Facile synthesis of ZnO nanorod functionalized carbon foam as a binder-free electrode for high-performance supercapacitor applications

Modern society faces serious energy challenges, including the depletion of fossil fuels, environmental degradation, and global climate change. These pressing issues underscore the urgent need for sustainable energy storage and conversion technologies. In this context, carbon foam (CF) functionalized with ZnO nanorods (NRs) shows significant promise. To fabricate the carbon foam, a polyurethane (PU) foam template was used along with phenolic resin as the carbon source. The structure was stabilized by oxidation and then sintered at 1000 °C under a nitrogen atmosphere. ZnO NRs were subsequently grown on the CF using an in situ hydrothermal method, with loading concentrations ranging from 0 to 10 wt%. The structural and morphological characteristics of the ZnO NRs-functionalized CFs were analysed using XRD, SEM, and Raman spectroscopy. The SEM results revealed that ZnO were uniformly distributed across the CF surface. The electrochemical characteristics of binder-free electrodes based on ZnO NRs-functionalized CFs were systematically examined using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge (GCD) measurements. In a three-electrode system, the CF electrode functionalized with 10 wt% ZnO NRs exhibited a remarkable specific capacitance of 360 F g −1 at a scan rate of 5 mV s −1 . Furthermore, an asymmetric supercapacitor device was assembled using the 10 wt% ZnO NRs-functionalized CF as the positive electrode and pristine CF as the negative electrode (denoted as CF-ZnO-10//CF). This device demonstrated excellent electrochemical performance, delivering a specific capacitance of 272 F g −1 at a current density of 0.5 A g −1 , together with an energy density of 38 Wh kg −1 and a power density of 125 W kg −1 . These results confirm the strong potential of ZnO NRs functionalized CF as a high-performance, binder-free electrode material for next-generation supercapacitor applications.