Fabrication and characterization of PPy/rGO|PPy/ZnO composite with varying ZnO concentration as electrode for energy storage applications

• Main Author: Llenarizas, Bryan D.
• Format: text
• Language: English
• Published: Animo Repository 2025
• Subjects: Electrodes; Energy storage; Pyrroles; Graphene > Oxidation; Zinc oxide; Physics
• Online Access: https://animorepository.dlsu.edu.ph/etdm_physics/15; https://animorepository.dlsu.edu.ph/context/etdm_physics/article/1017/viewcontent/2024_Llenarizas_Fabrication_and_Characterization_of_PPy_rGO_PPy_ZnO_Composite_Full_text.pdf
• Institution: De La Salle University

The rapid growth of electricity demand has led to a pursuit of alternative energy sources with high power output and not harmful to the environment. Electrochemical devices such as fuel cells, batteries, and supercapacitors are devices that generate and/or stores electricity via chemical reactions and/or charging mechanism. This study investigates the potential of PPy/rGO|PPy/ZnO composite as electrode for electrochemical devices. A two-electrode electrochemical cell was used for the galvanostatic electrochemical deposition method to prepare PPy/rGO|PPy/ZnO composite electrode material. In the preparation, the first solution comprised 0.1M pyrrole monomer and 1mg of rGO, while the second solution had 0.1M pyrrole monomer and variations of ZnO concentration ranging from 0.08M, 0.09M, 0.1M, 0.11M, and 0.12M. A constant current density of 8mA/cm² was applied for 1 hour of polymerization. Scanning electron microscopy (SEM) of the PPy/rGO|PPy/ZnO composite material shows a globular surface with white spots. These white spots are the ZnO particles confirmed by energy-dispersive x-ray spectroscopy, indicating a successful deposition of the PPy/ZnO onto the PPy/rGO. AC measurements were conducted to obtain the AC resistance of the fabricated film. Results show a decrease in AC resistance as the concentration of ZnO increases (3.32Ω, 3.53Ω, 3.33Ω, 3.12Ω, and 2.88Ω), respectively. For the capacitance, the PPy/rGO|PPy/ZnO composite have a significant increase in capacitance wherein PPy/rGO|PPy/ZnO-0.11M obtain the highest specific capacitance with 17.7048 F/g compared to ZnO (1.86299 F/g) and PPy/rGO (2.7006 F/g). It has been found out that the maximum capacitance was achieved at the 100th cycle for all electrodes before dropping to almost zero at the next 100th cycle. The performance of the composite electrodes is further investigated through linear sweep voltammetry and electrochemical impedance spectroscopy. The exchange current density obtained from the tafel plot reflects the rate of electron kinetics in the electrode-electrolyte interface wherein the PPy/rGO|PPy/ZnO-0.11M obtained the highest exchange current density of 0.936 mVcm-2. A circuit fitting model was employed in the Nyquist plot for estimating the charge transfer resistance of the electrode and 1M NaCl solution. With all fitting errors less than 10%, the charge transfer resistance of 0.11M was estimated to be 15.61Ω, twice less than PPy/rGO with 38.13Ω while PPy/ZnO obtains 86.21Ω.