Hierarchically Porous Carbon Derived from <i>Neolamarckia cadamba</i> for Electrochemical Capacitance and Hydrogen Storage

Abstract

The specific surface area, pore volume, and pore size distribution of biomass-derived porous carbon are crucial factors when they are applied in energy and gas storage. Each application has specific requirements, and a large number of porous carbons with various characteristics have been designed to tailor their applications. In this work, using Neolamarckia cadamba (NC) as the starting material, a simple method is applied to synthesize hierarchically porous carbon with a high specific surface area (2743–3462 m2 g–1) and a large pore volume (1.09–1.67 cm3 g–1). The various characteristics of porous carbon caused by varying degrees of activation have great potential in supercapacitors and hydrogen storage. Applied as an electrode material, NC-4700, activated at a KOH/C ratio of 4 and 700 °C, exhibits a high specific capacitance of 411 F g–1 at 1 A g–1 with a long-term stability of 97% after 20 000 cycles at 20 A g–1 in a three-electrode system. As for hydrogen storage, NC-3800, activated at a KOH/C ratio of 3 and 800 °C, is more suitable and shows a capacity of 2.81 wt % at 1 bar and 77 K, which is a relatively high hydrogen uptake at low pressure. Porous carbon with various activation levels is more suitable for different applications, which is of great significance for its multifunctional applications.