磺化石墨烯/活性炭复合电极的制备及其不对称电容器脱盐

doi:10.7503/cjcu20131177

摘要/Abstract

摘要：

在还原剂NaBH₄存在下, 采用对氨基苯磺酸重氮盐与氧化石墨(GO)表面共价键合制备磺化石墨烯(GP-SO₃H). 傅里叶变换红外光谱(FTIR)证明磺酸基团在石墨烯表面接枝. 采用扫描电子显微镜(SEM)研究了磺化石墨烯的表面形貌. 以磺化石墨烯为添加剂, 制备了磺化石墨烯/活性炭(GP-SO₃H/AC)复合电极. 循环伏安及阻抗分析结果表明, 该复合电极的电容特性及导电性有明显改善. 以活性炭电极为对电极组装了不对称电容器(GP-SO₃H/AC|AC), 研究了该不对称电容器的电化学脱盐性能. 与对称电容器(AC|AC)相比, 不对称电容器中由于电极内磺酸基团对反离子的屏蔽作用, 电容器的电流效率达到89.4%以上, 脱盐量提高2.4倍, 单个循环脱盐量达到10.87 mg/g.

关键词: 氧化石墨烯, 磺化石墨烯, 活性炭, 电容法脱盐

Abstract:

Sulfonated graphene(GP-SO₃H) was prepared by grafting reaction of sulfonated diazoniun salt. The sulfonated graphene was characterized by Fourier transform infrared spectrometry(FTIR) and scanning electron microscopy(SEM), respectively. The experimental results indicate that the sulfonic groups have been grafted onto graphene oxide. The sulfonated graphene/activated carbon composite electrode(GP-SO₃H/AC) was prepared by mixing 10%(mass fraction) GP-SO₃H as dopant. Compared with AC electrode, this composite electrode exhibits an ideal double layer capacitive behavior and high conductivity, confirmed by cyclic voltammetry and electrochemical impedance spectroscopy. The hybrid capacitor was assembled by the resultant GP-SO₃H/AC as negative electrode and AC as counter electrode for capacitor deionization(CDI). Under the constant current charging-discharging condition, the salt removal amount of 10.87 mg/g in single cycle was obtained, about 2.4 times that of the normal AC capacitor. And the current efficiency was improved dramatically owing to the facile adsorption of sulfonic groups to cations, and the shielding effect of sulfonic groups on the counter-ions. The asymmetric capacitor is expected to be used for actual application in brackish water desalination.

Key words: Graphene oxide, Sulfonation graphene, Activated carbon, Capacitive deionization

中图分类号:

O646

TrendMD:

卢淼, 刘建允, 王世平, 程健. 磺化石墨烯/活性炭复合电极的制备及其不对称电容器脱盐. 高等学校化学学报, 2014, 35(7): 1546.

LU Miao, LIU Jianyun, WANG Shiping, CHENG Jian. Preparation of Sulfonated Graphene/Activated Carbon Composite Electrode for Asymmetric Capacitive Deionization^†. Chem. J. Chinese Universities, 2014, 35(7): 1546.

图/表 11

Fig.1 SEM images of G(A) and GP-SO3H(B)

Fig.2 XRD patterns of G(a), GO(b), GP(c) and P-SO3H(d)

Fig.3 Raman spectra of GP(a) and P-SO3H(b)

Fig.4 FTIR spectra of GO(a) and GP-SO3H(b)

Fig.5 SEM images of GP-SO3H/AC(A) and AC(B) electrodes

Fig.6 CVs of the GP-SO3H/AC(a), GP/AC(b) and C(c) electrodes in 1 mol/L NaCl solution Scan rate: 2 mV/s.

Fig.7 EIS of the GP-SO3H/AC(a), GP/AC(b) and C(c) electrodes in 1 mol/L NaCl solution

Fig.8 Conductivity change with time during charge-discharge process of the GP-SO3H/AC|AC(a), GP/AC|AC(b) and AC|AC(c), respectively

Fig.9 Effect of the doping amount of GP-SO3H on salt removal AC corresponds to the AC|AC cell. Doping amount of GP-SO3H, w(%): a. 5; b. 10; c. 5.

Fig.10 Current efficiency of the GP-SO3H/AC|AC(a), GP /AC|AC(b) and AC|AC(c) capacitors at different current density

Fig.11 Changes of conductivity(a) and voltage(b) of GP-SO3H/AC|AC during charge-discharge cycling

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