Nanofibrillar alginic acid‐derived hierarchical porous carbon supercapacitors

Abstract

A versatile route has been demonstrated for the preparation of hierarchical porous carbon films derived from nanofibrillar alginic acid extracted from brown seaweeds. An acetic acid‐sodium acetate buffer was used to adjust pH of the nanofibrillar alginic acid gels, giving rise to a stable aqueous homogeneous suspension at the concentration of 5.0 wt% and pH ∼4.5. A crack‐free nanofibrillar alginic acid film with a diameter of several centimeters was cast from the suspension. Self‐condensing silica around nanofibrillar alginic acid formed silica‐alginic acid composites that were carbonised and then etched the silica to generate mesoporous carbon films. The aligned mesochannel carbon was originated from the hierarchical parallel organisation of the self‐assembled nanofibrillar alginic acid. The introduction of mesoporosity into the carbon structure afforded the high‐surface‐area mesoporous carbon film‐based supercapacitor that exhibits an ultrahigh‐rate capability and highly electrical capacitance.