Activated carbons prepared by hydrothermal pretreatment and chemical activation of Eucommia ulmoides wood for supercapacitors application

Eucommia ulmoides Oliver (EUO) wood goes through hydrothermal pretreatment (HTP) followed by chemical activation to produce activated carbons (ACs), which are then applied as electrode materials for supercapacitors application. The porous structure, surface chemistry and electrochemical characteristics of the ACs have been investigated in detail. The specific surface area (S-BET) of the ACs enlarges from 1272.38 to 1534.06 m(2) g(-1) following the increase of HTP temperature from 150 to 170 degrees C, and then decreases to 1284.69 m(2) g(-1) when HTP temperature increased further to 200 degrees C, indicating that HTP temperature of 170 degrees C is the turning point on SBET of the ACs. Moreover, the ACs obtained at HTP temperature of 170 degrees C are observed with highest mesopore pore volume (1.66 cm(3)g(-1)) and mesopore pore diameter (6.02 nm). Additionally, the Raman and FTIR spectrum of the ACs also prove that HTP temperature of 170 degrees C can enhance the graphitization during the activation process, indicated with low I-D/I-G ratio (0.74) and vibrational amplitude. These results reveal that the HTP effectively influences the porous structure and surface chemistry characteristics of the ACs by manipulating substrate structure of the ACs precursor. The characterization of the porous structure and surface chemistry illustrate that the activated carbon produced via HTP at 170 degrees C for 1 h exhibited high specific surface area (1456.69 m(2) g(-1)) along with large percentage of mesopores pore volume (93%), which then result in high specific capacitance of 185 Fg(-1) and long-term cycling performance. This study prove that the EUO derived ACs are promising materials for supercapacitor application and can expand EUO wood for feasible application in supercapacitors.