Eco-friendly and easily separable ZIF-8/MP composites with efficient Congo red adsorption and spent reusability as supercapacitors

The development of multifunctional materials capable of serving both as high-efficiency adsorbents and high-performance supercapacitors is a critical challenge for environmental and energy applications. In this study, a novel zeolitic imidazole framework-8/mycelial pellet (ZIF-8/MP) composite was successfully synthesized using a simple in-situ growth and staged adsorption process. The MP with its three-dimensional porous structure, served as a scaffold, facilitating the uniform distribution of ZIF-8 across the porous carbon matrix. The resulting ZIF-8 in the ZIF-8/MP composite demonstrated a remarkable adsorption capacity for Congo red (CR), with a maximum capacity of 1428.57 mg/g. The adsorption mechanism was attributed to electrostatic interactions, zinc coordination, hydrogen bonding, and π–π conjugation, as confirmed by FTIR, XPS, and DFT analyses. After adsorption, the carbonized ZIF-8/MP composite demonstrated outstanding supercapacitor performance, achieving a specific capacitance of 113.4 F/g at 1 A/g, and maintaining 93 % capacitance retention after 5000 charge/discharge cycles. Additionally, the ZIF-8/MP composite effectively reduced the toxicity of CR, as demonstrated by phytotoxicity assays, underscoring its potential for environmental remediation. This innovative approach provides an eco-friendly, easily separable, efficient, and practical multifunctional material for transforming hazardous waste into valuable resources for environmental detoxification and energy storage applications.