Development of ceramic nanofiber based electrochemical hydrogen peroxide and glucose sensors

In this study, composite ceramic materials containing substances with catalytic effects such as graphene, palladium and silver in nanofiber structure are prepared by electrospinning method, these nanofibers are turned into ash in the ash furnace and modified to glassy carbon electrode surfaces; It is aimed to develop a hydrogen peroxide and glucose sensitive sensor. Graphene oxide (GO) supported palladium-silver nanocomposite materials have been used as catalysts in electrochemical sensor applications. Efficient and enzyme-free electrochemical sensors have been developed through the use of low-cost and high-performance nanocomposite materials. In order to produce nanofibers by electrospinning method, graphene oxide, silver nitrate and palladium chloride were added to polyvinyl alcohol solution and PVA/GO/PdAg solutions were prepared by sol-gel method. Solutions prepared in different ratios and contents were spun by electrospinning method to produce nano-sized fibers. The resulting nanofibers are calcined at a temperature of 400°C. The characterizations of the prepared nanocomposite materials were made using Scanning Electron Microscopy (SEM), Energy Separation Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), Thermo-gravimetric Analysis (TGA/DSC), Transmitting Electron Microscopy (TEM) and X-Ray Diffraction (XRD) methods. GO/PdAg/DMF suspension was prepared in dimethylformamide (DMF) using nanocomposite materials whose characterization processes were completed. These prepared suspensions were applied on a glassy carbon electrode in sensor applications as catalyst suspensions. Hydrogen peroxide (H2O2) and glucose were used as target molecules in sensor studies, and the determination of H2O2 and glucose amounts was made by amperometric method. In this method, the cleaned glassy carbon electrode surface was modified with the prepared GO/PdAg/DMF suspension to obtain electrochemical sensor surfaces. The prepared surfaces are then placed in the electrochemical cell with three electrodes to ensure sensor performances under a constant potential; examined for calibration sensitivity, linear operating range, repeatability and shelf life. For the linear operating range of the designed enzyme-free hydrogen peroxide sensor, the linear correlation coefficient is 0,99, and the sensitivity is 15,70 µA/mM for the 0,05-65 mM range; The smallest detectable concentration (LOD) was calculated as 61 µM and the limit of detection (LOQ) was calculated as 203,57 µM. Relative standard deviation (RSD) was calculated as 1,02% as a result of reproducibility studies and as 5,06 as a result of reproducibility study. In the long-term stability study, it was observed that the hydrogen peroxide sensor designed at the end of the thirtieth day preserved its initial activity by 86,58%. For the linear operating range of the designed enzyme-free glucose sensor, the linear correlation coefficient was 0,99, and the sensitivity was 1,17 µA/mM for the 0,1-50 mM range; The smallest detection limit (LOD) that it could detect was calculated as 92.46 µM and the limit of detection (LOQ) was calculated as 308,22 µM. Relative standard deviation (RSD) was calculated as 3,75% as a result of repeatability studies, and as 3,9% as a result of reproducibility study. In the long-term stability study, it was observed that the glucose sensor designed at the end of the thirtieth day preserved its initial activity by 89,39%.