Bio-Assisted Self-Activation of Porous Carbon in the Presence of Endogenous Silica for High-Performance Supercapacitors

Abstract In the pursuit of high-performance supercapacitors, it remains a key challenge to rationally engineer carbon electrodes with concurrently optimized porosity, surface chemistry, and structural integrity. In this work, a plant-mediated self-activation strategy is developed to construct hierarchically porous and nitrogen-doped carbon materials via endogenous nanosilica uptake. During plant growth, uniformly distributed SiO2 acts as both an in situ hard template and a catalytic promoter during carbonization, enabling the formation of a hierarchical pore structure without external activation. Meanwhile, SiO2-regulated nitrogen metabolism induces intrinsic nitrogen doping in the derived carbon framework, establishing a coupled biological-chemical pathway for heteroatom incorporation. The optimized SiO2-100@C delivers a high specific capacitance of 259.3 F g–1 at 0.5 A g–1 and retains 85% at 5.0 A g–1, together with excellent cycling stability of 95.53% after 20,000 cycles. The superior performance is attributed to synergistic effects of hierarchical porosity, enhanced ion transport, and regulated heteroatom configuration within a robust C-SiO2-derived framework. This work provides a sustainable and scalable strategy that integrates biological uptake with nanoscale structural engineering for advanced carbon-based energy storage materials.