Fanen Zeng,Xun Yang,Yaning Zhang,Chunyang Li,Bing Xu,Guojun Li
This study aimed to develop more environment–friendly supercapacitor (SC) electrode materials with enhanced performance. Herein, an easy and eco–friendly method was devised for the preparation of hierarchical porous lignin–based carbon materials (LBCMs). During the preparation process, air as an activator favored the formation of mesopore–dominated structures, whereas, static air acted as a protective agent for the carbon skeleton. Additionally, the hierarchical porous structure and electrochemical performance of LBCMs were regulated by changing the reaction temperature and time. The optimized LBCM–800–1 showed a large specific surface area (1471.27 m 2 g –1 ) and mesopore rate of 71.58 %. As an SC electrode material, the three–electrode system showed a high specific capacitance of 194.2 F g –1 at 0.5 A g –1 in 6 M KOH and a multiplicative performance of 88.64 % at 5 A g –1 . Symmetric SC based on LBCM–800–1 exhibits an energy density of 10.4 Wh kg –1 at a power density of 250 W kg –1 and a 100 % cycle retention rate after 10,000 cycles of charging/discharging. The sustainability of the precursor, the simple and environmentally benign preparation process, and the excellent electrochemical performance of LBCM–800–1 demonstrate its potential as an electrode material for wide–ranging applications.
Mengshuo Du,Youyu Cao,Xueli Luo,Weixia Yang,Wanmei Lin,Yingying Wang,Wenzhi Tang,Zhonghong Li
Threats caused by heavy metal ions have prompted people to develop porous and functionalized materials to remove them. Metal–organic frameworks (MOFs) show potential for heavy metal ions removal due to the high specific surface area, tunable pore size, flexible designability and favorable stability. However, the intrinsic microporous structure and powder form limit their applications. Herein, we designed a shapeable aerogel bead incorporated with L-cysteine-modified defective UiO-67 for Pb(II), Cd(II) and Cu(II) adsorption. The pristine UiO-67 powders were firstly modified by introducing the modulator (octanoic acid) and an extra ligand (2,2′-bipyridine-5,5′-dicarboxylic acid) to construct defects, both of them competed with the original ligand to coordinate to Zr clusters, resulting in an increased BET surface area (from 337.66 to 1,037.14 m 2 /g) and mesoporous ratio (from 34 % to 74 %) of the pristine UiO-67. Then, the graft of L-cysteine containing –COOH and –SH introduced more active adsorption sites. Moreover, the powder material was incorporated into sodium alginate aerogel beads which enhanced the recyclability and further improved the adsorption capacity for Pb(II), Cd(II) and Cu(II). These appealing advantages endow the adsorbent with quicker adsorption equilibrium (240 min), and outstanding removal capacities for Pb(II) of 661.2 mg/g, Cd(II) of 296.2 mg/g and Cu(II) of 326.4 mg/g. The chelation and ions exchange between the numerous functional groups including –COOH, –OH and –SH and the heavy metal ions are the main mechanisms for effective adsorption. This work provided a novel approach for the application of MOFs in environmental remediation.
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