Zinc oxide-decorated MIL-53(Al)-derived porous carbon for supercapacitor devices

Abstract

In this study, we present a facile and direct approach for the synthesis of ordered mesoporous metal–organic framework (MOF)-derived carbon materials, uniformly adorned with zinc oxide (ZnO), to serve as electrode materials for supercapacitor applications. The method involves the impregnation of zinc nitrate into both the as-synthesized (as) and activated low-temperature (lt) forms of the MIL-53(Al) metal–organic framework, which are subsequently employed as precursors to fabricate ZnO-decorated carbon structures (ZnO@C) through simultaneous decomposition under thermal treatment in an Ar atmosphere. The resultant ZnO@C(as) and ZnO@C(lt) materials exhibit a channel-like carbon morphology with uniformly distributed ZnO and residual alumina nanoparticles and a bimodal porous structure with pores approximately 8.5 and 15 nm in size. Additionally, a greater concentration of carbon-related defect centers was identified in ZnO@C(as) relative to ZnO@C(lt), as evidenced by Raman, and electron paramagnetic resonance spectroscopy. When utilized as electrode materials in both symmetric and asymmetric supercapacitor devices, the ZnO@C materials demonstrated exceptional performance, achieving energy and power densities of up to 30.5 W h kg⁻¹ and 388 kW kg⁻¹, respectively, and exhibiting coulombic efficiencies exceeding 95% in all instances.