray diffraction (XRD), scanning electron microscopy (SEM), SEM-EDAX (energy-dispersive X-ray spectroscopy), BET (Brunauer-Emmett-Teller), XPS (X-ray photoelectron spectroscopy), and UV-visible. Phase analysis revealed mixed monoclinic crystal structure and crystallite size decreases from 32 to 22 nm. Plate/flake-like morphology resulted upon the incorporation of Cx on Sm2O3/C0(3)O(4) crystal lattice. Redshift in the optical absorption peak resulted with an increase in C-x concentration on Sm2O3/Co3O4 NC and the optical band gap (E-g) decreases from 3.26 to 2.61 eV. The sensitive and selective determination of hydrogen peroxide (H2O2) is very important because it is a product of reactions catalyzed by oxidase enzymes, a powerful effector of redox signaling, versatile biomarker, and is widely used in the food industry. H2O2 is known to cause toxicity and they form hydroxyl radicals. The accurate detection of H2O2 can indicate the presence of enzyme activity, explosives, and cell signaling pathways. Additionally, H2O2 has become a signal propagator within signal amplification methodologies used to enhance selectivity of the diagnostic assays. The developed modified sensor (C15%:Sm2O3/Co3O4) showed amperometric detection of H2O2 with 96% steady current within 3-4 s, linear range was found to be 0.2 mu M to 6 mu M, limit of detection (LOD) 0.04 mu M, and having a sensitivity of 0.483 mu A/mu M (R-2 = 0.996). Further, sensitivity and selectivity were detected with glucose, dopamine, ascorbic acid, and uric acid at + 0.36 V and no current response was observed. The modified electrode material possess high selectivity, less response time, high stability, reusability, and high repeatability and can find applications in the field of real-time monitoring of hazardous materials, fabrication of biosensors, H2O2 sensors, and in optoelectronics.