功能化石墨烯/活性炭复合电极及不对称电容器脱盐

以3-氨丙基三乙氧基硅烷(AMPTS)修饰氧化石墨(GO)还原合成氨基功能化石墨烯(GP-NH₂). 傅里叶变换红外(FTIR)光谱和X射线能谱(EDX)分析证明了氨基基团的成功接枝. 以GP-NH₂为添加剂, 制备胺化石墨烯/活性炭(GP-NH₂/AC)复合电极, 并以GP-NH₂/AC 为正极, AC电极为对电极, 组装不对称电容器(AC||GPNH₂/AC)用于电容脱盐. 实验表明, AC||GP-NH₂/AC 单循环脱盐量为7.63 mg·g^-1, 电流效率达77.6%. 利用磺酸重氮盐接枝石墨烯制备磺化石墨烯(GP-SO₃H)及磺化石墨烯/活性炭(GP-SO₃H/AC)复合电极. 并以GPSO₃H/AC为负极, GP-NH₂/AC 为正极, 组装不对称电容器(GP-SO₃H /AC||GP-NH₂/AC)用于电容脱盐, 其平均脱盐速率可达0.99 mg·g^-1·min^-1, 比纯AC电极提高了接近5倍. 充放电速率提高了30%; 而且由于正、负极表面固有电荷的存在, 大大降低了反离子效应, 电流效率由40% (纯AC||AC对称电容器)提高到92.8%. 表明电极内功能化导电石墨烯的存在既提高了导电性, 又兼具离子选择性的作用, 从而明显改善电极的脱盐性能.

Functionalized Graphene/Activated Carbon Composite Electrodes for Asymmetric Capacitive Deionization

Aminated graphene (GP-NH₂) was fabricated via the modification of graphite oxide (GO) with 3-aminopropyltriethoxysilane (AMPTS), and the covalent grafting of the amine functional groups was confirmed using Fourier transform infrared (FTIR) spectroscopy and energy-dispersive X-ray (EDX) spectroscopy. The aminated graphene (GP-NH₂)/activated carbon (AC) composite electrode (GP-NH₂/AC) was prepared, using the GP-NH₂ as an additive. An AC||GP-NH₂/AC asymmetric capacitor for capacitor deionization was then assembled using the GP-NH₂/AC electrode as the positive electrode and AC as the negative electrode. A salt removal of 7.63 mg·g^-1 was achieved using the AC||GP-NH₂/AC capacitor, and current efficiency was increased to 77.6%. AGP-SO₃H/AC electrode was then prepared by mixing AC with sulfonated GP. With GP-NH₂/AC as the positive electrode, and GP-SO₃H/AC as the negative electrode, a GP-SO₃H/AC||GP-NH₂/AC asymmetric capacitor was assembled for capacitive deionization. An average desalting rate of 0.99 mg·g^-1·min^-1 was achieved, almost five times higher than that achieved using an AC||AC symmetric capacitor. The chargedischarge rate showed a 30% increase. The existence of the intrinsic charge on the electrode surface greatly inhibited the migration of counter ions, so that the current efficiency was significantly enhanced (to 92.8%) in comparison with the value achieved using an AC||AC capacitor (40%). These results demonstrated that the functionalized graphene in the AC electrode not only enhanced the conductivity, but also controlled the selective adsorption of ions, thereby significantly improving the deionization performance.