Alginate-Derived Porous Carbon Obtained by Nano-ZnO Hard Template-Induced ZnCl2-Activation Method for Enhanced Electrochemical Performance

Biomass-derived hierarchical porous carbons have attracted considerable attention due to their low cost, environmental friendliness and sustainability. However, the preparation of porous carbon with typically hierarchical pores is still challengeable. In this work, a facile and efficient strategy was proposed to obtain alginate-derived porous carbon by a combination of hard-template and chemical-activation technique. During the fabrication process the nano-ZnO particles displayed triple functions: (a) The nano-ZnO particles were behaved as the hard template to generate more pores. (b) ZnCl2 derived from the nano-ZnO particles acted as a cross-linking agent for obtaining zinc alginate (Zn-SA) hydrogel beads. (c) ZnCl2 was also employed as an activating agent to form micropores during the high-temperature carbonization process. As a subsequence, the obtained carbon exhibited well-developed hierarchical porous structure with high specific surface area of up to 2589 m2 g−1. Due to the high specific surface area, good electrical conductivity and synergistic effect among the typically hierarchical pores, the PC-ZnO-ZnCl2-650 exhibited a high specific capacitance of 316 F g−1 at the current density of 0.5 A g−1 and excellent cycling stability with capacitance retention of 94.4% at 5 A g−1 over 5000 cycles. This ingenious synthesis strategy can provide a new way for efficient preparation of hierarchical porous material.