Sustainable and recyclable synthesis of porous carbon sheets from rice husks for energy storage: A strategy of comprehensive utilization

Abstract

Converting rice husks into valuable chemicals or advanced materials has attracted significant interests of economic and environmental benefits. In this study, we prepared rice husk-derived porous carbon sheets (PCS) by sustainable and recyclable salt activation. The employed NaCl/KCl salt mixture was not only the template agent for mesopores, but also necessary for the formation of 2D carbon structure. The evolution of porosity and carbon morphology after activation was systematically investigated. The optimal product 4PCS-800-2 owned a high surface area and numerous open micro-/mesopores arraying on planar carbon sheet. Benefiting from these features, 4PCS-800-2 exhibited high specific capacitance (288 F g−1 at 0.5 A g-1), efficient pore utilization, excellent rate capability and cyclic stability as electrode material. It was noting that rice husks were also continuously converted into xylose and lignin/silica nano-spheres in prior to the synthesis of PCSs. Hence a comprehensive utilization of rice husk was realized and the whole components had been converted into valuable products.