Fe₃O₄ nano assembly embedded in 2D-crumpled porous carbon sheets for high energy density supercapacitor

Due to the copious development of industries and depletion of fossil fuels generate deteriorating environmental pollution and appalling economic crisis. Thus, there are increasing unmet for developing well-defined nanostructures to mitigate energy and environmental issues. Herein, we firstly report a unique concerted method to convert agro bio-waste into an economical wealth material. By the inspiration of nature, we selected a waste 2D garlic husk (Allium sativum) as a torchbearer to make a unique material. The garlic extract was applied for the synthesis of Fe₃O₄ NAs@2D-CCS composite nano-assemblies (NAs). Interestingly, the small-sized Fe₃O₄ nanocrystals (<20 nm) underwent nucleation in the presence of biogenic 2D-CCS and formed a pomegranate like a cluster (200 nm) forming a conglomerate on porous carbon layers. Most importantly, no secondary waste was generated in this work. This Fe₃O₄ NAs@2D-CCS composite affords high specific capacitance of 820F g⁻¹ at a current density of 0.5 A g⁻¹, which is nearly 5 to 3 times higher than pristine Fe₃O₄ NPs (<20 nm) electrode with an outstanding power density (3500–8000 W kg⁻¹) and specific energy density (115.5 to 65.9 Wh Kg⁻¹), which is superior among most of all reported iron oxide and graphitic carbon composites. This simple work stimulates a new door for the generation of waste to well-defined nanostructure materials for energy, catalysis, and environmental applications.