ZrO2-embedded nitrogen-doped carbon-derived MOF/COF for supercapacitors

Abstract

Porous materials, including hybrid materials (e.g., metal–organic frameworks, MOFs) and pure organic materials (e.g., covalent organic frameworks, COFs), were investigated for electrochemical energy storage. This study produced a hybrid material composed of UiO-66 MOF and a COF, which was subsequently carbonized at different temperatures to yield ZrO₂-embedded nitrogen-doped carbon for supercapacitor applications. The materials were analyzed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results confirmed the synthesis of UiO-66@COF and the generation of ZrO₂@N-doped carbon through post-carbonization. Electrochemical experiments revealed that the carbonized composite exhibits enhanced capacitance performance compared with UiO-66 and COF materials. The UiO-66@COF_700 electrode showed a specific capacitance of 195 F/g at 1 A/g, remarkable rate capability, and stable cycling performance over 5000 cycles. The energy storage mechanism includes both capacitive and diffusion components, with a primary emphasis on surface contributions following carbonization. The results demonstrate that carbon composites produced from MOF–COF are effective electrode materials for supercapacitors.