Abstract
Porous nickel foam was used as a conductive scaffold to fabricate bilayer electrodes composed of polyaniline (PANI) and zinc oxide (ZnO) through electrodeposition. Two sets were prepared: PANI/ZnO, where PANI was deposited first and then coated with ZnO, and ZnO/PANI, where ZnO was deposited first and followed by a PANI layer. Electrochemical characterization demonstrated that the sequence of deposition plays a decisive role in performance. Cyclic voltammetry revealed that PANI/ZnO exhibited broader CV profiles and excellent electrochemical accessibility within the 0–1 V potential window. Galvanostatic charge–discharge tests confirmed that both bilayer electrodes outperformed single-component ZnO and PANI, with ZnO/PANI showing slightly longer discharge times and higher capacitance at increased current densities. Ragone analysis indicated that ZnO/PANI delivered superior energy–power balance under high-rate conditions, whereas PANI/ZnO maintained remarkable cycling stability, retaining nearly its full capacitance after prolonged cycling. These results show that both bilayer configurations benefit from PANI and ZnO, but with distinct advantages: PANI/ZnO is highly stable, while ZnO/PANI is better suited for high-rate applications. The findings highlight the importance of deposition order in optimizing hybrid polymer/oxide.