Synthesis of Nitrogen and Phosphorus co-doped Carbon with Tunable Hierarchical Porous Structure from Rice Husk for High Performance Supercapacitors
Yuning Qu, Lin Liu, Lisha Li, Shuya Wen, Dan Wei, Ningru Xiao, Feng Yan, Jiaguo Yu, Lili Wang
Abstract
Nitrogen and phosphorus co-doped porous carbon(N/P-PC) was prepared via a simple direct pyrolysis method using rice husks as the carbon source and H 3 PO 4 as the phosphorus source and activator. The acquired products are typical hierarchical porous carbons with a multiple-peaked pore size distribution of microporous and mesoporous structure, which has ahigh surface area and pore volume. The N 2 adsorption-desorption results show that the mesoporous distribution of N/P-PCcan be adjusted in the range of 2-10 nm and the meso-porosity can be varied by changing the H 3 PO 4 content. In particular, among the N/P-PC samples, N/P-PC-1:5 hasthe highest surface area of 2188m 2 /g, pore volume of 3.025 cm 3 /g, and pore diameter of 5.537 nm. Electrochemical measurements also indicate that the assembled symmetric cell of N/P-PC-1:5 displays the highest specific capacitance of 236 F/g at a scan rate of 5 mV/s and 130 F/g at a current density of 0.5 A/g; it also has an excellent capacity retention of 100 % after 6000 cycles. The hierarchical porous structure and the synergistic action of nitrogen and phosphorus contribute to the advantageous electrochemical performance of the carbon material. The proposed strategy provides a facile method for preparing porous carbon from biomass waste.